Download Early Proterozoic Assembly of Tectonostratigraphic

Early Proterozoic Assembly of Tectonostratigraphic Terranes in Southwestern North America
Author(s): Karl E. Karlstrom and Samuel A. Bowring
Source: The Journal of Geology, Vol. 96, No. 5 (Sep., 1988), pp. 561-576
Published by: The University of Chicago Press
Stable URL: http://www.jstor.org/stable/30053570 .
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EARLY PROTEROZOIC ASSEMBLY OF TECTONOSTRATIGRAPHIC
IN SOUTHWESTERN NORTH AMERICA'
KARL E. KARLSTROM
AND SAMUEL
TERRANES
A. BOWRING
of Geology,Northern
Department
ArizonaUniversity,
Flagstaff,
Arizona
St. Louis, Missouri
University,
of Earthand Planetary
Sciences,Washington
Department
ABSTRACT
A 500kmwideearlyProterozoic
orogenicbeltinArizonaand adjacentareasis dividedintolithotectonic
and U-Pbzirconstudiessuggestthatthese
shearzones. Structural
blocksby northeastand north-trending
juxtaposition
blocksmayhaveexperienceddifferent
tectonichistories
and strike-slip
priorto their
bythrust
on shearzones. A northwestern
herecalledtheYavapai Province,is composedofat
province,
movements
leastfivetectonicblocksand was assembledat about1700Ma. A southeastern
province,herecalledthe
Mazatzal Province,is composedof at least threeblocksand was assembledand juxtaposedwiththe
provinceduringtheMazatzalorogeny,
between1695and 1630Ma. Thediversity
northwestern
ofseemingly
nowinclose proximity
to each other,andtheabsenceofsystematic
1700Ma tectonicregimes
incompatible
plutonism,
cross-strike
ofdeformation,
suggesta model
changesin age and character
and metamorphism,
wherebythe orogenicbelt developed,and NorthAmericagrew,by assemblyof diversetectonostratito previousmodelsofprogressive
graphicterranes.Such a modelprovidesan alternate
hypothesis
working
growth
southward
of
ofNorthAmerica.Thismodelprovidesa betterexplanation
fortherapiddevelopment
theorogenicbelt(1700-1630),theaccretion
oflargevolumesofjuvenilecrust,andthecomplexity
intiming
and stylesof EarlyProterozoictectonism
in southwestern
NorthAmerica.
INTRODUCTION
More than 50% of the present crust of
North America was assembled in the period
2.0-1.6 Ga. Studies of the development of
earlyProterozoic orogenic belts are therefore
essential for understandingthe historyand
mechanisms of continental growthof North
America. In Canada and the northernUnited
States, Proterozoic orogenic belts surround
Archean cratons and record a major period of
continental assembly 2.0-1.8 Ga (Hoffman
1988). Much of the continentalcrustin these
orogens consists of older sialic crustthatwas
modifiedby tectonism, with relativelyminor
additions of juvenile crust (Patchett and
Arndt1987). The wide orogenicbelt in southwesternNorth America is fundamentallydifferent in that it apparently represents the
generation of large volumes of juvenile Proterozoic (1.8-1.6 Ga) crust (DePaolo 1981;
Nelson and DePaolo 1985; Wooden et al.
1987).
The north margin of the Proterozoic orogenic belt in southwesternNorth America is
the Cheyenne belt of southern Wyoming, a
' ManuscriptreceivedSeptember14, 1987;acceptedApril22, 1988.
OF GEOLOGY,1988, vol. 96, p. 561-576]
[JOURNAL
© 1988by The University
of Chicago.All rights
reserved.
0022-1376/88/9605-0006$1.00
wide mylonitezone interpretedto representa
suture zone between the Archean Wyoming
Province, with its miogeoclinal cover sequence, and accreted 1.8-1.7 Ga island arc
terranes(Hills and Houston 1979; Karlstrom
and Houston 1974; Duebendorfer and Houston 1987). From southern Wyoming, early
Proterozoic crust extends southward for
more than 1300 km to northernSonora, Mexico. Based on our work in central Arizona,
we propose a model which views the developmentof this orogenic belt, and hence early
Proterozoic growth of southwestern North
America, in terms of the independent development and subsequent accretion of diverse
tectonostratigraphic
terranes.This "terrane"
interpretation
from
is fundamentallydifferent
previous tectonic models for the Proterozoic
of the Southwest (for example, Van Schmus
and Bickford 1981; Condie 1982, 1986; Anderson 1986; Conway and Silver in press) that
propose southward growth by progressive
addition of continentalmarginvolcanic arcs
and arc-related or continental margin sedimentarybasins.
In the absence of paleomagnetic and biostratigraphicdata, which have been used successfully to definefar-traveledtectonostratigraphicterranesin the Cordillera (Jones et al.
1983), our approach is as follows. (1) We first
identifytectonic blocks where a block is
defined as an area of Proterozoic basement
bounded by major Proterozoic faults and
561
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562
KARL E. KARLSTROM AND SAMUEL A. BOWRING
shear zones or, if a tectonic boundary is not
exposed or mapped, an area with distinctly
differentgeologic character than adjacent
areas. (2) Kinematic indicators are used to
deduce sense and history of movements
across shear zones. (3) Geologic history
withineach block is established by determining the relative timing of sedimentation,
plutonism,deformation,and metamorphism.
(4) U-Pb zircon geochronology is utilized to
constrainthe geologic history.(5) Similarities
and differencesin geologic historyare used to
help identifytectonostratigraphic
terranes.A
terrane is defined here as a block or group
of blocks that represent a semi-coherent
segment of Proterozoic lithosphere which
evolved, at least in part, separately fromadjacent terranes.(6) We then attemptto define
the timingofjuxtaposition of terranesand the
assembly of orogenic provinces. A province
is definedas a large tract of the orogen that
was assembled during one major pulse of
convergenttectonism.
The quality of available geologic and geochronologic data is variable across the transect so that our identificationof blocks and
the way in which the proposed blocks are
grouped into tectonostratigraphicterranesis
preliminary.Our hope is that by pointingout
importantdifferencesbetween blocks, and by
emphasizingthe importanceof the major network of shear zones, we will stimulatefurther
work to evaluate stratigraphicand tectonic
links between blocks and therebydistinguish
tectonic boundaries that separate fundamentally differentterranes fromboundaries that
record relatively minor movements within
terranes.
TECTONOSTRATIGRAPHIC
PROVINCES
IN ARIZONA
Figure 1 shows that Arizona's Transition
Zone between the Colorado Plateau and Basin and Range Province, combined with adjoining areas of the Basin and Range Province
of Nevada, southeasternCalifornia, and Sonora, expose a 500 km long outcrop belt that
is subperpendicular to the Proterozoic orogenic strike. This outcrop belt exposes an
orogenic cross section thatis as wide as many
of the world's major orogens. For perspective, a comparable cross-strike distance in
the Cordilleran and Appalachian orogens in
most places would extend fromthe continental slope to the undeformedforeland.
Structuralstudies and geologic mappingin
Arizona have identifieda familyof north-and
northeast-trendingEarly Proterozoic shear
zones that divide this transect into at least
eighttectonic blocks (figs. 1 and 2). Some of
these shear zones were recognized fromearly
mapping (Shylock fault zone and Chaparral
fault zone of Anderson and Creasey 1958);
othersare emergingfrommore recentstudies
(Moore Gulch fault-Maynard 1986; Karlstromand Conway 1986; Slate Creek shear
zone-Roller and Karlstrom 1986; Roller
1987). We can now document thatseveral of
these blocks experienced differentdeformational and tectonic histories and therefore
should be considered distinct tectonostratigraphicterranes.
In central Arizona the Moore Gulch fault
(fig. 1) is part of a major boundarythatseparates a northwesternprovince, the Yavapai
Province, froma southeastern province, the
Mazatzal Province. This fault zone contains
mylonites with subvertical foliation and
stretchinglineation thatrecord movementafter 1700 Ma, the age of the youngest rocks
deformedalong the Moore Gulch fault. This
tectonic boundary approximately coincides
witha geochronologic boundary proposed by
Silver (1965, 1967, 1969) and Silver et al.
(1977, 1986) based on U-Pb zircon data. This
geochronologic boundary was believed to
separate an older 1800-1700 Ma province to
the northwestfroma younger 1700-1600 Ma
province to the southeast.
