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PGJ/F-012(82)
National Uranium Resource Evaluation
AZTEC QUADRANGLE
NEW MEXICO AND COLORADO
U.S. Geological Survey
Golden, Colorado
Issue Date
September 1982
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY
Assistant Secretary for Nuclear Energy
Grand Junction Area Office, Colorado
Neither the United States Government nor any agency thereof, nor any of their employees,
makes any warranty, express or implied, or assumes any legal liability or responsibility for
the accuracy, completeness, or usefulness of any information, apparatus, product, or
process disclosed in this report, or represents that its use would not infringe privately
owned rights. Reference therein to any specific commercial product, process, or service by
trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or
imply its endorsement, recommendation, or favoring by the United States Government or
any agency thereof. The views and opinions of authors expressed herein do not necessarily
state or reflect those of the United States Government or any agency thereof.
This report is a result of work performed by the U.S. Geological Survey, through an
interagency agreement with the U.S. Department of Energy, as part of the National Uranium
Resource Evaluation. NURE was a program of the U.S. Department of Energy's Grand
Junction, Colorado, Office to acquire and compile geologic and other information with
which to assess the magnitude and distribution of uranium resources and to determine areas
favorable for the occurrence of uranium in the United States.
Available from: Technical Library
Bendix Field Engineering Corporation
P.O. Box 1569
Grand Junction, CO 81502-1569
Telephone: (303) 242-8621, Ext. 278
Price per Microfiche Copy: $8.00
PGJ/F-012(82)
NATIONAL
RESOURCE EVALUATION
AZTEC QUADRANGLE
NEW MEXICO AND COLORADO
URJU~IUM
Morris W. Green, Principal Investigator
Virginia P. Byers
Steven M. Condon
A. Curtis Huffman, Jr.
Russell F. Dubiel
Allan R. Kirk
Robert D. Lupe
Charles T. Pierson
Jennie 1. Ridgley
Jacques F. Robert son
Keith Robinson
Pamela G. L. Sikkink
J:.Iark R. Stanton
Robert E. Thaden
Robert S. Zech
September 1982
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY
GRAND JUNCTION AREA OFFICE
UNDER CONTRACT NO. DE-All3-78GJ01686
This report has not been edited for conformance
with U.S. Geological Survey stratigraphic
nomenclature or resource classification.
This is the final version of the subject-quadrangle
evaluation report to be placed on open file. This report
has not been edited. In some instances, reductions in the
size of favorable areas on Plate 1 are not reflected in
the text.
ii
CONTENTS
Abstract • • •
1
Introduction •
1
Purpose and scope (by M. W. Green).
1
Acknowledgments •
2
Procedures (by P.G.L. Sikkink, M. W. Green, and
Keith Robinson) • • • • • • • • • • • • •
2
Geologic setting. (by J. L. Ridgley, M. W. Green, and
P.G.L. Sikkink) • • • • •
• ••••••••
4
...........
Paleozoic age .
.... ...........
Mesozoic age. . •
.... ..........
Cenozoic age.
....
Quaternary age. .
....
Rocks of Precambrian age
Rocks of
Rocks of
Rocks of
Rocks of
.
6
10
10
12
13
Definition of favorability and criteria used for evaluation ••
13
Environments favorable for uranium deposits.
15
Area favorable for uranium deposits in the Burro Canyon(?)
Formation (by J. L. Ridgley) • • • • • . . • • • . • • • • •
15
Stratigraphy and environments of deposition.
16
Uranium mineralization and host rock characteristics •
18
Favorable area •
20
Summary. • • •
21
Area favorable for uranium deposits in the Ojo Alamo
Sandstone (by J. L. Ridgley) • • • • • • • • • • • •
21
Stratigraphy and environments of deposition.
22
Uranium mineralization and host rock characteristics .
23
Favorable area •
24
Summary. • • • •
25
iii
CONTENTS (Continued)
Area favorable for uranium deposits in the Morrison
Formation (by M. W. Green). •
• • • • •
25
Stratigraphy, structure, and lithology •
25
Environments of deposition •
27
Uranium mineralization and area favorable ••
28
Summary. • • •
30
Environments unfavorable for uranium deposits.
31
Precambrian igneous rocks (by P.G.L. Sikkink)
31
Pennsylvanian formations (by J. L. Ridgley) •
31
Permian formations (by J. L. Ridgley)
32
32
Cutler Formation • •
Triassic formations (by R. E. Thaden) •
35
Jurassic formations (by M. W. Green).
36
Cretaceous formations (by R. S. Zech) •
37
Dakota Sands tone (by M. i>l. Green). •
Tertiary formations (by V. P. Byers and P.G.L. Sikkink)
39
40
Nacimiento Formation (by J. L. Ridgley) ••
41
San Jose Formation (by J. L. Ridgley) • • •
42
Quaternary volcanic rocks (by P.G.L. Sikkink) ••
45
Unevaluated environments (by M. W. Green) • • • • .
45
Aerial radiometric data (by P.G.L. Sikkink) ••
45
Interpretation of hydrogeochemical and stream sediment
reconnaissance data (by Keith Robinson, R. F. Dubiel,
M. R. Stanton, and P.G.L. Sikkink) • • • • • • • • • •
46
Interpretation of U.S. Geological Survey streamsediment and
data • • •
Geochemistry of stream sediments •
iv
51
52
CONTENTS (Continued)
Geochemistry of ground and surface waters.
55
Interpretation of results ••
57
Geochemical data (by M. W. Green) ••
59
Recommendations to ·improve evaluations (by M. W. Green
and J. L. Ridgley) . • • . • • • •
• ••••
59
Selected bibliography (compiled by J. F. Robertson and others) ••
61
Appendix
A.
Uranium occurrence table of the Aztec Quadrangle
(compiled by A. C. Huffman, Jr., A. R. Kirk,
W. Aubrey, and P.G.L. Sikkink) •
• In pocket
Appendix Bl.
Table of chemical analysis • .
Appendix B2.
USGS field data and chemical analysis of streamsediment samples (compiled by Keith Robinson,
J. J. Irwin, and Deborah Archelger). • •
• • • • In pocket
Appendix B3.
USGS field data and chemical analysis of water
samples (compiled by Keith Robinson, J. J. Irwin,
and Debora Archelger). • • • • • • • . • • •
Appendix B4.
• • In pocket
• • In pocket
USGS statistical summary of geochemical data from
stream-sediment, ground- and surface-water samples
(compiled by Keith Robinson and C. Adkisson) •
• In pocket
. In pocket
Appendix
C.
Uranium-occurrence reports
Appendix
D.
Partial list of test wells which penetrate the
Morrison Formation (compiled by P.G.L. Sikkink) . • • • In pocket
Appendix
E.
Partial list of measured stratigraphic sections
(compiled by S. M. Condon) • • • • . • • • • • • • • • In pocket
ILLUSTRATIONS
Figure
1.
Location of Aztec Quadrangle • • • • • •
5
2.
Generalized stratigraphic column (upper part) of the
Aztec l 0 x 2° Quadrangle • . . • • • . •
7
Generalized stratigraphic column (middle part) of
the Aztec 1° x 2° Quadrangle • • • • • . • • • • •
8
2a.
v
ILLUSTRATIONS (Continued)
2b.
3.
Table
1.
la.
2.
3.
Plate
Generalized stratigraphic column (lower part) of
the Aztec 1° x 2 ° Quadrangle. • • • • •
• • • •
9
Index map of the San Juan Basin, Grants mineral belt,
the Aztec l 0 x 2° Quadrangle, and adjacent areas
29
Summary of HSSR data (sediment samples)
47
Summary of HSSR data (water samples) • • •
49
Summary of element concentrations in less-than 170 mesh
(88-micron) stream sediment samples collected from
outcrop areas of Tertiary sedimentary units,
Aztec Quadrangle • • • • • • • • • • • • •
53
Summary of chemical analyses and physical
parameters in ground- and surface-water samples,
Aztec Quadrangle. • • • • • • • • • • • • • • • • • • • • •
56
1.
Areas favorable for uranium deposits in the Burro Canyon
Formation, Ojo Alamo Sandstone, and the Brushy Basin and
Westwater Canyon Members of the Morrison Formation
2.
Uranium occurrence map
3.
Interpretative map of aerial radiometric uranium anomalies
4.
Summary of anomalous sediment and water samples, hydrogeochemical
and stream-sediment reconnaissance
4a.
Uranium/conductivity in water samples
4b.
Distribution and concentration of uranium (ppm) in streamsediment samples
4c.
Distribution and concentration of uranium (ppb) in ground- and
surface-water samples
4d.
Distribution and concentration of uranium (ppb) x 1000/
conductivity in ground- and surface-water samples
4e.
Interpretive map of USGS hydrogeochemical and stream-sediment
data
5.
Sa.
Rock sample locality map
Location map of oil and gas test wells and measured stratigraphic
sections including the Morrison Formation
vi
ILLUSTIL~TIONS
(Continued)
5b.
Location of stream-sediment samples (partial)
5c.
Location of stream-sediment samples (partial)
5d.
Location map of Ground- and Surface- water samples
6.
Drainage map
7.
NONE
8.
North-south stratigraphic sections in the San Juan Basin area
8a.
9.
10.
East-west stratigraphic sections in the San Juan Basin area
Index map to location of stratigraphic sections in the Aztec and
some adjoining NURE quadrangles
Preliminary geologic map of the Aztec 1° x 2° Quadrangle,
northwestern New Mexico *
lOa.
Major structural and tectonic features
lOb.
Schematic distribution of Precambrian rocks in northwestern New
Mexico, northeastern Arizona, southwestern Colorado, and
southeastern Utah
lOc.
Schematic distribution of Tertiary igneous rocks in northwestern
New Mexico, northeastern Arizona, southwestern Colorado, and
southeastern Utah
11.
Geologic-map index
12.
Generalized land status map
13.
Culture map
Plates in accompanying packet
*
This map is available as U.S. Geological Survey Open-File Report 78-466
and may be obtained from the Open-File Services Section, Branch of
Distribution, U.S. Geological Survey, Box 25425 Federal Center, Denver,
co 80225.
vii
ABSTRACT
Areas and formations within the Aztec 1°x2° Quadrangle, New Mexico and
Colorado considered favorable for uranium endowment of specified minimum grade
and tonnage include, in decreasing order of favorability:
(1) the Early
Cretaceous Burro Canyon(?) Formation in the southeastern part of the Chama
Basin; (2) the Tertiary Ojo Alamo Sandstone in the east-central part of the
San Juan Basin; and (3) the Jurassic Westwater Canyon and Brushy Basin Members
of the Morrison Formation in the southwestern part of the quadrangle.
Favorability of the Burro Canyon(?) is based on the presence of favorable
host-rock facies, carbonaceous material and pyrite to act as a reductant for
uranium, and the presence of mineralized ground in the subsurface of the Chama
Basin. The Ojo Alamo Sandstone is considered favorable because of favorable
host-rock facies, the presence of carbonaceous material and pyrite to act as a
reductant for uranium, and the presence of a relatively large subsurface area
in which low-grade mineralization has been encountered in exploration
activity. The Morrison Formation, located within the San Juan Basin adjacent
to the northern edge of the Grants ~ineral belt, is considered favorable
because of mineralization in several drill holes at depths near 1500 m (5000
ft) and because of favorable facies relationships extending into the Aztec
Quadrangle from the Grants mineral belt which lies in the adjacent Albuquerque
and Gallup _Quadrangles.
Formations considered unfavorable for uranium deposits of specified
tonnage and grade include the remainder of sedimentary and igneous formations
ranging from Precambrian to Quaternary in age. Included under the unfavorable
category are the Cutler Formation of Permian age, and Dakota Sandstone of Late
Cretaceous age, and the Nacimiento and San Jose Formations of Tertiary age.
The Nacimiento and San Jose Formations contain isolated uranium occurrences
and locally favorable facies characteristics, but no evidence of specified
minimum grade and tonnage is present to indicate a favorable classification
for these formations. Other formations, particularly those which were
deposited in marine and arid eolian depositional environments, do not show
favorable facies, radioactiviby, or geochemical characteristics.
INTRODUCTION
PURPOSE AND SCOPE
The purpose of the National Uranium Resource Evaluation (NURE) program of
the u.s. Department of Energy (DOE) is to identify and delineate areas and
environments within the Aztec 1°X2° Quadrangle, New Mexico and Colorado, that
exhibit characteristics favorable for the occurrence of uranium deposits that
have the potential to contain at least 100 metric tons U303 total endowment
with a minimum grade of 100 ppm (0.01 percent) u3o8 • Evaluation is based on
geochemical, mineralogic, hydrologic, aerial radiometric, sedimentologic, and
general geologic characteristics of the formations in the quadrangle.
1
Formations of both volcanic and sedimentary or~g~n have been evaluated by
surface investigations and subsurface data analysis to a depth of 1500 m (5000
ft). The evaluation involved a comprehensive review and synthesis of the
geologic literature, knowledge of on-going research, fieldwork, and the work
of several geologists with uranium-related experience and knowledge of the
rocks in the quadrangle.
The NURE program was conducted from January, 1978, to March, 1980, by
geologists and support personnel of the USGS (USGS). This study was managed
by the Grand Junction Office of the DOE, and quadrangle evaluation has
involved approximately 4.5 man-years of literature search, fieldwork,
laboratory work, data evaluation and final report writing by USGS personnel.
ACKNOWLEDGMENTS
Evaluation of the Aztec Quadrangle has required the support of many other
professional and technical personnel in the USGS. Compilation of the landstatus map was coordinated by Phil Mudgett, computer support was made
available by Cheryl Adkisson and Ron Wahl, and tables and cross sections were
compiled, in part, by D. P. Bauer and W.M. Aubrey, all of the USGS. We also
gratefully acknowledge the clerical support within the USGS provided by M. L.
Frisken and staff, and the drafting support provided by Mary Durrett. We owe
special thanks to Glenn R. Scott, Kim Manley, and Reinhard Wobus of the USGS
for providing the geoloic map (Pl. 10) of the Aztec Quadrangle. Rock, water,
and sediment samples were analyzed by personnel of the USGS analytical
laboratories in both Menlo Park, California, and Denver, Colorado. Discussion
of geology and resource assessment with Fritz Loomis of Bendix Field
Engineering Corporation (BFEC) and H. K. Holen of the Albuquerque office of
the DOE have also contributed significantly to the evaluation of the Aztec
Quadrangle.
We gratefully acknowledge the release of data on mineralization in the
Ojo Alamo Sandstone by the Triple S Development Company. Permission granted
by the Tennessee Valley Authority {TVA) for USGS geologists to examine logs of
uranium mineralization in the Burro Canyon is also acknowledged. (M. w. G.)
PROCEDURES
In the Aztec Quadrangle, a representative number of the uranium
occurrences listed in Appendix A and shown on Plate 2 were visited, except
where access was either prohibited by terrain or denied by landowner. It was
impossible to fielu check all occurrences due to the time constraints of the
NURE program. The locations of these uranium occurrences were determined from
Preliminary Reconnaissance Reports of the u.s. Atomic Energy Commission and
from published literature.
Of the occurrences visited, only those considered significant were
described using the uranium occurrence reports supplied by BFEC. An
2
"anomalous occurrence" was arbitrarily defined as one containing a minimum of
two times the background radioactivity at each location. Information on
general geology, lithology, mineralogy, structure, m~n~ng activity, and
radiometric values was recorded at each occurrence on the uranium occurrence
forms (App. C).
Rock samples were also collected at most of the anomalous areas (Pl.
5). All rock samples were grab samples from the mineralized zone and not
systematically collected from the geologic unit(s) at each occurrence. The
rock samples were analyzed at USGS laboratories in Menlo Park, California, and
Denver, Colorado. Samples were analyzed by delayed-neutron activation for
uranium and thorium content; and by semiquantitative emission spectrometry for
45 other elements. Results of these analyses are shown in Appendix B1.
Raw data for the Aztec Quadrangle from the National Hydrogeochemical
Stream and Sediment Reconnaissance (HSSR) program conducted by Los Alamos
Scientific Laboratories (Bolivar, 1978) were analyzed by USGS personnel to
determine areas anomalous in uranium concentration. The interpretation of the
HSSR data involved: (1) dividing the quadrangle into areas by distinct
drainage systems; (2) dividing the drainage areas on the basis of geologic
units of similar age~ the presence of igneous and metamorphic rocks; and (3)
performing a statistical analysis on the raw data for each of these areas.
For each area sho\vn in Plate 4, the uranium concentration of both water and
stream-sediment samples was analyzed for mean, standard deviation, and
variance. Extremely high uranium concentrations were normally left out of the
statistical calculations but are plotted on the interpretation map (Pl. 4).
Anomalous values are defined as values greater than two standard deviations
above the mean. Results of the statistical analysis on these areas and
samples are shown in Tables 1 and 1A. Raw data from water samples were also
standardized using the uranium-to-conductivity ratio rather than the uranium
concentration. Results of these calculations are plotted in Plate 4A. A
total of 338 water and 1744 stream-sediment samples were analyzed according to
the previously mentioned procedures.
A total of 1003 stream-sediment and 186 water samples were collected in
the Aztec Quadrangle by USGS personnel under a program directed by Keith
Robinson in a followup study to the National HSSR program. Sampling was
confined to selected areas of Paleocene and Eocene sediments in the western
half of the quadrangle and to a small area of Miocene and Pliocene sediments
in the southeast corner of the quadrangle. The USGS followup HSSR program in
terrain underlain by Tertiary rock units within the quadrangle was designed to
enhance information on resource potential and add information concerning the
potential of Tertiary volcanic rocks as a possible source of uranium contained
in adjacent sedimentary sequences. Sample sites were located to afford
optimum density coverage, access, and integrity of the resultant geochemical
data. Replicate or duplicate stream-sediment and water samples were collected
at several localities in order to test the variance of analytical results and
sampling error. The sediments were obtained from both dry and actively
flowing stream beds. Approximately 10 pounds (4.5 kg) of sediment was
collected at each site. The samples are composites of material collected at
3
several points along the active drainage channel.
All the stream-sediment samples were oven dried at a temperature of less
than 100°F and sieved to obtain a less-than-170-mesh (88 micron) fraction.
The less-than-170-mesh fraction was then routinely analyzed, without further
preparation, for 34 elements, based on a 6-step, DC-arc, semiquantitative
emission spectrographic method. Uranium was determined by a modified
extraction fluorimetry method, described by the American Society of Testing
Materials (ASTM), in the Annual Book of ASTM Standards (1975). A weighed
subsample of the fine fraction was also ignited at 550°C for 10 minutes and
the loss of weight, in percent, reported.
The water samples were collected from wells, springs, streams, and
ponds. At each site three unique water samples were obtained. A 1000-mL
sample was collected, filtered through a 0.45-mm membrane filter into an acid
rinsed polyethylene bottle and then acidified with an ultrex-grade
concentrated nitric acid to a pH of <2. This sample was analyzed for uranium
by an extraction fluorimetry method. An untreated and unfiltered 250-mL water
sample was obtained for analysis of the degree of alkalinity and a 125-mL
filtered but untreated sample was collected for sulfate, phosphate, and
nitrate analysis. The latter sample was kept at a near-freezing temperature
at all times. In addition, at each site, water temperature, specific
conductance, pH, and dissolved oxygen were also measured using untreated
water.
Subsurface analysis of Jurassic through Cretaceous rocks included a
systematic study by R. D. Lupe, D. P. Bauer, and others of more than 300 oil
and gas well logs located throughout the San Juan Basin area. Using virtually
all usable well logs of holes that penetrate the entire Jurassic section (App.
D), outcrop stratigraphy was projected into the subsurface, gamma-ray
anomalies were located and noted, and some knowledge of the distribution of
potential uranium host rocks in the subsurface was gained. Surface control
was maintained using measured sections from outcrops in the area (Pl. SA and
App. E). The location of selected borehole logs used in the final analysis
and the cross-section diagrams are shown in Plates 8 and 8A, and indexed in
Plate 9. (P. G. L. S., M. W. G., and K. R.)
GEOLOGIC SETTING
The Aztec Quadrangle is located between latitude 36° N and 37° N and
longitude 106° Wand 108° W (Fig. 1). The western two-thirds of the Aztec
Quadrangle includes the San Juan Basin and the Chama Basin of the southeastern
part of the Colorado Plateau physiographic province. The Colorado Plateau
portion of the quadrangle is underlain by generally flat-lying sedimentary
rocks of continental and marine origin which range in age from Paleozoic
through Cenozoic, and by Precambrian rocks of intrusive and metasedimentary
origin. The sedimentary rocks reach a maximum total thickness in the San Juan
Basin of approximately 3600 m (11,880 ft) and are intruded locally by volcanic
rocks of Tertiary and Late Cretaceous age. As is characteristic of other
4
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OKLAHOMA
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Location of the Aztec Quadrangle
5
-
-
parts of the Colorado Plateau, folding and faulting of the sedimentary
sequence in the Aztec Quadrangle is subtle and restricted to the marginal
areas of broad uplifts such as the Nacimiento Uplift, the Brazos Uplift, and
the Archuleta Anticlinorium (Pl. lOA). The dip of formations along these
uplifts may be moderate to steep; however, the dip of formations in the Chama
and San Juan Basins, in areas away from these marginal uplifts, is generally
low (1° to 5°).
The eastern one-third of the Aztec Quadrangle is located within the
southern part of the Rocky Mountain physiographic province. It is
characterized by generally north-south-trending anticlinal structures
separated from each other by intermontane down-folded and down-faulted
basins. The basins are floored by Tertiary sedimentary and volcanic rocks
several hundred meters thick. Erosion of anticlinal mountains has exposed
cores of Precambrian granite and metamorphic rocks in the northern part of the
Nacimiento and Tusas Mountains.
A preliminary geologic map of the Aztec Quadrangle was compiled by Kim
Manley and others in 1978 (Pl. 10) using smaller geologic maps indexed in
Plate 11 and doing extensive fieldwork. The present stratigraphic
nomenclature and generalized lithologic descriptions of the area are
summarized in Figures 2 through 2b. Major structural and tectonic elements
are compiled on Plate lOA. Plate lOA includes the important faults,
anticlines, synclines, and monoclines within each major tectonic division of
this quadrangle.
Rocks of Precambrian Age
In the northern part of the Nacimiento Mountains Woodard and others
(1977) have recognized 14 Precambrian rock units of metasedimentary,
metavolcanic, and plutonic igneous origin. The metasedimentary rocks include
meta-quartz wacke, meta-arkose, metaquartzite, metagraywacke, and silty
argillite. The metavolcanic rocks consist predominantly of metaquartz
latite. The rocks were derived by regional metamorphism of siliceous
volcanics and were later locally metasomatized near the contacts with a
tonalite intrusion (Woodard and others, 1977). Amphibolite derived from basic
igneous rocks also is locally present. The plutonic igneous rocks include
ultramafic rocks, gabbro, diorite, tonalite, leucogranodiorite, quartz
monzonite, muscovite-biotite granite, biotite granite, leucogranite, and mafic
dikes.
In the Tusas Mountains, Bingler (1974) noted the occurrence of quartzite,
quartz-muscovite-biotite schist, hornblende-chlorite schist, leptite, granitic
gneiss, quartz diorite gneiss, and granite porphyry. Bingler (1965)
summarized the major Precambrian events in this area. Plate lOB shows the
distribution of Precambrian rocks in the Aztec and adjacent quadrangles.
6
Santa Fe Group
' ~ ~!
: !l.ll
!~ 0::
f-'
-------------:-"":"-':~-:-':"'--ln_t_r_u_si_v_e_ro_c_k_•_ _ __,i,_,·"":..:.·,...:_,·_:,·_:,_·_
·. "'1-
1 I
1
:
V··:.· .... ~
f-j _ _ _ _
Los Piiios Formation 2
l~ril ------------------~~:_-:~:~.~-:~·>7>~>~'1
Abiquiu Tuff 3
.
I
~ A A A A
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k yAy AyAy A y;;
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4
Tr~::asure Mountain Tuff"
Conejos Formation
~·-~
·:.:
~···
:·
R itit.O Conglomerates
...
'..
'
...
..
.' • •• •, ~ • • • • I
El R:to Format10n
~
"u0
uJ
San Josfi Formation •
.:Favorable for uran1um deoos1ts based primar·!y on tne presence of uranium occurrences.
Uran1um Deoostts
· Sources: Manley, Kim, and Scott. GR .. 1978, Barker, F, 1958; and Smnh, H.T., 1938.
7 Rests disconformably on Treasure Mountam Tuff m north. Further soutr the basal contact ts graoattonal or
intenonguing With the Rmto Conglomerate.
l Of Smi.th (19381; overlies E! Rno Formation unconformably. Uoper part orobably equivalent to upper part of
Los Pu1os Formanon. Present m east-centra~ oart of the mao.
4
D1sConformabiy overl1es R:tno Cong1cmerate or ConeJOS Format1on.
'Of Barker (1958); oresent onlv 10 eastern part of map. Rests disconformably on El Rita Formation; locally
contact between the two is gradational.
5
1
Present from Colorado-New Mexico border north of Chamas southward to Chaves Creek near Brazos.
Of Smith (1938); present only in eastern parts of map. Rests unconformably on rocks of Precambrian to
Early Cretaceous age .
......_....-unconformity
Figure 2.
Generalized stratigraphic column (upper part) of the Aztec
10 x 2° Quadrangle (compiled by P. G. L. Sikkink)
7
....w
"'a:w
"'>- w
"' "'
)o
a:
<(
t=
a:
w
1-
STRATIGRAPHIC UNIT
GENERALIZED ROCK DESCRIPTION'
Nacimiento Formation
"c:
~
~
Ojo Alamo Sandstone • • 6
i
Animas Formation
Picture Cliffs Sandstone
19
Lewts Shale
La Ventana
"'
0
Tongue
20
:J
22. SdtHL.-'>tone, tan and brown; some ,;r...1y .:;h:J.le; tl5-
u.J
u
21
....<
u.J
a:
u
13. Shale, gray co olive gray, and minor interbedded
sandstone; as much as 1900 ft
14. Sandstone, brown, crossbedded; conglomerate near
base; contains minor lenses of gray shale; abundant
petrified wood; 50-200 ft
15. Conglomerate, sandstone, and shale, greenish gray
and tan, andesitic; unconformably overlies
I
Fruitland Fonnation or Lewis shale in north-central
part of mapped area; grades southward into the
1
::laci;nic:nto Fm.; lJ00-3300.±. fc
16. Shale, greenish gray with int~rb~dded yellowishbrown, crossbedded sandstone: 0-lUOU! it
17. Dark shale and yellowish-brown crossbedded ~and­
stone; coal; 50-150! ft
18. Sandstone, yellowish gray to grayish orange;
interbedded with brown sandstone and gray shale;
0-250+ ft
19. Sandy-shale, olive gray (upper part); shaly sandstone, gradational (lower part); 300-2100:!: ft
20. Sandstone, tan, fin~-to medium-grain~d, ~ith some
interbedded thin gray shale; 50-lJSOj: ft
21. Sandstone, tan and brown; gray and bra·~ shale
and coal; layers of large ironstone and limestone
concretions; 350-2300:!: ft
Po1nt lookout
Sanastone
22
215 f t
23. Shdlt:, gr:1y and dark olive gr:.:1/, ...:~l'i_,:,lr~u~ . ..; 1n,j
sandy shale; some limestone cor.t.:r':'.'tLvns in up;_Jt->r
pdrt
24. Sl1ala, hard to soft, calcareou~; ~ome llilrd ~r3y
li:ne~tone oeds
25. Shale, dark, r..;ith he~s of platy, _;;and'! li!!1t-'...,tOne
and septarian
concr~tions
26.
