Download geologic map of orange county, north carolina

QUATERNARY
36 14' 30"
alluvium (Qal)
colluvium (Qcv)
Qcv
Qal
Jd
A
Trq-breccia
MPzgb
Padid
Pdad
CZtgd
Qal
sandstone with interlayered siltstone
of the Chatham Group Lithofacies Association I
Padid
CZgr-gd
Padid
Qal
Qal
Dikes present in Prospect Hill Pluton
dacitic dikes (Pdad)
andesitic to dacitic dikes (Padid)
NEOPROTEROZOIC
Zefg-4
Zefg-6
Zefg-2
Padid
Zefg-3
Zefmd
Zwfd
85
Zhft (l)
77
Zgd-gb
Zdi
Zdi-gd-b
Zt-qdi
Zdi-fine
Zdi-gb
Zgb
Zhft (l)
79
71
36 07' 30"
granite (Zgr) and (Zgr2); granite to diorite (Zgr-di); granodiorite (Zgd)
Jd
Zhe
Zhe-m1
Zhe-m2
Zhe/p-n
Zhablt
?
Zhasi
Zhdlt (u)
Zhdsi (u)
Zhdlt (l)
Zhdsi (l)
Zhe/p
Zhdlt-a (l)
69
20
Jd
Qal
75
Zgd-gb
76
Zhqdp
Zhft (l)
Zhft (l)
Zhe
Qal Zhablt
77
66
72
Jd
79
Qal
Qal
80
84
76
Qal
81
Zhdlt (u)
88
Padid dike - inferred
Zhdsi (u)
88
Qal
88
Zhp/e
Qal
gabbro to gabbro porphyry dike - inferred
quartz vein or zone-inferred
in cross section - inferred axial trace of large-scale fold
in cross section - interpreted fold form lines of
noncylindrical asymmetric folds
primary road
76
86
80
88
Qal
STRUCTURAL SYMBOLS
Equal Area Schmidt Net Projection of
Contoured Poles to Foliation and Cleavage
Contour Interval = 1 N = 2,779
strike and dip of primary
bedding and layering
Zdi
74
Zwfd
Qal
strike of vertical bedding and layering
85
strike and dip of overturned bedding
strike and dip of primary volcanic
compaction and/or welding
71
80
Zhiflt
70
strike and dip of foliation
strike and dip of cleavage
Zdi
3
Zhqdp
85
Zhablt
Zhablt
35 52' 30"
79 15' 00"
strike of vertical foliation
68
70
Qal
82
Qal
74
Zhdsi (l)
Zhqdp
Zgr 70
82
71
Zhe/p-n
Zgr2
12
Zhiflt
67
Zhdlt (l)
79
79
Zhe/p
Jd
7
Zgr
Zhiflt
Zhablt
Qal
Jd
Zhiflt
Zgr2
Zhqdp
Jd
MPzgb
Qal
85
Zefmd
Zefmd
Zwfd
Zhiflt
Zhqdp
80
82
80
76
Jd
80
79
82
75
85
80
Qal
75
84
Zgr
Zhdlt (l)
84
82
Zdi
61
Zhdlt (l)
Zgd-ch
29
CZgb
Zhft (l)
Zhe-m1
86
84
84
Mine or Prospect - abandoned
Qal
Zefg-m
Zefg-m1
Qal
1
Unidirectional Rose Diagram of Joints N = 3,530
Outer Circle = 4%
Quarry-active
U-Pb age date location
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ou
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h
Ca
ld
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ss
ro
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nu
By
em
ug
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R
t
on
t
es
w m
h
rt rha
No Du
So
Du uth
rh w e
a m st
W
te
hi
C
ve
Hi
lls
bo
r
nd
la
Ef
M
Sa
xa
pa
ha
w
G
ro
Ch
ap
el
Hi
ll
r
da
Ce
eb
an
e
Bu
r
lin
NE gt
o
n
19 - Murray pyrophyllite prospect - abandoned
20 - Mebane quarry - abandoned
21 - former quarry - abandoned
22 - former quarry - abandoned
23 - Occoneechee Mountain quarry - abandoned
24 - Bacon quarry - abandoned
25 - Coile (Eno) quarry - abandoned
26 - quarry (building stone) - active
27 - quarry (crushed stone) - active
28 - quarry (crushed stone) - active
29 - gravel pit (Chapel Hill grit) - active
30 - mine (pyrophyllite) - active
31 - U-Pb age date ca. 613 Ma (Bradley and Miller, 2011)
32 - U-Pb age date ca. 628 Ma (Bradley and Miller, 2011)
33 - U-Pb age date ca. 633 Ma (Wortman et. al., 2000)
34 - U-Pb age date ca. 630 Ma (Bradley and Miller, 2011)
35 - U-Pb age date ca. 633 Ma (Wortman et. al., 2000)
36 - U-Pb age date ca. 579 Ma (Tadlock and Loewy, 2006)
rr
Fa
i
to
ng
n
ORANGE COUNTY
1:24,000 QUADRANGLES
0.5
0
3,000 1,500
1
1
0
0.5
3,000
2
6,000
0
1
9,000
2
3
12,000
3
15,000
4
4
18,000
Zhe/p –n - Mixed epiclastic-pyroclastic rocks of Neville Creek area: Heterogeneous unit of felsic to intermediate composition tuffs and lavas, mudstone, siltstone, tuffaceous sandstones and conglomeratic sandstones. Unit appears to contain more andesitic to basaltic lavas and tuffs than Ze/p unit.