Karlstromet al. (1987) presentedtwo models for the juxtaposition across the Moore
Gulch fault. In the firstmodel, the 1700 Ma
supracrustalsequence of the Mazatzal province was deposited with angular unconformity on the previously accreted island arc
volcanic and batholithicrocks of the Yavapai
Province. Younger dip-slip motion along the
Moore Gulch faultjuxtaposed deep levels of
the Yavapai Province and shallow levels of
the Mazatzal Province. The second model
considers the two provinces to representseparate tectonostratigraphicterranes that record verydifferent
tectonic histories.In itthe
Moore Gulch faultis considered to be part of
the suture between rocks of the two provinces.
This paper presents argumentsthatsupport
the second model of Karlstrom et al. (1987),
involvingtectonicjuxtaposition of these two
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ASSEMBLY
115°
114°
OF TECTONOSTRATIGRAPHIC
113°
112°
TERRANES
111
563
110
FIG. 1.-Distribution of early Proterozoic rocks (stippled) in Arizona and adjacent areas. Proposed
tectonostratigraphicblocks: MO-Mojave block; HB-Hualapai-Bagdad block; G-Green Gulch block;
B-Big Bug block; A-Ash Creek block; M-Mazatzal block; S-Sunflower block; P-Pinal block. Major
Proterozoic shear zones: CH-Chaparral fault zone; SH-Shylock fault zone; MG-Moore Gulch fault;
SC-Slate Creek movement zone. Lineaments on Colorado Plateau: SI-Sinyala fault system; BABrightAngel faultsystem; MB-Mesa Butte faultsystem;G-northwest boundary of gravityhigh;HOHolbrook lineament,a gravityand magnetic lineament(see Shoemaker et al. 1978; Lysonski et al. 1980;
Sauck and Sumner 1970). Other boundaries: Pb (shortdashed line)-boundary between Pb isotope provinces proposed by Wooden et al. (1987); Sm/Nd(dot-dash)-boundary between Sm/Ndprovincesproposed
by Bennettand DePaolo (1987); C (dots)-geochemical boundaryproposed by Condie and Demalpas (1985)
and Copeland and Condie (1986).
major provinces. Each province is composed
of smaller tectonostratigraphicterranes; we
argue that the orogenic belt in central Arizona is a collage of blocks and terranesthat
experienced differenttectonic histories and
then were assembled perhaps starting as
early as 1740 Ma and continuinguntil about
1630 Ma. The following section reviews the
distinctive tectonic features of each block
and the nature of the major shear zones.
More detailed discussion of various aspects
of the geology are in Karlstromand Conway
(1986), Conway and others (1987), Karlstrom
and others(1987), and referencestherein.All
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TIMING OF TECTONIC
ROCK UNITS
PINAL SCHIST
TONTO BASIN SUPERGROUP AND
DIAMOND POINT INTRUSIVE SUITE
GRANITIC ROCKS
VOLCANOGENIC ROCKS, INCLUDING
YAVAPAI SUPERGROUP
MO
HB
A
MOJAVE
HUALAPAI/BAGDAD
NEVADA
GREEN GULCH
ARIZONA
BIG BUG
ASH CREEK
MAZATZAL
SUNFLOWER-
CALIF
PINAL
FIG. 2.-Block diagramshowingproposed tectonostratigraphic
blocks in Arizona and adjacent regions.The
province(5 blocks) froma composite southeasternprovince(3 blocks). Timingof tectonicevent
northwestern
dates in Karlstromet al. (1987) and unpublisheddata.
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ASSEMBLY
OF TECTONOSTRATIGRAPHIC
TERRANES
ages, unless otherwise referenced,are U-Pb
zircon ages taken fromTable 1 of Karlstrom
and others (1987).
565
thatis axial planar to tight-to-isoclinalfolds.
This foliation is cut by unfoliateddikes and
plutons of the Cherrybatholith,which is not
penetrativelydeformedexcept along the marYAVAPAI PROVINCE
BLOCKS AND SHEAR ZONES
gins of the block, in the Moore Gulch and
The Yavapai Province is divided into five
Shylock fault zones. Thus, timingof deformationin the Ash Creek Group is bracketed
blocks, the Ash Creek, Big Bug, Green
between 1790 and 1740 Ma and is the oldest
Gulch, Hualapai-Bagdad, and Mojave blocks
(figs. 1 and 2). These blocks are made up of
known deformationin central Arizona.
supracrustal rocks of the Yavapai SuperShylock Fault Zone.-The Shylock fault
zone is a several kilometerwide zone of vertigroup and associated calc-alkaline batholiths
(Andersonet al. 1971). (The lithostratigraphic cal foliation,with dominantlyvertical lineation, that extends some 60 km north-south
term Yavapai Supergroup is used here in
place of the chronostratigraphictermYavaand separates the Ash Creek and the Big Bug
pai "Series" used by Anderson et al. (1971)
blocks. This zone records a complex deforin accordance with amendments to the U.S.
mation historythat we interpretto have reCode of stratigraphicnomenclatureproposed
sulted fromtranspressionalconvergence beby Henderson et al. 1980). The Yavapai
tween blocks (Karlstrom 1988). Deformation,
at least in part, post-dated the 1720 Bland
Supergroupis a diverse sequence of maficto
intermediate volcanic rocks and volcaniquartz diorite of the Cherrybatholith of the
Ash Creek block. The Bland quartz diorite is
clastic sedimentaryrocks in centralArizona.
intenselyfoliated along its west margin and
These rocks were divided by Anderson et al.
(1971) into two groups, the Ash Creek Group
contains the vertical lineation that is characteristicof early movements on the Shylock
and the Big Bug Group, the lattermade up of
fault zone. The vertical L-S fabric records
the Green Gulch Volcanics, Spud Mountain
Volcanics, and Iron King Volcanics. The
shorteningand dip-slip movementacross the
zone. Vertically-plungingisoclinal folds in
blocks in centralArizona correspondto these
the Shylock fault zone are overprinted by
stratigraphicsubdivisions, as each of the
groupsis, forthe most part, areally restricted folds with consistent sinistral asymmetry,
to the fault-boundedblocks definedin figure and early vertical foliationis reactivated in a
2. (The followingdiscussion of northwestern zone several hundredmeterswide and 25 km
long by sinistral strike-slipmovement. This
blocks proceeds from the southeast to the
northwest.)
reactivated zone in the Shylock is called the
Ash Creek Block.-The Ash Creek block is
Cleator mylonitezone (Darrach et al. 1986).
bounded on the southeast by the Moore
Transpressional movement involving both
Gulch fault and on the west by the Shylock
shorteningacross the Shylock fault and sinfault zone. It contains: (1) the Ash Creek
istral strike-slipappear to have been tempoGroup, the oldest rocks in central Arizona
rally related to intrusion of the 1699 Ma
(ca. 1790 Ma), with the importantmassive
Crazy Basin Quartz Monzonite (Karlstrom
sulfide deposit at Jerome; (2) the Cherry
and Conway 1986; Conway et al. 1987).
batholith,a large calc-alkaline batholithwith
Big Bug Block.-The Big Bug block is
numerousplutons thatrange in age from1740
bounded by the Shylock fault zone on the
to 1720 Ma and in composition fromquartz
east and the Chaparral faulton the northwest.
dioriteto granodiorite,and (3) a sequence of
Big Big Group rocks in thisarea include mafic
metavolcanic and metasedimentary rocks
to felsic volcanic and volcaniclastic rocks
thatcrop out near the Moore Gulch faultand
thatare dated at 1755 Ma and are intrudedby
1750-1735 Ma granodiorites. One of these
are intruded by the Cherry batholith. The
metamorphicgrade of the Ash Creek Group
granodiorites,the Brady Butte granodiorite
has not been studied in detail, but pet(1750 Ma), intrudesthe Big Bug Group and is
rographic descriptions by Anderson and
unconformablyoverlain by metasedimentary
Creasey (1958) suggest upper greenschistto
and metavolcanic rocks of the Texas Gulch
lower amphibolite grade metamorphism. Formation.The Brady Buttegranodioriteand
the Texas Gulch Formation are folded toRocks of the Ash Creek Group contain a
steeply dipping, northwest-trending
foliation
getherinto recumbentisoclinal folds (F1) that
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566
KARL E. KARLSTROM AND SAMUEL A. BOWRING
plunge shallowly to the northand verge west
or northwest. This early recumbent folding was associated with northwest-directed
thrustingas shown by asymmetricalfabricsin
the mylonitic Brady Butte Granodiorite
(Karlstrom 1988). Recumbent folds (F1) are
refolded by uprightfolds (F2) with variable
plunge and subvertical axial plane foliation.