Li::::12~conc,
27
calcar2ous ~ilAL0
3halt:, gray ~~J jlack, evenly
Mancos unit; ljQrJ-2550± ft
lL~ht
-sr..:1y,
jensa, .Jnd ·i.-trk:er gr3.y
2S. Sandstone, gr2y to 3rayish
massive to
29.
cros~b~dded,
;
oran~0,
locally
~!lCire
~ell
cem~nted,
con~Lomeratic;
dark-gray carbonaceous shale and coal; 70-250:!: ft
Sand~tone and conglomeratic sandstone, ~hite to
buff
JO.
~r~eni~h ~ray and orange, int2rheJded
with olive-tan to rusty-tan, fine- to ~o~r52~udsc0ne,
~rain2d
u
v;
"'a:
<(
..,
:J
~Jnd~:o~e
and cLl::st·)r>,•..!, interbe,J:..!-_·:i, l:;:-:c to
dark reddish-~rc~n. very fine-to fin~-~rqin~d;
toc1l ~or!':"i~vn '!Dit .:lbout 900 ft
32. Limes tone, gray, :ned itim-gralned; lvc:.1lly ,5r.1des
upward into very pure gypsum; some platy shale;
11.
S:ln~._L;tone
0-lOO ft
33. Sandstone, white and reddish
medium-~rain~d, well sorted,
100-350:!: ft
oran~e,
massiv~,
fine-to
cro~~b~dd~d;
•Favorable for uranium deposits based pnmarily on the presence of uranium occurrences.
••uranium deposits
-....rtJnconformity
1
Source>: Manley, Kim, and Scott, G.R .. 1978; Barker, F., 1958; and Smith, H.T., 1938.
• Unconformity between Ojo Alamo Formation and Kirtland Shale. Also unconformable on lower part of
Animas Formation in the northwestern part of map area.
1
Upper conglomeratic sequence is possibly equivalent to Burro Canyon (7) Formation of Early Crf!taceous aqe.
Figure 2a.
Generalized stratigraphic column (middle part) of the Aztec
1° x 2° Quadrangle (compiled by P. G. L. Sikkink)
8
~
ii:
ai
1-
:~
STRATIGRAPHIC UNIT
w
LITHOLOGY'
GENERALIZED ROCK DESCRIPTION
I~~~:=~----~~~~----------------------------------------------------~
' ·
' Uppershale f-=--::::::.-_-_-_-=:;34 34. Shale, red, green, and maroon, interbedded with
1
u
il "';:;:;
!J.
Chinle
Formation••
5
1 ~
1-
member
r~:::=-::::j___
Poleo Sandstone r-,·· . ,-;:-:;::J Lentil•
~_:-=i 3 )
Salitral Shale ;-_-..=-_-_-:_-: ,
Member
f=-:::=-:::=-:;:-.::::-::::: 3 0
Aqua Zarca Sand-L..
1 ~
31
stone Member
1
!
~~ ~~
d:
z! ~
w ::;
;;
1~
0
~II ~
I
I
1
•
Cutler Formation
z
•
•
;,&:
1
38
=~~~
~~~·
I~
Z<:
I~> i
~~
F~/k
Madera Formation
!~·.,
' ''
· .~•
''
=-----------=;
39
lenticular sandstone and siltstone; 500-650± ft
35. Sandstone, micaceous, conglomeratic, fine-to
coarse-grained; some subordinate green and maroon
shale; as much as 17 5 f t
36. Shale, maroon and minor green; 0-115 ft
37. Sandstone and conglomerate, white to buff, fineto coarse-grained, quartzose; 0-132 ft
38 • Sandstone and siltstone, crossbedded, arkosic;
also purple-orange mudstone; 1650+ ft
39. Limestone, light gray, fossiliferO"us; also gray to
buff orthoquartzite, pink arkose, minor reddish
and light gray shale, and arkosic limestone.
~~:::~ ''· illil:~;~i;l;::;~;;;;i;:;~;iiii;;;;;::iii;;i:,::,
south-central areas; thickness varies
*Favorable for uranium deposits based primarily on the presence of uranium occurrences.
••uranium Deposits.
~Unconformity
' Sources: Manley, Kim, and Scott, G.R., 1978; Barker.
Figure 2b.
F.; 1958; and Smith, H.T., 1938.
Generalized stratigraphic column (lower part) of the Aztec
1° x 2° Quadrangle (compiled by P. G. L. Sikkink)
9
Rocks of Paleozoic Age
By the close of the Precambrian, the surface in the Aztec area was eroded
to a peneplain (Hilpert, 1969). Throughout most of the Paleozoic era this
area remained a stable shelf. A warm, humid to subtropical climate prevailed
and seas invaded the area numerous times. Cambrian through Mississippian age
rocks are absent in the quadrangle, although this is probably due to uplift
and erosion of the marine sediments rather than to nondeposition (Ridgley and
others, 1978). Evidence of Cambrian, Devonian, and Mississippian seas is
present, but only in the subsurface to the west and south of the Aztec
Quadrangle.
During early and mid-Pennsylvanian time the relative crustal stability of
the area ended. Several structural highs formed that affected later
Pennsylvanian and Permian sedimentation. The highs included the southern
Colorado Uncompaghre Uplift, Zuni-Defiance Platform, Sierra Grande Uplift,
Pedernal Uplift, and Penasco Uplift in New Mexico and Arizona. The birth of
the Ancestral Rocky Mountains also began at this time in Colorado, Utah, and
Wyoming. Concurrent with development of these structural highs a large trough
formed between the Zuni-Defiance Platform and the Uncompaghre Uplift. This
trough extended from southeast Utah to northwest New Mexico. Shallow seas
transgressed the area depositing sediment into the trough in a sequence of
interbedded fossiliferous limestone, arkosic limestone, arkosic sandstone, and
shale which is known as the Madera Limestone in the Aztec Quadrangle. The
basal part of the Madera Limestone is absent owing to nondeposition in the
vicinity of the Penasco Uplift (Ridgley and others, 1978).
Yne Pennsylvanian period was a time of extensive erosion as well as
vigorous mountain building. Structural highs during this time were
continually being eroded, adding vast quantities of sediment to the system.
In the Aztec area, only the Madera Limestone was deposited. By the end of
Pennsylvanian time, only the Uncompaghre Uplift remained as an important
structural high and source of sediments during the Permian.
During the Permian Period continental deposition resumed. Coarse fluvial
sediments from the Uncompaghre Uplift make up the Cutler Formation in the
Aztec area. The sediments were transported primarily by a system of streams
which flowed south-southwest from uplifted areas toward the sea which lay to
the southwest of the Aztec area. The shoreline fluctuated widely, leaving
shoreline and shallow-marine sandstones intertongued with continental red
beds. By mid-Permian time, the structural highs were diminished and clastic
sediment was greatly reduced. By the close of the Permian Period, erosion of
Permian rocks resulted in a widespread unconformity between Permian and
Triassic strata.
Rocks of Mesozoic Age
During Triassic time, the maximum extent of the paleo-San Juan Basin was
attained. The southern rim of the basin, known as the Mogollon area, was
10
uplifted and sediments were deposited on a vast floodplain that was tilted to
the west and northwest. According to Colbert (1950), this floodplain was a
vast lowland traversed by streams and dotted with scattered forests and
lakes. Facies coarsen generally southward toward the Mogollon region. At the
same time, volcanism occurred south of the Aztec Quadrangle area, and the
Uncompaghre Uplift was rejuvenated to form the northern boundary of the
basin. The slightly positive Zuni and Defiance Uplifts of Arizona and New
Mexico, and the Uncompaghre Uplift, Colorado, served as important sediment
sources for the Triassic Chinle Formation (Ridgley and others, 1978). In the
Aztec Quadrangle, the Chinle Formation consists of sandstone, siltstone, and
mudstone of fluvial and lacustrine origin.
Relatively stable conditions marked the change from Triassic to Jurassic
time. An erosional period is evidenced in the area by a widespread
unconformity between Triassic and Upper Jurassic rocks. The erosion surface
was covered by the vast dune fields of the Entrada Sandstone. After eolian
and sabkha deposition of the Entrada Sandstone, the area was covered by a
large lake. In this lake was deposited the limestone and gypsum facies of the
Todilto Limestone and the equivalent units such as the Pony Express Limestone.
Uplift to the southwest, in the Mogollon region (Craig and others, 1955),
preceded deposition of the Jurassic Morrison Formation and is believed to be
the source for much of the sediment in the Morrison Formation. The various
members of the Morrison Formation were deposi~ed on a vast plain in a variety
of fluvial and lacustrine environments. Deposition was also accompanied by
volcanic activity and much of the Morrison contains volcanic debris (Ridgley
and others, 1978).
During deposition of Jurassic sediments the basin sank and land masses to
the west and south rose. These tectonic movements caused folding and flexing
in the basin, especially around the southern margin. The presence of folds
and flexures probably influenced the course of sedimentation in the basin.
Although the folds and flexures developed at this time may not be directly
related to all uranium deposits, their influence on sedimentation patterns may
have permitted accumulation of sediments favorable as sites for subsequent
uranium deposition (Ridgley and others, 1978).
Sediments of the transitional period from Jurassic to Cretaceous time are
absent over most of the area because of pre-Cretaceous erosion. Sometime in
Late Jurassic to Early Cretaceous time the southern part of the basin was
uplifted and beveled. It was a time dominated by the Sevier Orogeny to the
west, and intense overthrust faulting and mountain building in the Cordilleran
geosyncline. Only in the northern part of the San Juan Basin and in the Chama
Basin are rocks of Early Cretaceous age preserved. Here rocks of the
Cretaceous Burro Canyon(?) Formation reflect deposition under fluvial and
local lacustrine conditions. The basin uplift and beveling of sediments
resulted in the subsequently deposited Cretaceous Dakota Sandstone resting on
progressively older rocks from north to south within the basin and basin
margin.
11
The Aztec area, in Late Cretaceous time, was a broad, subsiding plain
(Hilpert, 1969). It was traversed by streams and dotted with swamps in which
carbonaceous siltstones and coals accumulated. As subsidence continued the
area was covered by marine waters entering from the north. Numerous
transgressions and regressions followed (Peterson and Kirk, 1977), depositing
intertonguing sequences of shale and sandstone and lesser amounts of limestone
and coal. These sediments were deposited in marine, nearshore marine, beach,
paludal, and fluvial environments and compose the stratigraphic sequence from
the upper part of the Dakota Sandstone through the Pictured Cliffs
Sandstone. The Pictured Gliffs Sandstone was deposited as shallow marine and
beach sands during the final regression of the sea from the area (Ridgley and
others, 1978).
As the sea withdrew, the area was once again dominated by terrestrial
sedimentation. The area was a vast alluvial plain traversed by streams and
dotted with swamps. The Cretaceous Fruitland Formation and Kirtland Shale
were deposited in this environment.
At the end of the Cretaceous Period or early in the Tertiary Period there
was renewed tectonic activity accompanied by a mountain-building pattern which
consisted of essentially vertical basement uplifts of the Rocky Mountain
geosyncline. These tectonic events are referred to as the Laramide orogeny
and they shaped much of the present-day configuration of geology and
physiography in the Aztec Quadrangle. During this period, the final emergence
of the San Juan, Nacimiento, San Pedro, and Brazos Uplifts occurred around the
margins of the area. The San Juan and Chama Basins formed and were separated
by the Gallena-Archuleta Arch.
Rocks of Cenozoic Age
Fluvial conditions persisted into the Tertiary Period in both the San
Juan and Chama Basins. However, as a result of their structural separation
during the Laramide Orogeny, both basins were the sites of deposition of
different, unrelated sediments. In the San Juan Basin, fluvially deposited
conglomerate, sandstone, siltstone, and mudstone characterize the Paleocene
Animas Formation (also Late Cretaceous in part), Ojo Alamo Sandstone, and
Nacimiento Formation. In the Chama Basin, rocks of similar age are absent due
to erosion or nondeposition.
During the early Tertiary Period, numerous structural features formed,
especially along the margins of the San Juan Basin. Deepening of the San Juan
Basin occurred, and its margins were beveled. The Eocene San Jose Formation
was deposited over the beveled surface of earlier Tertiary rocks in the San
Juan Basin. During the same period in the Chama Basin, arkose, sandstone, and
conglomerate of the Blanco Basin Formation were deposited on the beveled
erosion surface in the northern part of the basin. At about the same time
along the east side of the basin, the El Rito Formation was deposited as a
fanglomerate derived from highlands to the north and east (Smith, Budding, and
others, 1961).
12
At the end of Eocene time the San Juan Basin was tilted to the north.
Deposition continued into Oligocene and Miocene time and was accompanied by
renewed volcanic activity in the San Juan Mountains, Mogollon Highlands, and
Jemez Mountains. Volcanic debris was contributed to fluvial systems, and lava
flows of basic composition covered large areas. The Abiquiu Tuff of the Santa
Fe Group was deposited during this period in the Chama Basin.
During late Miocene or early Pliocene time there was a broad regional
uplift, and large areas of the San Juan and Chama Basins were eroded. Large
amounts of Tertiary and pre-Tertiary rocks were removed. This period was also
accompanied by faulting or rejuvenation of old faults. Mobilization and
redeposition of uranium in the Grants mineral belt on the southern edge of the
San Juan Basin probably occurred at this time (Ridgley and others, 1978).
Structural features that formed during Oligocene-Miocene time include the
Nacimiento Uplift and Rio Grande Trough (Pl. lOA).
Volcanic activity in the Aztec Quadrangle during Miocene time was
centered in the Jemez Volcanic Field and on the Taos Plateau (Pl. lOC).
Igneous rocks of pyroclastic and tuffaceous composition and flows of
intermediate to silicic composition covered parts of the eastern half of the
quadrangle. Widespread basalt flows along with local silicic, alkali rhyolite
flows spread out as sheets over erosional surfaces. In the Aztec Quadrangle,
these igneous rocks include the Lobato Basalt, the dacite and latite members
of the Tschicoma Formation, the basalts and andesites of the Hinsdale
Formation, and the tholeiite basalts of the Servilleta Formation.
Lamphrophyre dikes and sills were also intruded during this time.
Rocks of Quaternary Age
Quaternary rocks in the Aztec Quadrangle are primarily surficial deposits
of alluvial, landslide, and glacial origin. In the southern part of the
quadrangle, Quaternary rocks also include the nonwelded to densely welded
rhyolitic tuff of the Pleistocene Bandelier Tuff. Chenoweth (1974b) has
speculated that the weakly radioactive Bandelier Tuff may have been the source
of uranium for many of the small uranium deposits in the southern part of the
Chama Basin and in the northern Nacimiento area. (J. L. R., M. W. G., and P.
G. L. S.)
DEFINITION OF FAVORABILITY AND CRITERIA USED FOR EVALUATION
All rocks to a depth of 1500 m (5000 ft) within the Aztec Quadrangle have
been evaluated as either favorable or unfavorable for the occurrence of
uranium deposits which could contain at least 100 metric tons of u3o8 with an
average grade not less than 100 ppm (0.01 percent) u3o8 • The evaluation has
been conducted according to DOE as stated in Mickle and Mathews (1979).
Accordingly, rock formations (or environments within formations or rock
bodies) can be classified as favorable if (1) there are known uranium
13
occurrences; (2) there are uranium anomalies detectable by hydrogeochemical,
ground, or aerial surveys; (3) the potential host rock possesses geologic and
geochemical characteristics similar to known uranium-producing, environments;
and/or (4) there is evidence, based on the above criteria, for the potential
to contain uranium deposits in the formation (or environment) of minimum grade
and tonnage as specified above.
In this folio, several recognition criteria have been used to delineate
and evaluate each formation (or environment) insofar as time and data have
allowed. These criteria include the recognition criteria established by BFEC
(1979) as well as criteria which, in the experience of the investigators, are
pertinent to uranium occurrence in rock units of the quadrangle. These
include the following:
(a)
Lithology of the formation/environment. This includes consideration
of mineralogic composition, texture, and diagenetic alteration of
potential host rocks.
(b)
Environment of deposition of the rock. This includes consideration
of depositional conditions, climatic factors, tectonic factors
affecting depositional patterns and energy levels, and resultant
sandstone to-siltstone (shale) ratio and configuration; it also
includes any other depositional factors related to and controlling
facies distribution and host-rock geometry.
(c)
Presence of uranium and/or gamma radioactivity. This includes
consideration of the relative background radioactivity of the
formation (or environment) away from mineralized ground; the size,
geometry, quantity, grade, and distribution of mineralized ground;
and the possible sources of uranium.
(d)
Presence of reductants. This includes consideration of the type,
quantity, origin, and distribution of organic matter with respect
to uranium, as well as, other potential reductants and uranium
precipitation.
(e)
Transmissivity. This includes consideration of porosity,
permeability, cementation, and fracturing of potential host rocks
and the lateral and vertical continuity of aquifer conduits for
the flow of mineralizing and/or oxidizing solutions.
(f)
Tectonic framework. This includes consideration of local and
regional strike and dip, faulting, and folding affecting the rock
formation (or environment) and uranium.
(g)
Preservation conditions. This includes consideration of oxidation
history, and the availability of confinement and barrier
mechanisms (i.e., caprock, shale, siltstone). It also includes
consideration of the relative age of the host rock, its uranium
deposits, and the possibility that deposits may have been
14
destroyed with time and adverse geologic and geochemical
conditions.
Areas designated as favorable are shown on Plate 1. The areas have not
been subdivided into areas of relative favorability since subdivisions would,
in most areas, be based either on proprietary information or on geologic and
geochemical criteria which are speculative or transitional in nature.
Boundaries of favorable areas shown by dashed line indicate only the
approximate limits of a favorable area or environment as determined
geologically or by the 1500 m (5000 ft) overburden contour.
Rocks or environments within favorable areas exhibit a majority of the
recognition criteria. They also show evidence of the existence of uranium
deposits of minimum grade and tonnage as specified. Such evidence includes
the presence of known orebodies or high-grade uranium in outcrop occurrences
and/or drill holes. Boundaries of the favorable areas are placed to include
these mineralized areas and adjacent areas in which geologic and geochemical
characteristics are similar. All areas outside of favorable areas are
considered unfavorable even though they may· locally contain rocks or
environments which exhibit a few favorable recognition criteria.
Areas designated as unfavorable commonly contain one or more favorable
criteria for uranium mineralization. However, from present data the
unfavorable environments show little evidence of containing deposits of the
minimum grade and tonnage. Additional information, not presently available
for this evaluation, could conceivably change some unfavorable evaluations of
rocks or their environments to the favorable category. A few units are
considered geologically more favorable but lack sufficient evidence of
extensive uranium mineralization. These units include the Permian Cutler
Formation, the Cretaceous Dakota Sandstone, and the Tertiary Nacimiento and
San Jose Formations. They include scattered uranium occurrences, favorable
facies and environments of deposition, but no evidence of large deposits to
warrant designating them as favorable. These formations, therefore, are
discussed in greater detail in this report than other formations considered
unfavorable.
ENVIRONMENTS FAVORABLE FOR
URJu~IUM
DEPOSITS
AREA FAVORABLE FOR URANIUM DEPOSITS IN THE BURRO CANYON(?)FORMATION
The Burro Canyon(?) Formation is considered favorable for sandstone-type
uranium deposits (Class 240, subclass 241) based on the recognition criteria
established by Austin and D'Andrea (1978), and Mathews and others (1979).
15
Stratigraphy and environments of deposition
The Burro Canyon(?) Formation crops out in the southern part of the Chama
Basin (Pl. lOA) and is present in the subsurface in the rest of that basin and
in the northeastern part of the San Juan Basin. It is absent south of Cuba,
New Mexico, where it wedges out under the pre-Dakota erosion surface, and east
of the Chama Basin due to erosion or nondeposition. In the subsurface in the
western part of the Aztec Quadrangle, the Burro Canyon(?) is not easily
recognized and, thus, is generally lumped with the Dakota Sandstone in surface
and subsurface correlations (Pls. 8, 8A).
As defined by several workers (Swift, 1956, Ridgley, 1977; Saucier,
1974), the Burro Canyon(?) Formation in the Chama Basin is the conglomeratic
sandstone, sandstone, and mudstone interval occurring stratigraphically
between the Brushy Basin Member of the Morrison Formation and the Dakota
Sandstone (Fig. 2). The exact correlation of this lithologic sequence and the
extension of the Burro Canyon nomenclature into the Chama Basin has been the
subject of controversy, due primarily to the absence of datable fossils. In
the past, some workers (Lookingbill, 1953; Sears, 1953; Woodward and
Schumacher, 1973; and Woodward and others, 1976) have included this sequence
with the Morrison Formation, whereas others (Grant and Owen, 1974;
Muehlberger, 1967; Smith and others, 1961) have included it with the Dakota.
The latter workers recognized the possible equivalence of this stratigraphic
interval the Burro Canyon Formation in Colorado.
Although the determination of age and correlation of this stratigraphic
interval may seem purely academic, there are also some economic
considerations. Because of the stratigraphic relation of this interval to the
Brushy Basin and Dakota Sandstone, there has been a tendency for many
geologists to correlate this interval with the Jackpile sandstone (of economic
usage). However, based on paleocurrent measurements and facies relationships,
Grant and Owen (1974), Owen and Siemers (1977), Ridgley (1977), and Saucier
(1974) suggest that this interval is not equivalent to the Jackpile and, at
present, should be considered equivalent to the Burro Canyon(?) Formation in
Colorado.
In the Chama Basin the Burro Canyon(?) may be divided into t\vo distinct
lithologic sequences--basal and upper. The basal sequence consists of 18 to
35 m (60-115 ft) of conglomerate, conglomeratic sandstone, and sandstone. The
conglomerate and sandstone are generally buff, tan, orange, or white at the
outcrop; they are usually gray or yellow gray in the subsurface. The
sandstones may be subarkosic, feldspathic, or quartzose and are fine to coarse
grained. They consist mainly of subrounded quartz with variable amounts of
feldspar, chert, and accessory minerals. Kaolinite is present throughout the
sequence. It occurs especially near the top in the southern part of the
basin.
Sedimentary structures in the basal sequence consist mainly of trough
cross-stratification, ripple lamination, and parallel lamination. The ratio
of conglomerate to sandstone is low and decreases upward. The basal sequence
16
is also characterized by numerous fining-upward sequences that begin with a
conglomerate and end with a medium- to fine-grained parallel- or ripplelaminated sandstone. The contact between the sandstone and overlying
conglomerate is commonly sharp and may be gradational or scoured. Clay-gall
zones and thin gray-green mudstone seams occur at the scour interfaces in
places. Laterally, the basal sequence is very persistent, may form steep
cliffs, and has an almost sheet-like geometry.
The upper sequence of the Burro Canyon(?) consists of a basal red
mudstone interval, a white to pink friable sandstone interval, and an upper
pale-red, pale-purple, or pale-green mudstone interval. Proportion of
mudstone to sandstone is variable; thickness of this sequence ranges from a
few meters to 23m (75ft). In the southern part of the basin much of this
interval is absent owing to pre-Dakota erosion. In the subsurface in the
eastern part of the basin, electric logs show that sandstone is the dominant
lithology of this interval and that the sandstone horizon is somewhat
persistent laterally. The sandstone of the upper sequence is fine to medium
grained and is composed of subangular to subrounded quartz and minor amounts
of feldspar. Kaolinite alteration is abundant at the outcrop, and has also
been found in the subsurface where the sandstones are various shades of
gray. Mudstones at the outcrop are siliceous and contain kaolinite and
illite. The red and green colors found in mudstones at the surface are also
present in the subsurface.
The Burro Canyon(?) is unconformably overlain by the Dakota Sandstone.
The contact is generally sandstone on sandstone but may also be sandstone on
mudstone. The Burro Canyon(?) may disconformably overlie the Brushy Basin
Member of the Morrison Formation. This contact, where exposed, is generally
sandstone on gray-green mudstone but may also be sandstone on sandstone.
From outcrop studies by Ridgley, the basal part of the Burro Canyon(?)
Formation is interpreted to have been deposited by a series of high-energy
braided streams. This interpretation is based on the dominance of trough
cross-stratification, on the geometric relation of conglomerate to sandstone
intervals that indicate the presence of channel bars and channel-fill
deposits, and on the lateral continuity of the sandstone interval, which
includes very little of fine-grained overbank deposits. Measurements of
crossbeds indicate a NNW to NNE direction of transport, with a probable source
area to the south and southwest (Ridgley, 1978). These observations are in
agreement with those reported by Grant and Owen (1974), and Saucier (1974).
The upper sequence of the Burro Canyon(?) reflects deposition by lower
energy, braided to meandering streams. Lower energy conditions are reflected
by an increase in proportion of mudstone, the presence of finer grained
sandstone, and a decrease in the lateral persistence of the main sandstone
interval.
17
Uranium mineralization and host rock characteristics
Little has been reported on uranium mineralization in the Burro Canyon(?)
Formation. There are no known surface uranium occurrences of any consequence
in the Burro Canyon(?), and aerial radiometric and hydrogeochemical studies
did not indicate the presence of any uranium anomalies. In the course of
mapping in the southern part of the basin, Ridgley located two very small
uranium anomalies that were associated with clay galls. Samples contained 6
and 27 ppm u3o8 • In this area the Burro Canyon(?) is extensively oxidized at
the outcrop. Uranium occurrences purported to be in the Burro Canyon(?) were
examined and were found to occur in the underlying Brushy Basin mudstones or
in overlying distributary-channel sandstone of the Dakota Sandstone.
Uranium occurrences, however, have been found in the subsurface on the
east side of the basin. The following discussion of these occurrences is
based in part on the author's interpretations derived from examination of a
limited number of electric and lithologic logs provided by the TVA and in part
on a report by Saucier (1974). Uranium minerals in the Burro Canyon(?) at
this area occur as numerous ore pods that are associated with oxidationreduction interfaces, thus indicating the deposits are roll-type uranium
deposits (Saucier, 1974).
Uranium occurences have been found at all levels in the Burro Canyon(?),
although the largest concentration of uranium occurs in the lower part of the
basal sandstone sequence and to a lesser extent in the top of the upper
sandstone sequence. Gamma-logs also indica~e that uranium occurs locally in
an underlying Brushy Basin sandstone and in overlying Dakota Sandstones.
Depths of anomalous uranium range from 60 to 180m (200-600 ft).