Zhe/pl - Mixed epiclastic-pyroclastic rocks with interlayered dacitic lavas: Grayish-green to greenish-gray, locally with distinctive reddish-gray or maroon to lavender coloration; conglomerate, conglomeratic sandstone, sandstone, siltstone and mudstone. Lithologies are locally bedded; locally tuffaceous with a cryptocrystalline-like groundmass. Siltstones are locally phyllitic. Locally contain interbedded dacitic lavas
identical to Zhdlt unit. Contains lesser amounts of fine- to coarse tuff and lapilli tuff with a cryptocrystalline-like groundmass. Minor andesitic to basaltic lavas and tuffs present. Silicified and/or sericitized altered rock similar to Zhat unit are locally present. Conglomerates and conglomeratic sandstones typically contain subrounded to angular clasts of dacite in a clastic matrix. Zhe/pl distinguished from Zhe/p by presence of
dacites and is interpreted to represent a facies change to an area more proximal to the active volcanic centers compared to Ze/p. Cloud et al. (1976) fossil locality from unit in Durham County (Bradley et al., 2011b).
Trcs/si1
Zhp/e – Mixed pyroclastic-epiclastics: Gray to green, felsic tuffs interlayed with mudstone, siltstone, and sandstone and distinctive immature, monomictic, conglomeratic sandstone to conglomerate containing subangular to angular clasts of plagioclase porphyritic dacite. Minor andesitic to basaltic lavas and tuffs. The contact with the Zhdlt (u) unit is interepreted to be gradational.
Zhdlt (u) – Dacitic lavas and tuffs of the upper portion of the Hyco Formation: Greenish-gray to dark gray, siliceous, aphanitic dacite, porphyritic dacite with plagioclase phenocrysts, and flow banded dacite. Welded and non-welded tuffs associated with the lavas include: greenish-gray to grayish-green, fine tuff, coarse plagioclase crystal tuff and lapilli tuff. Locally, interlayers of immature conglomerate and conglomeratic
sandstone with dacite clasts are present. The dacites are interpreted to have been coherent extrusives or very shallow intrusions associated with dome formation. The tuffs are interpreted as episodic pyroclastic flow deposits, air fall tuffs or reworked tuffs generated during formation of dacite domes. The unit occurs as map scale pods surrounded by clastic rocks of Zhe/p, Zhe/pl or Zhe/p units. Wortman et al. (2000) reports
an age of 615.7+3.7/-1.9 Ma U-Pb zircon date for a dacitic tuff from the unit within the Rougemont quadrangle (Bradley et al., 2011b).
Zhdsi (u) – Dacitic shallow intrusive of the upper portion of the Hyco Formation: Gray-green, light green to green, greenish-gray to light gray; dacite, plagioclase porphyritic dacite with a granular-textured groundmass to micro-granodiorite (intrusive texture visible with 7x hand lens). Locally fine- to medium grained granodiorite present. Plagioclase phenocrysts, when present, range from less than 1 mm to 4 mm. Black
colored amphibole, when visible, occurs as phenocrysts (less than 1 mm to 1 mm) and as intergrowths with plagioclase. Amphibole intergrowths distinguish rock from fine-grained tuffs. Rock from the active quarry includes greenish-gray to light gray; aphanitic to weakly plagioclase porphyritic dacite to micro-granodiorite. Relict plagioclase phenocrysts are sausseritized in a matrix of recrystallized feldspar and quartz with dark
colored clots (less than 1 mm to 4 mm) interpreted in hand sample as chlorite(?) masses and/or relict enclaves of dark gray dacite. Contains lesser amounts of dark gray, aphanitic dacite. Interpreted as shallowly emplaced dacite probably co-magmatic with Zdlt (u) unit.
Zhablt – Andesitic to basaltic lavas and tuffs: Green, gray-green, gray, dark gray and black; typically unfoliated, amygdaloidal, plagioclase porphyritic, amphibole/pyroxene porphyritic and aphanitic; andesitic to basaltic lavas and shallow intrusions. Hyaloclastic texture is common and imparts a fragmental texture similar to a lithic tuff on some outcrops. Locally interlayered with meta-sediments identical to the Zhe/pl and Zhe/p unit.
Zhabsi – Andesitic to basaltic shallow intrusive: Distinctive; very dark-gray to black; aphanitic groundmass; magnetic; andesite to basalt porphyry. In thin section the rock is composed of a very fine matrix of plagioclase laths and apparent relict amygdules in-filled with epidote and quartz. Present in the Currie Hill area on the Hillsborough quadrangle.
Jd
Zhiflt – Intermediate to felsic lavas and tuffs: Heterogenous unit of felsic to intermediate composition tuffs and with lesser interlayers of andesitic to basaltic lavas and epiclastic rocks. Porphyritic andesitic to basalatic lithologies may be shallow intrusions. Felsic tuffs are locally phyllitic. Interpreted as equivalent to the Collins Creek and Collins Mountain units of Hauck (1977).
Metaintrusive rocks associated with Hyco Formation: lower portion (stratigraphic relations uncertain) ca. 630 Ma (Wortman et al., 2000)
Trcs/si1
Qal
Zgr - ch – Granite: Typically massive, fine- to medium-grained with dark green amphiboles (commonly rimmed by epidote and chlorite) and +/- biotite. Light-pink to pink, alkali feldspars are prominent and give the rock a pinkish hue. Orange-pink to grayish-orange pink, fine-grained aplite with a sub-graphitic texture is present in dikes ranging from centimeters to meters in width. Rocks of granitic composition occur primarily within the
informally named Chapel Hill pluton. Granite of the Chapel Hill pluton has an interpreted U-Pb zircon crystallization age of 633 +2/-1.5 Ma (Wortman et al., 2000). An unpublished U-Pb zircon age of 631.6 +/- 7.9 Ma was also reported by Mehlop (1994) for the Chapel Hill pluton.