In most of the Big Bug block, the dominant
verticalfabricis related to intense shortening
(F2) but is a composite fabric consisting of
rotatedand transposed bedding and S1 and S2
axial plane foliation. This composite foliation, with subvertical stretchinglineation,
can be traced eastward and is continuous
with the vertical fabric of the Shylock fault
zone, which exhibits similar sequence and
style of fold generations. If the correlationof
the vertical fabric (F2) in the Big Bug block
with the vertical fabric in the Shylock fault
zone (F2) is correct, F2 shorteningdeformation must have post-dated the 1720 Bland
quartz dioriteas discussed earlier. In the area
of the 1699 Ma Crazy Basin Quartz Monzonite the verticalfabricand associated upright
isoclinal folds (F2) of the Big Bug block are
deflectedaroundthe northernterminousof the
Crazy Basin Quartz Monzonite, and one
macroscopic uprightfold (F2) is crosscut by
an aplite which is similarin compositionand
age (1700 Ma) to the nearby Crazy Basin
Quartz Monzonite. This indicates thatthe recumbentfoldingand some of the uprightfolding of the Big Bug block took place before
1700 Ma. Further,the aplite and the Crazy
Basin Quartz Monzonite are foliated, presumably by continued shortening(F2). The
shorteningis therefore interpretedto have
been broadly synchronouswith 1700 Ma emplacement of the Crazy Basin Monzonite.
Sinistral strike-slipreactivation of the Shylock fault zone along the Cleator mylonite
zone was progressivelyrelated to F2 shortening (Darrach 1988) and was also contemporaneous with 1700 Ma plutonismas shown
by en echelon vein arrays filledwith Crazy
Basin Quartz Monzonite that are compatible
with sinistral strike-slip movement. Metamorphism post-dated the major shortening
(F2) deformationin the Crazy Basin area and
reached temperatures of about 550°C and
pressures of 3.7 kb, as recorded by garnetbiotite geothermometryand garnet zoning
profiles (Michael Williams pers. comm.
1987). The Crazy Basin Quartz Monzonite
contains muscovite, biotite, and garnet, an
assemblage that suggests the batholithcrystallized at pressures in excess of 2-3 kb (Miller 1985).
Distinctive features of the Big Bug block
include the following: (1) The supracrustal
rocks of the Big Bug Group (1755-1740 Ma)
are youngerthan the Ash Creek Group (1790
Ma). (2) The deformationalhistoryinvolved
northwestverging recumbentfolds (F1) and
thrustsoverprinted by tight-to-isoclinaluprightfolds (F2). The resultingfabricis characterizedby northeast-trending
subverticalfoliation with subvertical stretchinglineation
rotated to a northerlystrikewithinthe Shylock faultzone. (3) F1 recumbentfoldingwas
post-1750Ma, and F2 shorteningwas at 1700
Ma. (4) The Crazy Basin Quartz Monzonite is
a strongly peraluminous early Proterozoic
batholiththatwas intrudedat depthsof 10-15
km into a crust undergoingductile deformation at 5500C and 3.7 kb at 1700 Ma.
Chaparral Fault.-The
Chaparral fault
(Anderson and Creasey 1958) is a 2 km wide
vertical shear zone that trends northeast,
parallel to vertical foliation in the Big Bug
block. It contains well-developed shallowlyplunging stretchinglineation and abundant
kinematicevidence fora major componentof
dextral strike-slipmovement. Movement on
the zone post-dated intrusionof the 1735 Ma
Crooks Canyon Granodiorite.North-trending
foliationin the Green Gulch Volcanics north
of the Chaparral faultbecomes progressively
of the fault
deflectedinto the northeast-trend
demonstratingin excess of 3-5 km dextral
strike-slipbased on shear strains calculated
by measuring deflection of foliation trajectories (c.f. Ramsey and Huber 1983).
Green Gulch Block.-Yavapai Supergroup
rocks immediatelynorthwestof the Chaparral fault were named the Green Gulch Volcanics of the Big Bug Group by Anderson et
al. (1971). There are no published isotopic
ages on the supracrustal rocks, but they are
intrudedby 1740 Ma granodioritesand were
believed by Anderson et al. (1971) to be older
than the volcanics exposed in the Big Bug
block, based on stratigraphicarguments.Deformationof the Green Gulch Volcanics is
reportedby Krieger (1965) to be pre- to synintrusion of the 1740 Government Canyon
granodiorite. Tectonic history of the Green
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ASSEMBLY
OF TECTONOSTRATIGRAPHIC
567
TERRANES
0
0 km Present
surface
25
25
km
50
0
50
50
100
NW blocks deformed 1700 Mo
and metamorphosed calc-alkaline
at ca. 1700 Mo
plutons
post-deformationaol
NW blocks 1700 Mo strongly SE blocks
deformed
plutons, 1650-1630
deformed peraluminous
pre-1740 Mo
pluton
1690-1630 Ma
and 1400 Ma
Thrusts
Strike-slip foults
FIG. 3.-Schematic NW-SE cross-section throughthe TransitionZone of Arizona showing minimum
complexityof assembled blocks. At least three major terranesseem to be required by data on timingof
deformation.
Gulch Volcanics appears to be similarto the
Ash Creek Group, as indicated by the northwest trendof foliationin both blocks, similar
metamorphic grade, similar compositions
and ages of plutonic rocks (Krieger 1965),
and similar timingof deformation(pre-1740
Ma). We suggest that these two blocks may
be part of the same terranethatis folded into
a crustal-scale antiformcored by the Big Bug
block, as shown schematically in figure3.
Siliciclastic sedimentary rocks that are
similarin lithologyto the Mazatzal Quartzite
of the southeastern province occur in one
small outcrop in the Green Gulch block.
These rocks are very low-grade(theycontain
pyrophyllite,kaolinite, and other clay minerals) and not penetratively deformed, in
marked contrast with volcanic and granitic
rocks nearby. The lower contact of the quartzite is not exposed, so the relationshipbetween the quartzite and the underlyingunits
is in doubt (Karlstrom et al. 1987). If these
rocks do indeed correlate with the Mazatzal
Group-as all workers have proposed-they
represent a link between the southeastern
and northwesternprovinces. This link could
be stratigraphicor tectonic, an angular unconformityor a thrust.
volcanic
Hualapai-Bagdad Block.-The
and volcaniclastic rocks in the Bagdad area
have been correlatedwiththe Yavapai Supergroup (Anderson et al. 1955), although rhyolitic rocks that are interstratified
with mafic
volcanic rocks yield ages of 1709 Ma, younger than any rocks known in the Yavapai
Supergroupto the southeast. Published dates
fromgranitesin this area range from1720 Ma
to 1696 Ma, and deformationappears to be
bracketed between 1706 and 1696 Ma, the
ages of stronglyfoliatedplutonic rocks and a
syn- to post-deformationalgranite, respectively(Bryantand Wooden 1986). The timing
of deformationis thus similar to that of the
Big Bug block.
In the western Hualapai Mountains, Stensrudand More (1980) described a sequence of
supracrustalrocks thatincludes amphibolites
and pelitic schists intrudedby several types
of graniticintrusives.The metamorphicgrade
is reported to be upper amphibolite facies,
which may be compatible with either a general increase in metamorphic grade to the
northwestin the Hualapai-Bagdad block or
withthe presence of several distinctblocks.
Graniticrocks make up the western Hualapai
plutoniccomplex (Stensrud and More 1980),
a northwest-trending80 km long belt of
granodioriteplutons which may be a distinctive feature of the Hualapai-Bagdad block.
New U-Pb zircon dates on several plutons in
the western Hualapai Mountains range between 1660 and 1730 Ma (Chamberlain et al.
1988).
The Majave Block.-Early
Proterozoic
rocks in the Mojave desert occur within
rangesof the Basin and Range province. The
geologic historyof these uplifts is complex
and generally involves Mesozoic compression followed by ductile and brittleTertiary
extensional tectonism. Although the Proterozoic historyin the Mojave is still incompletelyknown, it contains remnantsof 19002300 Ma supracrustal rocks, and isotopic
evidence indicates that this area is a distinct
tectonostratigraphicterrane relative to the
rest of Arizona (Wooden et al. 1988). We in-
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568
KARL E. KARLSTROM AND SAMUEL A. BOWRING
clude the Mojave block in the Yavapai Province because it experienced deformationand
metamorphismat about 1700 Ma (Wooden et
al. 1988).