The variation in depth of uranium mineralization reflects the variation
in position of oxidation-reduction interfaces within the thick lower and upper
sandstone sequences of the Burro Canyon(?). Variations in permeability within
the sandstone have probably affected the rate at which the oxidation front has
travelled through any portion of the thick sandstone bodies. Gamma-logs
indicate that many of the thinner radioactive intervals are associated with
slight breaks in spontaneous potential (SP) and resistivity curves. These
breaks do not appear to be associated with discrete mudstone intervals.
Corresponding lithologic logs do not show any mudstone breaks within the thick
sandstone sequences, but they do indicate periodic changes in grain size.
These changes in grain size are probably similar to those observed at the
outcrop in the fining-upward sequences, that were previously described.
Nothing is known about the uranium mineralogy. Uranium appears to be
associated with small amounts of carbonaceous and "humicn material and
pyrite. Alteration of the host rock in the subsurface includes the presence
of kaolinite and trace amounts of hematite and limonite. At the outcrop the
host sandstones are extensively oxidized; the sparse amounts of iron-bearing
minerals have been oxidized to hematite and limonite. No sulfides or
carbonaceous material have been observed at the outcrop; only local pockets of
silicified wood have been found near the base of the formation.
18
According to Saucier (1974) some of the ore pods lie above the water
table and are oxidized, while others lie at or below the water table and have
not been oxidized. He reported that ore pods in the lower sandstone interval
have a south to southwest orientation, suggesting ground-water movement to the
northwest, and that those in the upper sandstone interval are related to
ground-water movement to the north and northeast.
There appears to be a good relationship of the position of the uranium
occurrences to regional and local structural features. The regional dip of
pre-Tertiary strata in the area is to the north and northwest and is generally
less than 5°. Locally dips may be to the northeast and dips in the vicinity
of a major fault in the mineralized area are to the southeast (Smith and
others, 1961). The relationship of this major fault to uranium occurrences is
unknown. It is possible that the fault is post-mineralization as ore pods
near it on the upthrown side (northwest side of northeast-trending fault) are
oxidized.
Structure contours drawn on the base of the Dakota Sandstone in the area
indicate the presence of several broad, gentle folds that plunge to the
northwest (Smith and others, 1961). These folds are bounded on the east by a
homocline that has dips of 10o to 12°. The pattern of mineral occurrences
appears to be coincident with ground water moving in the direction of the
regional dip, with perhaps local modification of ground-water movement in the
vicinity of the shallow folds.
The age of mineralization and source of uranium are not known.
Mineralization, however, appears to be related in time to basin-margin uplift
to the south and possibly east. Uplift of the basin margin as well as other
regional and local structural features, previously mentioned, are related to
tectonic events of late Cretaceous and early Tertiary times. This period of
deformation was followed by extensive erosion, which is recorded in the
southeast-dipping unconformity below the El Rito Formation of probable Eocene
age. In turn, the El Rito Formation ~v-as eroded prior to deposition of the
overlying Miocene Abiquiu Tuff.
Chenoweth (1974b) and Saucier (1974) have speculated that the >veakly
radioactive Pleistocene Bandelier Tuff was the source for uranium. This would
mean that the uranium deposits in the Burro Canyon(?) are no more than 2 m.y.
old. As an alternative, Ridgley proposes that the Abiquiu Tuff of Miocene age
should also be considered as a possible source of the uranium.
The Abiquiu Tuff is composed of light-gray to pale-orange silty tuff,
micaceous, tuffaceous sandstone, and conglomerate, and may be as much as 390 m
( 1300 ft) thick. The average uranium content of the tuffaceous portions is
unknown. A few scattered uranium anomalies were found in the Abiquiu Tuff by
aerial radiometric and hydrogeochemical surveys (Pls. 3, 4). Source areas of
the Abiquiu Tuff were in the San Juan Mountain region (Smith and others,
1961).
The principal reason for considering the Abiquiu Tuff as the source of
19
the uranium is that along the northern flank of the Jemez Volcanic Field,
located in the southern part of the Aztec Quadrangle, the Abiquiu Tuff
directly overlies the Dakota Sandstone, and Burro Canyon(?) and Morrison
Formations (Pls. 10, lOa). A portion of this area lies to the south and
southeast of the mineralized area, on the south side of the Rio Chama. It is
speculated that during erosion of the Abiquiu Tuff in late Miocene and early
Pliocene time, but prior to deposition of the Bandelier Tuff, which
unconformably overlies it, uranium was leached from tuffaceous portions and
transported by ground water to the northwest. Access to the Morrison and
Burro Canyon(?) Formations, and Dakota Sandstone by the ground water would
have been possible as these formations would have been located at or near the
surface.
The Burro Canyon(?) Formation exhibits many characteristics considered
favorable for the presence of uranium. These characteristics are very similar
to those found in the host rocks of the Wyoming roll-type uranium deposits
(Austin and D'Andrea, 1978). The Burro Canyon(?) is composed of dominantly
feldspathic sandstone deposited as channel-bar and channel-fill deposits in
braided-stream environments. The sandstone bodies are thick, laterally
continuous, and possess excellent permeability. Permeability changes
associated with fining-upward sequences within the thick sandstones, mudstone
intervals, and overlying and underlying less permeable rocks of the Dakota
Sandstone and Brushy Basin serve to confine ground water to various parts of
the upper and lower sandstone bodies. The presence of carbonaceous and humic
material and pyrite in the subsurface indicates that potential reductants,
necessary to reduce and precipitate uranium were available. Alteration of
iron-bearing minerals to hematite and limonite and the occurrence of kaolinite
are much the same as in Hyoming deposits. The presence of hematitic and
limonitic sandstone thus can be used as an exploration guide.
The structural setting in which the Burro Canyon(?) uranium deposits
occur is similar to that of the 1-lyoming deposits. In
both cases, uranium
was deposited from uraniferous ground water moving through the host rock,
which dipped basinward from the basin margins. Moreover, in both cases,
tuffaceous rocks are known to have overlain truncated beds of the host rock in
the vicinity of the basin margins.
Comparison of the geochemistry and uranium mineralogy of the Burro
Canyon(?) deposits to the "Wyoming"-type is not possible as data for the Burro
Canyon(?) deposits are not available.
Favorable area
The Burro Canyon(?) Formation is considered favorable for containing
"Wyoming" roll-type uranium deposits, subclass 241 (Austin and D'Andrea (in
Mickle and Mathews) 1978). The formation is known from drilling to contain
uranium concentratations in excess of the minimum endowment requirement and
it also exhibits other characteristics of favorability previously discussed.
The area considered favorable for containing uranium deposits is shown in the
20
eastern part of the quadrangle on Plate 1. The outline of this area is based
in part on the location of known uranium deposits, as well as on geology based
on the theory of origin previously discussed. Scattered drilling in the
western half of the favorable area has been relatively unproductive (Saucier,
1974); this suggests that the western half will be less favorable than the
eastern half.
The favorable area covers approximately 492 km 2 (190 mi 2). The entire
Burro Canyon(?) should be considered favorable as mineralization is known to
have occurred at all horizons within it. The average thickness of the
combined upper and lower sandstone intervals is about 40 m (132 ft). Usi~g
this average thickness, the total volume of favorable rock is about 20 km
(7.7 mi 3 ). Depths to the Burro Canyon(?) range from about 60 m (200 ft) to as
much as 365 m (1200 ft) or more.
Land included in the favorable area is sparsely populated. Most of the
land lies within the Carson National Forest (Pl. 12). The rest of the land is
divided among the u.s. Bureau of Land Management, the State of New Mexico, and
private parties.
That portion of the Burro Canyon(?) Formation that lies to the north and
northwest of the favorable area remains unevaluated due primarily to the lack
of drilling. This unevaluated portion of the Burro Canyon(?) is discussed
further in a later section on unevaluated environments. The Burro Canyon(?)
to the south and southwest of the favorable area is considered unfavorable as
it has been highly oxidized.
Summarv
In summary, using the recognition criteria set forth by Mathews and
others (1979) the uranium deposits in the Burro Canyon(?) Formation may be
classed as Wyoming roll-type deposits (subclass 241). The recognition
criteria used are as follows:
(1) the tectonic setting during mineralization
was one of a basin with adjacent uplands; (2) the host rock for the deposits
is fine-grained to conglomeratic quartzose to feldspathic sandstone, which
contains scattered carbonaceous material and pyrite grains; (3) the host rock
was deposited as mixed-load and channel-fill deposits by braided to meandering
streams; (4) associated mudstones and fine-grained sandstone intervals provide
permeability controls to ground-water flow; (5) overlying tuffaceous rocks,
along the southern basin margin, may have been the source for the uranium; and
(6) alteration of the host sandstone includes oxidation of iron-bearing
minerals and kaolinization of feldspar.
(J. L. R.)
AREA FAVORABLE FOR URANIUM DEPOSITS IN THE OJO ALAMO SANDSTONE
The Ojo Alamo Sandstone is considered favorable for sandstone-type
uranium deposits (class 240, subclass undetermined) based on the recognition
criteria established by Mathews and others (1979).
21
Stratigraphy and environments of deposition
The stratigraphy of the Ojo Alamo Sandstone of Tertiary age has remained
controversial for many years. The original stratigravhic sequence defined by
Brown (1910) was redefined by Bauer (1917). Bauer's description was later
revised by Baltz and others (1966), who restricted the name Ojo Alamo to
include only the upper conglomeratic sequence of Bauer (1917). The section
originally defined as Ojo Alamo by Brown is now included in the Kirtland
Shale. The age of the Ojo Alamo has been considered to be Late Cretaceous
(Dane, 1936) or Paleocene (Knowlton, 1924; Anderson, 1960), partially as a
result of the disagreement in the location of the formation boundaries. At
present, work by Anderson (1960) and R. H. Tschudy (in Fassett and Hinds,
1971) indicate a Paleocene (Tertiary) age for the Ojo Alamo.
The Ojo Alamo crops out in an irregular pattern from the vicinity of
Cuba, New Mexico, on the east side of the San Juan Basin, to the Farmington
area in the northern part of the basin and is present in the subsurface north
of this outcrop belt (Pl. 10).
Thickness of the Ojo Alamo sandstone ranges from 6 to 120 m (20 to 400
ft). Along the east margin of the San Juan Basin, the Ojo Alamo may be as
much as 60 m (200 ft) thick; in the western part of its areal distribution the
Ojo Alamo may be as much as 120 m (400 ft) thick. Overburden thickness may
range from 0 m in the southern part of the outcrop area to over 1200 m (0 to
4000 ft) in the northern part of the basin. South of the outcrop belt and in
the Chama Basin the Ojo Alamo is absent owing to nondeposition or erosion.
The Ojo Alamo Sandstone is composed of interbedded buff or rusty-tan
sandstone, conglomeratic sandstone, and olive-green and gray shale. The
sandstone is arkosic, locally conglomeratic near its base, and contains
scattered fragments of fossil carbonized and silicified wood. Trough crossstratification and large-scale channeling at the base of the sandstone units
are common. Sand bodies are c,ommonly multilateral, display a discontinuous
sheet-like geometry (Fassett and Hinds, 1971). Vertically, individual
sandstone sheets often merge with overlying and underlying sandstone sheets as
a result of channeling by individual channel sandstones; laterally, individual
sandstone sheets wedge out in shale beds.
The Ojo Alamo is thinner in the southern part of the outcrop area and
thickens to the north. Limited paleocurrent studies of the Ojo Alamo have
been done by Baltz (1967). He indicates that the sandstones of the Ojo Alamo
in the Farmington area were deposited by streams flowing from areas westnorthwest and northwest of Farmington. Transport was probably toward the
southeast. This interpretation is supported by the decrease in the size of
pebbles in the conglomerate from west to east across the northern part of the
San Juan Basin (Fassett and Hinds, 1971). The Ojo Alamo also shows an
increase in grain size from south to north along the east side of the San Juan
Basin, which suggests an additional source area to the northeast (Baltz,
22
1967).
The contact of the Ojo Alamo Sandstone with the overlying Nacimiento
Formation is conformable and intertonguing (Fassett and Hinds, 1971). The
contact with the underlying Kirtland Shale is unconformable. The Ojo Alamo
rests on progressively older parts of the Kirtland Shale from west to east
across the northern part of the San Juan Basin (Fassett and Hinds, 1971).
Little work has been done on reconstruction of the environments of
deposition of the Ojo Alamo Sandstone. Sedimentary structures within the
sandstone channels and the geometric relationship of sandstone channels to
shales suggest that much of the Ojo Alamo was deposited by distal braided to
meandering fluvial systems.
Uranium mineralization and host rock characteristics
At present only one area of uranium occurrences in the Ojo Alamo is
known. This locality is on Mesa Portales, southwest of Cuba, New Mexico
(Green and others, 1980a, Pl. 10). Recent drilling of the Ojo ~~amo at this
location has encountered large, low-grade, disseminated concentrations of
uranium. The presence of uranium there is also confirmed by the presence of
radioactivity anomalies at the outcrop along the southern and eastern rims of
the mesa (Green and others, 1980a, App. C); by anomalous stream- and springsediment samples (Green and others, 1980a, Pl. 4), and by a cluster of aerial
radiometric anomalies in the southern part of the mesa (Green and others,
1980a, Pl. 3).
According to data provided by Dale Carlson of Triple S Development
Company (oral commun., 1979), the uranium deposit has a blanket-like geometry
and occurs at several sandstone horizons. Although the ~verage concentration
of uranium is low (less than 0.01 percent) at least part of the deposit
apparently contains sufficient uranium to meet the NURE endowment requirement.
At the outcrop, radioactivity is associated with solution iron banding,
clay galls, and carbonized fossil plant material in the sandstone and also
occurs in the interbedded carbonaceous shales. It is possible that the
uranium was adsorbed onto the surface of the iron oxides, clay minerals, or
carbonized plant matter. Discrete uranium minerals, either primary or
secondary, were not observed. Alteration of the sandstones at the outcrop
includes oxidation of iron-bearing minerals, imparting an orange color to the
sandstsones, and kaolinization of feldspar. In the subsurface, the uranium is
associated with pyrite and carbonaceous material.
The association of radioactivity with altered sandstone at the outcrop
suggests that the uranium was or is being deposited from uraniferous,
oxidizing ground water where suitable reducing environments exist. Some data
suggest that the deposit is young and may be in the process of forming.
According to Dale Carlson (oral commun.), the distribution of uranium does not
fit the roll-type uranium model. However, in gamma logs and core examined by
23
the author, the pattern of radioactivity, as well as the distribution of
altered (containing oxidized iron minerals) versus unaltered (containing
unaltered iron minerals) sandstone are similar to those found in roll-type
deposits, although very diffuse. The lack of a clear pattern of distribution
of uranium may be a reflection of a youthful age for the deposit and of the
process of mineralization. But until more detailed studies are done, one must
also consider the possibility that the deposit represents a remnant of a
preexisting deposit that is presently being destroyed by modern ground-water
flow. Thus, until more work is done, the uranium deposit in the Ojo Alamo is
placed in the sandstone deposit category (class 240) with a subclassification
not determined. The determination of the origin and timing of the uranium
mineralization will ultimately affect the favorability for the remaining part
of the Ojo Alamo in the Aztec Quadrangle.
The Ojo Alamo exhibits a number of host-rock characteristics generally
considered favorable for the occurrence of uranium deposits. The Ojo Alamo is
composed of arkosic sandstone and shale which contain local concentrations of
carbonaceous debris. The carbonaceous matter may have provided locally
reducing environments which would have been instrumental in the reduction of
uranium from oxidizing ground water. The multilateral and multistoried sand
bodies possess excellent permeability; their geometry provides excellent
access to large volumes of ground water. Interbedded shale beds would provide
excellent permeability barriers by reducing ground-water flow in certain
directions, allowing deposits to form and be preserved.
Structurally, the Ojo Alamo consists of very gently dipping beds, except
along the very east margin of the San Juan Basin where the beds dip steeply,
or are overturned. According to Baltz (1967), this structural pattern is
related partialiy to tectonic events of late Paleocene time and partially to
tectonic events of Early Eocene time (post-San Jose Formation deposition). In
the vicinity of Mesa Portales, the beds of the Ojo Alamo dip gently
northward. The northward tilt of the strata was imparted in post-early Eocene
time and influenced the subsequent hydrology of the area. The change in
ground-water movement from dominantly southeast in early Paleocene time to
northerly in post early Eocene time may ultimately be useful in determining
the timing of mineralization and thus, whether the mineralization is related
to post-early Eocene-basin margin tilting.
Favorable area
The determination of the type and timing of uranium mineralization will
ultimately determine how much of the Ojo Alamo can be considered most
favorable for containing additional uranium deposits. The area of the Ojo
Alamo considered favorable for containing uranium of minimum requirements is
shown on Plate 1 along the southern border of the quadrangle. This area
adjoins the favorable area in Albuquerque quadrangle as shown by Green and
others, 1980a, Pl. 1C). The boundaries shown are based on the consideration
that the known uranium mineralization is somehow r1lated to basin margin
uplift. This projected area covers roughly 474 km (183 mi 2 ) in this
24
quadrangle and an additional 243 km 2 (94 mi 2 ) in the adjacent Albuquerque
1°x2° Quadrangle (Green and others, 1980a, Pl. 1C). Within the favorable
area, the Ojo Alamo has an average thickness of about 40 m (130 ft) and may be
overlain by as much as 600 m (1950 ft) of younger rock. If one predicts that
about 60 percent of the average thickness of the Ojo Alamo consists of
suitable host-rock sandstone, then the favorable area contains approximately
11.4 km 3 (7.7 mi 3 ) of favorable rock.
Much of the land containing Ojo Alamo strata lie on the Jicarilla Apache
Indian Reservation; the rest of the land is privately or publicly owned (Pl.
12). Population throughout the area is sparse; most of the land is used for
ranching (Pl. 13).
Summary
In summary, due to a lack of knowledge as to whether the uranium deposit
- in the Ojo Alamo Sandstone represents a primary roll-type deposit or remnants
of preexisting peneconcordant deposits undergoing redistribution by later
ground-water flow, the uranium deposit in the Ojo Alamo is simply classified
under the general category of sandstone-type uranium deposits (Class 240) and
no subclassification is made. Although no subclassification is shown, it is
the author's opinion that many of the recognition criteria set forth by
Mathews and others (1979) for "Wyoming" roll-type deposits, subclass 241, are
exhibited by the Ojo Alamo deposit. These recognition criteria include:
(1)
a tectonic setting of basin with adjacent uplands to the east; (2) the host
rock for the deposit is composed of quartzose to feldspathic sandstone that
contains carbonaceous material and pyrite; (3) the host rock was deposited as
mixed-load sediments by braided to meandering streams that occurred on an
alluvial fan; (4) associated mudstone intervals may provide permeability
barriers to ground-water flow; (5) younger tuffaceous rocks may have once
covered portions of the host rock, although evidence for such is now lacking;
and (6) alteration of host rock includes kaolinitization of feldspar and
oxidation of iron-bearing minerals. (J. L. R.)
AREA FAVORABLE FOR URANIUM DEPOSITS IN THE MORRISON FORMATION
The Morrison Formation is considered favorable for sandstone-type uranium
deposits (Class 240, subclass 243 and 244) based on recognition criteria
established by Austin and D'Andrea (1978), Mathews and others (1979).
Stratigraphy, structure and lithology
The Morrison Formation (Cross, 1894) of Late Jurassic age is present
throughout the extent of the Aztec Quadrangle. It crops out in the eastern
half of the quadrangle along the margins of the San Juan and Chama Basins.
Structurally, the formation dips gently away from the basin margins toward the
basin centers where it is covered by several hundred meters of overlying
Cretaceous and Tertiary sedimentary formations (Pl. 10).
25
In general, stratigraphy of the Morrison Formation and its members in the
quadrangle is fairly well known. However, distinct problems still exist in
(1) determination of stratigraphic boundaries between members of the Morrison;
(2) resolution of nomenclature for various members of the formation; and (3)
definition of the contact between the Burro Canyon·(?) Formation and the
Morrison (Ridgley, 1977).
Three members of the Morrison are recognized in the quadrangle. In
studies along the east side of the San Juan Basin, Craig (1959) and others
have recognized the Recapture Member, Westwater Canyon Member, and Brushy
Basin Shale Member. In the adjacent Chama Basin, Ridgley (1977), in order to
avoid some of the existing localized nomenclature and correlation problems,
has divided the formation into the lower member, middle member, and Brushy
Basin Member. Ridgley's divisions, however, correspond closely to those of
Craig's.
The lower (Recapture) member, according to Ridgley (1977), contains two
distinct lithologic sequences: (1) a basal sequence of sandstone, shale, and
limestone; and (2) a thicker overlying upper sequence of sandstone and
claystone. The lateral and vertical relationships between the lower member
and underlying Jurassic units remains somewhat uncertain. However, because
the lower member is not considered favorable for uranium deposits, the
resolution of these correlation problems is not considered important in this
report. For a more detailed description of the lower (or Recapture) member,
the reader is referred to reports by Ridgley (1977), Craig and others (1955),
and Craig and others (1959).
The middle (Westwater Canyon) member, according to Ridgley (1977), is
composed of two sandstone beds separated by shale layers. It ranges from 18
to 36 m (5.5-11 ft) thick in outcrops within the Chama Basin. Contact with
the lower member is conformable and is marked by a change in mineral
composition and grain size. No interfingering of the two members has been
observed. The sandstones are dark olive tan to yellowish gray, medium to fine
grained, and fairly to moderately well sorted. They are composed of
subangular to subrounded quartz grains, microcline, plagioclase, chert
fragments, and black accessory minerals. Sedimentary structures are not often
observed because of the friable nature of the sandstone. The associated shale
layers are reddish brown and greenish gray, and are calcareous and arenaceous.
The Brushy Basin Shale Member is an average of 84 m (25 ft) thick in the
Chama Basin and is composed of claystone and shale with minor amounts of
sandstone and dense siltstone. The siltstone and claystones are pale red
orange, greenish gray, red brown, and gray, and are calcareous and
arenaceous. They contain minerals of the montmorillonite group. Intervening
sandstone beds are light buff to rusty tan, medium to fine grained, and
moderately well sorted. They are composed of quartz, feldspar, minor amounts
of rock fragment and black accessory minerals. The sandstones are lenticular
and discontinuous and contain low-angle wedge, planar, and trough crossstratification. The sandstone beds form ledges between the claystone and
shale intervals. Contact with the underlying middle (Westwater Canyon) member
26
is placed at the base of a lower red-orange claystone bed and at the top of
the upper sandstone bed of the middle member. The upper contact with the
overlying Burro Canyon(?) Formation is frequently covered in the Chama
Basin. When observed, however, it is placed where the lower-most basal
conglomerate ledge of the Burro Canyon(?) is in contact with sandstone, shale,
or claystone beds of the Brushy Basin.
In the subsurface of the western half of the quadrangle, the ratio of
sandstone to shale and claystone in the Brushy Basin Member increases
considerably west southwestward, indicating that the source of sediment in the
Brushy Basin probably lay west-southwest of the quadrangle boundary beyond the
western and southwestern margins of the San Juan Basin. Correlation of the
Morrison and adjacent formations into areas of the San Juan Basin are shown by
matching subsurface cross-sections (Pls. 8 and 8A) in the Aztec Quadrangle
with those of the adjacent Albuquerque, Gallup, and Shiprock Quadrangles
(Green and others, 1980a, 1980b, 1980c, Pls. 8 and 8A).
Environments of Deposition
The environments of deposition of the Harrison Formation include fluvial
(stream channel and flood plain), mixed fluvial-lacustrine, and lacustrine.
No marine or marginal-marine influence has been detected. Eolian deposits_
within the formation are minimal and restricted to areas west of the
quadrangle. Based upon the mode and medium of deposition, and the nature of
vegetal and animal remains in the Morrison, inference is that climatic
conditions during this time were-probably humid to subhumid. The presence of
montmorillonite minerals as alteration products of volcanic debris, suggests
volcanic activity during Morrison time.
The depositional energy levels during Harrison time ranged from high (in
fluvial-dominated environments) to low (in lacustrine-dominated
environments). The middle (Westwater Canyon) member was deposited during the
higher-energy, sandstone-dominated interval and represents a mid-fan facies in
the formation. It is interpret~d to have been deposited as bedload in
meandering- and braided-stream complexes upon coalescing alluvial fans. The
fans radiated northeast, east and southeast from sediment source areas. The
lower (Recapture) member and Brushy Basin Member, on the other hand, were
deposited in low-energy, claystone- and shale-dominated environments and
represent a distal-fan facies in the formation. TI1ey were formed by the
deposition of suspended load sediment in overbank floodplain areas
(interfluves) and in standing bodies of water (lakes) at the toe of the
alluvial fans.
The boundaries between the lateral and vertical lithofacies in mid-fan
and distal-fan sequences contrast sharply. The lateral lithofacies are
actually transitional over great distances within the fan system. The
vertical lithofacies changes, on the other hand, are quite sharp and distinct
and serve as the basis for dividing the formation into its various members.
Superposition of the members occurred as a result of transgression and
27
regression of fan facies over the Morrison depositional area in response to
tectonic and climatic fluctuations in Jurassic time.
The Morrison depositional system covered an area much greater than the
area of the Aztec Quadrangle. The formation and its equivalents are
recognized throughout the Colorado Plateau and adjacent regions as far north
as the north-central United States. In general, the formation becomes coarser
grained to the west and southwest. This suggests that its primary source lay
somewhere in the southwestern United States. However, additional study of the
facies relationships, sediment transport directions, and composition are
needed before a west-southwesterly source can be identified. It has been
observed, however, that the coarser-grained proximal and mid-fan facies
interfinger north-northeastward with the finer grained distal facies of the
formation. The exact location of the interfingering is not known well enough
to draw a line between the two facies. The Morrison in the Aztec Quadrangle,
however, lies almost entirely within this distal facies.
The location of major uranium-producing districts in the Morrison of the
Colorado Plateau is probably related to the regional lithofacies
relationship. The presence of both the sandstone facies and the claystoneshale facies in the area of the Colorado Plateau is a necessary criterion in
terms of regional uranium favorability. The sandstone facies (Westwater
Canyon and Saltwash Members) serve as conduits for the migration of both
uranium-bearing fluids and mobile reductants. They also serve as host rocks
for uranium deposits. The claystone-shale facies (Brushy Basin and locally
the Recapture Members) serve as barriers to confine movement of fluids, and as
possible sources of reductants and uranium.
Uranium mineralization and area favorable
The largest sandstone-type uranium deposits in the United States are
contained in sandstone host rocks of the Westwater Canyon and Brushy Basin
Members of the Morrison Formation within the adjoining Albuquerque and Gallup
Quadrangles (Green and others, 1980~ and 1980c). Most of the deposits are
tabular and trend generally east west in the Grants mineral belt approximately
40 km (24 mi) southwest of the Aztec Quadrangle boundary (Fig 3).