Qal
D
Zdi
D
Zgd - ch – Granodiorite: Leucocratic to mesocratic, fine- to medium-grained, equigranular to porphyritic granodiorite. In the central and southern portions of the Chapel Hill quadrangle the granodiorite is mainly whitish-gray, fine- to medium-grained, biotite, +/- hornblende granodiorite with minor pink-colored alkali feldspar. Plagioclase grains are often sericitized and saussuritized and exhibit a greenish color throughout the unit.
Metamorphosed volcaniclastic sedimentary and pyroclastic rocks associated with Hyco Formation: lower portion (stratigraphic relations uncertain) ca. 629 - 633 Ma (Wortman et al., 2000 and Bradley and Miller, 2011)
Zhat (l)– Altered tuffs of the lower portion of the Hyco Formation: Very light gray to light greenish gray (whitish in areas) with red and yellow mottling. Alteration consists of silicified, sericitized and pyrophyllitized rock. Sericite phyllite, pods of pyrophyllite, and quartz + phyrophyllite rock all with less than 1 mm to 2 mm diameter weathered sulfides are common. Fine-grained chloritoid porphyroblasts (less than 1 mm) are present
in some pyrophyllite bearing rocks. Relict lithic clasts and kaolinitized feldspar crystal shards are visible in some exposures. Relict structures are obliterated in heavily altered rocks. Map area contains boulders (up to several feet in diameter) and outcrop of massive milky quartz and quartz + sericite rock.
U
D
Jd
Zhmst – Matrix supported tuffs: Green-gray to green; weakly foliated to well foliated; matrix supported; polymictic; lapilli tuffs and tuff breccias. Angular to sub-rounded, lithic fragments range from less than 1 mm up to 0.5 m diameter. Unit is interpreted as a resedimented syn-eruptive volcaniclastic deposit in which texturally unmodified volcaniclastic debris and entrained
texturally more mature accidental clasts are incorporated into a rapidly resedimented package of sediment. May be emplaced via submarine mass flows, subaerial landslides and/or lahars. Dacitic to andesitic lavas locally present.
Zhft (l) - Felsic tuffs: Grayish-green to greenish-gray and silvery-gray; massive to foliated volcaniclastic pyroclastic rocks consisting of fine- to coarse tuffs, lapilli tuffs and minor welded tuffs. Tuffs are differentiated from other volcaniclastic rocks by the presence of zones of cryptocrystalline texture that exhibit conchoidal-like fractures in between foliation domains. Layering
ranges from massive to thinly bedded. Contains lesser amounts of volcaniclatic sedimentary rocks consisting of volcanic sandstones, and greywackes with minor siltstones and phyllite.
Jd
76
67
66
Zefg-m
Zhdlt (l) – Dacitic lavas and tuffs of the lower portion of the Hyco Formation: Distinctive gray to dark gray, siliceous, cryptocrystalline dacite, porphyritic dacite with plagioclase phenocrysts, and flow banded dacite. Welded and non-welded tuffs associated with the lavas include: greenish-gray to grayish-green, fine tuff, coarse plagioclase crystal tuff; lapilli tuff; and tuff breccia. The dacites are interpreted to have been coherent
extrusives or very shallow intrusions associated with dome formation. The tuffs are interpreted as episodic pyroclastic flow deposits, air fall tuffs or reworked tuffs generated during formation of dacite domes. Wortman et al. (2000) report a 632.9 +2.6/-1.9 Ma zircon date from a sample within the unit in the Chapel Hill
quadrangle.
52
Jd
Zhdlt (u)
Qal
B'
Zhdlt-a – Altered dacitic lavas and tuffs: Gray to dark-gray; massive to foliated, aphanitic rocks. Rare plagioclase crystal fragments are present. 5–10% accessory sulfide minerals commonly present. Rock is relatively featureless. Interpreted as dacitic lavas and tuffs. Present in the Cates Creek area southeast of Hillsborough.
Zhdlt-porph - Porphyritic dacite associated with Zdlt: Dominantly light gray to medium dark gray, porphyritic dacite. Acicular shaped zones of mafic mineral phenocrysts resemble amphiboles in hand sample and consist of fine-grained actinolite/chlorite(?) intergrowths under 20 X magnification. Dacites are locally siliceous and flow banded. Unit may contain tuffs and is
interpreted as a very shallow intrusive closely associated with Zdlt domes.
Trcs/si1
Zhablt
Jd
Trcs/si1
Jd
Qal
Zefg-3
Zefg-2
Zhft-b (l) – Felsic tuffs of the Blackwood area: Green-gray to gray coarse tuff and lapilli tuff. Plagioclase crystals and crystal fragments are common. Lithic clast types includes dark-gray to black; magnetic; 1 to 70 mm; cryptocrystalline lava, or clasts of porphyritic lava with feldspar phenocrysts. Porphyritic clasts are identical to the porphyritic phases of unit Zdlt. Outcrops
and thin sections show a prominent welding and/or compaction foliation with fiamme-shaped clasts. Outcrops typically occur as very resistant fin-like outcrops.