Isotopic Data.-Sm-Nd
and Pb isotopic
data suggest the presence of a boundary (fig.
1) thatis subparallel to the California-Arizona
border. Rocks west of this boundary have
high Nd/Sm ratios that require mixing of a
significantcomponent of older crustal material duringcrustalformationat 1800-1700 Ma
(Bennett and DePaolo 1987). In contrast,
rocks in Arizona east of this boundary have
low Nd/Sm ratios that are consistent with
derivationofjuvenile early Proterozoic crust
from a MORB-like mantle source at 18001700 Ma. In addition, Mojave rocks have a
more radiogenic Pb isotope signature than
Arizona rocks (Wooden et al. 1987; 1988).
The higher Pb 207/206ratio in the Mojave
seem to require either addition of Pb from
Archean sources or from ca. 2.1 b.y. old
crust. Mojave rocks also have lower Pb 206/
204 ratios, which probably reflectthe higher
regional metamorphic grade of Proterozoic
rocks in the Mojave (highT, low P, granulite
facies in the New York Mountains according
to Elliott et al. 1986).
MAZATZAL PROVINCE BLOCKS AND SHEAR ZONES
The area southeast of the Moore Gulch
faultis divided into threeblocks: the Mazatzal, Sunflower,and Pinal (fig.2). These areas
expose predominantly1710-1690 Ma supracrustal rocks and associated hypabyssal intrusions. The nature of the basement to the
supracrustal succession and hypabyssal intrusions is poorly known.
Mazatzal Block.-The Mazatzal block is
distinct from the northwesternblocks in
termsof stratigraphy,style and timingof deformation, and metamorphic grade. Supracrustal rocks have been named the Tonto Basin Supergroup (Conway et al. 1987),whichis
divided into three groups: Alder, Red Rock,
and Mazatzal. This sequence is intrudedby
penecontemporaneous shallow level granites
and granophyrescalled the Diamond Rim IntrusiveSuite (Conway et al. 1987). Rocks that
may be part of the basement to the Tonto
Basin Supergroup include the Gibson Creek
batholith, a 1738 Ma calc-alkaline gabbrodiorite complex, metasedimentaryand metavolcanic rocks found as screens in the batho-
lith, and sedimentary packages that may
correlate with the screens, for example the
East Verde River Formation (Conway and
Wrucke 1986). However, the lower Alder
Group has not been found in depositional
contact with older basement rocks.
The lower Alder Group is up to several
kilometersthick and contains pillow basalts,
graywacke, small exhalative sulfidedeposits,
and slates. This sequence is widespread and
presumablyrecords marine sedimentationin
arc-related basins. Upper Alder rocks consists of several kilometers of slates, lithic
arenites, intermediate-to-felsicpyroclastic
rocks, quartzarenite,and rhyolite.Upper Alder Group felsic pyroclastic rocks have been
dated at 1710-1700 Ma and thus appear to
overlap in age the overlyingRed Rock Group
rhyolites.
The Red Rock Group is dominated by alkaline highsilica rhyoliticash flowtuffs,rhyolitic lava flows, and related hypabyssal intrusives that range in age from 1703-1692
Ma. This group is several kilometers thick
locally, has a volume of several thousand
cubic kilometersregionally,and has been interpretedto record caldera-related rhyolitic
volcanism analogous to Yellowstone or the
Basin and Range province (Conway 1976;
Conway and Silver 1984). Red Rock Group
volcanism gave way to fluvial and shallow
marinesiliciclastic sedimentationin the Mazatzal Group. The Mazatzal Group is 1-2 km
thick and generally disconformablyoverlies
the Red Rock Group. This sequence has been
interpretedto be part of a regionallyextensive miogeoclinal sand blanket (Trevena
1979). Dated sills and domes of rhyoliteintrudethe lower Mazatzal Group and indicate
thatsiliclasticsedimentationimmediatelyfollowed and overlapped in time with rhyolitic
volcanism.
The structuralstyle in the Mazatzal block
is that of a shallow-level foreland fold and
thrust belt. Major thrusts have ramp-flat
geometries with duplex systems. Folds of
three major types characterize the Mazatzal
block; all are related to the northwestdirectedthrusting:(1) fault-bendfolds above
ramps are seen at mesoscopic to macroscopic
scales; (2) large-scale uprightfolds above detachmentsare associated with shorteningdue
to tectonic wedging; and (3) northwestvergingasymmetricalfolds occur associated
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ASSEMBLY
OF TECTONOSTRATIGRAPHIC
with thrusts in less competent units. The
thrustingin the Tonto Basin Supergroupis of
regionalextent. Puls (1986) estimatedgreater
than 50% (>18 km) shorteningin one area of
the northern Mazatzal Mountains on the
basis of a restoredcross section of the Mazatzal thrustsystem, which consists of a roof
thrustabove a duplex system. This estimate
of thrust transport, as well as observed
geometries,necessitates that all of the Tonto
Basin Supergroupin the southeasternpart of
the Mazatzal block is allochthonous relative
to the northwestpart of the block (fig.2).
The Gibson Creek batholith(1738 Ma) also
is involved in thrusting(Conway 1976), so if
thisis a portionof the basement on whichthe
Tonto Basin Supergroup was deposited, the
basement and cover are intimatelyshuffled.
Thrustingtook place between 1692 and 1630
Ma, the youngest rocks involved in thrusting and the age of the Young Granite respectively. The Young Granite intrudesthe
Alder Group south of the Slate Creek shear
zone and is reported to be syn- or postdeformational(Conway and Silver 1988).
Rocks exposed in the Mazatzal block are of
low metamorphicgrade. Kaolinite is present
in argilliticquartzites, and pyrophylliteis observed at slightlydeeper levels in slates. Xray data on dioctahedral illite shows about
90% ordered (2 m) polymorph, suggestingT
of 200-3500C (Maxwell and Hower 1967).
This is compatible with fluid inclusions in
syntaxial quartz fibersalong thrustsurfaces
that have homogenization temperatures of
less than 2500C. These conditions and the
predominance of pressure solution as the
dominant deformationmechanism, are consistentwith shallow crustal conditionsduring
deformationand metamorphism.
The Mazatzal block is distinct from the
Ash Creek block in the following ways: (1)
The distinctive1700 Ma supracrustalpackage
and alkalic granitesof the Mazatzal block terminateabruptlyat the Moore Gulch fault.(2)
The Mazatzal block was deformed between
1692 and 1630 Ma at low metamorphicgrade,
whereas the Ash Creek block records pre1740 and 1700 Ma deformations at higher
metamorphicgrades. (3) The two blocks have
distinctlydifferentmetalogenic characteristics, as discussed by Titley (1987).
Slate Creek Movement Zone.-The Slate
Creek movement zone is an east-northeast
TERRANES
569
strikingnetwork of shear zones up to 5 km
wide thatseparates the Sunflowerand Mazatzal blocks. It is exposed fora strikedistance
of 40 km and may be extended to coincide
with the Holbrook lineament, a magnetic
(Sauck and Sumner 1970) and gravity (Lysonski et al. 1980) lineamentof the Colorado
Plateau (fig. 1). The movement history includes south-side up (and sinistral) oblique
slip (fig. 2) followed by shorteningacross
conjugate but predominantlydextral shear
bands (Roller 1987). Early south-side up
movementsare interpretedto be temporally
and kinematicallyrelated to the thrustingin
the Mazatzal block, and cross sections suggest that the movement zone in part reflects
above a ramp in the regional decolflattening
lement(see Conway et al. 1987). Large southside-up displacements across the zone are
suggestedby very high strainsand by higher
grade metamorphicrocks south of the movementzone.
Sunflower Block.-The
Sunflower block
contains a supracrustal package of rhyolite
and quartz arenite that is similar to the
Mazatzal block but is distinguishedby a generally higher grade of metamorphism.The
Sunflower block also contains a suite of
1640-1630 Ma graniticintrusivesthatare unknown north of the Slate Creek movement
zone. Supracrustal rocks make up only a
small percentage of the exposed Sunflower
block relative to granites (both 1640-1630
and 1400 Ma granites).