The Westwater Canyon-Brushy Basin interval in the favorable area shown on
Plate 1 averages approximately 170 m (550 ft) in thickness as determined from
dr~ll-hole 1ogs in the vicinity.
The favorable area to§als approxima§ely 670
km (260 mi ), and its volume is estimated to be 114 km (about 27 mi ).
Drilling in the southwest corner of the Aztec Quadrangle and northeast corner
of the Albuquerque Quadrangle has encountered uranium anomalies in 7 of 15
holes penetrating Westwater Canyon and Brushy Basin rocks. Based on
information from these drill holes, this southwest corner of the quadrangle is
considered favorable for uranium deposits of minumum grade and tonnage
Although favorability lines are drawn on the basis of the 1500-m (5000-ft)
depth line in the San Juan Basin, favorability for uranium endowment at depths
beyond 1500 m (5000 ft) is probable in deeper parts of the basin.
28
10r
Blanding
Basin
San Juan
Mountains
s
A N
J UA N
I
BA S I N
c
·.-I
Ul
co
I:Q
co
@
..c:
u
SHIPROCK
GALLUP
Defiance
Uplift
AZTEC
ALBUQUERQUE
36.
Gallup
Sag
Rio
Grande
Trough
0
Figure 3.
30
45
60
miles
Index map of the San Juan Basin, Grants mineral belt, the
Aztec 1° x 2° Quadrangle, and adjacent areas
29
As near as can be determined without additional information, uranium
anomalies in the drill holes occur in sandstone intervals near the contact
between the Westwater Canyon and Brushy Basin Members. The nature of
occurrence is thought to be similar to that found in the Grants mineral belt
where the large uranium deposits occur in sandstone beds in association with
humates. Humates occur as concentrations of structureless humic matter
derived from the decay of plant remains in the host formation itself (Squyres,
1970); or they may be derived from adjacent formations such as the overlying
organic-rich Dakota Sandstone (Granger, 1968). The uranium deposits in the
mineral belt associated with concentrations of detrital organic debris
contained in the host sandstones are relatively small in size and are
considerably higher in average ore grade than the larger humate deposits.
The source of uranium in the Harrison is believed to have been from the
alteration of uranium-bearing minerals contained in the host rock sediment.
Morrison sediments are first-cycle arkosic to subarkosic and were probably
derived from a granitic source terrain that was anomalously rich in uranium.
Th~ Harrison also contains an appreciable quantity of volcanically derived
sediment that could have served as another likely source of uranium.
In the northeastern part of the Aztec Quadrangle, the lack of uranium
favorability in the Westwater Canyon-Brushy Basin interval is attributed to a
change in favorable facies. Lack of good porosity and laterally continuous
permeability of sandstone host rocks is characteristic of the sequence.
Overall grain size in host sandstones tends to decrease in a northeasterly
direction from the mineral belt. Also the sandstone conduit system for
transmission of organics and uranium probably were not developed favorably
because of lateral facies transition from the mid-fan to the distal-fan facies
in a northeasterly direction away from the sediment source areas.
Summary
Uranium deposits in the Morrison Formation of Late Jurassic age in the
Aztec Quadrangle are classed (Austin and D'Andrea, 1978; and Mathews and
others, 1979) as sandstone type (Class 240). Both channel-controlled
peneconcordant (subclass 243) and non-channel-controlled penecondordant
(subclass 244) deposits are believed to be present in the favorable area. The
deposits are classified on the basis of the following criteria:
(1) Tectonic setting: Harrison rocks were deposited on a stable
platform in a large sedimentary basin probably bounded on the south,
southwest, and west by highlands of unknown proximity to the favorable area.
Subsequent Tertiary epeirogenic tectonic activity formed the present San Juan
Basin and locally folded and faulted the Morrison sequence adjacent to
marginal uplifts.
(2) Host rock: Host rocks are first-cycle arkosic to subarkosic
carbonaceous sandstone deposited predominantly in braided streams of the midfacies in a "wet" coalescing alluvial-fan complex.
30
(3) Associated rocks: Siltstone, shale, claystone, and minor thin beds
of limestone and chert are associated with host sandstones.
(4) Alteration: In that uranium anomalies are known so far only in
boreholes in the favorable area, alteration patterns have not been determined.
(5) Uranium and uranium-bearing minerals: Primary uranium minerals are
uraninite and coffinite. Secondary minerals are carnotite, tyuyamunite,
uranophane, autunite, torbernite, and anhydrous species. Primary minerals
occur in close spatial relationship to detrital and humic carbonaceous matter
in the host rocks. Associated elements include V, Mo, As, Se, Co, Ni, Ti, Yb,
and Pb. (M. w. G.)
ENVIRONMENTS UNFAVORABLE FOR URANIUM DEPOSITS
PRECAMBRIAN IGNEOUS ROCKS
Precambrian igneous rocks are present in the Tusas Mountains and in the
San Pedro Mountains (Pl. lOB). These include phaneritic to porphyritic,
siliceous rocks of granitic, monzonitic, and dioritic composition.
Few uranium occurrences are found within the Precambrian igneous rocks.
Uranium occurs in the Tres Piedras Granite in veins of quartz and fluorite and
in some plutonic intrusions in the granite but the uranium minerals have not
yet been identified. Analysis of samples from these rocks show uranium
contents of 14.2 ppm (in granite), 54 ppm (in granite with fluorite veins) and
1280 ppm (in granodiorite). The potential for containing uranium deposits of
minimum grade and tonnage is considered poor. Some mining has been done in
the past; however, it has been for mica, beryl, and fluorite.
The majority of uranium occurrences that occur in igneous rocks are found
in the pegmatites of the Petaca Schist of late-Precambrian age. Uranium
occurrences are found in and around the pegmatite bodies and in associated
pegmatite veins. Uranium content varies considerably in the pegw~tite, from
0.6 to 16.9 ppm (sample from dump of mine tailings). Areas of high
radioactivity are usually very small. Associated minerals include muscovite,
quartz-gel and feldspars. According to field observations by s. M. Condon and
D. P. Bauer, mineralization appears to be both hydrothermal and pegmatitic.
Radioactivity seems to be more concentrated in the altered zones between the
pegmatite and the country rock. However, no large area of mineralization is
evident (App. C). (P. G. L. S.)
PENNSYLVANIAN FORMATIONS
Pennsylvanian rocks in the Aztec Quadrangle are represented by the Madera
Limestone in the eastern part of the quadrangle, and by the Molas, Hermosa,
and Rico Formations in the western part of the quadrangle. Outcrops of the
31
Madera Limestone are found along the northeast flank of the Nacimiento
Mountains and at a few localities along the western and eastern margins of the
Chama Basin (Pl. 10). Elsewhere in the quadrangle Pennsylvanian rocks occur
entirely in the subsurface.
The Madera Limestone is composed of an interbedded sequence of arkosic
sandstone, arkosic limestone, fossiliferous limestone, and shale and was
deposited in environments ranging from coastal marine to marine.
The Molas Formation consists of clastic red beds, limestone, and
siltstone. The basal red bed sequence is interpreted as representing a
paleosol developed on the eroded surface of the underlying Mississippian
limestone. The upper fossiliferous limestone and siltstone sequence contains
fossil assemblages indicative of marine environments of deposition (Peterson
and Ohlen, 1963).
The Hermosa Formation consists of a complex intertonguing sequence of
clastics (sandstone, siltstone, and shale), carbonates (limestone and
dolomite), and evaporites. The various members of the Hermosa Formation were
deposited in a variety of marine environments ranging from shallow shelf to
deeper basinal areas. No uranium occurrences are known in the formation.
The Rico Formation consists of a lower marine carbonate sequence overlain
by a continental clastic sequence.
Pennsylvanian rocks in the western part of the quadrangle are considered
unevaluated for the occurrence of uranium as they are found at depths greater
than the 1500 m (5000 ft) depth limit of evaluation, and there are
insufficient subsurface data to make an evaluation at this time.
Pennsylvanian rocks in the eastern part of the quadrangle are considered
unfavorable for the occurrence of uranium. Although several uranium
occurrences have been found in the Madera Limestone (App· A, Pl. 2), it does
not appear that the minimum endowment of uranium occurrences totaling at least
100 metric tons at 0.01 percent u3o8 or greater could be attained. This
determination is based on the lack of potential reductants in the host rock.
At the occurrences visited or reported in the literature, the uranium is
associated with small pockets of carbonaceous material. However, an
examination of the Madera Limestone indicates that carbonaceous material,
occurring in pockets or as disseminations, is sparse to nonexistent. (J. L.
R.)
PERMIAN FORMATIONS
Cutler Formation
The Cutler Formation crops out in the southern part of the Chama Basin,
located in the southern part of the Aztec Quadrangle (Pl. 10). It is present
in the subsurface in the remainder of the quadrangle. Cutler outcrops consist
of interbedded sandstone, siltstone, and shale and locally, thin beds of
32
nodular limestone. It is approximately 150 m (500 ft) thick in the southern
part of the quadrangle and thickens to about 750 m (2500 ft) in the northern
part of the quadrangle. The Cutler thins and grain size decreases from north
to south through the quadrangle. South of latitude 36° north the Cutler
changes facies and has been divided into the Abo and Yeso Formations. Source
area for Cutler sediments is believed to be the ancient Uncompaghre Uplift or
San Luis Uplift, located in southern Colorado and northern New Mexico (Baars,
1974; Campbell and Steele-Mallory, 1979).
In the southern part of the quadrangle the Cutler is divided into two
distinct, but gradational, lithologic sequences (basal and upper parts) which
reflect deposition in different sedimentary environments. The basal part of
the Cutler is characterized by buff to red-brown arkose, arkosic sandstone,
and shale and by lesser amounts of gray-green sandstone, gray-green to black
shale, gray-green limestone-pebble conglomerate, and thin nodular limestone
beds. Carbonaceous material, as both finely disseminated and larger
fragments, is found only in the gray-green sandstone, siltstone, shale, and
limestone-pebble conglomerate; it is absent in the red-brown rocks.
The sandstones of the basal part are lenticular in shape, commonly
forming multilateral bodies which have a sheet-like geometry and a high widthto-thickness ratio (Timmer, 1976). Individual sand bodies vary in thickness
from 3 to 13m (10-42 ft). The sandstones are thinly laminated, ripplelaminated, or trough cross-stratified. Soft-sediment deformation features,
which include contorted laminae and ripples and incipient to well developed
ball and pillow structures, are locally common. These features suggest that
deposition took place while the sands were saturated and that sedimentation
was probably rapid.
Sandstone channels are typically enclosed by finer grained, micaceous
sandstone, shales, or siltstone. Mottling of the silty mudstones is common.
Locally the siltstones and shales may contain thin coaly horizons.
The basal part of the Cutler Formation is believed to have been deposited
in a variety of marginal-marine or coastal-plain environments. Ynis
interpretation is based on the recognition of distributary-channel systems
(which have a dominantly southward direction of transport), crevasse-splay
sandstones, and coaly and highly carbonaceous siltstones and shales
representing deposition in poorly drained swamps or on levees. In addition,
sedimentary structures found in these rocks are consistent with those found in
modern marginal marine-fluvial systems.
Throughout the area, sedimentation appears to have been continuous from
Pennsylvanian to Permian time. The base of the Cutler is arbitrarily placed
at the top of the last limestone bed of the Pennsylvanian Madera Limestone
that contains datable marine fossils. Thus, it is conceivable that the basal,
fine-grained sandstone and shale sequence of the Cutler may, in fact, be of
marine origin. At least two upward-coarsening sequences of rocks are present
above the last Pennsylvanian marine limestone. These upward-coarsening
cycles, which terminate with thick, coarser grained, channel sandstones, are
33
indicative of a prograding sequence with a fluctuating shoreline.
The upper part of the Cutler Formation consists of dominantly orange,
medium- to coarse-grained sandstone and mudstone. It was deposited by fluvial
systems on flood plains which were further inland from marginal marine
environments.
A large number of uranium occurrences have been found in the Cutler
Formation in the southern part of the Aztec Quadrangle (Chenoweth, 1974b;
Timmer, 1976; App. A; Pl. 2). The occurrences are concentrated in three
clusters: south of Gallina (Brown, 1955);. near Coyote (Baltz, 1955); and near
Jarosa (Baltz, 1955; Timmer, 1976). In all occurrences examined, the uranium
is in the basal 60 m (200 ft) of the Cutler in a variety of gray-green or
black rock types which have been described above.
The age and extent of uranium mineralization is unknown. All known
uranium occurrences in the Cutler Formation are at the outcrop; the effects of
leaching by ground water subsequent to original deposition are unknown.
Reconnaissance studies of the basal part of the Cutler Formation indicate that
these rocks were originally deposited under reducing conditions~ This
interpretation is based on the remnants of reduced-rock sequences which grade
laterally and vertically into oxidized equivalents. Post depositional
oxidation of the originally reduced sediments by subsequent ground-water flow
has decreased in size the areas of more favorable ground within the Cutler.
Uranium in the Cutler is. associated with copper minerals, vanadium,
hematite, and limonite, and locally silver (Apps. B, C). The uranium was
deposited from ground water in reduced rock that contains sparse to abundant
amounts of fossil carbonized plant matter. At most localities, the manner in
which the uranium occurs is unknown because discreet crystals were not
observed. The uranium may be adsorbed onto the surface of the fossil
carbonized plant matter, iron oxides or clay minerals or it may occur as
individual minerals. At a few localities, yellow to yellow-green, oxidized
uranium minerals were visible. Vizcaino and others (1978) reported the
presence of carnotite and andersonite at two of the prospects.
Using the current criteria of favorability, the Cutler Formation in the
Aztec Quadrangle is considered unfavorable for containing the required minimum
endowment of uranium occurrences totalling 100 metric tons at 0.01 percent
u3o8 or greater. Although many of the occurrences contain the required grade
of uranium, it is doubtful that the aggregate tonnage requirement could be
met. A few of the occurrences have been mined in the past, with tonnages of
mined ore being small (Vizcaino and others, 1978, App. C). Although the
Cutler Formation in the Aztec Quadrangle has been considered unfavorable for
containing the required amount of uranium, it is probable that additional
uranium occurrences are present in the subsurface elsewhere in the quadrangle
where similar marginal marine environments are present. This concept is
reinforced by the presence of uranium occurrences in marginal marine rocks in
the Cutler Formation in the Cortez Quadrangle (Campbell and Steele-Mallory,
1979). Any deposits encountered during subsurface exploration would likely be
34
comparable in size and grade to those found at the surface. It is unlikely
that any single or cluster of deposits would contain the required endowment in
a minable configuration. (J. L. R.)
TRIASSIC FORMATIONS
Members of the Upper Triassic Chinle Formation present in the Aztec
Quadrangle include an upper informal siltstone member, the Petrified Forest
Member, the Poleo Sandstone Lentil, the Salitral Shale Tongue, an informal
sandstone member, and the Agua Zarca Sandstone Member, at the base. The
siltstone member, mostly reddish brown clayey siltstone, is present only in a
small area north of the Jemez Mountains. It is as thick as 70 m (230 ft) near
Ghost Ranch. It grades southwestward into the Petrified Forest Member. The
Petrified Forest Member, with a thickness as great as 215m (710 ft), is the
major unit of the Chinle in this quadrangle. It is indistinguishable from the
Salitral Tongue where the intervening Poleo Sandstone Lentil is missing, and
rests on Permian rocks where the Agua Zarca Sandstone Member and the informal
sandstone member are missing. The Petrified Forest Member consists of
reddish-brown, green, and purple claystones with a few red to light-gray
sandstone lenses. The several sandstone members, at or near the base of the
Chinle, individually reach thicknesses of 30-45 m (100-150 ft), but none is
present everywhere. They consist of red purple, and light-gray to yellowishgray sandstone which includes beds and lenses of conglomerate, siltstone, and
claystone. Deposition was by streams flowing variously to the northeast, to
the northwest, and to the southwest from several highland source areas thought
to have been in southern Arizona, in southern New Mexico, and in the
Uncompaghre Highland in western Colorado.
The Chinle crops out over a rather large area in the southern part of the
Chama Basin, along the west side of San Pedro Mountain, and in the valleys of
Canones and Chavez Creeks (Pl. 10). Although the Chinle thins northeastward
onto a highland source area, it is missing in the northeast part of the
quadrangle, probably largely as a result of post-Chinle erosion. It thickens
in the subsurface in the southwest corner of the quadrangle to over 424 m
(1,400 ft).
In places where the Chinle is thickest, the lower part contains abundant
volcanic material derived from sources to the south. In the Aztec Quadrangle,
however, the lowest units are derived from nearby nonvolcanic sources to the
north and east, and correlate with beds in the well-developed Chinle section
that are nearly at the top of the richly volcanic zone. The high gradient,
with lack of ponding, and consequent high flow-through rate for ground water
in the Chinle in this quadrangle, oxidized the entire Chinle. This destroyed
most of the included organic material and carried any uranium that might have
leached from volcanic-rich beds downdip and out of the quadrangle, thus the
Chinle is considered unfavorable. (R. E. T.)
35
JURASSIC FORMATIONS
Formations of Jurassic age that are considered unfavorable in the Aztec
Quadrangle include, in ascending order, the Entrada Sandstone, Todilto
Limestone~ and the overlying lower member (Ridgley, 1977) of the Morrison
Formation. The general lack of uranium occurrences, radioactivity and
unfavorable lithologies and environments of deposition of these formations
have excluded them from the favorable category.
The Entrada Sandstone (Gilledy and Reeside, 1928) in the Aztec Quadrangle
consists of 18-100 m (60-330 ft) high-angle crossbedded, light-reddish-orange,
medium-to fine-grained, well-rounded to subrounded, well-sorted, quartzose
sandstone and mediu~ to fine-grained, massive to parallel- and ripplelaminated quartzose sandstone. Both facies of the Entrada are interpreted to
represent deposition in arid eolian dune and inland interdune sabkha
environments. Evidence of fluvial deposition in the Entrada is absent. The
composition and texture of the Entrada indicate that its source was preexisting sedimentary rocks (probably the Glen Canyon Group of TriassicJurassic age west of the San Juan Basin).
There are a number of reasons why the Entrada is considered unfavorable
for uranium deposits. First, climatic condi~ions during the deposition of the
Entrada were apparently extremely arid and not conducive to the growth of
vegetation to serve as a source of organic precipitants for uranium. Second,
the Entrada sediments are multicyclic and contain no volcanic constituents for
a good uranium source. Third, no uranium occurrences are known in the Entrada
in the Aztec Quadrangle. It is not considered favorable for uranium deposits
of any size or grade.
The Todilto Limestone (Gregory, 1917) is composed of a lower salinelacustrine limestone facies and an upper gypsum-anhydrite facies that are in
conformable contact with the Entrada and overlying lower member of the
Morrison Formation. The limestone facies is from 0 to 5 m (0-16 ft) thick and
the gypsum-anhydrite facies ranges from 0 to about 30 m (0-100 ft) thick.
Only five occurrences of uranium ore are reported in outcrops of the
Todilto within the Aztec Quadrangle (App. A). In the Grants mineral belt,
where Todilto deposits were first discovered, primary controlling mechanisms
for Todilto deposits are believed to be interstitial organic matter, which
serves as a uranium precipitant and intraformational folds which serve as
depositional sites for uranium in the host rock. In the Aztec Quadrangle,
however, this intraformational folding is not evident from present studies.
Also, most of the Todilto in this quadrangle lies deeply buried in the
subsurface. Exploration is incomplete and data are lacking. For these
reasons, the Todilto is considered unfavorable for deposits that meet the
minimum grade or tonnage requirements. Future exploration, however, may
reveal mineralization in the southwestern part of the Aztec Quadrangle near
the Grants mineral belt.
The lower member (Ridgley, 1977), or Recapture Member (Craig and others,
36
1959), of the Morrison Formation consists of an alternating sequence of thinly
bedded, light-yellow, grayish-white, and reddish-brown quartzose sandstone,
gray limestone, and reddish-brown and green shale and claystone. The
sandstones are fine to very fine grained, well sorted, and subrounded. They
are multicyclic and were primarily deposited with the limestone, shale, and
claystone in a medium- to low-energy, fluvial-lacustrine depositional
environment. Eolian deposition of some of the sandstone beds is apparent.
The lower member neither contains uranium occurrences nor any other
evidence of favorability.· Organic matter incorporated in the sequence is
rare. Background radioactivity is low. In addition, permeability and
porosity conditions are poor, and there is no source for the uranium. Lateral
equivalants of this sequence elsewhere in the San Juan Basin and adjacent
region are also barren of uranium. Therefore, the lower member of the
Morrison (Ridgley, 1977) is considered unfavorable for the occurrence of
uranium deposits. (M. w. G.)
CRETACEOUS FORMATIONS
The Mancos Shale and Lewis Shale represent offshore marine deposition and
have similar lithologies. They consist of medium dark-gray to nearly black,
calcareous claystone, siltstone, and mudstone with a few thin, silty
limestones and bentonic claystones. The Mancos Shale crops out in the Chama
Basin and is present in the subsurface in all of the western half of the Aztec
Quadrangle (Pl. 10). The Lewis Shale crops out in the southwest corner of the
quadrangle and on the margins of the Chama Basin. It is present in the
subsurface in the western half of the quadrangle and in the Chama basin.
Although both the Mancos and Lewis Shales contain a few thin bentonitic
beds that could have been favorable sources for uranium, these units are
considered unfavorable for uranium deposits. Aerial radiometric anomalies
have been detected in the Mancos but these seem to result from the overall
higher radioactivity of the entire formation in relation to the surrounding
area (see discussion on aerial radiometric data). The lack of a suitable
host-rock lithology and the low porosity and permeability of these rocks
inhibit ground-water movement which was required for the concentration of
uranium.
Rocks of the Mesaverde Group are present throughout the western half of
the quadrangle and in the Chama basin. In both areas, the Mesaverde Group
contains several rock units: the Point Lookout Sandstone, the Menefee
Formation, and the Cliff House Sandstone. These unfavorable environments may
be most efficiently discussed by grouping those units with similar
lithologies.
The coal-bearing rock unit of the Mesaverde Group is the Menefee
Formation found in the western third of the quadrangle. The Menefee may be
separated into a upper and lower coal-bearing units. The lithologies of these
units include lenticular, interbedded sandstone, siltstone, carbonaceous
37
shale, and coal.
The noncoal-bearing member of the Menefee is the Allison Member. It is a
continental deposit that is similar in lithology to the coal units except for
a greater amount of sandstone, less carbonaceous shale., and fewer coal beds.
It is present only in the eastern part of the Aztec Quadrangle.
Both the coal and the noncoal-bearing units are considered unfavorable
for uranium deposits for a number of reasons: (1) their poor porosity and
permeability; (2) the discontinous nature of the sandstones, which are
isolated from post-burial ground-water circulation; and (3) the abundant
supply of reducing material throughout the formation, which prevented the
concentration of uranium. In the Aztec Quadrangle, a few reported occurrences
of uranium in the Menefee Formation (App. C) actually occur as placer deposits
in tongues of the Point Lookout Sandstone within the Menefee (Brookins, 1977).
The Point Lookout Sandstone and Cliff House Sandstone of the Mesaverde
Group represent regressive coastal-barrier sandstone deposits. Their
lithology generally is a fine- to very fine grained, well-sorted, calcareous
sandstone. These formations are not considered favorable for uranium
deposition for the following reasons: (1) the high percentage of carbonate
cement; (2) the general fine-grained nature of the sandstone; (3) the lack of
arkosic material; (4) the isolation from ground-water flow after deposition;
and (5) the lack of organic concentrations. Uranium does occur, however, in
the Point Lookout Sandstone as shoreline heavy-mineral placer deposits. The
deposits are very low grade and small.
Overlying the Mesaverde Group formations, the Picture Cliffs Sandstone is
yellowish-brown, medium- to fine-grained, well-sorted, cross-bedded,
regressive marine coastal barrier-sandstone. This unit is not considered as a
favorable environment for many of the same reasons as the Point Lookout and
Cliff House Sandstones. The minor uranium deposits that are found in the
Picture Cliffs are comparable in origin, size and grade to those in the Point
Lookout and Cliff House Sandstones.
The northeast-dipping Fruitland Formation crops out in the extreme
southwest corner of the Aztec Quadrangle and is present in the subsurface
throughout the western half of the quadrangle (Pl. 10). The rock unit
consists of a few thin limestones and interbedded, medium-grained, well-sorted
sandstone, shale, carbonaceous shale, carbonaceous sandstone, siltstone, and
coal. The various rock units of this formation were deposited as a regressive
coastal swamp, river, and floodplain complex (Fassett and Hinds, 1971).
The Fruitland Formation is considered a poor host rock for uranium
deposition because of the generally discontinuous nature of the sandstone, the
isolation from ground-water circulation and the abundance of disseminated
carbonaceous material which would inhibit the concentration of uranium. Past
production from the Fruitland reported in the Shiprock Quadrangle (Green and
others, 1980c, App. C) has been small; uranium occurs in channel lag at the
base of a fluvial channel. However, deposits of this type are generally
38
restricted to thin, small, isolated pods; none is known in the Aztec
Quadrangle.
The Kirtland Formation is present in the subsurface in the western half
of the Aztec Quadrangle; it crops out along the Nacimiento Uplift and in the
southwest corner of the quadrangle (Pl. 10). It consists of two main
lithologies: (1) upper and lower gray shales with thin interbeds of
lenticular fine-grained sandstone; and (2) medium- to fine-grained, poorly
sorted, lenticular sandstone with interbedded shale called the Farmington
Sandstone Member. The depositional environment of the Kirtland Shale is a
coastal-plain sequence with levee, floodplain, and aggrading-stream deposits.
Both lithologies in the Kirtand Shale are considered unfavorable
environments for uranium deposits. The upper and lower shale units lack the
porosity and permeability for ground-water circulation and the interbedded
sandstones are too thin and discontinuous to make suitable host rock. The
Farmington Sandstone Member contains thicker and more continuous sandstones;
however, the transmissivity is greatly reduced by an intergranular clay
content of as much as 20 percent (Fassett and Hinds, 1971). In addition, the
Farmington Sandstone was blocked from post-burial ground-water movement by the
upper and lower shale units.
The Animas Formation crops out along the northern part of the western
limb of the Archuleta Anticlinorium (Pls. 10, lOA). The majority of the
Animas Formation present in the quadrangle is the upper member (Upper
Cretaceous? and Tertiary) which consists of fine- to coarse-grained, fluvial,
conglomeratic, andesitic sandstone beds; scattered, thin, interbedded shale
beds; and thin coal beds. r.~e southern limit of the Animas is uncertain;
however, structural and lithologic relationships indicate a lateral gradation
and interfingering into the Tertiary Nacimiento Formation, with a gradual
compositional change from abundant andesitic material in the north to no
andesitic material in the south (Fassett and Hinds, 1971; Baltz and others,
1966). This indicates that the Animas is a less mature deposit of the same
fluvial system that deposited the Nacimiento Formation.