54
Zhe-m2
Jd
Zdi
Zhe/p-d – Mixed epiclastic-pyroclastic rocks of the Duke quarry area: Grayish-green to greenish-gray, massive to strongly foliated, tuffaceous sandstones, conglomeratic sandstones, siltstones, phyllite, tuff and lapilli tuff (locally welded). Tuffs are differentiated from other volcaniclastic rocks by the presence of zones of cryptocrystalline texture that exhibit conchoidal-like fractures in between foliation domains. Minor
lithologies include interlayers of amygdaloidal basalt and fine-grained mafic tuffs that have been altered to epidote/chlorite. Unit appears to contain more felsic tuffs than Ze/p unit.
Qal
U D
Zhasi - Andesitic shallow intrusive: Grayish-green to light green, plagioclase porphyritic andesite with a granular-textured groundmass to very fine-grained diorite (with intrusive texture visible with 7x hand lens). Contains lesser amounts of fine- to medium grained diorite. Plagioclase phenocrysts typically range from 1 mm to 4 mm. Dark green to black colored amphibole, when present, occurs as phenocrysts (less than 1 mm to
1 mm) and as intergrowths with plagioclase. Screens of volcaniclastic rocks are commonly present.
Jd
Zefg-m Zhe-m1
Zhe-m1
Qal
Zhdsi (l) – Dacitic shallow intrusive of the lower portion of the Hyco Formation: Gray-green, light green to green; plagioclase porphyritic dacite with a granular-textured groundmass to micro-granodiorite (intrusive texture visible with 7x hand lens). Contains lesser amounts of fine- to medium grained granodiorite. Plagioclase phenocrysts typically range from 1 mm to 4 mm.
Black colored amphibole, when visible, occurs as phenocrysts (less than 1 mm to 1 mm) and as intergrowths with plagioclase. Amphibole intergrowths distinguish rock from fine-grained tuffs. Enclaves of dark gray, plagioclase porphyritic dacite are common and at times give rock a psuedo-clastic appearance. Bradley and Miller (2011) report an age of 628.5 ±1 Ma for a dacite from this unit in southern Orange County.
35 52' 30"
79 00' 00"
Zhadlt – Andesitic to dacitic lavas and tuffs: Distinctive black to dark gray; porphyritic lava with plagioclase phenocrysts (up to 4 mm), and flow banded lava with local amygdules. Interlayed with the lavas are gray to black; welded and non-welded; coarse tuff, lapilli tuff, and tuff breccia.
Qal
Zhqdp - Quartz dacite porphyry: Strongly porphyritic with aphanitic groundmass and sub- to euhedral phenocrysts (2-6 mm) of white to salmon plagioclase and gray to dark gray (beta-) quartz; phenocrysts typically constitute 20 to 25% of the rock; local weak alignment of plagioclase; interpreted as either lava flows or shallow intrusives possibly associated with domes.
12
REFERENCES
Disclaimer:
This Open-File report is preliminary and has been reviewed
internally for conformity with the North Carolina Geological Survey
editorial standards. Further revisions or corrections to
this preliminary map may occur.
SCALE 1:50 000
Quarry-abandoned
64
Qal
Zdi
Qal
79 07' 30"
Zhe/p - Mixed epiclastic-pyroclastic rocks: Grayish-green to greenish-gray, tuffaceous sandstones, conglomeratic sandstones, siltstones and minor phyllite. The siltstones typically are weakly phyllitic. Contains lesser amounts of fine- to coarse tuff and lapilli tuff. Tuffs are differentiated from other volcaniclastic rocks by the presence of zones of cryptocrystalline texture that exhibit conchoidal-like fractures in between
foliation domains. Minor andesitic to basaltic lavas and tuffs present. Silicified and/or sericitized altered rock similar to Zhat unit are locally present. Unit is interpreted to grade into Zhe/pl unit. Contact with Zhe/pl designated at first occurrence of dacitic lavas.
Zgr-ch
65
Zhe-m2
Zhdlt (u)
36
80
34
Zhft (l) 88
62
Zhe-m1 and Zhe-m2 – Morgan Creek epiclastics: Contains well bedded, greenish-gray to gray, siltstone, sandy siltstone, sandstone, conglomeratic sandstone, and conglomerate. The unit was divided into two lithofacies, Ze-m1 and Ze-m2: Zme1 is exposed mainly along Morgan Creek; it is mostly well bedded siltstones with lesser sandstone and conglomerate beds; Ze-m2, occurs to the south and southwest of Ze-m1 and
is overall coarser, containing mostly sandstones and conglomerates with lesser well bedded siltstones. Siltstones range from thinly laminated to very thinly bedded (less than 1 mm to 10 mm) with individual beds that can be traced continuously in the outcrops. Sandstone and conglomerate beds often fill scour channels in the siltstones. The conglomerates range from matrix-supported to clast-supported, contain subrounded to
rounded lithic clasts of porphyritic dacite, aphanitic volcanic rock, and granitoid in a silt to sand matrix. Individual beds are typically graded from sand-size to silt-size with abrupt upper surfaces.