Metamorphic grade is highersouth of the
Slate Creek movement zone, suggestinggenerallydeeper crustal levels than are exposed
in the Mazatzal block. At Four Peaks, andalusite and sillimanite coexist in pelitic
metasedimentary rocks. In the McDowell
Mountains near Phoenix, Couch (1981) reportedkyanite,sillimanite,and K-feldsparin
peliticrocks. These assemblages, along with
garnet-biotitegeothermometry,were interpreted by Couch (1981) to record an early
regional metamorphismwith T=350-450°C
and P= 4-6 kb, followed by "contact
metamorphism" with T= 550-580°C and
P=3-3.7 kb. Assemblages found on Squaw
Peak, in Phoenix, contain Mn-andalusite,kyanite, staurolite, and chloritoid(Thorpe and
Burt 1978) similar to regional metamorphic
assemblages seen in New Mexico which representpeak conditions of T= 5000C, P= 4 kb
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570
KARL E. KARLSTROM AND SAMUEL A. BOWRING
(Grambling 1986). All of these amphibolite
assemblages in the Sunflower block have
been interpretedto be the productsof contact
metamorphism.However, the highpressures
indicate depths of 10-20 km at least in some
areas of the Sunflower block and, at Four
Peaks for instance, the effect of contact
metamorphismaround the 1400 Ma granite
appears to be retrogressive. The higher
metamorphic grades and the presence of
1640-1630 granitoids in the Sunflowerblock
both suggest differentcrustal levels and/or
differentlithospheric sections for the two
blocks.
The southern boundary of the Sunflower
block is unknown but is shown (dashed) in
figure1 south of the southernmostoutcrops
that have been correlated with the Mazatzal
Group and north of the northernmostoutcrops of Pinal Schist. Voluminous 1400 Ma
post-tectonicgranitesare exposed in thisarea
and conceal the boundary.
Pinal Block.-The Pinal block differsfrom
the othersoutheasternblocks in thecharacter
of its supracrustalpackage. Outcrops of Proterozoic rocks in southeasternArizona have
traditionallybeen referred to as the Pinal
Schist (Ransome 1903, 1905; Cooper and Silver 1964; Silver 1978). Condie and DeMalas
(1985) and Copeland and Condie (1986) have
proposed that this area can be divided into
two assemblages with differentpetrologic
and geochemical characteristics, a western
assemblage of quartz wacke turbiditesand an
easternassemblage of basalt, rhyolite,and diverse metasedimentaryrocks (fig. 1). Their
proposed boundary between assemblages
strikesnorthwest,perpendicularto the trend
of foliation, folds, and faults in the Pinal
Schist and to the trend of the shear zones
discussed above.
The western assemblage contains quartz
wacke turbiditesthatare uniformin composition over a wide area, and minorbasalt and
rhyolite. Widely-scattered outcrops occur
over an area of several thousand square
kilometers, and some workers have interpreted this to represent a large basin filled
submarinefans. However,
withinterfingering
thereis no evidence that the turbiditeswere
deposited in the same basin or at the same
time (Swift 1987).
U-Pb zircon ages for the Pinal block are
few. Silver (1978) reported an age of 1680-
1700 Ma for rhyodacite sills that intrudeturbidites and basalts in the JohnnyLyon Hills.
These sills were intrudedbefore the end of
deformationand metamorphism,and Cooper
and Silver (1968) interpretedthe sills to be
entirelypretectonic. In contrast,Swiftinterpretedthemto be broadly syntectonic,noting
the presence of a xenolithof stronglyfoliated
basalt within less-foliated rhyodacite. The
1625 Ma JohnnyLyon Granodioritehas been
interpretedto be late syn-kinematicto postkinematic(Cooper and Silver 1964) because it
crosscuts foliated rocks of the Pinal Schist
and is itself generally unfoliated. However,
one body, identifiedas JohnnyLyon Granodiorite by Cooper and Silver (1964), is
foliated with foliationtruncatedby flatlying
Middle Proterozoic Apache Group sedimentaryrocks. This suggeststhatsome earlyProterozoic deformationmay have affectedthe
JohnnyLyon Granodiorite.
Correlation of the Pinal Schist with rocks
of the lower Alder Group of the Tonto Basin
Supergroup has been proposed by Conway
and Silver (1986; 1988) who suggest that the
turbiditesreflecta facies change to more distal parts of a large successor basin. A gradual
transitionfromone package to the other has
not been documented, and our view is that
this correlation is not supported by existing
data.
TECTONIC LINKAGES BETWEEN BLOCKS
The identification of tectonic blocks
bounded by major shear zones and having
one or more distincttectonicfeaturesrelative
to adjacent blocks is a firststep in identifying
the architecture of an orogenic belt. The
next, and necessarily more interpretive,step
is to attempt to identifylinkages between
blocks and therebyidentifythe geometryand
timingof assembly of terranesthat may represent once separate lithospheric plates or
microplates. Figure 3 is a schematic cross
section of a possible post-collisional geometryof juxtaposed terranes. In this cross section, we suggest that the eight blocks described earlier can be grouped into three
major terraneson the basis of timingof deformation in the various blocks. This cross section is almost certainlyan oversimplification
because each of the three terranes may be
composites of one or more microplates.
However, by using timingof deformation,we
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ASSEMBLY
OF TECTONOSTRATIGRAPHIC
present a new criterionfor evaluating linkages between terranes that can be combined
withstratigraphic,
petrologic,and geochronologic data.
Three blocks of the Yavapai Province, the
Mojave, Hualapai-Bagdad, and Big Bug
blocks (figs. 1, 3) show broadly similartiming
and styles of deformationand metamorphism
about 1700 Ma. There are certainlymajor differences between these blocks, including
very old supracrustal rocks (2300-1900 Ma)
and distinctiveNd and Pb isotopic signatures
in the Mojave and parts of the HualapaiBagdad blocks relative to central Arizona,
and younger supracrustal rocks (1710 Ma) in
the Hualapai-Bagdad block relativeto the Big
Bug block (1755 Ma). These and otherdifferences suggest the probabilityof distinctpre1700 Ma tectonic histories for these blocks.
However, these blocks were apparently in
close enough proximityto have been affected
by the same 1700 Ma tectonic event; they
were apparently becoming part of a single
large terraneby about 1700 Ma.
The other two northwesternblocks, the
Ash Creek and Green Gulch blocks, were deformedbefore 1740 Ma but show no evidence
of penetrative deformationat 1700 Ma, except withinthe bounding faultzones, and no
evidence for the voluminous ca. 1700 Ma
granitic plutonism that affected the other
northwestern blocks. Figure 3 tentatively
suggeststhatthe Ash Creek and Green Gulch
blocks were part of a singleterrane,now antiformallyfolded across the Big Bug block.
Transpressional convergence across the Shylock fault and the nearly synchronouspenetrative deformationin the far northwestern
province could both have been driven by
1700 Ma collision of the Ash Creek-Green
Gulch terrane with other Yavapai Province
blocks. The absence of penetrative1700 Ma
deformation in the Ash Creek and Green
Gulch blocks could be explained if these
blocks were part of an upper plate during
thrust-relatedconvergence (fig. 3).
Blocks of the Mazatzal Province were deformedbetween 1692 and 1630 Ma, afterthe
composite Yavapai Province was assembled
by collision of two or more terranesat about
1700 Ma. Informationon timingof deformation in the Mazatzal Province is not yet detailed enough to evaluate whether these
blocks are all part of one terranethatcollided
TERRANES
571
with the Yavapai Province, or whether the
Mazatzal Province is itselfa composite of terranes. At present,the tentativecorrelationof
quartzites and rhyolitesblock to block suggests a single terrane (Conway and Silver
1988), whereas highermetamorphicgrades in
the Sunflower block, an absence of 16401630 granites in the Mazatzal block, and
thick turbiditepackages in the Pinal block
all may suggest that differentterranes may
be presented. The presence of syn- to postdeformational1640-1630 granitesin both the
Sunflower and Pinal blocks suggests that
these blocks were togetheror in close proximityat 1640-1630 Ma.
The designationof three terranesbased on
timingof deformationshown in figure3 is tentative and needs to continue to be evaluated
in termsof analysis of possible stratigraphic
and petrologic linkages between blocks.
Stratigraphicand petrologiclinkages between
the Yavapai and Mazatzal Provinces have
been proposed by various workers (e.g., Anderson 1986; model one of Karlstrom et al.
1987; Conway and Silver 1988). For example,
the 1738 Ma Gibson Creek batholith of the
Mazatzal block is the same age and is similar
to the Cherry batholith of the Ash Creek
block, and neitheris penetrativelydeformed.