The predominance of a very permeable conglomeratic coarse grained
andesitic lithology in the Animas Formation and the exposure to oxygenated,
acidic surface waters make this formation a likely source for mobile uranium
but unfavorable for uranium deposition. This is further supported by the lack
of occurrences despite the extensive area of outcrop and substantial
subsurface drilling. It should be noted that the interfingering finer grained
facies of the Nacimiento Formation contains several favorable characteristics
for uranium deposition and is discussed separately under Tertiary FormationsNacimiento Formation. (R. S. Z.)
Dakota Sandstone.
The Dakota Sandstone of Late and Early (?) Cretaceous age in the Aztec
Quadrangle crops out marginal to the San Juan and Chama Basins and is
39
comprises three lithologically distinctive units (Ridgley, 1977). The basal
unit consists predominantly of conglomerate and sandstone. The middle unit is
characterized by sandstone and carbonaceous shales and siltsones. The upper
unit is composed of fine-grained sandstone.
The Dakota was deposited in three somewhat different but transitional
environments. The basal unit was deposited under dominantly fluvial
conditions, whereas the middle unit was deposited in mixed fluvial and
shallow-marine environments. The upper unit was deposited in a variety of
near-shore littoral environments.
Two uranium occurrences are present in the basal unit of the Dakota near
the contact with the underlying Burro Canyon Formation. In that the Burro
Canyon is known to contain uranium deposits, it is likely that the source of
uranium for the Dakota occurrences was the Burro Canyon. Thus, these Dakota
uranium occurrences may be similar to Dakota uranium deposits in the adjacent
Gallup and Albuquerque Quadrangles, which apparently were derived from the
underlying uranium-rich Morrison Formation (Pierson and Green, 1977). The
Dakota Sandstone is not considered favorable for uranium deposits of minimum
grade and tonnage because of the lack of surface and subsurface.evidence for
uranium concentrating processes. Geologically, the formation contains a
limited degree of favorability in that it is similar to the Dakota discussed
in the adjacent Albuquerque and Gallup Quadrangles (Green and others, 1980a,
b). (M. w. G.)
TERTIARY FORMATIONS
Tertiary igneous rocks are found within three distinct volcanic fields,
namely the San Juan, Taos Plateau, and Jemez Mountain Volcanic Fields (Pl.
10C). Although all of these volcanic fields have undergone a similar Tertiary
history, only the Jemez Volcanic Field contains significant uranium
occurrences which are located in the Albuqueruque Quadrangle to the south
(Green and others 1980a, App. C). There are no known uranium occurrences in
the Tertiary volcanics of the Aztec Quadrangle. However, there are a few
hydrogeochemical water and stream-sediment anomalies in samples from drainages
of Tertiary volcanics (see areas V, VI, IX and X on Pls. 4, 4A). The most
concentrated group of anomalous sediment and water samples includes eight
samples along or near Polvadera Creek in the Jemez Volcanic Field. They are
found in drainages of the Tschicoma Formation which contains a number of flows
and pyroclastics. A few other anomalous samples are also found scattered
within the Brazos Uplift area (Pls. 4, 4a). The small uranium concentrations
in these samples and the small numbers of anomalous HSSR samples are not
enough, however, to consider the Tertiary volcanics favorable for uranium
deposits that meet the minimum grade and tonnage requirements. However, these
volcanics may have served as a source for uranium in adjacent favorable
sedimentary formations and environments.
With the exception of the Ojo Alamo Sandstone, which is considered a
favorable environment for uranium deposits, and the Nacimiento and San Jose
40
Formations, which are considered to have limited favorability, other Tertiary
sedimentary rocks of the quadrangle are considered poor potential host rocks
for uranium deposits. These rocks lack significant quantities of organic
material to serve as a uranium precipitant. It is postulated that
insufficient time had elapsed to yield a sufficiently large uranium deposit.
There is a possibility, therefore, that uranium deposits may be forming in
some Tertiary units at the present time. (V. P. B. and P. G. L. S.)
Nacimiento Formation
The Nacimiento Formation crops out in an irregular pattern from near
Cuba, New Mex. on the east side of the San Juan Basin, to the Farmington area
in the northern part of the basin (Pl. 10). It is absent south of this
outcrop belt and in the Chama Basin due either to erosion or nondeposition.
In the northern part of the San Juan Basin, the Nacimiento changes facies and
grades laterally northward into the Animas Formation. The contact between the
Nacimiento and underlying Ojo Alamo Sandstone is gradational and
intertonguing. Tne contact between the Nacimiento and overlying San Jose
Formation is an angular unconformity.
Thickness of the Nacimiento is variable. It ranges from 240-260 m (800850 ft) in the southern part of the outcrop belt to at least 530 m (1750 ft)
in the northern part of the San Juan Basin. This southward thinning is a
result of depositional thinning and pre-Eocene erosion.
Lithologically, the Nacimiento Formation is characterized by two
different, but laterally gradational, facies. In the southern part of the
outcrop belt, the Nacimiento consists of purple, gray, and olive-green clayey
shale and siltstone; lenticular, fine- to coarse-grained sandstone; and
locally it contains thin coaly or lignitic beds. Siltstone and clayey shale
are more abundant than sandstone. Laterally, individual sandstone beds are
wholly enclosed within shale beds; vertically, several fining-upward sequences
of sandstone, siltstone, clayey shale, and coal are present (Baltz, 1967, Fig.
10).
To the north of the southern outcrop belt, the proportion of sandstone in
the formation increases. In this area, the lower part of the formation
consists of thick, fine- to coarse-grained sandstone and interbedded gray and
olive-green carbonaceous shale. Sandstones in this part of the formation
contain coarse angular grains, fine- to medium-grained, well rounded sand, and
rounded pebbles. These constituents represent a mixture of first-cycle
sediments derived from Precambrian rocks and multi-cycle sediments from
Cretaceous and older rocks eroded from the Four Corners Platform and adjacent
areas (Baltz, 1967). The middle part of the formation is characterized by
gray and olive-green shale and lenticular sandstone. The upper part of the
formation contains conglomeratic, coarse-grained, arkosic sandstone
interbedded with gray and olive-green shale. It was derived from highlands to
the north and northeast of the San Juan Basin (Baltz, 1967). This upper
sequence of lithologies is absent farther south as a result of pre-Eocene
41
erosion.
The lower part of the Nacimento Formation was deposited in low energy
fluvial environments at the distal parts of a large alluvial-fan system. The
presence of coal beds indicates that part of the area of deposition was poorly
drained or swampy. Fossil fish, aquatic lizards, crocodiles, and turtles
indicate the presence of lakes. The upper, coarse-grained facies of the
Nacimiento Formation was deposited by somewhat higher energy, fluvial systems
of a separate alluvial fan complex.
Using DOE's criteria for favorability, the Nacimiento Formation is
considered unfavorable in that there is no satisfactory evidence that
processes of uranium concentration could be reasonably expected to have
produced deposits containing the minimum endowment of uranium occurrences
totalling 100 metric tons of at least 0.01 percent U)o 8 • Although the
Nacimento Formation is considered unfavorable by DOE s standards, it does in
fact, exhibit some criteria considered favorable for the occurrence of
uranium. This evaluation is based on the presence of favorable host rock
properties and characteristics, the low dip of the beds and the presence of
reductants in the form of carbonaceous material, and a generally favorable
geologic setting. In addition, there are numerous scattered uranium anomalies
present in the southern and western parts of the outcrop area. These
anomalies have been delineated by hydrogeochemical studies (Pl. 4) and aerial
radiometric studies in this and adjacent quadrangles (Green and others, 1980a,
Pl. 3, Green and others, 1980c, Pl. 3). The radioactivity is associated with
carbonaceous material in limonitic sandstone (Hilpert, 1969) and the source of
the uranium is unknown. The uranium appears to have been deposited from
oxidizing, uraniferous ground water. The lack of known large areas of uranium
mineralization in the Nacimiento Formation suggests that only small amounts of
uranium have been available to the ground-water system.
(J. 1. R.)
San Jose Formation
The San Jose Formation of Eocene age crops out in an irregular pattern
from near Cuba, New Mex., to the area northeast of Farmington, New Mex. (Pl.
10). It is absent south of this outcrop belt and in the Chama Basin due to
erosion and nondeposition. The San Jose is the surface formation in the
north-central part of the San Juan Basin. In this area, the San Jose is
divided into four members. In ascending order, they are the Cuba Mesa Member,
Regina Member, Llaves Member, and Tapicitos Member.
The Cuba Mesa Member crops out in the southern part of the quadrangle and
consists primarily of conglomeratic, arkosic sandstone. The sandstones are
coarse- to very coarse grained and composed of first-cycle subangular quartz
and feldspar grains and chert. Pebbles in the conglomerate range in size from
granule to cobble. They are mainly of quartzite and quartz, but may also be
of granite, chert, and volcanic rock (Baltz, 1967). Silicified and carbonized
logs are common. The sandstones are also cr6ssbedded and form laterally
persistent bodies; individual sand bodies have scour bases. Intertonguing
42
with gray, green, and red shale and thin, friable, white sandstone of the
Regina Member is common. Where shale and sandstone beds of the Regina Member
wedge,out, the Cuba Mesa Member consists of vertically stacked sandbodies
which may be as much as 100 m (328 ft) thick. The sandstones of the Cuba Mesa
Member are stream-channel deposts formed on a large alluvial fan whose source
area was in the Brazos and Sangre de Cristo uplifts to the northeast (Baltz,
1967).
The Regina Member consists of a thick sequence of clayey shale and
siltstone, friable to indurated sandstone, and local ash beds. Carbonaceous
material occurs both as fragments and disseminations and is locally abundant,
especially in the finer grained facies. Shaly beds in the basal part of the
formation are typically gray, tan, or olive gray, and those in the upper part
are pale red to maroon. Sandstones are white, buff, gray or brown in color
and are lenticular in shape. The Regina Member was deposited in fluvial and
lacustrine environments. Fossil fauna from the lower part of the member
indicate the presence of swampy conditions and those from the upper part are
indicative of savanna-like conditions. Intertonguing of the Regina Member
with the underlying Cuba Mesa Member and with the overlying Llaves Member is
common. Along the east side of the San Juan Basin, the Regina Member
unconformably overlies the Cuba Mesa Member. This unconformable relation is
confined to the basin margin and is related to tectonic events associated with
the emergence of the Nacimiento uplift. Much of the Regina Member consists of
detritus of Cretaceous and older rocks which were eroded from the Nacimiento
uplift (Baltz, 1967).
The Llaves Member is composed mainly of massive, arkosic, conglomeratic
sandstone and minor amounts of red and variegated shale and sandstone. The
sandstones are buff, tan, or gray in color and composed of first-cycle,
angular to subangular quartz and feldspar grains. They are crossbedded and
lenticular in shape. Individual channels merge laterally, forming persistent
sandstone bodies having a sheet-like geometry. Pebbles in the conglomerate
are well rounded, and consist of metaquartzite, granite, gneiss, schist,
chert, volcanic rock, sandstone, or shale. The Llaves Member consists of
fluvial sediments deposited on a large northwest-trending alluvial-fan system
whose source area was in the vicinity of the Brazos Uplift (Baltz, 1967). The
direction of transport was determined by a decrease in grain size from east to
west across the north-central part of the San Juan Basin and by the
composition of the granitic pebbles. The composition of these pebbles is
similar to that of granites of the Brazos Uplift and unlike that of granites
in the Nacimiento Mountains.
Along the southern margin of the fan system, coarse clastics of the
Llaves Member interfinger with finer sediments of the Regina Member (a partial
lateral equivalent), whose source area was in the Nacimiento Uplift, and with
the overlying Tapicitos Member. Along the northern margin of the fan, coarse
clastics of the Llaves intertongue with finer sediments of the unnamed shale
and sandstone sequence, whose source area was most likely the San Juan Dome,
located in southwestern Colorado (Baltz, 1967). \~ere the Regina Member
wedges out to the north, the Llaves Member conformably overlies the Cuba Mesa
43
Member. In the northern part of the area, the lower part of the Llaves
interfingers laterally with an unnamed shale and sandstone sequence that is
similar in lithology and stratigraphic position to the Regina Member (Baltz,
1967).
The Tapicitos Member is composed of red, maroon, and variegated shale,
siltstone, and mudstone, and intercalated beds of friable white and yellow
sandstone. The sandstones are coarse grained, locally conglomeratic,
crossbedded, and lenticular in shape. Many are similar in composition to
sandstones of the Llaves Member. From its outcrop area in the north-central
part of the San Juan Basin, the Tapicitos interfingers laterally to the east
and north with the upper part of the Llaves Member. The Tapicitos consists of
stream-channel and flood-plain deposits formed along the western margin of the
same fan system that deposited the coarser facies of the Llaves Member to the
east (Baltz, 1967).
A small number of uranium anomalies in the San Jose Formation have been
delineated by field reconnaissance and hydrogeochemical studies (App. A, Pl.
4). Preliminary results of the aerial radiometric survey also indicate the
presence of one radioactivity anomaly in the San Jose Formation along the east
side of the San Juan Basin (Pl. 3).
At the outcrop, radioactivity is associated with lignite and carbonaceous
material and with limonite staining. Alteration of the host rock includes
oxidation of iron-bearing minerals and alteration of feldspar to kaolinite.
The uranium appears to be locally confined to low-energy fluvial rocks
deposited in poorly drained environments, such as those found in swamps or
lakes. The association of uranium with carbonaceous material suggests that
locally reducing conditions in the vicinity of the carbonaceous trash was
sufficient to precipitate uranium from the ground water.
Using the DOE's criteria for favorability, the San Jose is not considered
favorable. This evaluation is based on the lack of any known large
radioactivity anomalies at the surface and in the subsurface. Most of the
radioactive anomalies detected were on the order of 2-3 times background.
There is no satisfactory evidence that the processes of uranium concentration
could be expected to have produced deposits of the minimum required grade and
tonnage and no economic deposits are present.
In spite of the lack of evidence for mineralizing processes, the San Jose
does exhibit many geologic characteristics of a favorable host rock. Some of
these characteristics include: (1) the presence of first-cycle sediments
deposited above an unconformity; (2) the presence of laterally persistent
sandstone beds possessing good permeability; (3) the presence of carbonaceous
material to act as a reductant; and (4) a generally favorable geologic
setting. The lack of large radioactive anomalies may reflect low
concentrations of uranium in the system. The subsurface of the San Jose
remains essentially unevaluated for uranium. If uranium deposits do exist in
the subsurface, it is speculated that they would be similar in type and origin
to those found in the Ojo Alamo. (J. L. R.)
44
QUATERNARY VOLCANIC ROCKS
Quaternary volcanic rocks are located in small outcrops within the
eastern portion of the Aztec Quadrangle (Pl. 10). They include an old basalt
unit, a rhyolite-tuff-rhyolite flow sequence, and a younger basalt unit.
There is no evidence to indicate the presence of uranium occurrences that
would meet the minimum grade-tonnage specifications. (P.G.L.S.)
UNEVALUATED ENVIRONMENTS
With the exception of unconsolidated surficial deposits and part of the
Burro Canyon(?) Formation, all formations and environments in the Aztec
Quadrangle were evaluated to a depth of 1500 m (5000 ft) as specified in the
terms of the contract with DOE and insofar as available data and time have
allowed. Evaluations were restricted in some areas by the lack of subsurface
data and the reluctance of some property owners to have surveys conducted on
their lands. In addition, some of the evaluation has been hampered by the
late arrival of HSSR and aerial radiometric data. As a result, field checking
of parts of these data was not completed. Ho\vever, t~e areal extent of
exposure of most of the formations and environments is great enough for a
relatively complete evaluation using field geologic methods.
Also unevaluated is that portion of the Burro Canyon(?) Formation present
in the subsurface in the northern and central parts of t~e Chama Basin. In
these areas the Burro Canyon(?) remains essentially unevaluated due primarily
to the lack of drilling information. (M. w. G.)
AERIAL RADIOMETRIC DATA
The airborne gamma-ray spectrometer and magnetometer survey for the Aztec
Quadrangle was conducted by Aero Service Division of Western Geophysical
Company of America during the winter of 1979. Preliminary flight-line
profiles were received by the USGS in January 1980 for preliminary quadrangle
evaluation. Plate 3 is a preliminary analysis by USGS personnel. Final
copies of company analyses and reports will be released when available.
The analysis of aerial radiometric data of the Aztec Quadrangle was made
by visual inspection of the raw-data flight-line profiles. No statistical
manipulations were performed. Criteria used to place locations of anomalies
on flight lines on Plate 3 were: (1) high peaks in the Bi, Bi/Th, and Bi/K
profiles; and (2) corresponding low areas in the Th, K, and Th/K profiles.
Much of the Aztec Quadrangle had relatively high background radiation
levels. High intensity peaks were rare, but there were some peaks that
plotted in the Mancos Shale that were broad and covered a relatively large
area. Those peaks indicate the presence of anomalous uranium within the
sedimentary rocks of the Colorado Plateau geologic province. The results of
45
this preliminary analysis show two general clusters of anomalies (Pl. 3). One
is in the Mancos Shale of the Archuleta Arch and Chama Basin regions, and the
other is in the Precambrian rocks of the Nacimiento uplift. Only the latter
are associated with any known occurrences. Other very scattered anomalies
that may also be of interest do occur (Pl. 3). However, the data arrived too
late to be field checked and statistically analyzed before the stated
completion date of the folio.
(P. G. L. S.)
INTERPRETATION OF HYDROGEOCHEMICAL AND STREAM-SEDIMENT
RECONNAISSANCE DATA
Raw data for the Aztec Quadrangle's hydrogeochemical and stream-sediment
reconnaissance were obtained from Los Alamos Scientific Laboratories (Bolivar,
1978) and were analyzed by USGS personnel to determine anomalous areas of
uranium concentration. The analysis procedure differed significantly from the
analysis used by LASL in Bolivar's report.
The results of the statistical analysis described in procedures section
for each drainage and/or geologic area are shown on Tables 1 and la. Plate 4
is an interpretative map of anomalous values for stream-sediment and water
samples based on each statistical and geologic area; Plate 4A also contains
anomalous values of water samples based on the uranium to conductivity ratio
for the eleven separate areas.
~~ny of the anomalous sediment samples occur in drainages of the Tertiary
San Jose Formation within the San Juan Basin. Very few are associated with
uranium occurrences, and anomalous values appeared evenly scattered throughout
the eastern half of the quadrangle. There are few anomalous stream-sediment
samples either associated with known uranium occurrences or located downstream
from them.
Because the data were received too late to analyze completely
before the end of field season, no anomalous samples were field checked.
Therefore, more study needs to be done in this area to determine the
significance of these anomalies.
The water samples were analyzed for uranium to conductivity ratios (Table
1a, Plate 4A). High ratio values occurred in stream water, ground water and
lake water. The high values correlated with high values in sediment
samples. High uranium to conductivity ratios in stream water were in close
proximity to the Precambrian rocks in the San Pedro Mountains and Brazos
Peak. Ground-water samples showed high values in the Tertiary sediments of
the San Juan Basin and in the volcanic Tertiary units. Two anomalous lake
water samples were in Cretaceous sediments of the Mesaverde Group and the
Kirtland Shale. Again, none of these anomalies was field checked because the
data arrived after the field season was completed. (P. G. L. s.)
46
Table 1.
Area
No. of
Samples
Mean
(ppm Ur)
Summary HSSR Data
Standard
Deviation
lL
(Sediment Samples), Aztec 1° x 2° Quadrangle
Variance
Range
(ppm Ur)
Drainage or geologic area
Anomalous Uranium
Concentration
Values (>2 Std Dev.)
- --
I
II
36
128
5.7
4.1
3.09
2.8
9.3
8.0
2.5 - 15.8
1.5- 30.00
+:---.1
III
IV
694
347
4.99
3.66
2.31
.83
5.3
.7
.l - 23.2
1.5- 7.0
v
30
4.19
2.15
4.6
2.2 -14.3
VI
128
3.49
.89
.8
1.6- 7.4
Drainage off Nacimiento Fm
and San Jose Fm. (Tertiary)
into Animas River
>11.91 ppm
Drainage off Nacimiento Fm and
some Kirtland - Fruitland
Shale (Cretaceous) into Kimbeto,
Betonnie-Tsosie, Escavada and
Chaco Washes
> 9.7 ppm
Drainage off Nacimiento Fm
and San Jose Fm into
San Juan River
> 9.51 ppm
Drainage off variety of
Cretaceous sediments into
Rio Chama
> 5.32 ppm
Drainage off Tertiary volcanics
into Rio Brazos
Drainage off Precambrian and
Tertiary volcanics into
Rio Tusas
> 8.49 ppm
> 5.3 ppm
Table 1.
Area
No. of
Samples
He an
(ppm Ur)
Summary HSSR Data
Standard
Deviation
!L
Variance
(Sediment Samples) (Continued)
Range
(ppm Ur)
Drainage or geologic area
Anomalous Uranium
Concentration
Values (>2 Std Dev.)
----
VII
VIII
20
148
3.53
3.39
.62
1. 53
.4
2.3
2.7 - 5.8
1.4 - ll.O
+:-
Drainage off San Jose Fm
(Tertiary) into Rio Gallina
(east of Continental Divide)
> 4.77 ppm
Drainage off of a variety of
sediments from Pennian to
Cretaceous in age into the
Rio Chama
) 6.45 ppm
Drainage off Precambrian and
Tertiary volcanics into
Rio Chama
) 6.15 ppm
Drainage off of San Jose
sediments flowing south to
to Rio Puerco
) 7.49 ppm
co
IX
X
XI
!J
-
133
46
27
3.25
4.33
4.10
1.45
1.58
1.18
2.1
2.5
1.4
1.4 - 11.8
2.3 - 10.40
2.0- 7.8
Drainage off of Precambrian
Tertiary volcanics flowing
south to Rio de las Vecas and
Raw data from Uranium Hydrogeochemical and Stream Sediment Reconnaissance of the Aztec NTHS Quadrangle, New Hexico:
Los Alamos Scientific Labortories LA-7238-HS
Table la.
Area
No. of
Samples
Summary of HSSR Data 1/ \Hater Samples)
Aztec 1° x 2° Quadrangle (Uranium/Conductivity) x 1000 Values
Mean Ratio
Uranium/
Conductivity
X
Standard
Deviation
1000
---
--
--- ·-
- -
Variance
--·--~------------
Range of
ratios
Drainage or geologic area
----·----
I
0
II
27
2.24
2.38
4.77
.02 - 21.43*
Drainage off Nacimiento Fm and
some Kirtland - Fruitland
Shale (Cretaceous) into Kimbeto,
Betonnie-Tsosie, Escavada and
Chaco \<lashes
III
138
1.38
1.52
2.32
.01 - 41.9*
Drainage off Nacimiento Fm and
San Jose Fm into San Juan River
IV
16
l. 76
1.28
1.64
.18 - 4.27
Drainage off variety of
Cretaceous sediments into
Rio Chama
v
23
2.37
1.84
3.39
.47 - 32.05*
Drainage off Tertiary volcanics
into Rio Brazos
VI
36
2.21
1.97
3.92
.18 - 13.28*
Drainage off Precambrian and
Tertiary volcanics into
.p'-0
wiped out a line
Table la.
No. of
Samples
Area
VII
2
VIII
46
IX
X
\..n
0
XI
18
Summary of HSSR Data ]J_ (Water Samples) (Continued)
Mean Ratio
Uranium/
Conductivity
X 1000
2.3
1.78
Standard
Deviation
1.42
1.04
Variance
2.03
1.09
Range of
ratios
Drainage or geologic area
18.77-44.11
Drainage off San Jose Fm
(Tertiary) into Rio Gallina
(east of Continental Divide)
.28 - 75.80*
Drainage off of a variety of
.66 - 38.52*
Drainage off Precambrian and
Tertiary volcanics into
Rio Chama
10
2.04
2.05
4.20
.11 - 5.97
Drainage off of San Jose
sediments flowing south to
Rio Puerco
ll
2.7
1.9
3.67
.25 - 15.62*
Drainage off of Precambrian
and Tertiary volcanics flowing
south to Rio de las Vecas and
Rio Puerco
_/
Raw data from Uranium Hydrogeochemical and Stream Sediment Reconnaissance of the Aztec NTMS Quadrangle, New Mexico:
Los Alamos Scientific Laboratories Rept. LA-7238 - MS
J:j
Statistics performed on Uranium/Conductivity x 1000 Values.
Extrem~ly
high ratios not figured in statistics
INTERPRETATION OF U.S. GEOLOGICAL SURVEY
HYDROGEOCHEMICAL DATA
STRE&~-SEDIMENT &~
In the winter of 1978 and spring of 1979, a geochemical survey was
conducted in selected areas of the Aztec Quadrangle. The primary objective
was to identify areas that possibly contain anomalous concentrations of
uranium.
This study incorporates the results of analyses for uranium from stream
sediment, and ground and surface water samples. The samples were collected by
members of the USGS and analyzed under contract by GEOCO, Inc., Wheatridge,
Colorado.
Hydrogeochemical and stream sediment sampling was conducted in the
quadrangle by both the USGS and the Los Alamos Scientific Laboratory (LASL),
under the auspices of the 1fURE Program. Both geochemical surveys were made
independently. Stream-sediment and water samples were collected over the
entire quadrangle by LASL. These samples were analyzed for uranium by
delayed-neutron counting and fluorometry, and the results are contained in a
report by Bolivar, (1978). The original intent was that USGS geochemical
sampling would be conducted as a followup to the LASL survey and would be
confined to areas of apparent uranium anomalies delineated by the LASL data.
The LASL data, however, was not available in time to serve as a basis for the
USGS sampling. USGS geochemical sampling was confined to selected outcrop
areas of Tertiary sedimentary rocks, which include localities of apparent
uranium enrichment delineated by the LASL data.
Two areas in this quadrangle were sampled by USGS. In the eastern part
of the quadrangle, stream-sediment and water samples were obtained following
procedures described previously from outcrop areas of the Tertiary Santa Fe
Group and the Servilleta Formation. In the western part of the quadrangle,
stream-sediment and water samples were obtained from outcrop areas of the.
Tertiary San Jose Formation, the Nacimiento Formation, and the Ojo Alamo
Sandstone.
The areal distribution and relative concentrations of uranium in streamsediment and water samples are shown on Plates 4B, C, and D. Each plate
contains an accompanying histogram and cumulative frequency probability plot
of the distribution of uranium concentration in the sample media. Uranium
values are represented by symbols on the map and have been grouped into
specific class intervals based on a logarithmic scale. The symbols and their
range of values are annotated on the histogram and cumulative frequency
probability plots. A graphical representation of analytical values,
categorized into specific class intervals, permits easy observation of large
variations in geographically clustered sample analyses and results in a
smoothing of the data.
51
For the purpose of statistical evaluation, stream sediment samples have
been treated as one group, and are considered to reflect source-rock type and
character. The sediment samples were collected from outcrop areas of
previously described Tertiary sedimentary rocks.