4
Trcs/si1
Jd
Qal
Zefg-4
70
U
Zgd-ch
Qal
Qal
Qal
Jd
26
Qal
Zefg-m
Zefg-m
74
Zgr-ch
Zgr-ch
Zhdlt (l)
Jd
19
12
Zhdlt (u)
Zgr-ch
Jd
Zefmd
Zwfd
33
Qal
Qcv
Zhdlt (l)
Zhe/p
Trcs/si1 U
D
Zhdlt (l)
Zdi-gb
U D
Qal
77
Zhe/p
Zhe - Epiclastics: Mixed unit of metasedimentary rocks. Lithologies present include mudstone, siltstone, sandy siltstone, sandstone, pebbly sandstone, and conglomerate. Mudstones are greenish-gray to gray, typically silicified, with continuous, parallel to slightly wavy, very thin to medium lamina occasionally with small-scale loading structures. Siltstones are light green-gray to gray, with continuous, parallel to
slightly wavy, thin lamina to very thin beds, occasionally with small-scale loading structures. The siltstones are composed of quartz, sericite, and traces of a black detrital heavy minerals (less than 1 mm in diameter). Siltstones are typically interbedded with the sandstones. Sandstones are dark-gray, gray, greenish-gray, grayish-green, litharenites and feldspathic litharenites composed of volcanic rock fragments,
feldspar, quartz, and rare intrusive rock fragments. Textures range from fine-grained, and well sorted to very coarse-grained, and moderately poorly sorted. Bedding in the sandstones is continuous, parallel to inclined, thin lamina to thin beds; also massive bedding and cross-beds are present. Individual beds are sometimes graded from sand-size to silt-size with abrupt upper surfaces. Conglomerates include
matrix supported and clast supported polymictic conglomerate composed of angular to rounded, pebbles to large cobbles (up to 30 cm). Conglomerates are generally massive bedded, rarely with any imbrication of the clasts. Clast types include: dark-gray to gray, angular to subangular, microcrystalline volcanic rock fragments; black, subangular to subrounded, plagioclase-porphyritic dacite; black to dark gray,
subrounded, flow-banded dacite; and greenish-gray to grayish-green, rounded to well rounded, fine to coarse plagioclase crystal tuff. Rare clast types include: white, subangular to rounded, granite and granodiorite (up to 12 cm); dark-brown, rounded, vesicular basalt (up to 2.5 cm); and gray, angular siltstone (up to 25 cm). Sandstone and conglomerate beds often fill scour channels in the siltstones.
Qal
Qal
Zgr-ch
Zgr-ch
Zhat (u) – Altered tuffs: Very light gray to light greenish gray (whitish in areas) with red and yellow mottling, altered volcaniclastic rocks. Alteration consists of silicified, sericitized and pyrophyllitized rock. Sericite phyllite, pods of pyrophyllite, and quartz + phyrophyllite rock all with less than 1 mm to 2 mm diameter weathered sulfides are common. Relict lithic clasts and kaolinitized feldspar crystal shards are visible
in some exposures. Relict structures are obliterated in heavily altered rocks. Map area contains boulders (up to several feet in diameter) and outcrop of massive milky quartz and quartz + sericite rock.
Zdi
Trcs/si1
Zgr
Zq – Quartz bodies: White, beige, red, and tan; sugary to porcelaneous; very fine- to medium-grained massive quartz rock to quartzite-like rock. Outcrops are usually massive. Quartzite-like rock is occasionally mixed with sericite and/or pyrophyllite. The addition of sericite and/or pryophyllite gives the otherwise massive quartzite-like rock a foliation. Pyrite is present as cubic crystals and empty cubic molds of
crystals (up to 12 mm). Map areas contain boulders (up to several feet in diameter) and outcrops of white colored massive quartz.
36 00' 00"
Trcs/si1
Zgd
Qal
10
Qal Zhe/p
Zhe/p
Zt-qdi
Zmi – Porphyritic mafic intrusive: Grayish-green to dark-green, very hard, plagioclase porphyritic mafic rock. Greenish-white, euhedral, plagioclase phenocrysts (up to 8 mm) and black amphibole/pyroxene? phenocrysts (up to 2 mm) are present in a green and yellow mottled, very fine-grained (less than 1 mm) matrix. Typically weathers to rounded boulders and outcrops. The plagioclase phenocrysts weather
in positive relief, creating a distinctive bumpy or pustulate surface. Newton (1983) identified this unit as an amphibole-porphyry lamprophyre dike.
Qal
Zhe/p
Zdi
Zefg-m
Jd
72
Qal
OTHER POINTS
LOCATION OF ORANGE COUNTY
84
77
strike of vertical cleavage
1 - Martin Morrow pyrophyllite mine - abandoned
2 - unnamed prospect - abandoned
3 - Dell Dawson prospect - abandoned
4 - pyrophyllite prospect - abandoned
5 - Teer pyrophyllite prospect - abandoned
6 - Oaks pyrophyllite prospect - abandoned
7 - Stroud copper prospect - abandoned
8 - pyrophyllite prospect - abandoned
9 - Bradshaw pyrophyllite mine - abandoned
10 - North State gold mine - abandoned
11 - Ray gold prospect - abandoned
12 - unnamed prospect - abandoned
13 - unnamed prospect - abandoned
14 - Duke Forest gold prospect - abandoned
15 - Weaver-Carr gold prospect - abandoned
16 - Nunn Mountain gold mine - abandoned
17 - Chapel Hill Iron mine - abandoned
18 - Laurel Hill quartz prospect - abandoned
71
Zgd
Qal
35
Zum
Zhe/p
78
81
84
72
76
88
86
82
79
Qal
Zhe/p
Zhdlt (l)
Zhdlt (l)
81
72
Zdi
Zhe/p
71
Zum
Metamorphosed volcaniclastic sedimentary and pyroclastic rocks associated with Hyco Formation: upper portion (stratigraphic relations uncertain) ca. 613 - 616 Ma (Wortman et al., 2000; Bowman, 2010; and Bradley and Miller, 2011)
Zhe/p
Zhe/p
Zhe/p
Zdi
Zhdlt (u)
78
Jd
Qal
Zgd
Qal
79
Zgd
88
Zdi
75
84
Zhe/p
Jd
Jd
Zgd
17
Zdi
Zhdlt (l)
Zhe/p
88
Zhe/p-n
Zhe/p-n
Qal
Zhe/p
Zhe/p
Jd
Zqmd - Quartz monzodiorite: Greenish-gray to gray, mesocratic, medium-grained, equigranular quartz monzodiorite. Major minerals include plagioclase and hornblende. In field, rock is indistinguishable from typical diorite except for rare pinkish alkali feldspar in some samples (specifically on the south side of Blackwood Mountain). Rock type designation based on recalculated whole rock
chemical analyses of Bland (1972).