Consequently,these plutonicrocks may have
been a continuous basement for deposition
of the rhyolite-quartzitesuccession of the
Mazatzal block. However, this interpretation
is difficultto reconcile with data that suggest
that at the same time that these 1700 Ma
quartzitesand rhyoliteswere being deposited
in the Mazatzal block, the Ash Creek block
was undergoing deformationat its margins
and the 1700 Ma strongly peraluminous
Crazy Basin Quartz Monzonite was being
emplaced duringcompressional deformation
at 10-15 km depths.
Syntectonic deposition of the rhyolitequartzite succession of the Tonto Basin
Supergroup may be compatible with the interpretationof Middleton (1986) that conglomerates in the Mazatzal Group outcrops
of the Green Gulch block are syntectonic
fluvialdeposits. However, it is inconsistent
with the other interpretationsthat the rhyolite-quartzitesuccession is related to fluvial
to shallow marineplatformsedimentation
(Trevena 1979; Conway and Silver 1984).
Further,it seems difficultto reconcile with
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572
KARL E. KARLSTROM AND SAMUEL A. BOWRING
the absence of 1700 Ma plutonicrocks in the
Ash Creek block thatwould representequivalents of the extensive 1700 Ma rhyolitic
plutonism and volcanism in the Mazatzal
block and it ignoresthe differencein timingof
deformationbetween the provinces.
One way to evaluate proposed linkagesand
the magnitudeof displacementsbetween terranes is to assess the compatibilityof inferred
tectonic and structuralevolution. The apparent diversityof tectonic regimes at 1700 Ma
in centralArizona suggeststo us thatthe proposed terraneswere at distances greaterthan
100's of km fromone another, prior to their
juxtaposition. This interpretation
more easily
explains the extremelydiverse 1700 Ma tectonic events such as: (1) calc-alkaline plutonism in the northwest;(2) ductile deformation
and metamorphism in the northwest; (3)
stronglyperaluminousgraniticmagmatismin
the Big Bug block; (4) extrusion of calderarelated alkaline rhyolitesfollowed shortlyby
deposition of maturesiliciclasticsedimentsin
the Mazatzal and Sunflowerblocks; and (5)
deposition of turbiditesin the Pinal block (fig.
3). Using the Indonesian or Caribbean regions as actualistic models, such complexities are easily explained in termsof separate
terranes that become incorporated into an
orogenic collage. This interpretationalso
readily explains the absence of systematic
cross-strikechanges in age of magmaticrocks
and age and style of deformationand metamorphism.
ASSEMBLY
OF OROGENIC
PROVINCES
Our workinghypothesis is that early Proterozoic rocks in Arizona representdiverse
tectonostratigraphicterranes that were assembled during several episodes of convergent tectonism. This is in contrastto earlier
interpretations.Wilson (1939) proposed the
term "Mazatzal Revolution" for a profound
compressional disturbance that post-dated
deposition of the Mazatzal Group and affected all the older Precambrian rocks of
Arizona. Althoughdisputed by Hinds (1938),
Wilson and most subsequent workers have
believed that early Proterozoic rocks in
Arizona have been affected by one major
Proterozoic orogenic event, and most workers have used the termMazatzal orogenyfor
this event (Silver 1978). Conway and Silver
(1988) give age brackets of 1680-1630 Ma for
this orogeny.
Evidence for pre-1740 and 1700 Ma deformations in northwestern Arizona demonstratesmultipletectonic events and raises the
question of how to apply the termMazatzal
orogeny. We agree with Conway and Silver
(1988) thatthe termMazatzal orogenyshould
be used for the post-1690 Ma compressional
deformationin the southeastern blocks. We
interpretthis deformationto be the resultof
collision of the Mazatzal Province blocks
withthe previouslyassembled Yavapai Province. However, this tectonic interpretation
need not be implicitin use of the termMazatzal orogeny.
The termMazatzal orogeny should probably not be used for deformation of the
Yavapai Province, which was apparently
older and of ductile character. Using figures2
and 3 as guides, it seems reasonable to define
a major 1700 Ma orogeny in Arizona thatresulted from the assembly of northwestern
blocks. Pre-1740 Ma deformationin the Ash
Creek and Green Gulch blocks represents
stillearlier tectonic events.
It seems inescapable that the tectonic
events that produced deformationand metamorphism in Arizona also affected other
areas of southwesternNorth America. Deformation in New Mexico involved thrusting
and recumbentfolding at amphibolitefacies
conditions. The intense late stages of deformation in New Mexico in part post-dated
1650 Ma (Bowring et al. 1983). Deformation
of cover rocks in the Needle Mountains of
southernColorado took place between 1680
and 1430 Ma (Tewksbury 1985; Harris et al.
1987; Gibson and Simpson 1988) and involved regional compression and strike-slip
faulting.Both the timingand style of these
deformations may be compatible with the
southeastern province of Arizona, and the
termMazatzal orogeny may be applicable to
regional post-1690 Ma early Proterozoic deformationin the Southwest.
Earlier deformationsat 1700 and pre-1740
may also have affected a larger region, althoughthis will require much more detailed
data on timingof deformations.In the Needle
Mountains of southern Colorado, Harris et
al. (1987) and Gibson and Simpson (1988),
followingBarker (1969), suggested that the
Uncompahgre Group was deposited uncon-
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ASSEMBLY
OF TECTONOSTRATIGRAPHIC
formablyon a gneissic basement thatwas deformedbefore intrusionof 1690 Ma granites.
In other areas of southern Colorado, deformation and metamorphismreportedly took
place 1730-1714 Ma (Bickfordand Boardman
1984; Reed 1986). Farthernorth,Reed (1986)
reported deformationin the Sawatch Range
1670-1658 Ma; deformation in the central
Front Range post-1700 Ma; and deformation
in the northernFront Range at 1710 Ma.
Along the Cheyenne belt, Duebendorfer and
Houston (1987) reported that thrust-related
deformationtook place before 1750 Ma.
It should be noted that interpretationof
timingof deformationin most of these areas
involves evaluation of the pre-, syn-,or postkinematic character of datable plutonic
rocks. Such evaluations are not straightforward, as plutonicrocks have markedlydifferent material properties than their country
rock, and diapiric emplacementof plutonsoften imparts strains on country rocks and
granitemarginsthat must be understood before the component of strainimpartedby regional deformationcan be evaluated. As a
consequence, interpretationsof timingof deformation will need to be continually reevaluated with more detailed structuralstudies.
It seems clear to us fromavailable data that
REFERENCES
ANDERSON,C. A.; BLACET,P. M.; SILVER,L. T.;
and STERN, T. W., 1971, Revision of the Precambrian stratigraphyin the Prescott-Jerome
area, Yavapai County,Arizona: U.S. Geol;. Survey Bull. 1324-6, p. 1-16.
, and CREASEY,S. C., 1958, Geology and ore
deposits of the Jerome area, Yavapai County,
Arizona: U.S. Geol. Survey Prof. Paper 308,
185 p.
----;
SCHOLZ,E. A.; and STROBELL,J. D., 1955,
Geology and ore deposits of the Bagdad area,
Yavapai County, Arizona: U.S. Geol. Survey
Prof. Paper 278, 103 p.
ANDERSON,P., 1986, Summary of the Proterozoic
plate tectonic evolution of Arizona from 1900
to 1600 Ma, in BEATTY, B., and WILKINSON,
P. A. K., eds., Frontiersin geology and ore deposits of Arizona and the Southwest: Arizona
Geol. Soc. Digest, v. 16, p. 5-11.
BARKER,F., 1969, Precambrian geology of the
Needle Mountains, southwestern Colorado:
U.S. Geol. Survey. Prof. Paper 644-1A, p. 1-33.
BENNETT,V. C., and DEPAOLO, D. J., 1987, Proterozoic crustal history of the western United
States as determined by neodymium isotopic
TERRANES
573
the deformation history in Colorado and
southernWyomingis complex and cannot be
viewed in terms of progressive southward
growthof the continent.This is in contrastto
the interpretationof Reed et al. (1987). The
tectonostratigraphic
terrane model proposed
here for Arizona suggests that complexities
of assembly of the entire orogen fromWyomingto Mexico are likelyto be greatand correlationsof stratigraphicand tectonic events
as well as tectonostratigraphicterranes and
orogenic provinces, need to be made cautiously. Using actualistic models, it is reasonable to assume that there may have been
tensofdiscrete tectonic events duringassembly of the 1300 km wide orogen in southwestern North America and there is certainlyno
reason to believe that collisions of terranes
would necessarily have preceded fromnorth
to south.