The distribution and relative concentration of uranium, measured in parts
per million (ppm), in sediments collected from streams draining areas of the
Tertiary sedimentary units is shown on Plate 4B~ Stream-sediment sample
numbers and locations are shown on Plates 5B and c. Two separate location
maps are necessary because of the large number of samples involved. The
sample localities are confined to two areas, one in the southeast corner of
the quadrangle, and one in the western part of the quadrangle. The results of
analyses, field data, and the coordinate locations of samples collected in
these areas are given in Appendix B2. An explanation of the codes used in the
columnar entries of Appendix B2 is included.
A summary of all elements detected in sieved stream-sediment samples,
collected from outcrop areas of the Tertiary sedimentary units, .is given in
Table 2. The following elements were also analyzed for, but were either not
detected or were detected at a concentration less than the lower limit of
detection (in parentheses): As (200 ppm), Au (10 ppm), Bi (10 ppm), Cd (20
ppm), Li (100 ppm), Sb (100 ppm), and W (50 ppm).
A complete statistical summary of selected geochemical data from streamsediment samples collected by the USGS is given in Appendix B4.
A comparison of the median value for uranium of 1.0 ppm in Table 2, with
the arithmetic mean of 1.89 ppm and geometric mean of 1.60 ppm, suggests that
the uranium concentration in stream-sediment samples from outcrop areas of
Tertiary sedimentary rocks is lognormally distributed. The histogram and
cumulative frequency distribution diagrams for uranium concentration in
sedments collected from the Aztec Quadrangle (Pl. 4B), suggest a bimodal
distribution and the possibility that at least two intermixed sample
populations are present •. This conclusion may be more induced than real,
because of the large number of samples with uranium concentrations below the
lower limit of detection. The lumping of samples with uranium values below
the detection limit into one class biases the data. It is probable, however,
that the grouping of stream-sediment samples, obtained from relatively diverse
lithologic units into one data set also influences the statistical
distribution. If the stream-sediment samples are treated as a single
population, and ~f the threshold value between anomalous and background values
is placed at two geometric deviations above the geometric mean, then streamsediment samples containing more than 4.57 ppm uranium may be significantly
anomalous.
52
Table 2.--Summary of element concentrations in <170-mesh (88-micron)
stream sediment samples collected from outcrop areas of
Tertiary sedimentary units, Aztec Quadrangle
Element
Minimum
Maximum
Median
Mean
Standard
Deviation
Geometric
Mean
Geometric
Deviation
Data in percent
Al
3
7
7
6.57
0.69
6.53
1.13
Fe
1
15
2
2.66
1.22
2.46
1.45
Mg
0.1
1.5
0.3
0.43
0.21
0.38
1.58
Ca
0.1
7
0.7
0.82
0.55
o. 72
1.62
Na
0.3
7
1.5
1.66
0.49
1. 59
1.38
0.5
0.46
0.18
0.43
1.46
Ti
L(.002)
G(l)
Data in parts per million
u
L(l)
Mn
100
As
N(0.5)
18
2,000
2
50
1.89
1.56
1.60
1.69
470.89
181.48
436.26
1.50
0.75
0.61
0.63
1.76
15
15.28
5.66
14.58
1.33
700
943 .5"'0
381.7 4
881.43
1.44
1.00
500
N(0.5)
B
N(lO)
Ba
100
Be
1
30
3
4.38
4.01
3.35
1.96
Co
5
70
15
12.87
3.69
12.39
1.33
Cr
20
500
70
86.65
43.40
78.39
1.55
Cu
5
150
15
18.46
10.18
16.77
1.52
La
20
500
100
115.26
64.55
102.15
1.62
Mo
N(5)
100
N(5)
26.00
41.59
11.34
3.69
Nb
N(lO)
100
N(lO)
13.93
7.80
12.68
1.48
Ni
N(5)
70
21.50
8.53
19.93
1.49
G(5000)
20
53
Table 2.--Summary of element concentrations in <170-mesh (88-micron)
stream sediment samples collected from outcrop areas of
Tertiary sedimentary units, Aztec Quadrangle (Continued)
Pb
10
70
50
43.84
13.12
41.83
1.37
Sc
N(5)
50
15
15.26
5.95
14.20
1.47
Sn
N(lO)
50
N(lO)
15.92
8.21
14.45
1.52
Sr
L(lOO)
1000
300
290.97
149.29
260.29
1.60
Th
N(lOO)
150
N(lOO)
101.82
9.45
101.49
1.08
v
15
700
70
89.92
49.97
78.30
1. 73
y
10
500
70
65.47
41.62
55.49
1.83
233.33
48.80
228.94
1.22
586.55
262.83
516.88
1. 72
Zn
Zr
N(200)
50
300
G(lOOO)
N(200)
700
N--not detected at the lower limit of determination, in parantheses.
L--detected, but below the lower limit of determination, in parantheses.
G--detected, but at a value greater than the upper limit of determination, in
parentheses.
54
Geochemistry of ground and surface waters
For the purpose of statistical evaluation, ground and surface water
samples collected in the hydrogeochemical sampling program in the Aztec
Quadrangle have been treated as one population. The ground and surface waters
were combined into one population because of the sparse su~face-water sample
coverage, which is directly attributable to the lack of available surface
waters throughout the quadrangle. A total of 180 ground-water and 6 surfacewater samples were obtained. Although the uranium data for water samples from
ground and surface sources are not strictly comparable, the mixing of the
populations does not unduly influence the statistical data. It is possible to
detect any surface water samples containing anomalous concentrations of
uranium by the normalization of uranium content with conductivity.
The distribution and relative concentration of uranium, measured in parts
per billion (ppb), in ground and surface waters, is shown on Plate 4C,
together with a histogram, a cumulative frequency probability plot, and other
statistical parameters. Sample numbers and locations are shown on Plate SD.
If available, water samples were collected in the same areas as streamsediment samples. The results of analyses, field data, and the coordinate
locations of samples collected in these areas are given in Appendix B-3, under
the headings of "Ground Water" and "Surface Water." An explanation of the
codes used in the columnar entries of Appendix B3 is included.
A summary of the chemical analyses and measured physical parameters of
water samples is given in Table 3. Phosphate, (P0 4 ), was also analyzed for by
ion chromatography, but >vas generally not detected or \vas detected at levels
lower than the lower limit of detection of 1 mg/L.
A complete statistical summary of selected geochemical data from water
samples is given in Appendix B4.
Ground- and surface-water samples were normalized for comparative
purposes by multiplying the uranium concentration in ppb times 1000, and
dividing by conductivity (micromhos/cm). This procedure has the effect of
normalizing the data in samples collected from different sources, and
correcting for dilution effects, by giving a measure of the uranium content
compared to the total amount of dissolved material in solution. The
distribution and relative concentration of uranium in water samples,
normalized by conductivity, is shown on Plate 4D, together with a histogram, a
cumulative frequency probability plot and other statistical parameters. Those
samples whose uranium content was below the lower limit of detection have not
been included in the normalized data set. The locations of these samples are
indicated on Plate 4D, using the letter L to denote uranium concentrations
which are below the lower limit of detection. Sample MBD 530, located near
Black Mesa, contains the highest normalized uranium content of all water
samples collected in the quadrangle. The sample was obtained from a domestic
drinking-water well. Tne conductivity measurement for this sample is
abnormally low, which suggests an error in measurement or possibility of a
deionization system being present. For these reasons the sample is omitted
55
Table 3.--Summary of chemical analyses and physical parameters in
ground and surface water samples, Aztec Quadrangle
Minimum
u ( g/liter)
!1aximum
1(.05)
Mean
Median
Standard Geometric
mean
deviation
Geometric
deviation
44.00
4.00
6.60
7.87
3.74
163.80
421.65
769.72
166.86
18.38
19.96
11.08
3.07
S04 (mg/liter)
4.40
L(l)
7,873.70
N03 (mg/liter)
2.94
N(l)
106.20
Alkalinity (mg/liter)
1.88
1(7)
1,040.00
283.00
293.21
148.69
251.25
L(l)
Temperature (oC)
1.59
0.50
25.00
13.00
l3 .01
4.11
12.06
pH
5.00
10.60
7.80
7.84
0.88
7.79
64.00 17,500.00
1,100.00
1,499.29
1,584.28
1,118.50
1.12
Conductivity ( mhos/ em)
2.14
Dissolved oxygen (ppm)
1.64
1.20
25.00
5.30
5.98
3.01
5.32
Ux1000/cond
3.05
0.15
93.75
3.33
6.10
8.99
3.32
N--not detected at the lower limit of determination, in parentheses.
L--detected, but below the lower limit of determination, in parentheses.
G--detected, but at a value greater than the upper limit of determination, in
parentheses.
Analyses for S04, N03, and P04 by H. C. Day, U.S. Geological Survey.
56
from any further consideration.
A comparison of the median value for uranium of 4.00 ppb in Table 3, with
the arithmetic mean of 6.60 ppb and the geometric mean of 3.74 ppb, suggests
that the uranium concentration in water samples is lognormally distributed.
This same conclusion appears true for the uranium concentration normalized by
conductivity, the median and geometric means being 3.33 and 3.32
respectively. The semilogarithmic histogram and the cumulative frequency
probability plot for uranium in water samples, shown on Plate 4C, strongly
suggests a single-sample population. This is substantiated by the close
correspondence between median and geometric mean uranium values. If the
threshold value between anomalous and background values is placed at two
geometric deviations above the geometric mean, then water samples containing
more than 35 ppb uranium may be significantly anomalous, and samples
containing uranium values in the range 20-35 ppb may be considered marginal or
weakly anomalous.
The histogram and cumulative frequencey probability plots for uranium
concentration in water samples, normalized by conductivity, shown on Plate 4D,
substantiate the presence of a single sample population. A clearly defined
break in slope occurs at 20 Ux1000/conductivity values, on the cumulative
frequency probability plot. If the threshold value between anomalous and
background values is placed at two geometric deviations above the geometric
mean, then water samples containing more than 31 normalized uranium units may
be significantly anomalous, and samples containing normalized uranium values
in the range 20 to 31 units may be considered marginal or weakly anomalous.
Interuretation of results
The LASL and USGS geochemical data show a similar distribution of uranium
within geographic localities. A generally close correspondence exists between
the analytical results obtained by the USGS and by LASL for water samples from
the same areas. There are, however, some differences in the relative
concentration of uranium in stream-sediment samples from the same
localities. The uranium concentration reported by LASL is generally higher
than the uranium values obtained by the USGS. This suggests the delayedneutron counting analytical method employed by LASL detects total uranium,
whereas the USGS method of analysis, by extraction fluorometry, detects only
partial uranium. The difference may be attributable to the presence of
uranium-bearing refractory or resistate type minerals, such as zircon, from
which the uranium is not totally extracted in the fluorometric method. The
LASL data contain analyses of stream-sediment samples obtained from multiple
rock types and assemblages. The data in Bolivar (1978), have been treated as
one statistical population on the uranium concentration distribution map.
This results in high uranium concentrations contained in refractory minerals
in stream-sediment samples from specific areas overwhelming any potentially
anomalous concentrations of uranium contained in stream sediments from the
other areas. If the LASL data is separated into populations representative of
source rock type, statistical treatment will produce information of value in
57
any existing areas of uranium enrichment
At the 95-percent confidence level, analyses of sediments collected from
streams draining outcrop areas of the Tertiary sedimentary units show a
statistically significant correlation of uranium with Fe, Ti, Mn, B, Ba, Cr,
La, Nb, Sc, Sn, V, Y, and Zr. This assemblage strongly suggests the close
association of uranium with resistate or refractory-type heavy minerals such
as zircon, monazite, xenotime, samarskite, and euxinite, in stream sediments
from Tertiary sedimentary units in the Aztec Quadrangle. At the 95-percent
confidence level, surface- and ground-water samples collected throughout the
quadrangle show a statistically significant correlation between uranium and
conductivity, alkalinity, sulfate, and nitrate. The correlation between
uranium in water and sulfate suggests the oxidation and leaching of uraniumbearing sediments containing disseminated pyrite by oxygenated ground
waters. The correlation between uranium and nitrate may be more coincidental
than real, and suggests the possibility of the contamination of ground water
in the Aztec Quadrangle by the application of agricultural fertilizers. There
is no correlation between uranium and phosphate content, the latter being
detected in only one water sample.
Interpretation of geochemical data resulting from a stream-sediment and
hydrogeochemical survey conducted in the Aztec Quadrangle is based on an
integration of available statistic? established for all sample media. The
interpretation is subjective. Threshold values of uranium between anomalous
and background concentrations in both stream-sediment and water samples have
been utilized in defining areas of possible uranium enrichment.
Within the limitations of the geochemical survey conducted by the USGS in
selected areas of Aztec Quadrangle, 17 stream-sediment and 11 ground-water
samples appear to contain anomalous or slightly enriched concentrations of
uranium. The locations of these samples are shown on Plate 4E. In general,
the uranium concentration in stream-sediment samples is relatively low, but is
considered to be above the background level established for stream-sediment
samples in this area. At each locality, the sample type, sample number, well
depth if relevent and available, and the concentration of uranium and/or
normalized uranium is given.
The stream-sediment and ground-water samples considered to be enriched in
uranium are widely scattered throughout the sampling area. No geographic
clustering of anomalous values is evident, rather they exist as isolated
occurrences. With the exception of samples MBD 447 and MBD 807, the remaining
15 stream-sediment samples enriched in uranium, are also enriched in Zr, Y,
La, Nb, Cr, and Ti. Thorium was detected in eight of these samples. This
suggests that the uranium in the 15 stream-sediment samples is probably
contained in, or associated with, uranium-bearing heavy minerals. Of the 11
ground-water samples considered to be enriched in uranium, only samples MBD
513, 562, 604, and 987 contain significantly anomalous concentrations.
In summary, a few isolated and widely scattered stream-sediment and
ground-water samples appear to be enriched in uranium. These isolated
58
occurrences may warrant additional investigation. In most instances,
the uranium enrichment detected in stream-sediment samples appears to
with, and be related to, the presence of resistate or refractory-type
minerals. The overall results of the USGS geochemical survey, in the
Quadrangle, suggest low favorability for any significant accumulation
uranium in Tertiary sedimentary units. (K. R., R. F. D., M. R. S.)
however,
coincide
heavy
Aztec
of
GEOCHEMICAL DATA
Rock sample analyses are found in Appendix Bl. Uranium and thorium were
analyzed by delayed neutron activation. The remaining elements were analyzed
by emission spectrometry. The table is organized into two parts: (1) Basic
information about the samples, and (2) the analytical results. Analyses are
reported to two significant figures. These results arrived too late, however,
to be analyzed by USGS personnel for the folio deadline. (M. w. G.)
RECOMMENDATIONS TO IMPROVE EVALUATIONS
Potential uranium host rocks in the Aztec Quadrangle are the least
adequately explored of any potential host rocks in the San Juan Basin. In
order to obtain the data for evaluation, a long-range (3-5 years) scientific
research program is necessary. This research must include the geochemistry of
uranium, sedimentology and stratigraphy of host rocks, evaluation of probable
sources of uranium in the area, and the drilling of these host rock units.
Future assessment of uranium potential of the Burro Canyon(?) Formation
in the unevaluated portion of the basin should take the form of testing the
subsurface along the east part of the basin, adjacent but basinward to the
Brazos uplift.
If the theory of the origin of mineralization, based on the reltionship
of the Abiquiu Tuff to truncated beds of the Dakota Sandstone and Burro
Canyon(?) and Morrison Formations, is valid then these may be places where
such relationships are duplicated. Places where the Abiquiu Tuff or the
partially equivalent Los Pinos Formation come in contact with the DakotaMorrison rocks should be examined closely. Oxidized outcrops of MorrisonDakota rocks should be evaluated for the possibility of '~yoming" roll-type
uranium deposits in the subsurface.
The presence of the intervening El Rito Formation should be noted and
would probably decrease the potential for finding additional roll-type uranium
deposits on the east side of the basin. If the Bandelier Tuff was the source
for uranium, it is highly unlikely that any additional uranium deposits will
be found in the unevaluated part of the basin. This evaluation is based on
the premise that the original distribution of the Bandelier Tuff was confined
to areas adjacent to the Jemez Volcanic Field, although in reality the
59
original distribution is unknown.
Additional studies will be necessary in order to resolve some of the
problems of age of mineralization and origin of uranium previously
mentioned. Studies are underway to try to date some of the ore pods. Results
may be useful in relating mineralization to tectonic history and possible
source rocks. Additional field and geochemical studies are necessary in order
to evaluate the theory that the Abiquiu Tuff was the source ot uranium. (M.
W. G., J. L. R.)
60
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-----~1968b,
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.Santos, E. s., Hall, R. B., and Weisner, R. c., 1975, Mineral resources of the
San Pedro Parks \.Jilderness and vicinity, Rio Arriba and Sandoval
counties, Ne~• Hexico: u.s. Geol. Survey Bull. 1385-C, 29 P•
Saucier, A. E., 1974, Stratigraphy and uranium potential of the Burro Canyon
Formation in the southern Chama Basin, New Mexico, in Ghost Ranch,
Central-Northern New Mexico: New Mexico Geol. Soc. Guidebook, 25th Field
Conf., P• 211-217.
1976, Tectonic influence on uraniferous trends in the
---Harrison
Formation, in Tectonics and mineral resources
North America:
Late Jurassic
oE southwestern
New Hexico Geol. Soc. Spec. Pub. 6, P• 151-157.
Scott, G. R., 1978, Unpublished photogeologic map of Ojo Encina Mesa and
Starlake quadrangles New Mexico: u.s. Geol. Survey map, scale 1:24,000.
Sears, J. D., Hunt, c. B., and Hendricks, T. A., 1941, Transgressive and
regressive Cretaceous deposits in southern San Juan Basin, New Mexico:
u. s. Geol. Survey Prof. Paper 193-F, P• F101-F121.
Sears, R. E., 1953, Geology of the area between Canjilon Mesa and Abiquiu, Rio
Arriba County, New Mexico ( M. s. thesis): Albuquerque, New Mexico
University, 71 P·
75
Sears, R. s., Marjaniemi, D. K., and Blomquist, J. T., 1974, A study of the
Morrison Formation in the San Juan Basin, New Mexico and Colorado: u.s.
Atomic Energy Comm. GJ0-912-20, Open-File Rept., 102 P•
Shawe, D. R., and Granger, H. c., 1965, Uranium ore rolls; an analysis:
Geology, v. 60, no. 2, P• 240-250.
Econ.
Shomaker, J. H., Beaumont, E. c., and Kottlowski, F. E., 1971, Strippable low
sulfur coal resources of the San Juan Basin in New Mexico and Colorado:
New Mexico Bureau Mines and Mineral Resources Mem. 25, 189 P·
Siems, P. 1., 1964, Correlation of Tertiary strata in mountain basins,
southern Colorado and northern New Mexico: Mountain Geologist, v. 1,
no. 3, P• 161-180.
Silver, Leon T., 1977, A regional uranium anomaly in the Precambrian basement
of the Colorado Plateau [abs.]: Econ. Geology, v. 72, no. 4, p. 740.
Simpson, G. G., 1948, The Eocene of the San Juan Basin, New Mexico:
Sci., v. 246, no. 5, P• 257-282.
Am. Jour.
Smith, c. T., Budding, A. J., and Pitrat, c. H., 1961, Geology of the
southeastern part of the Chama Basin: New Mexico Bureau Mines and
Mineral Resources Bull. 75.
Smith, H. T. U., 1938, Tertiary geology of the Abiquiu quadrangle, New
Mexico: Jour. Geology, v. 46, no. 7, P• 933-965.
Smith, R. L., Bailey, R. A., and Ross, C. S., 1961, Structural evolution of
the Valles Caldera, New Mexico, and its bearing on the emplacement of
ring dikes, in Short papers in the geologic and hydrologic sciences: U.
s. Geol. Survey Prof. Paper 424-D, P• D145-D149.
Smith, R. L., Bailey, R. A., and Ross, c. s., 1970, Geologic map of the Jemez
Hountains, New Hexico: u.s. Geol. Survey Hisc. Geol. Inv. Hap I-571
scale 1:25,000.
Spiegal, Zane, Baldwin, Brewster, and others, 1963, Geology and water
resources of the Santa Fe area New Mexico: u. s. Geol. Survey WaterSupply Paper 1525, 258 P•
Squyres, J. B., 1970, Origin and depositional environment of uranium deposits
of the Grants region, New Mexico: Stanford University unpublished Ph.D.
thesis, 228 P•
Stearns, C. E., 1943, The Galisteo Formation of north-central New Mexico:
Jour. Geology, v. 51, no. 5, p. 301-319.
76
Steven, T. A., 1972, Precambrian, Upper Cretaceous and Cenozoic igneous rocks,
in Geologic atlas of the Rocky Mountain region: Rocky Mountain
Association of Geologists, P• 53-54, 229-232.
Steven, T. A., Mehnert, H. H., and Obradovich, J. D., 1967, Age of volcanic
activity in the San Juan Mountains, Colorado: u. s. Geol. Survey
Research 1967, P• 47-55.
Stokes, w. 1., 1944, Morrison formation and related deposits in and adjacent
to the Colorado Plateau: Geol. Soc. America Bull., v. 55, P• 951-992.
1961, Fluvial and eolian sandstone bodies in Colorado Plateau,
-------Geometry
of sandstone bodies: Am. Assoc. Petroleum Geologists,
in
P• 151-
178.
Stone, w. J., and Mizell, N.H., 1978, Basic subsurface data compiled for
hydrologic study of San Juan Basin, northwest New Mexico: New Mexico
Bureau Mines and Mineral Resources Open-File Rept. 89.
Swift, R., 1956, Study of the Morrison Formation and related strata, northcentral New Mexico: Univ. New Mexico M.S. thesis, 79 P·
Timmer, R. s., 1976, Geology and sedimentary copper deposits in the western
part of the Jarosa and Seven Springs quadrangles, Rio Arriba and Sandoval
Counties, New Mexico [M. s. thesis]: Albuquerque, University New Mexico,
151 P•
Trice, E. 1., 1957, Geology of the Lagunitas Lakes area, Rio Arriba County,
New Mexico [M.A. thesis]: Austin, University of Texas, 99 P•
Trieman, A. H., 1975, Precambrian geology of the Ojo Caliente quadrangle, New
Mexico [M. s. thesis]: Stanford, Stanford University.
Vine, J. D., 1962, Geology of uranium in coaly carbonaceous rocks:
Geol. Survey Prof. Paper 356-D, 170 P•
u. s.
Vine, J. D., and others, 1958, The role of humic acids in the geochemistry of
uranium: United Nations Internat. Conf. Peaceful Uses Atomic Energy,
Geneva, 2nd Proc., v. 2, P• 187-191.
Vizcaino, H. P., and O'Neill, A. J., 1977, Preliminary study of the uranium
potential of Tertiary rocks in the central San Juan Basin, New Mexico:
u.s. Energy Research and Development Admin. Open-File Report GJBX-78(77),
27 P•
Vizcaino, H. P., O'Neill, A. J., and Dotterer, F. E., 1978, Preliminary study
of the favorability for urartium in the Madera Limestone, and Cutler and
Chinle Formations of the Sierra Nacimiento-Jemez ~fuuntains area, New
Mexico: U.S. Dept. of Energy Open-File Report GJBX-4(78), 18 P·
77
\.Jassenburg, G. J., and Lamphere, M. A., 1965, Age determinations in the
Precambrian of Arizona and Nevada: Geol. Soc. America Bull., v. 76, no.
7, P• 735-758.
Waters, A. c., and Granger, H. c., 1953, Volcanic debris in uraniferous
sandstones and its possible bearing on the origin and precipitation of
uranium: u. s. Geol. Survey Circ. 224, 26 P•
Weide, David L., 1977, Unpublished photogeologic maps of Pueblo Bonito NW,
Pueblo Bonito, Kimbeto, Sargent Ranch, and Fire Rock Well quadrangles New
Mexico: u.s. Geol. Survey, scale 1:24,000.
Wenrich-Verbeek, K. J., 1976, Water and stream-sediment sampling techniques
for use in uranium exploration: u.s. Geol. Survey Open-File Report 76-
77.
1977, Anomalous uranium in the waters of the Rio Ojo Caliente, New
----·
Mexico, in Short papers of the u.s. Geol. Survey Uranium-rnorium
Symposium 1977:
u.s.
Geol. Survey Circ. 753, P• 73-75.
The effectiveness of stream - sediment sampling along the Rio Ojo
Caliente, New Mexico: u. s. Geol. Survey Open-File Rept. 78-843, 9 P•
----~·1978,
Wood, G. H., and Northrop, s. A., 1946, Geology of the Nacimiento Mountains,
San Pedro Mountain, and adjacent plateaus in Sandoval and Rio Arriba
Counties: u.s. Geol. Survey Oil and Gas Prelim. Map 57, scale 1:125,000.
Wood, G. H., Jr., Kelley, V. G., andMacAlpin,. A. G., 1948, Geology of
southern part of Archuleta County, Colorado: U.S. Geol. Survey Oil and
Gas Inv. Prelim. Map 81, scale 1:63,360.
Woodward, L. A., 1974, Tectonics of central-northern New Mexico, in Ghost
Ranch: New Mexico Geol. Soc. Guidebook, 25th Field Conferen~, P• 123135.
Woodward, L. A., Gibson, G. G., and McLelland, D., 1976, Geology of Gallina
quadrangle, Rio Arriba County, New Mexico: New Mexico State Bureau Mines
and 11ineral Resources Geol. Map 39, scale 1:24,000.
Woodward, L. A., Kaufman, w. H., and Anderson, J. B., 1972, Nacimiento fault
and related structures, northern New Mexico: Geol. Soc. America Bull.,
Vo 83, P• 2383-2396.
Woodward, L. A., McLelland, D., Anderson, J. B., and Kaufman, w. H., 1972,
Geologic map and section of Cuba quadrangle, New Mexico: New Mexico
Bureau Mines and Mineral Resources Geol. Map 25, scale 1:24,000.
Woodward, L. A., McLelland, D., and Kaufman, w. H., 1974, Geologic map and
sections of the Nacimiento Peak quadrangle, New Mexico: New Mexico
Bureau Mines and Mineral Resources Geol. Map 32, scale 1:24,000.
78
Woodward, L. A., McLelland, D., and Husler, J. w., 1977, Precambrian rocks of
the northern part of the Nacimiento uplift, New Mexico, in San Juan Basin
III: New Mexico Geol. Soc. Guidebook, 28th Field Conf., P• 93-98.
Woodward, L. A., and Schumacher, o. L., 1973, Morrison Formation of
southeastern San Juan Basin, New Mexico: New Mexico Bureau Mines and
Mineral Resources Circ. 129.
Woodward, L. A., and Timmer, R. s., 1979, Geology of Jarosa quadrangle, New
Mexico: New Mexico Bureau Mines and Mineral Resources, Geologic Map 47,
scale 1:24,000.
Wright, J. c., and Dickey, D. D., 1979:
in press.
u. s.