Zum - Ultramafic: Black, coarse-grained (5 mm to 10 mm), ultramafic rock consisting mainly of poikilitic crystals of relict brown hornblende that are partially replaced by actinolite and chlorite. Other minerals include serpentine, talc, chlorite, actinolite, and opaque minerals. Minor relict orthopyroxene is present. Hayes (1962) interpreted the protoliths as olivine-rich wehrlite (with approximately 50% olivine) and
clinopyroxenite. Bulter (1989) interpreted the body to be an intrusion of a crystal mush formed by differentiation of gabbroic magma at depth. Normalized whole rock analysis from a sample collected east of Iron Mine Hill (CH-2027) plots within the olivine-clinopyroxenite field on an Ol/Opx/Cpx
ternary diagram.
72
Zhe/p
78
Zgd
Zdi
Zhdlt (l)
86
76
Qal
81
Zdi
74
Zum
Zgd
Zgr
Zhe/p
64
Zdi
Qal
80
Zhdlt (l)
74
Zhqdp
Zhe/p
Zgd
Zgr2
76
78
Zhdlt (l)
Zhqdp
Zefg-6
Zhe/p
Zefmd
Zhiflt
75
Zgr2
77
88
65
81
Jd
Qal
89
Zdi
74
78
69
85
Zhe/p
Zhdlt (l)
Zhqdp
Zgd
Jd
16
Zdi
Qal
70
72
Zgr2
64
Zdi
Zhe/p
89
72
Qal
86
Zhdlt (u)
89
Qal
Zdi
Zhe/p
Zhe/p
Zdi
Zdi-fine – Fine-grained diorite: Small plutonic bodies of green, very fine-grained diorite. The rock is green in hand sample from saussuritization of plagioclase.
Zgb – Gabbro: Gabbro of the Meadow Flats pluton is Dark-gray to greenish-gray, mesocratic to melanocratic and medium-grained. Major minerals include plagioclase and augite. In outcrop, the diorites and gabbros are very similar in appearance and are difficult to distinguish from each other. According to Mann, et al (1965), the plagioclase crystals are zoned with cores of An53 and An31 at the margins. Augite
grains (present up to 3 mm) are fringed with uralite and are sometimes replaced by hornblende, chlorite, or magnetite. The map pattern of gabbro within the Meadow Flats pluton was drawn incorporating the Bland (1972) whole rock data with field data from this study. A small pod of gabbro is present in the southeast corner of the Hillsborough quadrangle that is dark green, melanocratic and fine-grained.
80
62
81
Zgd
Zgd
79
Zhe/p
85
Zgd
81
Zhe/p
Zgd
74 18
77
Zgb
Zgr2
22
Zdi-fine
75
Zgd
87
Zhe/p
Zdi
Zdi
15
Zdi – Diorite: Mesocratic (CI~50), greenish-gray to grayish-green, fine- to medium-grained, hypidiomorphic granular diorite. Major minerals include plagioclase and amphibole. Plagioclase crystals are typically sericitized and saussuritized. Amphiboles are typically altered to chlorite and actinolite masses. May be gabbroic locally.
Zgd-gr-p
Zhe/p
Qal
Zdi
84
Zt-qdi – Tonalite to quartz diorite: Light-gray, fine to medium-grained, hornblende tonalite to quartz diorite. Visible quartz content ranges from 5% up to 20%. Outcrops of this unit are typically finer-grained, lighter in color, and have visible quartz in comparison to typical medium-grained diorite.
Zgd-gr-p
Zhe/p
Jd
Zgd
Zgd-gb - Granodiorite to gabbro: Composite pluton of dominantly medium-grained, hornblende granodiorite; lesser amounts of medium-grained hornblende diorite, plagioclase porphyritic granodiorite, fine-grained granodiorite, and diorite; minor amounts of fine-grained gabbro. Fine-grained granodiorite and diorite are typically green in hand sample from saussuritization of plagioclase. Hornblende is
typically altered to chlorite and actinolite masses.
Qal
88
Zhablt Zdi
Zgd Zgd
Zdi Zgd
66
Zgd-porphyritic - Porphyritic granodiorite of the Buckwater Creek Pluton: Greenish-gray with a pinkish-hue; amphibole-bearing; porphyritic granodiorite with plagioclase phenocrysts. Plagioclase phenocrysts are green from saussuritization and range from 2 to 8 mm in a matrix of very fine-grained quartz and alkali-feldspar. Weathered surface exhibit a distinct strongly porphyritic texture. Porphyritic
rhyolite of Newton (1983).
Zdi-gb – Diorite to Gabbro: Greenish-gray to gray, medium-grained, equigranular, hornblende diorite intermingled with dark-gray to greenish-gray, medium-grained gabbro with pyroxene. Plagioclase crystals are typically saussuritized and exhibit a greenish color. Outcrops with heavily saussuritized plagioclase have a high Color Index causing difficulty in distinguishing between gabbro and diorite in the field.