ACKNOWLEDGMENTS.-Researchhas been
supported by National Science Foundation
Grants EAR-8411998 and EAR-8509354, by
donors of the Petroleum Research Fund
of the American Chemical Society (PRF16199GB), and by the NorthernArizona UniversityOrganized Research Fund. We thank
K. Eriksson, and J. Dann forhelpfulreviews
of thispaper.
CITED
mapping: Geol. Soc. America Bull., v. 99, p.
674-685.
BICKFORD,M. E., and BOARDMAN,
S. J., 1984, A
Proterozoic volcano-plutonic terrane,Gunnison
and Salida areas, Colorado: Jour. Geology, v.
92, p. 657-666.
BOWRING,
S. A.; KENT, S. C.; and SUMNER,W.,
1983, Geology and U-Pb geochronologyof Proterozoic rocks in the vicinityof Socorro, New
Mexico, in New Mexico Geol. Soc. Guidebook
to 34th Field Conference, p. 137-142.
BRYANT,B., and WOODEN,J. L., 1986, Early and
Middle Proterozoic crustal historyof the Poachie
Range, Arizona: Geol. Soc. America Abs. with
Prog., v. 18, p. 344.
CHAMBERLAIN, K.;
BOWRING, S.; KARLSTROM, K.;
and WOODEN,J. L., 1988, U-Pb zircon ages from
northwesternArizona: Geol. Soc. America Abs.
withProg., v. 20, p. 149.
CONDIE, K. C., 1982, Plate-tectonics model for
Proterozoic continental accretion in the southwestern United States: Geology, v. 10, p. 3742.
-,
1986, Geochemistryand tectonicsettingof
Early Proterozoic supracrustal rocks in the
This content downloaded from 129.24.37.22 on Mon, 6 Oct 2014 18:24:18 PM
All use subject to JSTOR Terms and Conditions
574
KARL E. KARLSTROM AND SAMUEL A. BOWRING
southwestern United States: Jour. Geology, v.
94, p. 845-864.
---,
and DEMALAS, J. D., 1985, The Pinal
Schist: an early Proterozoic quartz wacke association in southeasternArizona: Precamb. Res.,
v. 27, p. 337-356.
CONWAY,C. M., 1976, Petrology, structure,and
evolution of a Precambrianvolcanic and plutonic
complex, Tonto Basin, Gila County, Arizona:
Unpub. Ph.D. thesis, California Inst. Technology, Pasadena, 460 p.
, and SILVER,L. T., 1984, Extent and impli--cations of silicic alkalic magmatismand quartzarenite sedimentationin the Proterozoicof central Arizona: Geol. Soc. America Abs. with
Prog., v. 16, p. 219.
, and , 1986, Implicationsof thejux--taposition of two Early Proterozoic terranes in
central Arizona, in Int. Field Conf. Proterozoic
Geology and Geochemistry: Lawrence, KS,
Universityof Kansas, p. 91-92.
, 1988, Early Proterozoicrocks
, and of 1710-1610 Ma age in centralto southwestern
Arizona, in JENNY,J., and REYNOLDS,S., eds.,
Geology of Arizona: Arizona Geol. Soc. Digest,
in press.
--;
KARLSTROM,K. E.; SILVER,L. T.; and
WRUCKE,C. T., 1987, Tectonic and magmatic
contrasts across a two-province Proterozoic
boundary in central Arizona: Geol. Soc.
America Field Trip Guide, Ann. Meeting,
Phoenix, Arizona.
, and WRUCKE, C. T., 1986, Proterozoic
geology of the Sierra Anchas-Tonto BasinMazatzal Mountains area, road log and fieldtrip
guide, in BEATTY,B., and WILKINSON,
P. A. K.,
eds., Frontiers in geology and ore deposits of
Arizona and the Southwest: Arizona Geol. Soc.
Digest, v. 16, p. 227-247.
COOPER,J. R., and SILVER, L. T., 1964, Geology
and ore deposits of the Dragoon quadrangle,
Cochise County, Arizona: U.S. Geol. Survey
Prof. Paper 416, 196 p.
COPELAND,P., and CONDIE, K. C., 1986, Geochemistry and tectonic setting of lower Proterozoic supracrustal rocks of the Pinal Schist,
southeasternArizona: Geol. Soc. America Bull.,
v. 97, p. 1512-1520.
COUCH,N. P., JR.,1981, Metamorphismand reconnaissance geology of the eastern McDowell
Mountains, Maricopa County, Arizona: Unpub.
M.S. thesis, Arizona State University,Tempe,
57 p.
DARRACH,
M. E., 1988, A structuraland kinematic
analysis of the Early Proterozoic Cleator Shear
Zone, central Arizona: Unpub. M.S. thesis
NorthernArizona University,Flagstaff.
--; KARLSTROM,K.E.; and ARGENBRIGHT,
D.M., 1986, The Cleator mylonitezone: Sinistral
strike-slipadjacent to the Shylock fault zone,
central Arizona: Geol. Soc. America Abs. with
Prog., v. 18, p. 350.
DEPAOLO,D.J., 1981, Neodymium isotopes in the
Colorado Front Range and crust-mantleevolution in the Proterozoic: Nature, v. 271, p. 193196.
DUEBENDORFER,
E.M., and HOUsToN, R.S., 1987,
Proterozoic accretionarytectonics at the southern margin of the Archean Wyoming craton:
structure and metamorphism of lithotectonic
blocks within the Cheyenne belt, Wyoming:
Geol. Soc. America Bull., v. 98, p. 554-568.
ELLIOTT,G. S.; WOODEN,J. L.; MILLER,D. M.; and
MILLER, R. B., 1986, Lower-granulite grade
Early Proterozoic supracrustalrocks, New York
Mountains, southeast California: Geol. Soc.
America Abs. with Prog., v. 18, p. 353.
GIBSON,R. G., and SIMPSON,
C., 1988, Proterozoic polydeformationin basement rocks of the
Needle Mountains,Colorado,and its regional
tectonic implications: Geol. Soc. America Bull.,
in press.
GRAMBLING,
J. A., 1986, Crustal thickeningduring
Proterozoic metamorphismand deformationin
New Mexico: Geology, v. 14, p. 149-152.
HARRIS,C. W.; GIBSON,R. G.; SIMPSON,C.; and
ERIKSSON,K. A., 1987, Proterozoic cuspate basement-cover structure,Needle Mountains, Colorado: Geology, v. 15, p. 950-953.
J. B.; CALDWELL,W. G. E.; and HARHENDERSON,
RISON,J. E., 1980, North American Commission
on Stratigraphic Nomenclature. Report 8Amendmentof code concerningterminologyfor
igneous and high-grade metamorphic rocks:
Geol. Soc. America Bull., Pt. I, v. 91, p. 374-376.
HILLS, F. A., and HOUsToN, R. S., 1979, Early
Proterozoic tectonics of the central Rocky
Mountains, North America: Contrib. Geology,
v. 17, p. 89-111.
HINDS,N. E. A., 1938, PrecambrianArizonan revolution in western North America: Am. Jour.
Science, 5th Ser., v. 35, no. 210, p. 445-449.
HOFFMAN,P. F., 1988, United plates of America:
birthof a craton: Ann. Rev. Earth Planet. Sci.,
v. 16, p. 543-603.
JONES,D. L., 1983, Recognition, character, and
terranesin westanalysis of tectonostratigraphic
ern North America, in HASHIMOTO,M., and
UYEDA, S., eds. Accretion Tectonics in the
Circum-PacificRegions: Boston, D. Reidel, p.
21-36.
K. E., 1988, Early recumbentfolding
KARLSTROM,
during Proterozoic orogeny in central Arizona,
in Geol. Soc. America Spec. Paper, in press.
---;
BOWRING,S. A.; and CONWAY,C. M.,
1987, Tectonic significanceof an Early Proterozoic two-provinceboundary in central Arizona:
Geol. Soc. America Bull., v. 99, p. 529-538.
-,
and CONWAY,C. M., 1986, Deformational
styles and contrasting lithostratigraphicsequences within an Early Proterozoic orogenic
belt, central Arizona, in NATIONS,J. D.; CONWAY,C. M.; and SWANN,G. A., eds., Geology of
Northern Arizona and Central Arizona: Geol.
Soc. America Field Trip Guidebook, Rocky
Mtn. Sec., p. 1-25.