Geol. Survey Open-File Rept.,
Wright, R. J., 1955, Ore controls in the sandstone uranium deposits of the
Colorado Plateau: Econ. Geology, v. 50, no. 2, p. 135-155.
79
COLORADO
_ _ _ __;or•
,.
45'
- - - - --..,.---
.
::;·
···--
~-···-
lG!I'
-;,r•
. EXPLANATION
(
\
+
+
+
+
+
+
J.
+·
- lI
_j.
I
/
/---......------:.__.
\
~-
/
(
MOST FAVORABLE AREA
I
/'
\
\..
+
__ j .
I
/
/
-~
/
Brushy Basin Member-Westwater
Canyon Member of the Morrison
Formation
/
/-
/
I ., :.-----..~~~-. . . . . . . . . . ...,----.-
====~~~
-...-~--------·-=-~---~--........_~
URANIUM MESOURCE EVALUAflON
ISSUED BY fHE U.S. DEPAR(MENT OF ENEHGY
/
\
../
Approximate .subsurface boundary
---....,
//
I
\
\
/?
f
. 1.
/
I
//
L --.._.;--) / /
_i.
_,.
I
I
I
\
I
/
\
I
/'OST FAVORABLE\\
AREA
----
/I
1
Ojo Alamo Sandstone
I
/ ~
I
I
I
1.~·
. !
:>.•
_ _ _ _ _ _..........,____________.....__ _ _ _ _ _.,.--_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
10
0
5
...........
I
//
FAVORABLE AREA
\
I
\
Burro Canyon Formation
I
+
.
-L
I
I
I
I
+
---____
0
10
20
15
15
_j
20
25 KILOMETERS
~~---~-~0·~--~~~~--~~~~-~--~~
PLATE 1.--AREAS FAVORABLE FOR URANIUM DEPOSITS IN THE
BURRO CANYON FORMATION, OJO ALAMO SANDSTONE, AND
THE BRUSHY BASIN AND WESTWATER CANYON MEMBERS
OF THE MORRISON FORMATION
Plate 1.
1979
AZTEC
I
I
-
NEW MEXICO/ COLORADO
"'I1oa•---------
------
JC'
I~·
EXPLANATION
lOB"
JC'
107"
-37"
URANIUM OCCURRENCES
CLASSIFICATION
Sedimentary Plutonic
Minor prospect or mineral
lii70X
+
15'r-
+-
+
+
+
+
Volcanic
Other
-¢-
liiii
A
l<il
,...
Mine t1aving production o11er
200,000 pounds u3 o8
1\1
A
Not visited
DY
6Y
. •
• •*
QY
pv
Not found
ox
c::.x
ox
-Qx
Mininf;l District
---- - - '
D
Prospect or mine,
production unknown
'
6
Si(lnificant prospect or mine
reporting minor production
occurrence
(
0
()
\
-------""
-. 45'
~51
50~
..
+
1 3ll'r:
+
+
+
+
+
+
1X
~77Y
~3
0
2X
sx
10171 y
liil7
04
kii!46Y
~11
liiilsx
oax
12
~
liiiJ9X
13
101' ox
liiil14Y
10156
+
"'i-
+
+
101' 5
+
Eij65X
+
~BOY
~2x9 31
iiiii16
iiiii17X
-+-
+
-
15'
!iij22Y
28
liiii6BX
as~iiiit-33
30
32X
34X
73
101'8
59XIiiil;! 23 x
liiil6 8 X
67X
45Y:,5
26
10120
IOI19Y
27
liiil6 6
iiiil21
35X~
36liil
37
40 1iij 63X
41X
liiii82X
,.
_j_
lOB"
"'
URANIUM RESOURCE EVALUATION
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
,.l
liiil61
I
liiil4'1
,,.
~---L...--~---"
15'
Des
39~38
liiii64X
I
iiiil62 X
1:17"
l
10142
"'
H'
"'
106"
BASE MAP CONTROL FROM USGS
0
10
10
15
15
20
20
25 MILES
25 KILOMETERS
PLATE 2.--URANIUM OCCURRENCE MAP
Compiled
by
A. C. Huffman, Jr., Allan R. Kirk, and Pamela G. L. Sikkink, U. S. Geological Survey
Plate 2.
1979
AZTEC
NEW MEXICO/ COLORADO
~r·lr"'"--T-'---;----------17"'---------,---T"o:_'_ _ _ _ __:_,-------\1.:.:._•·--------,---r--T'J":_'------------T":_'1/
I
\
I
A.
j_
I
~~-----r---\-\_:______-J----..J<-Im--~-_~
~
!
\
Flight line
H-----~----~----~----~-+\--~~-~~Km~~~~~----~\----~
_____
.,..Km
.___ \
-
-~hamc
-
+
H--
+
e
Tectonic divisions
Kd/Km/
_\
rdjm
+-'~
Qal
Quaternary alluvium
Qg
Quaternary gravel
Tv
Tertiary volcanics
Lib
Lobato Basalt
1/
Ta
Abiquiu Tuff of Smith
.L
Tsj
San Jose Formation
Tn
Nacimiento Formation
Kkf
Kirtland Formation and
Fruitland Formation, undivided
Km
Mancos Shale
Kd
Dakota Sandstone
Ju
Morrison Formatio.n, Entrada
Sandstone, and Todilto
undivided
Jm
Morrison Formation
I
;I
ARCHU~TAARCH
BRAZOS UPLIFT
I F!ctp£
1- .,.
.--t
.--T-ie-rr_a_A_m~la_r_ili_a~--~~-------r--------------~
_\
_Lm
~t-~~----~+-------------~----------+-----------~----------~}-----~---~~----~~---4------~---i----------~~~
-
j
~
\
C:AMA BASIN
\
I
~---~~~--~--~~--~~~-,,~~-=~='~~-~--~
r----..
SAN JUAN BASIN
11111
\._
Km
.
Km
\
o· ~~------------~~----------~--~~r-----------~--~+~--------+-----~~-----t-t---~~-____2\_J~,f-~--~--------~J~Ki~~----------1-tillr-------------~~"
17
1/1
I
1
I
\
I
Tsj/Tn
1!411
tlill
)
J
FRENCH MESA
GALLINA UPI 1FT
Chinle Formation
·.v~
Il
)
1:
I+
+ L
-r~--------~-------~--------~-----~---------~~~~-r,~----+-----~~~7d~-~~~~~biq~uiu~,~~-----~
+
1~-
Cites and towns
GEOLOGIC UNIT
1: +
'
Uranium anomaly
MAP SYMBOL
--.
+
-
IIIW'K~ _..Km~-
\
(/
EXPLANATION
~------'----4"1!.:...'-.-.---------,-~r:··--------rilDIJ" 37"
I
RIO GRANDE TROUGH
+
-15'
IQg
Pc
Cutler Formation
pC
Precamb_rian rocks
Source of data: Geodata lnternatio.nal, l~c, U~79~ ..,-.·
~erial radiome.tric and magnetic su!'vey, tq:tec NTMS•.;..
Colorado and New Mexico; U.S. Department of
Energy Open-File report GJBX-65 '80
-_r:_-------_-----_---_-_-:_+;_-_-_-_-----_-_-~-----~p-£-t__N_A_C-IM-IE~N~T~~o-.l!l-c-/~-c+-/""-l--L---::::=J~~------T-Ib-._,t<~rL----~~,
1----t -----_-_-----:_---_-_-__-_j-t-----:_-_-------_-----:_j-+---------:_-_-----_------
1·/s
UPLIFT
\
Bll
( (
JEMEZ VOLCANIC FIELD
•
\
p~"" J,t_ --~
--------~----------~-----------4-----------4------~~~~..~~--J\-t~L_------i-----------~--)-----~--~~
~~T-:- ~j{a)./ _!a/Pc
.Cuba
'?,•..~---'--------~.;:--------_j--,~; - .__________j'----;+,1!.----------,---,1;~,.-:::=-------1 ~
URANIUM RESOURCE EVALUATION
ISSUED BY THE U.S. DEPARTMENT Of ENERGY
.!. (
-
l
30'
/1
IS'
,.
100
BASE MAP CONfROL FROM USGS
0
10
10
15
15
25 MILES
20
25 KILOMETERS
PLATE 3.--INTERPRET ATIVE MAP OF AERIAL
RADIOMETRIC URANIUM ANOMALIES
,
Preliminary analysis by Pamela G. L. Sikkink, U.S. Geological Survey
Plate 3.
1979
AZTEC
NEW MEXICO/ COLORADO
,.
1or•
,.
"'
1011•
15'
,.
EXPLANATION
Water Samples
Numbers beside symbol are (uranium/conductivity) x 1000.
bnly those ratios greater than 7 are shown
12.00.
*
VI
•
v
•
.6.75
.32.05
Springs
Stream
Well
Roman numerals designate areas divided on drainage or
geologic units. See table 1a in the text
+
+
+
"'
*10.80
IV
Data from Los Alamos Scientific Laboratory Report
LA-728-MS: Bolivar, S. L., 1978 Uranium hydrochemical
and stream sediment reconnaissance of the Aztec NTMS
Quadrangle, Department of Energy Open-File report
GJBX"-129 '78
i3.28
7.87
*11.60
8.80*
•
7.30
*14.00
*10.40
Ill
.,.
+
+
+
+
+
+
.9.05
"'
*9.00
...
*7.40
-.J1·29
IX
,..
+
+
+
VIII
+
+
+
_j_
I
"'
.._3.67
II
URANIUM RESOURCE EVALUATION
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
-.10.37
0
5 .
10
15
20
25 MILES
BASE MAP CONTROL FROM USGS
15
10
20
25 KILOMETERS
~~~~~~~~~
PLATE 4A.--URANIUM/CONDUCTIVITY IN WATER SAMPLES
Compiled by
Pamela G. L. Sikkink, U. S. Geological Survey
Plate 4A.
1979"
NEW MEXICO/ COLORADO
EXPLANATION
j ~·
3U'
107'
+
60
8
@@
+
@
@
(1)
+
8
50
~
@
Lower Limit of Detection (LLD) -1.00 ppm
Median -1.00 ppm
Maximum - 18.00 ppm
Minimum < LLD
45 2
· Total Number of Samples - 1003
Number of Samples ~ LLD - 550
+
,..
+
0
@
80
@ 8
@
8
+
+
8+
8
@
8
8
@
+
"
"'
8
~ 8
~
u.
®
c
"'
0
8
8
@
+
8
"'rr
8.
8
@
8
c
+
~
<ll
8
a.
+
+@
+
+
_j_ __
--'--1
+
:t
+
+
8
+
8
13
+
+
.01
0.1
100
10
1.0
1000
+
U (ppm)
@
8
+
@
8
+
+
+@ (1)
.()
+8
+
+
+
.0001
.0005
+
+
@>
+@
8
+
8
+
8+@
@
@
8
8
&
.0500
+
.c
co
.c
+
+
+
8
8.
+
@
+
lS@
~@
@
@+
#+
+
+
+
~
>
+
.+
.
::J
0
0
+
+
++0
+
<1>cv
+
~1)
8+
0+
4-
.::)
_.,.,
-+
., !'t"+
, ® G
0
8
".:J
I
I
I
I
I
I
r
r
r
I
I
I
I
I
I
I
I
r
I
I
I
I
r
r
r
I
I
I
I
I
r
I
I
I
'
-~--~-
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
.
1-~~!
I
I
I
I
I
I
I
I
I
I
I
I
r
I
I
I
I
I
I
I
I
I
I
-,---rI
I
r
--1---l.-
r
I
I
-~--T-
r
I
I
I
I
I
·I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
0.01
+
C!l
I
I
I
I
I
I
I
I
I
I
I
I
I
I
r
r
r
I
I
I
I
I
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I
I
I
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I
-+ti-
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
-r--~-
-r-,-
I
1
1
-+--1--
;
-,--,-
Ol
0
c:
I
+ 2.0
r:1l
"0
Q)
--~---,-
:::E
+ 1.0
-~--L
Q)
.c
E
r
r
0.0
0
I-
I
I
I
I
I
I
I
I
I
I
I
I
I
•I
I
I
I
I
I
I
I
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I
I
I
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I
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I
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I
I
I
I
f._
r
f. .
o·
I
r
r
I
I
I
I
r
r
r
"0
I
I
I
r
..;+--l-- -4---1---
--r--r--.L_--- I
I
I
I
I
I
I
I
r
I
10 .
I
_lI __ IL _
I
8101~ +I
1.0
rn
-1.0
I
I
>
Q)
1-
-3.0
+-+-
I I I
100.
c:
0
.~
r
I
--,--;-.---,-
I
-+--t-
-
I
I
I
I
r
I
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-T--r- -r--r-
-T--r--
+
Cumulative frequency
+
+(1)
+
@
r:ll
"0
c:
r:1l
en
1000.
0
+
distribution
of uranium (ppm)_
in stream- sediment samples
+
0
0
I
I
....
" Q
+
@
I
+ 3.0
r
I
+
+
++
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.......
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U (ppm)
+
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and
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+
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+ 8+
+
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+
f
0
_____ j;,:;·
8
15.
15'
OF CtJERGY
I
I
I
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I
-r--,--,--T-
.9999
+
+
·+
distribution
uranium (ppm) in stream -
--t--t-I
I
++
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I
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8
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+
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+
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co
@
+
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I
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I
I
-r---,-
0
._
++}
+
8 +
8+@
+
@
@8
+
Q
@
8
frequency
samples
-r--,- --r-,-
r:Jl
8
@
.0050
I
I
-J----iI
I
+
8
8
8
+
+
@
the
8
+
8
of
analytical range of
sediment
8
+
Histogram
@
Sample locality and symbols indicating U (ppm)
\i;i6°
Data in -any interval are greater than or- eqUal to the lower limit, and less
than the upper limit_for"that class
0
10
20
15
10
0
15
20
U (ppm)
25 MILES
25 KILOMETERS
~~~~~~~~~
PLATE 48.:-'--DISTRIBUTION AND CONCENTRATION OF URANIUM (PPM)
IN. STREAM - SEDIMENT SAMPLES
+
Samples collected and analyses compiled by the
following U.S. Geological Survey per~onner: T.R.
Analyses by
<
1.0
0 1.0-2.0
Peacock, R.F. Dubiel, D.J. Hammond, R.J. Noah, J.J._
Irvin, M.A. Stanton, L.K. Walker, J.R. McDonnell,
Keith Robinson, R.L. Reed.
.
·,
® 2.0-:-5.0
GEOCO, Inc., Wheatridge. Colorado
~
5.0-10
+1o- 2o
Compiled by
Jeffrey J. Irvin and Keith Robinson, U.S. Geologica! Survey
(1)- In locafities
where replicate
value is indicated
sampte.s were collected, only the highest
AZTEC
NEW
COLORADO
~EXICO/
EXPLANATION
1,'•
60
(_!•
•
s
Lower Limit of Detection (LLD) - 0.05 ppb
Median -. 4.00 ppb
Maximum - 44.00 ppb
Minimum < LLD
Total Number of Samples - 186
Number of Samples ::: LLD - 182
50
;>.
<.J
~
40
::1
rr
32.8
Q)
u:
,,
30
c::
Q)
<.J
~
"
a.
20
10
I~
0
0
c.s
.01
.05 0.1
1.0
100
10
0
u
1000
(ppb)
Histogram of the frequency di'strlbutlon and
analytical range of uranium (ppb) In groundand surface- water s_a.mplos
•
•.
. 0001
.0005
eo<1>
.0050
I
.c
«!
.c
0
(OJ
0
0
0
0
•
0
0
0
0
••
(1)
...0
a.
«!
(OJ
::l
E
".
::l
u
.9500
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-+---f-.I
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0.01
E
0.0
I
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-+--1--
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:;:::
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>
(])0
...
"0
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.!::::
rn
c
-1.0
I
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--r--r.-r---,-:- --J:--·I
-~--L-
+ 1.0
-~--T,-
-3.0
+-+-
l J I ~I ·I lo olol<!.l ~1•1 I I
_ __J_;_;_[_
I
Ol
0
+2.0
-f-.--~-
.9999
I
.......
+3.0
-+-...;.1-- -1----1-
_L.._.J_
.001
«!
"0
c
«!
Ci5
o
0.1
1.0
10.
100 .
1000.
u (ppb)
n
0
Cumulative frequency distribution of uranium (ppb)
1n ground- and surface- water _sam_ples
..,
Sample locality and symbols indicating U (ppb) value
o)
Datll in any interval are greater than
than the upper limit for t"hat class
u
---
·~~~-:--:--:--:--...;._-----------------,.-------------------------------'------~~-....
l "\ ·
r. ~
i!1, •
r ·; • :; •. ·
• . . 'j ·.: 0
10
15
20
25 MILES
!"'••·•• :
Samples
10
I
-,--,-
--i-
I
I
-,--,-
I
I
T7~I
I
-1--v
~JL!~I
I
I
I
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.9995
X
•
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I
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-~--T-
I
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I
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I
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I
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I
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_-:-:1_::-:--T::I
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I
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--,---r-
I
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u
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--~--,.-:-
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00">
0
.7500
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Q)
...>
I
I
:
.5000
I
I
I
I
.2500
I
I
-r-,-
0
.0500
I
I
-1---t- --;---t-
20
25 KILOMETERS
~~~~~~~~~
15
PLATE 4C.--DISTRIBUTION AND CONCENTRATION OF URANIUM
(PPB) IN GROUND- AND SURFACE- WATER SAMPLES
following
Peacock,
collected
the
0
U.S. Geofogfcal Survey personnel: T.R.
R.F. Dubiel, D.J. Hammond, R.J. Noah, J.J.
and
analys.es
0
Irvin, M.A. Stanton, L.K. Walker,
Keith Robinson, R.L. Reed.
Analyses
by
GEOCO, Inc.,
compiled
by
J.R. McDonnell,
Wheatridge,
0
0
Colorado
(!)
~
•
Compiled by
Jeffrey J. Irvin and Keith Robinson, U.S. Geological Survey
(1)- In
or
equal to
the
lower limit,
an_d less
(ppb)
< .05
.05r0.1
0.1-0.2
0.2-'0.5
0.5-1.0
1.0-2.0
2.0-5.0
5.0- 10
10 -20
20-50
localities where replicate samples were collected, only the lllghest uranium
value is indicated
s- Surface-water samples; all
others ar!3: ground-water samples
AZTEC
NEW MEXICO/
C~LORADO
EXPLANATION
H!f''~·---------------------------T''~·--------------------------~3~o·~----------------------~--~"~'--------------------------_ji~D7~·--------------------------~15~'--------------------------~3~D'___________;~---------------r"-'--------------------------'-,'''
l!l
0
30
0
Median - 3.33
Maximum • 93.75
Minimum .. 0.15
Total Number
of Samples - 181
26.5
25
>.
(.)
:;;
20
::J
.,
0'
0
0
u:
0
15
.,
c
0
0
0
(.)
a;
9.9
10
Cl.
0
0
0
0
-1-
+
0
+
0
0
®
0
+
+
+
+
5
.,.
0
0
0
0
0
2.8
0
0
.01
0.1
@
@
100
10
1.0
1000
U (ppb) X 1000 I conductivity
0
0
0
Histogram of the frequency distribution and
analytical range of uranium (ppb)_ X 1000 I
conductivity In ground- and surface water aamples
0
®
0
0
0
.0001
.0005
0
-+
,..
(1)
+
00
0
0
0
0 0
0
0
0
l"'
0
>-
0
0
0
0
0
-+
+
+
0
.0050
oo
0
®
L@
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®
0( 1 )
0
0
0
a;
0
0
.5000
.7500
:::J
(.)
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,..
0
oCb
0
0
+
0
0
0
+
@
0
0
0
+
+
+
+
.9905
0
@
0
0
0
®
I
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+3.0
+2_0
I
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--,--,-
+ 1.0
-1--~
e
I
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-<---1-- -1---1-
I
-+--1-- -1--+
-'I
I
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I
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I
I
L.
-r--,-
-T--r--
-+--!--
I
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0.0
I
-,--r.-L
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-..j..--1--
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,--,-
I
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-ry
--1--~-
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-+-+I
-,--,-
-~.t
I
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-t---1I
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-1.0
~2.0
--r---r-
I
-+-+- +-+
-3.0
I I I I +I · Io olol0 @1•1• I I
0.01
0.1
10.
1.0
100.
1000.
U (ppb) X 1000 I conductivity
@
0
Cumulative frequency distribution of- uranium
(ppb) X 1000 1 conductivity In ground - end
0
0
I
I
I
-L-.J_
.001
0
I
I
--,--T-r--JI
1-
®
Ol!l
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-r-,-
.9989
® 0
0
l!l 0
®
.9950
,.
I
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_,_I __,_I
0
0 @
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:::J
0
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-r--,--,--T-
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0
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>
e
l!lo
®
0
a.
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.,--,- -,--,- --+--+-
Q)
®
0
0
.2100
I
I
I
I
I
I
.a
Ill
.a
...0
@
0
0
.0500
I
I
_.__-t_
___,I__ ;I -
0
0
(1)
surface- water samples
®
e
0
0
®
Sample locality and symbols indicating U (ppb) X 1000 value
conduct.vlty .
..
®
@
L
®o
8
~~;~•.~~------------------------~,,~.------------------~~------~,,I~.--------------------------~~--~J2--------------------~~~07~'--------------------------~,~,.----------------------------,,,~.----------------------------~,~.----------------------------~~o;:·
URANIUM RESOURCE EVALUATION
ISSUED BY THE U.S, DEPARTMENT OF ENERGY
Data In any interval are greater than or ·equal
upper limit for that class
BASE MAP CONTROL FROM USGS
10
0
20
15
25 MILES
:
Samples corrected
0
10
15
20
25 KILOMETERS
PLATE 4D.--DISTRIBUTION AND CONCENTRATION OF URANIUM
(PPB) X 1000 I CONDUCTIVITY IN GROUND- AND SURFACEWATER SAMPLES
and analytee complied by
following U.S. Geological Survey peraonnel:
3 aamplea having U (ppb) content<
the
+
T.R.
Peacockt R.F. Dubiel, D.J. Hammond, R.J. Noah, J.J.
Irvin, M.R. Stanton. L.K. Walker, J.R. McDonnell.
Keith Aobinaon, R.L. Reed.
Analyses
b~
to the lower limit, and lesa than the
U (ppb) X 1000
conductivity
0
0
0
GEOCO, Inc., Wheatrldge, Colorado
®
@
••
Compiled by
Jeffrey J. Irvin and Keith Robinson, U.S. Geological Survey
(1)-
LLD not Included In norrnallze'd data
0.1-0.2
0.2-0.5
0.5-1.0
1.0-2.0
2.0-5.0
5.0-c 10
10-20
20-50
50 -100
In rocalltlaa where replicate aamplea were collected, only the hlghaet uranium
(ppb) )(
1000 J conductivity value Ia Indicated
·
---
W(543)
0
5(234)
21PPB0
9PPM
W(54B)
0
23PPB
C!D 5(307)
0
5(146)
5PPM
5PPM
0
~~~~~
0
W & NW(621)
(1!1 28PPB
5(129)
6PPM
30 N PPB
621 FT.
0
5(3a7>
8PPM
IIICuba
3~;~,.----------------------~,~,.~----------------------~,.~------------------------,,~,.------------------------~10'~.-----------------------.,.,~.-----------------------,,~o-------------------------~,.~----------------------1,,0~·
URANIUM RESOURCE EVALUATION
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
BASE MAP CONTROL
0
10
20
15
10
15
20
FRO~
I
USGS
25 MILES
25 KILOMETERS
PLATE 4E.--INTERPRETIVE MAP OF U.S.G.S. HYDROGEOCHEMICAL
AND STREAM - SEDIMENT DATA
Compiled by
Jeffrey J. Irvin and Keith Robinson, U.S. G'eological Survey
Plate 4E.
1980
AZTEC. NEW MEXICO/ COLORADO
EXPLANATION
..
Sediment Samples (ppm)
*
... /\···--. ..-"'
,.,, /
···-..."'{," _ __,. ..
,._.,~ ... .r·..-
£::..6.2
... - ...
- ... - ..\
~·......... , .•• , .• , ..-···-..
- -..
"'\,,•N'••
9.3
iaJ'· ..
··........ "
0
Stream
Chama
liiiJ 7.0
b..
Artificial lake or pond
liiiJ
Dry stream
13.4 1\ .......
liiiJ,__, ...
),.-::::"''"'"'"--lijjJ~3.2
··.\
+
1iiiJ
Water samples (pp b)
VI
*•
'-···..._
•*
......... '\..-. ............ "\... ..
+
+
II
IV
5A
14.9
....
··~ ... ,.... ..·-~ ~~;J5.6
5.4
·+
30'
Spring
Stream
Well
Uranium mines visited in this study
Towns
~
Roman numerals indicate drainage area and formations within
tbose areas from which HSSR samples were taken.
See Tables 1 and 1a in text
Data from Los Alamos Scientific Laboratory Report LA-7238-MS;
Bolivar, S. L., 1978, Uranium hydrochemical and stream
- sediment reconnaissance of the Aztec NTMS quadrangle,
Department of Energy open-file report GJBX-129 (78)
liiiJ Ll::6.7
il.6.8
Spring
5A
a.~- 6.5
.+
+
liiiJ11.00
67.3¥
,..
+
,..
+
URANIUM RESOURCE .EVALUATION
ISSUED BY THE U.S, DEPARTMENT OF ENERGY
BASE MAP CONTROL FROM USGS
0
10
15
20
25 KILOMETERS
~~--~~--~~--~
PLATE 4.--SUMMAH'(_ OFANOMALOUS SEDIMENT AND WATER SAMPLES,,
HYDROGEOCHEMICAL AND STREAM-SEDIMENT RECONNAISSANCE
Compiled by
Pamela G. L. Sikkink, U.S. Geological Survey
Plate 4.
1979
.r.•.i
..
EXPLANATION
.•
~~o
One·<oil or gas, well at location
Single measured section at location
e47
+
+
+
+
+
+
+
o4S
o4D
.35
JO'
+
+
+
+
+
+
+
o34
.33
.32
tt3o
.29
.28
.31
JJ.l
027
8 26
...5
....6
"25
20
+23
+
"
+
"
8 21
.19
• 24
+
+
0 16
.15
.,22
o17
JJ.2
JJ.3
+
+
-
15'
18
•
JJ.4
.12
.13
.14
011
0 10
.3
o4
,..
108.
•a
7
•a
"'
URAN 1UM RESOURCE EVALUATION
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
•
.,,
.. 2
,.
1
~"·~
A
.s
.s
15'
,.
...
107"
lO'
106"
15'
BASE MAP COnTROL
0
5'
0
10
10
20
15
15
20
FRO~
USGS
25 MILES
25 KILOMETERS
PLATE 5A.--LOCATION MAP OF OIL AND GAS TEST WELLS
AND MEASURED STRATIGRAPHIC SECTIONS
INCLUDING THE MORRISON FORMATION
Compiled by
Steven M. Condon and Pamela G. L. Sikkink, U. S. Geological Survey
Plate 5A..