Zgd
71 64
Zhablt
Zdi-gd-b – Diorite and granodiorite of the Buckwater Creek Pluton: Composite pluton of dominantly medium-grained hornblende diorite; lesser amounts of medium-grained hornblende granodiorite, fine-grained granodiorite, porphyritic diorite with plagioclase phenocrysts; minor amounts of porphyritic granodiorite with plagioclase phenocrysts, porphyritic granodiorite with potassium feldspar phenocrysts,
and gabbro. Unit contains abundant xenoliths of volcanic rocks and enclaves(?) of fine-grained granodiorite to diorite.
D
70
84
87
Jd
Zdi
77
84
Zhdlt (l)
76
74
Zgr
Zwfd
Zhiflt
28
Qal
84
Zq
84
80
70
76
75
76
79
Zdi
Zhft (l)
64
88
Zdi
86
Zhe
79
83
Zhe
Zhe
88
Jd
34
Zhablt
Zhdlt (l)
Zhe/p-n
81
Zdi
89
Zhe/p
Zhat (l)
81
32
85
Zgr
68
71
Qal
81
Zhe
Zgd-di-b – Granodiorite and diorite of the Buckwater Creek Pluton: Composite pluton of dominantly medium-grained, hornblende granodiorite; lesser amounts of medium-grained hornblende diorite, fine-grained granodiorite, and diorite. Unit contains abundant xenoliths of volcanic rock and enclaves(?) of fine-grained granodiorite to diorite.
Zhe/p
Zgb
Zdi
Jd
14
75
A'
Qal
54
Zdi
Zgd-gr-p – Granodiorite to granite of Piney Mountain Creek area: Composite pluton of dominantly medium-grained hornblende granodiorite with lesser amounts of medium-grained hornblende granite. Typically contains dark green to black less than 1 mm to 4 mm clots of actinolitic (?) amphibole and chlorite masses. Locally contains pinkish-hued feldspars.
Qal
Zhe/p
84
89
Zdi
82
89
Zhft-b (l)
Jd
75
Zhdlt (u)
Qal
88
Zhablt
87
86
Zhft (l)
Zhablt
58
Zdi
Jd
Zhmst
69
Qal
Zgd-gr-p
76
80
78
87
67
Qal
Zdi
Zhdlt (l)
79
85
84
65
80
strike of vertical primary volcanic
compaction foliation and/or welding
Zhe/p
75
13
70
88
78
69
78
77
Zdi
Zgd
Zhdlt (l)
85
80
Qal
Qal
78
74
Zhablt
69
Zgb
86
Zhe
74
88
70
Jd
76
81
69
83
84
65
84
78
Zwfd
80
Zwfd
78
88
75
84 Zhe/p
Zwfd
64
82
88
Zagd fine- Fine-grained altered granodiorite: Light-green, fine-grained (less than 1 mm), altered intrusive rock interpreted as a granodiorite. Rock is primarily a fine-grained mass of heavily saussuritized plagioclase and quartz with no visible mafic minerals in hand sample. Unit occurs as angular boulders in two small map bodies.
Zhdlt (l)
Eno Ri ver
78
64
76
71
Qal
Zhablt
Zdi
73
Zhdlt (l)
Zdi
85
Zhft-b (l)
88
25
Qal
62
79
Zhat (l)
60
64
87
74
Zhdlt (l)
Zdi
Zhdlt (l)
Qal
Zhft-b (l)
Zgb
Zgb
63
Zhe
88
Zgd
Qal
85
73
Zgd
80
Zhe
61
Qal
82
Zwfd
85
84
65
84
Jd
82
Zhe/p
86
79
68
74
88
83
Zqmd
Zdi
Zdi
Zdi
Zqmd
Zhe
Zhe
Zhadlt
88
Zgd
11
79
85
75
78
76
84
78
87
86
85
84
81
86
Zhdlt (l)
Zgd Qal
Zhp/e
85
87
87
74
Zhablt
77
Zgd
Jd
85
78
Jd
Zhdlt (u)
88
86
81
Jd
Zhat (u)
74
Zhdsi (u)
71
79
Zhdlt (l)
Zhat (l)
84
Zhat (l)
71
Zhft (l)
Zdi
Zqmd
Qal
77
84
Zqmd
Zhat (l)
Zhft (l)
Zhft (l)
Jd
60
51
80
Qal
Zgd-lueco – Fine-grained luecocratic granodiorite: Small pods of tan to light-gray, fine-grained (less than 1 mm), luecocratic granodiorite. Mafics present in rock are commonly biotite clusters up to 1 mm in diameter. Plagioglase mineral grains have a light greenish tint from epidote growth.
Zhdlt (l)
Qal
79
U
Qal
Zhdlt (l)
Qal
73
Qal
Zgd – Granodiorite: Leucoractic to mesocratic, fine- to medium-grained, equigranular to porphyritic granodiorite. May contain quartz diorite and diorite. Typically contains dark green to black less than 1 mm to 4 mm clots of actinolitic (?) amphibole and chlorite masses. Plagioclase grains are often sericitized and saussuritized and may exhibit a greenish color. Locally, granodiorite is pinkish hued,
fine- to medium-grained with dark green to black less than 1 mm to 4 mm clots of mafic minerals interpreted to be biotite and amphibole masses. Chlorite growth on biotite and amphibole is present. Medium-grained, with light pink to pinkish white alkali feldspars (up to 5 mm diameter), porphyritic granodiorite is intermingled in the northern portion of the Chapel Hill quadrangle. Locally, map scale
xenoliths are present.