---,
and HOUSTON,R. S., 1984, The Cheyenne
Belt: analysis of a Proterozoic suturein southern
Wyoming: Precamb. Res., v. 25, p. 415-446.
KRIEGER,M. H., 1965, Geology of the Prescott and
Paulden Quadrangles, Arizona: U.S. Geol. Survey Prof. Paper 467, 127 p.
This content downloaded from 129.24.37.22 on Mon, 6 Oct 2014 18:24:18 PM
All use subject to JSTOR Terms and Conditions
ASSEMBLY
OF TECTONOSTRATIGRAPHIC
LYSONSKI,J. C.; SUMNER,J. S.; ARKEN,C.; and
SCHMIDT,J. S., 1980, Residual Bouguer gravity
anomaly map of Arizona (IGSN 71) 1:1,000,000:
Laboratory of Geophysics, University of Ari-
zona, Tucson,Arizona.
D. T., and HOWER,J., 1967, High-grade
MAXWELL,
diagenesis and low-grade metamorphismof illite
in the Precambrian Belt Series: Am. Mineral., v.
52, p.843-857.
MAYNARD,S., 1986, Precambrian geology and
mineralizationof the southwestern part of the
New River Mountains, Maricopa and Yavapai
Counties, Arizona: Unpub. M.S. thesis, Universityof New Mexico, Albuquerque, 155 p.
MIDDLETON,L. T., 1986, Sedimentology and tectonic significance of Middle Proterozoic conglomerates and sandstones in central Arizona:
Geol. Soc. America Abs. with Prog., v. 18, p.
396.
MILLER,C. F., 1985, Are stronglyperaluminous
magmas derived from pelitic sedimentary
rocks?: Jour. Geology, v. 93, p. 673-689.
NELSON,B. K., and DEPAOLO, D. J., 1985, Rapid
production of continental crust 1.7 to 1.9 b.y.
ago: Nd isotopic evidence fromthe basement of
the North American mid-continent:Geol. Soc.
America Bull., v. 96, p. 746-754.
PATCHETT,J. P., and ARNDT, N. T., 1986, Nd
isotopes and tectonics of 1.9-1.7 Ga crustal
genesis: Earth Planet. Sci. Letters, v. 78, p. 329338.
PULS,D. D., 1986,Geometricandkinematic
analy-
sis of a Proterozoic forelandthrustbelt,northern
Mazatzal Mountains,centralArizona:Unpub.
M.S. thesis, NorthernArizona University,Flagstaff.
J. G., and HUBER,M. I., 1983, The TechRAMSAY,
niques of Modern Structural Geology Vol. 1:
StrainAnalysis: New York, AcademicPress,
307 p.
RANSOME,
F. L., 1903, Geology of the Globe copper district, Arizona: U.S. Geol. Survey Prof.
Paper 12, 168 p.
1905, Description of the Globe quadrangle:
---,
U.S. Geol. Survey Atlas Folio III, scale
1:62,500.
REED,J. C., JR., 1986, Timingof Early Proterozoic
deformationand metamorphismin the southern
Rocky Mountains: GeoL Soc. America Abs.
withProg., v. 18, p. 404.
; BICKFORD,M. E.; PREMO,W. R.; ALEINIKOFF,J. N.; and PALLISTER,J. S., 1987, Evolutionof the Early Proterozoic Colorado province:
constraintsfromU-Pb geochronology:Geology,
v. 15, p. 861-865.
ROLLER,J. A., 1987, Geometric and kinematicanalysis of the Proterozoic upper Alder Group and
the Slate Creek movement zone, centralMazatzal Mountains, central Arizona: Unpub. M.S.
thesis, Northern Arizona University,Flagstaff,
105 p.
and KARLSTROM,
K. E., 1986, Structural
---,
geometry of the upper Alder Group, Mazatzal
Mountains, central Arizona: Geol. Soc. America
Abs. with Prog., v. 18, p. 407.
SAUCK,W. A., and SUMNER,J. S., 1970, Residual
TERRANES
575
aeromagnetic map of Arizona: University of
Arizona, Tucson, scale, 1:1,000,000.
SHOEMAKER,
E. M.; SQUIRES,R. L.; and ABRAMS,
M. J., 1978, BrightAngel and Mesa Butte fault
systems of northernArizona, in SMITH, R. B.,
and EATON,G. P., eds., Cenozoic tectonics and
regional geophysics of the western Cordillera:
Geol. Soc. America Mem. 152, p. 341-368.
SILVER,L. T., 1965, Mazatzal orogeny and tectonic episodicity: Geol. Soc. America Spec. Paper 82, p. 185.
1967, Apparent age relations in the older
---,
Precambrian stratigraphyin Arizona (abs.), in
R. A., and MORTON,R. D., eds. GeoBURWASH,
chronologyof precambrianStratifiedRock: Edmonton, Canada, University of Alberta, p. 87.
---,
1969, Precambrian batholiths of Arizona
(abs.): Geol. Soc. America Spec. Paper 121, p.
558-559.
, 1978, Precambrian formations and Precambrian historyof Cochise County, southeastern Arizona: New Mexico Geol. Soc. Guidebook, 29th Field Conf., p. 157-163.
; ANDERSON,C. A.; CRITTENDEN,M.; and
ROBERTSON,
eleJ. M., 1977, Chronostratigraphic
ments of the Precambrian rocks of the southwestern and far western United States: Geol.
Soc. America Abs. with Prog., v. 9, p. 1176.
; CONWAY,C. M.; and LUDWIG,K. R., 1986,
Implications of a precise chronology for Early
Proterozoic crustal evolution and caldera formation in the Tonto Basin-Mazatzal Mountains region, Arizona: Geol. Soc. America Abs. with
Prog., v. 18, p. 413.
H. L., and MORE,S., 1980, Precambrian
STENSRUD,
geology and massive sulfide environments of
the west-central Hualapai Mountains, Mohave
County, Arizona, a preliminaryreport,in JENNY,
J. P., and STONE, C., eds., Studies in western
Arizona: Arizona Geol. Soc. Digest, v. 12, p.
155.
SWIFr, P. N., 1987, Early Proterozoic turbidite
deposition and melange deformation,southeastern Arizona: Unpub. Ph.D. thesis, Universityof
Arizona, Tucson, 134 p.
B. J., 1985, Revised interpretationof
TEWKSBURY,
the age of allochthonous rocks of the Uncompahgre Formation, Needle Mountains, Colorado: Geol. Soc. America Bull., v. 96, p. 224232.
THORPE,D. G., and BURT,D. M., 1978, Viradine,
Otcellite, and Piemontite from Squaw Peak,
North Phoenix Mountains, Arizona: Geol. Soc.
America Abs. with Prog., v. 10, p. 150.
TITLEY, S. R., 1987, The crustal heritage of silver
and gold ratios in Arizona ores: Geol. Soc.
America Bull., v. 99, p. 814-826.
TREVENA,A. S., 1979, Studies in sandstone petrology: originof the Precambrian Mazatzal Quartzite and provenance of detritalfeldspar: Unpub.
Ph.D. thesis, Universityof Utah, 390 p.
VAN SCHMUS,W. R., and BICKFORD,M. E., 1981,
Proterozoic chronology and evolution of the
midcontinentregion,NorthAmerica, in KRONER,
A., ed., Precambrian Plate Tectonics, New
York, Elsevier, p. 261-296.
This content downloaded from 129.24.37.22 on Mon, 6 Oct 2014 18:24:18 PM
All use subject to JSTOR Terms and Conditions
576
WOODEN, J. L.;
KARL E. KARLSTROM AND SAMUEL A. BOWRING
MILLER, D.
M.;
and HOWARD,
K. A., 1988, Early Proterozoic chronologyof the
eastern Mohave desert: Geol. Soc. America
Abs. Cordilleran Sect. Meeting, in press.
WOODEN,J. L.; STACEY,J. S.; DOE, B. R.; HowARD,K. A.; and MILLER, D. M., 1987. Pb isotopic evidence for the formationof Proterozoic
crust in the southwestern United States, in
ERNST, W. G., ed., Metamorphic and crustal
evolution of the western U.S., Rubey Volume
VII, in press.
WILSON,E. D., 1939, Precambrian Mazatzal revolution in central Arizona: Geol. Soc. America
Bull., v. 50, p. 1113-1164.
This content downloaded from 129.24.37.22 on Mon, 6 Oct 2014 18:24:18 PM
All use subject to JSTOR Terms and Conditions