1979
...
'.
NEW-MEXICO/ COLORADO
-Sample locality and number
•e
786
•
e
AREA 1 numbers are prefixed by MBC
764
AREA 2 numbers are prefixed by fVIBD
860
. 882
flltsso
~)878 .844
.602
.
0826
•
0855
0822
.606
.84
0574
•
+
-·
•
766
,j 31
684
846
0826
BOO
6288
•
794
e
;e
6
566(1)
•
562.564
554.
5560560
•
0
+
+
+
+
+
·+
602
sss0
522
. .524
AREA
516 514
516.
•
520.
•
.508
OS 52
602(1) •
• 5D4
750
• • •
8
664
119672
670
AREA
•
-
'.752
500
0636 6320
2
O(N820
+
1!J1440
•
• 746
662
+
. 636
• 634
648
•
(1)748
858
ett6o 8
.622
.fDfJ
"'
.810
780
••
•
(1)498
196
••
228
226• • •198
2oo
6')230
. 174
e
0854
686
•
580
5]6• . •
.
582
550•
(1)576
652
~(If
586
•
584
• •544
.672
•
664
668
(1)650 1111
678
•
•
.680
.590
682
592
8
•
600
676
594
• ·.(1)598
•
96
•
626
•
.630
8486
456
460
•
• •478
11_626
• 5 3 8 - + - - - - - -......------·7;.0;.;0_.,_422.
• (1)
462
,464
158
•
• . 204
162160
106 156(1,164 • •
••
454
•
134.(11132
+
072. •
07611!1
•
e238 .346
244 0
8
0252
242
a316
e
G
0
266
0 3o6
308
262 126
0012e
0S28
..,.314
..,.
0
376
.332
•o378
4000
3~~
•• ----~--------------~--~~
..~.--------------------------~,~,;.--------------------------~,~.-~-
396(1)
39641
3901/l)
0382
15'
082
.
I088
086
052. 042
roo
•
026 024
176
0
164
8
166
~50
034,.
- •
046
0 188
0400 ' ' • .026
.162
CI)D46 038 044 020 """22.176
...192
01...
•
......
194···.
0016
1711010 12
(1)190
0014
00
180
008 0
e214
222
.130
cr.1)334
336
036
'-o32
e
.330
208
··~1064
8os8
066.
.064
G
220
21s
Oo216
0224
•
060. ' .056 116
058
•
llj)062
!19054
0116
0300254
0 302
.304
162
07o 060 096
•
078
.240
fi44
..
10461 •
8102
oo4
092
....
07 4 090. • 098€11 .100
+
+
_294
Ill 256
136
•
166
16B..,.j_
202..164
106
452
.424
8172
.206
488
• •490
476
gs
136
.482
e
110
•
464
.670
..
URANIUM RESOURCE EVALUATION
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
•
.640
658 656
742
8
772.
570
~740 Ofi
.
•
0798
572
790
• J 88
0
'
842
o e
<1>733
.768
77
(1)762•
604
•
876
350
0
0212
384
,366
388_ 1!11210
0
30'
107"
eoo6
0002
-------------------~,_~;-.-----c-----------------------,:1oi.B'
BASE MAP CONTROL FROM USGS
10
0
0
10
20
15
15
PLATE 58.--LOCATION MAP OF STREAM
20
25 MILES
25 KILOMETERS
SEDIMENT SAMPLES (PARTIAL)
Compiled by
Raymond L. Reed and Keith Robinson, U.S. Geological Survey
(1)
-Indicates replicate sample
COLORADO
,.
15'
..EXPLANATION
...
107"
'\"':_'---~---------'-'-,as~ 31 •
-Sample locality and number
®767
.
71!;(1- .719
AREA 1 numbers are prefixed by 'MBC
791®®785
.
71-1. .
.717
.713
. 647
e
.881
76seJ65
767.
.613
e
789
®795
8.79.Cl>8ii··
(1)
.(1)732
.734 .730
s..
• .15
'
8
817
8
e1s
+
.736
791
• . 789
• •787
AREA
+
+
eras
• 775 76l•
+
+
+
·+
• 771.769
...
525
.523
~61 (!;;759
+
.728
801
0763
.865
.773
551 553
855
~857
.853
507
•
505
509 •
501(1!•
503
,;25 .823
•
_l_
4691
471.
•
.809
• 739
.639
.781
499
lL
-.
779
(1)497 •
•
8867
®415
417
•
.(1)419@411
473
•
.475
e
11447
4
13
.449
445
+
441-.d
""
43s
•
30'
•
195
777
.633
.641
.643
• 647
2
.819
•811
813
•
.751
AREA
.(1)821
817
.645
.
•
461
.459
685
.
.683
.207
.581
629• .
631 . .
$(1)57~583
591 627
+
27~
139(1). 137
®257
cr:os
e265
.239.241
147 .,.243
145. Cll..
..
VT49
317
283• •
.247
.249
.327
e 231e341
.343
0
311
313 315
307
•
• e
09'1
e
.293
o8a
07sl
I
0
.103
.125
eoa3o97
. 101
073
0 8 0
8
8095
o'99
079
071@
•
(1)083
077
@ 067
•
069 •
(!1° 81
.087
0085
059. •
. 115
57 • 117
061
tilL-·
.055 •
.053
.065
\051
.255
.245
107
.157-205
.155(1)1,. 1111
.105
"6;~1
-k
+
-.1)275
.135
e<1l133
•
Ell .
123
•113
8
z
.121
°
.251
030~253
179 185
041
•
035 .037
ff43.047
031 .
029
.025
177
23
•
~33 • •027
0039
021. .049
tl
.
°
045
015
017A · - · 0 1 3
"' o1a
e
183
0
187.
011
.003 .07 .009
~"'o"'o"',----:c"i·'· I
JO'
5
.
AREA 2 numbers are prefixed by MBD:
0
10
20
15
10
0
15
20
BASE MAP CONTROL FROM USGS
25 MILES
25 KILOMETERS
PLATE 5C.--LOCATION MAP OF STREAM- SEDIMENT SAMPLES (PARTIAL)
Compiled by
Raymond L. Reed and Keith Robinson, U.S. Geological Survey
.
'
-Indicates replicate sample
,-:;
AZTEC,.,, NEW MEXICO/ COL'ORADO
-;;·,:··
ir·'~,-~,~---------;~··-------:---'------,------:r"-'-------------,----r"l~·e=-ee-1--,-----------i~'·--~ -------~------1'"lc__·- - - - I
.923
,.
I
EXPLANATION
------1'::,''------------",6" 37"
I
e 655 -Sample locality and number
.922
All numbers are prefixed by MBD
s
-Surface- water sample;
all others are ground- water samples
.652
(1)
,:55.653
+
45'-
+
+
+
+
+
+
+
+
+
-
45'
.902
!0'-
I
+
I
.998
.617
610
-M'
0
.:91.564
563 .582
928
•
',
.565
.889
.999
•
.586
g(1)995.996
• 579,580
.988
8993
994
(1)554,555
,573
""
•
570 569
572"' .616 •
Ill
Ill
.997
.984
.981
553
.987
e982
.571 .615
I
••
561 562
.966
g983
.979
:i;
IS' I---
Elsea
+
g985
7
,978
.980
.978
•
542
4l
+
8
46
.541
+
+
55a+
e 567
+
503
501 • •
•
502
8557
-
,.
e:rJ05
504
~06
509• •607
8556
551
8
.515
.(1)520,521
URANIUM RESOURCE EVALUATION
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
BASE MAP CONTROL FROM USGS
0
10
0
10
20
15
15
20
25 MILES
25 KILOMETERS
~~~~~~~~~
PLATE 5D.--LOCATION MAP OF GROUND- AND SURFACEWATER SAMPLES
Compiled by
Raymond L. Reed and Keith Robinson, U.S. Geological Survey
-Indicates replicate sample
AZTEC, NEW MEXICO/ COLORADO
-~·-------------I "-'r' ' --- --------- ---
r
1
i
i
30'
_ _ _ _ _ __:,1 ~L·_
~
105"
___ ,.
.,_._----------------
----
EXPLANATION
e Rock sample locality and nuniber
All numbers are prefixed by MBC
I I
I I
I I
Analytical results are shown in Appendix B-1
I
i
I
I
I
i
I
.
r
I
j ...
I
!
I
+
I
+
+
_.,.
+
+
+
+
II
.
I
I
Ell
005-007
009,010
,.rI
+
+
+
+
+
+
+
003,008,
e
-I"'
001 ,002,004
j
208,209
(!)
.211
I
205
.213
•
15'f--
+
+
+
+-
+
+
848 101
• •202
203
850, • •
q;j 204 201
+
214
•
• 206,207
212
••
216,217
861
• • 849,862
• 103
• 860
'~;.~
•. ----------:------------,/b-,.-----------
- i~ --------------------.,.;,';-.--
•
~
1C7"
210
• 102
,.
j, ..
].<;•
URANIUM RESOURCE EVALUATION
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
10
15
20
PLATE 5.--ROCK SAMPLE LOCALITY MAP
Compiled by
Pamela G. L. Sikkink, U.S. Geological SuiVey
Plate 5.
1979
AZTEC
NEW MEXICO/ COLORADO
)
\
'K
/
/;,
~.
I
I
""'
'- -
4.,!¥"
/
I
,y
'~I
,_,
/
\
7
f
/
'
~
~
(
y
I I
t
I
, I
'
/A
,.
--r-1)
+""
./ (<
-1-.
/r:
'li
' (
-1// 1_))\-.._.::::.....~.,~l
/( I II_ ' .· '
/ - ' , ; __ ·
~
'-~ ~- ~
URANIUM RESOURCE EVALUATION
ISSUED BY THE U, S. DEPARTMENT OF ENERGY
.->
..
BASE MAP CONTROL FROM USGS
0
10
15
20
25 KILOMETERS
~~~~~~~~~
PLATE 6.--DRAINAGE MAP
.
'
Plate 6.
1979
WEST
D
Delhi-Taylor 011 Corp.
Florance-Federal N50
514 T30N RSW
San Juan County, New MeKico
El Paso Natural Gas co.
#50 .SJU 29-5
NW1/4SE1/4 57 T29N R5W
Rio Arriba County, New MeKico
Continental Oil Company
#1 South Dulcie
SE1/4SE1/4 S6 T2BN R2W
Rio Arriba County, New Mexico
83
73
65
.
D'
MANCOS SHALE
DAKOTA SANDSTONE·
BURRO CANYON FORMATION
UNDIVIDED
. CRETACEOUS
-----Datum -----i-......----1=1*
BRUSHY BASIN MEMBER
INDEX MAP
JURASSIC
37'
65
73
·GR ·Gamma Ray
SP ·Spontaneous Potential
·
R • Resistivity
S-Sonic
· C · Conductivity
MIDDLE MEMBER
(WESTWATER CANYON MEMBER)
D'
LOWER MEMBER
(RECAPTURE MEMBER)
SP
R
R
36'
SP R
AlbuQuerQue
107'
c
SP
R
R
106'
c
C'
VI
El Paso Natural Gas Co.
Huertano . ~265.
S12: T26N R10W
San Juan County, New Mexico
47
Southern Union Production Co.
Nickson #17
S22 T26N RBW
San Juan County, New Mexico
46
Superior Oil Company
Sealy Government #1q
SW114SE114 57 T25N R6W
Rio Arriba County, New Mexico
40
Pan American Petrol.eum Corp.
Jlcarilla Tribal 72 #1
SW114SW1/4 56 T23N R3W
RIO Arriba County, New MeKICO
191
Magnolia Petroleum Company
lngwerson-Federal #4
SW1/4SE114 520 T24N R2W
Rio Arriba County, New Mexico
34
Magnolia Petroleum
#1 Henry
NE1/4SE1/4 534 T24NR1W
Rio Arriba County, New Mexico
195
Ghost Ranch Section
S35 T25N R4E
S2.T24N R4E
Rio Arriba county, New Mexico
CRETACEOUS
-----Datum - - - t - - , r - - - -
i
I
I
'I
R
R
SP R
PLATE 8A.--EAST-WEST STRATIGRAPHIC SECTIONS IN
THE SAN JUAN BASIN AREA
Compiled by
Robert Lupe, Douglas P. Bauer, and Others,
U.S. Geological Survey
. URANiUM RESOURCE EVALUATION
.
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
Plate SA.
1979
..
AZTEC, NEW MEXICO
SOUTH
NORTH
L
Sun Oil Company
Navajo Lands #1
SE1/4NW1/4 S25 T22N R9W
San Juan County, New-Mexico
29
Sun Oil Company
AH DES PI AH Navajo #1
S12 T23N R9W
San Juan County, New Mexico
193
.
Southern Union Production Co.
Nickson #17
S22 T26N RBW
San Juan County, New Mexico
. 46
L'
Delhi-Taylor Oil Corp.
. Florance-Federal #50
S14 T30N RBW
San Juan County, New Mexico
83
CRETACEOUS
DAKOTA SANDSTONE
BRUSHY BASIN MEMBER
WESTWATER CANYON MEMBER
JURASSIC
SP
ENTRADA SANDSTONE
EXPLANATION OF LOG TYPES
GR- Gamma-Ray
SP- Spontaneous Potential
R- Resistivity
C- Conductivity
Cal- Caliper
S-Sonic
GRSP
R
M
SP
R
R
R
Sun Oil Company
#1 McElvain Government
SW1/4NW1/4 S23 T21N R2W
Sandoval County, New Mexico
Magnolia Petroleum
#1·A Jicarilla
SW1/4SE114 S18 T23N R2W
Rio Arriba County, New Mexico
22
190
Magnolia Petroleum Company
lngwerson·Federal #4
SW1/4SE114 S20 T24N R2W
Rio Arriba County, New Mexico
34
Continental Oil Company
#1 South Dulce
SE114SE114 S6 T28N R2W
Rio Arriba County, New Mexico
Pan American Petroleum Corp.
Pagosa-Jicarlila 11
NW1/4NW114 S23 T32N R3W
Rio Arriba County, New Mexico
65
99
MANCOS SHALE
CRETACEOUS
DAKOTA SANDTONE ·
BURRO CANYON FORMATION
UNDIVIDED
INDEX MAP
Cortez
BRUSHY BASIN MEMBER
L'
M'
108'
Durango
106'
272
107
37'+-----~----------------~~~--------------~
99
83
65
MEMBER
JUSRASSIC
Shiprock
RECAPTURE MEMBER
Raton
46
ENTRADA SANDSTONE
34
193
SP
R
R
190
29
Gallup
~'~~--+---------~--~~------~------~--+
108 ~
Albuquerque n
1
. Index Map Cross section lines within the Aztec Quadrangle
154
L
1.06
PLATE 8.--NORTH-SOUTH STRATIGRAPHIC SECTIONS IN
THE SAN JUAN BASIN AREA
Compiled by
Robert Lupe, Douglas P. Bauer, and Others,
U.S. Geological Survey
URANIUM RESOURCE EVALUATION
. ISSUED BY THE U.S. DEPARTMENT OF. ENERGY
SP R R
R
GR
Cal S
M'
To Cortez
EXPLANATION
Line of stratigraphic sections
e162
eVIl
Location· and number of drill-hole
log used in the stratigraphic sections
Location and number of measured
section used in the stratigraphic
sections
Major roads
111
Uranium Resource Evaluation
laaued by the U.S. Department of Energy
PLATE 9.--INDEX MAP TO LOCATION OF STRATIGRAPHIC SECTIONS IN THE
AZTEC AND SOME AD'JOINING NURE QUADRANGLES
Compiled by
Robert Lupe and others, U.S. Geological Survey
a
ALL UP
Major towns
EXF'LANATION
~
~
Precambrian roc_ks
bali'
High-angle normal fault, bar and
on• downthrown side~d~shed·where· .....·.
location is aJlproximate or uncertain :
+,/"/
-----
/
,/
I(
~UPLIFT
+
D
o(
Lagunas
f
I
ARC:~~~TA ~ room~~
North
El
~
/
~;:o
t
t
l fa
e.
o~:"'$
High,..angle· reverse fault; rectangles
on upthrown side .
.
.
.
Anticline showing axis and dlrec:tion
of. plunge, dashed whe,-e location is·.
approximate or unc.ertain, dotted
where concealed
Syncline
Monocline
Anticlinal bend, arrow
of dip
Synclinal bend, arrow
of dip
South
B Vado
Dome
Boundary· of major
CHAMA
SAN JUAN BASIN
BASIN
REFERENCES
+
+
+
0
.~+
+
Baltz, 1967
Doney, 1968
FRENCH MESA -
Kelley, 1955
.Kelley, 1963
~aniE~y and Scott, 1978
Muehlberger, 1967
Ridgl!'lY and others, 1978
I
+
+
Smith, Bailey, ·and ~oss, 1970
Smith; Budding, and Pitrat,
.. ·~ 1961
Woodward, .1974
+
+
Woodward and Timmer,
1979
NACIMIENTO
UPLIFT
JEMEZ VOLCANIC
FIELD
Johnson
Anticline
'r~ -----------~,;i;,~-_:_----------,!,,-,---------'------:c,J:..------)-'-----___.,,.b--~-'-L_j__~~T..-'-;J~L----------~,1,..
•.
URANIUM RESOURCE EVALUHIO~
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
----------
.LL~----j__-------c;:loi·&'
BASE MAP CONTROL FROM USGS
0
5
0
10
10
20
15
15
20
25 Ml LES
25 KILOMETERS
.
PLATE 1 GA.--MAJOR STRUCTURAL .AND TECTONIC FEATURES
Compiled by
Pamela G.L. Sikkink, U.S. Geological Survey
114.
40'
39'
113'
...,
112'
111'
11 a·
107'
108'
109'
106'
105"
103'
102"
EXPLANATION
~----------~----~
Precambrian Outcrop
~---------t----------+-----~--~----------~--------4-----------~----------+--
. 38'~--~----t---~--~--------~---------+--------~---------t---------~--------~~
'
i'
i
'
..I'
UTAH !coLORADO
ARIZONA :NEW MEXICO
I
:
I
'
i
I
:
I
36'
104'
~-----t--------.jf-----~r------~1------i.:--~S!:!H!!:IP~R:_:O:.!;C~K~A~Z;.!T,SE~C~----..}i
GALLUP
'-_
ALBUQUERQUE
zunl
,~ountaln
Lad ron
Mountains~
'f\ 1
Magdalena.'-.·
Mountains
3
0
.
Milos
Kilometers
PLATE10B.--SCHEMATIC DISTRIBUTION OF PRECAMBRIAN ROCKS
IN NORTHWESTERN NEW MEXICO, NORTHEASTERN ARIZONA,
SOUTHWESTERN COLORADO, AND SOUTHEASTERN UTAH
·.Compiled by
Pamela G. L. ·slkkink, U.S. Geological Survey
Sources of geologic data: Foster and Stipp (196,t)j
King and Beikman, 1974; and Dane and Bachman,'
1965
·
EXPLANATION
Tertiary intru~ives--Many contain uranium
deposits
B~undary of volcanic field--Data· from Akers, .. ··.
Shorty, and Stevens, 1971
Grand Mesa
field
Other Tertiary. and Quaternary flows--Data ·
mainly from New Mexico State Geologic
Map, Geologic Atlas of the Rocky Mountain ·
Region, King and Beikman, 1974; and ·
Dane and Bachman, 1975
I
I
San 1laf1111l
. intruslves
0
LA SAL
MOUNTAINS
0
I
1
~
1
1
~~
I
i
I
i
I
()
HENRY
MOUNTAiNS
.. O
0
o%
0
ABAJO
MOUNTAINS
oo
~
0
Mt.~~
ro'~P
3 Miles
4 Kilometers
0
PLATE 10C.--SCHEMATIC DISTRIBUTION OF TERTIARY IGNEOUS ROCKS IN
NORTHWESTERN NEW MEXICO, NORTHEASTERN ARIZONA,
SOUTHWESTERN COLORADO, AND SOUTHEASTERN UTAH
Compiled by
Pamela G. L. Sikkink, U.S. Geological Survey
URANIUM RESOURCE EVALUATION
ISSUED BY THE U.S. DEPARTMENT OF ENERGY
Plate 100.
1979
AZTEC
NEW MEXICO/ COLORADO
------~-----;:~-- --·------~~ _
_::____--i'~'·------.---------r'r:'·-~----------''71~~·
37"
1.
Baltz, 1967, pl. I, scale 1:63,360 •.
2.
Barker, 1958, pl. 1, scale 1:48,000.
3.
Barkerandothers,1974, Fig. 1, scale
1:125,000.
4.
Singler, 1965, scale 1:24,000.
10
26
20
20
D
10
+
+
19
+9
+
5 • . Bingler, 1968, pl. 1, scale
/
(
15
15
1~63,360.
6.
Singler and others, 196Ba, scale
1:24,000.
7.
Singler and others, 1968b, scale.
I :24,000.
8.
Dane, 1936, pl. 39, scale I:E;3,360;
9.
Dane, 1948, scale 1:62,500.
10.
Dane and Bachman, 1965, scale
1:500,000.
II.
Doney, 1968, pl. 1, scale 1:48,000.
12.
~resens
13.
Hutchinson, 1968, unpub., scale
unknown.
14.
Johns and others, 1960, unpub., scale
1:24,000.
15.
Landis and Dane, 1968, scale I :62,500.
16.
Lindholm, 1963, unpub., scale unknown.
17.
Manley, 1977, unpub., scale 1:24,000.
18.
McLeroy, 1970, scale 1:94,900; scale
lrl5,840.
19.
Muehlberger, 1967, pi·. 1, scale
1:48,000.
18
5
11
22
,---------
-- - - - -- -- r-
+
+
i.. ______ ,I
-i""""9c---._
,....------+-------,--------1------,------j"'
1
24
21
21
5
24
24
4
6
10
27
24
24
14
24
and Stensrud, 1974, scale
1:763,000.
I
,...
.
~7
20 ... J1uf.'h Iberger, 196.8, . sca_l ~ 1 : 48, 000.
21.
0 Ison, 1977, unpub., sea Ie 1:48, 000;
scale 1:62,500.
·
22.
Ritchie, 1969, unpub., scale 1:24,000.
23.
Santos and others, 1975, scale
1:24,000.
24.
Smith and others, 1961, pis. t-6, scale
1:24,000.
25.
Smith and others, 1970, scale
1:125,000.
26.
Trice, 1957, unpub., scale 1:24,000.
27.
Trieman, 1975, unpub., scale 1:24,000.
28.
Weide, 1977, unpub., scale 1:24,000.
29.
Woodward and others, 1976, scale
1:24,000 •
30.
Woodward and others, 1972, scale
1:24,000.
31.
Woodward and others, 1974, scale
I: 24,000.
14
"'t--------------129
-------r--------:
' 21
23
!
26
28
25
21
17
!
10
21
25
25
10
30'
"'
IS'
BASE MAP CONTROL fROM USGS
. URANIUM RESOURCE EVALUATION
ISS OED BY THE U. 5. DEPARTMENT OF ENERGY
10
15
0
20
25 KILOMETERS
~~~~s-~~~~
PLATE 11.--GEOLOGIC-MAP INDEX
Compiled by
Kim Manley and G. R. Scott, U.S. Geological Survey
NEW MEXICO/
15'
IS'
.!J"
l
106.
---------
INDEX
,.
A.
Areas Managed by National Park Service
F-2
A-1
B.
N-1
\
E-1~
~
rr-1
+
\E-1iR
\E-~
+
+
F-2
+
'
\;1
E-1
...
+
__L
Forest ServIce WI J derness, Wilderness
Study; and Primitive Areas
B-1
San Pedro Parks Wilderness Area
B-2
Chama River Canyon WIlderness Area
c.
Forest Service RARE II Roadless Area
0.
Bureau of Land Management Wilderness
Inventor~ Unl ts
E.
Bureau of Land Management Withdrawn
Nat I anal Resource Lands and Bureau of
ReclamatIon WIthdrawals
1<-1
F-2
Chaco Canyon National Monument
F.
E-1
Reclamation and Water Power Project
WIthdrawal
E-2
Powersite Withdrawals
Indian Lands
F-1
Indian Lands
F-2
Jicari II a Indian Reserva t i on ·
F-3
San Juan Pueblo Reserva t I on
L-1
L.
+
+
-L
Nat lanai Trails
_L
I
"
N.
L-1
Dominguez-Escalante Trail
L-2
Cent inental Dlvlqe Trail
Other Land Categories
N-1 ·Tierra Amari I Ia Grant
,,,
F-1
0
00~0
0
0
F -1
URAN!Ui.l ~ESOURCE EVALUAT[ON.
ISSUED BY .THE U.,S, DEPARTMENT OF ENERGY
F-2
[~]
0
+
+
+
Jl'
BASE MAP CONTROL FROY USGS
10
0
0
10
20
15
15
20
25 MILES
25 KILOMETERS
~~~~~~~~~
PLATE 12. -'--GENERALIZED LAND STATUS MAP
N-2
Piedra Lumbre .Grant
N-3
Plaza Blanca Grant
N-4
Lobato Grant
N-5
Ojo Call ente Gran(
N-6
Black Mesa Grant
•.;.
. -'·'
MEXICO/ COLORADO
\.,
__ _
-I
I
~~Cow Cam~
I
I
\
GU 0
Ill!
'-................
!
\
SlJG.ULOAf
·" v'
MOU~TAIN
.~::;;1~\igo
',,
·eo. em~~.,
.
.......... ..........
"'~~~-.. .....
a
•
·•
c.,,..l,
~~ 'f'n~[
0
'
Sm;:"
CARSON
[OWCimp
.-.~'
\
I
".
)
//
\eaf:
'<:."' '
,
I
I
I
I
~,5
i
I
~ _n ..\~.nt
I_____ _
I
I roJ~
i
I
+
.,w
I
\,o:,o
I
I
•CowCamo \
I
I
S"!;mill
\ ..........
CARSON
NATI NAL
FOREST
,__~__:_::::._~~~--'-r~l--'-"'-'~-·~~f--~
'-,1
I
I
..._ 1 1:. ~~~,
I
I
I
I
I
RESERVATION
c.m~
I
I
I
I
I
jRm!J.
IL'S~l
'"""'
-;
... DU lA'N
"'
Jt'·
' . · Gn•ells•
•'
o<J'el
I
~tOWAMlN
I
I
I
:·
0
c....n ~·
. : ••
~.
0
n
I
,llu·•
I
I
Guwoll1
'
! ""•0
I
~an
h,
I
,I
,,J",-------o~00S
Gas
well•
I
!
tit
C.~ 1-10 ,I ~anw"
1.
o
~
iR.,thtl
I'
I
I
I
I
~~~-~-~~~--~~---~-
URANI UU RESOURCE EVALUATION
ISSUED BY THE U.S, DEPARTMENT OF ENERGY
10
0
10
BASE UAP CONTROL FROU USGS
20
15
15
20
25 MILES
25 KILOMETERS
~~~~s-~~~~
PLATE 13.--CULTURE MAP
Plate 13.
1979
",r,-·