71
Zgd-fine – Fine-grained granodiorite: Light-gray to green; ranges from equigranular fine-grained (less than 1 mm) granodiorite to very fine-grained porphyritic granodiorite with plagioclase phenocrysts (1 mm to 4 mm). Black colored amphibole, when visible, occurs as phenocrysts (less than 1 mm to 1 mm) and as intergrowths with plagioclase; amphibole intergrowths distinguish rock from
fine-grained tuffs.
76
69
79
78
Zhablt
Zdi
Zhablt
Zhft (l)
Zhat (l)
Zhft (l)
Zdi
Zhat (l)
80
Zhdlt (l)
Zgb
79
89
88
Zhdlt (u)
4
76
80
Zhablt
84
82
86
Zhablt
71
Zhablt
70
73
89
Zhat (u)
secondary road
77
1
86
75
84
87
82
Zhdsi (u)
Qal
88
89
Zhablt
84
85
Jd
46
86
Zdi
Zhdsi (u)
89
Zhat (l)
Zhablt
Zdi
Zhablt
74
Zgd
80
Zhdlt (l)
Zhdlt (l)
Zhp/e
2
Jd
10
86
84
Zdi
78
Zhablt
Zhft (l)
75
60
U D
72
Jd
Qal
22
Zhdlt (l)
Zhmst
Zhe/p
75
72
78
Zhat (l)
82
85
Zdi
Qal
Zhablt
76
Zhat (l)
Zhmst
86
Qal
Zhablt
Zhablt
8
85
88
Zhablt
6
88
Zhp/e
Zhdlt (u)
Zhp/e
Zhdsi
(u)
Zwfd
88
56
84
71
76
40
84
74
87
Zhdlt (u)
Pdad dike - inferred
80
78
86
77
42
Zgd-leuco
Zgd-fine
Zgd-fine
Qal
71
88
Zhablt
88
Zhdsi (u)
86
88
84
Zhdlt (u)
5 70
Zhat (u)
84
Qal
71
Qal
Zhat (l)
74
Qal
79
Zhdlt (l)
Zhablt
Zhabsi
Qal
Zhdlt (l)
74
80
Zdi
Zgd
Zhablt
86
Qal
61
Zhft (l)
87
Zdi
78
Qal
Jd
Jd
Zhdlt (l)
86
82
88
75
Qal
74
Zhablt
84
Qal
Zhablt
84
87
Zgr2 – Granite: Light pink to pink and orange; fine- to coarse-grained granite. May be foliated.
Qal
Zgr-di – Granite to diorite: Composite pluton exhibiting a variety of rock types ranging from granite to diorite. Lithologies include grayish pink, medium- to coarse-grained granite; pinkish-white, medium-grained hornblende granodiorite; and dark-gray, fine- to coarse-grained diorite.
Zhft (l)
66
Metaintrusive rocks associated with Hyco Formation: upper portion ca. 613 and 614 Ma (Wortman et al., 2000)
Zgr – Granite: Light brownish to beige or creamy, and locally pale pink or green; medium- to coarse-grained, equigranular metamorphosed leucocratic granodiorite and granite; locally weakly porphyritic with beta-quartz forms; grades to quartz porphyry in zones of cleavage development; quartz may be bluish; locally reddish weathering; locally contains epidote and/or chlorite clots possibly
pseudomorphic after a hornblende; feldspar and quartz grains resist weathering and produce a bumpy surface; plagioclase and quartz phenocrysts sit in a granophyric matrix of alkali feldspar and quartz. Correlative to the Chatham granite of Hauck (1977) in Bynum Quadrangle.
Zhmst
84
Qcv
Zhablt
Zhmst
Zhe/p
Zhe/p
Qal
Zhablt
65
Qal
Zhdlt (l)
Qal
Zhe
Jd
83
Zhdlt (l)
77
Qal
84
Zgd-leuco
64
Zgd-fine
Zhe
Zhablt
Zdi
Zhdlt (l)
Zhablt
72
76
86
Zhat (u)
Jd
72
72
Zdi
84
87
86
84
Zhe/p
74
Zhablt
Qal
Zgdleuco
71
Zhablt
Zhe
Qal
Qal
80
Zhat (l)
Qal
86
73
80
Zhablt
Zdifine
Zhablt
Zhe/p
79
80
82
9
84
Zhablt
82
Qal
82
Zhe
81
Zhat (l)
87
89
Zhe/p
75
Qal
Zdi-fine
Zgd
85
Qal
Zhablt
82
86
79
82
79
HYCO FORMATION
80
89
64
72
Qal
61
80
Trq
breccia
Zhablt
52
85
Zhat (l)
71
Zwfd – West Farrington pluton diorite: White to cream-colored, unfoliated, medium- to coarse-grained, with dark green amphibole (actinolite after hornblende) diorite. Locally with chlorite/biotite; dominantly equigranular but locally weakly plagioclase porphyritic; includes quartz diorite, grano-diorite, quartz monzodiorite, and onalite; commonly contains ovoid enclaves of green to black
microdiorite to 0.5 m; grades to local patches of more mafic diorite and gabbro; fine dense to slabby hornfelsed country rocks occur locally as enclaves and near contacts; locally strongly saussuritized and pale greenish; white weathering with plagioclase occurring in positive relief giving “bumpy” texture.
Zgdporphyritic
Zgd-di-b
Zhft (l)
Zhe/p
Qal
Zhft (l)
74
63
Qal
Zhablt
72
64
Zhdlt (l)
24
Zgd
78
Qal
80
Zhdlt (l)
78
Zhe
Zdi
Zdi
Zhe
Zdi-gd-b
84
Zhablt
R ivJd
er
80
85
Qal
Qal
Zhft (l)
Zhablt
Zhft (l)
72
81
Qal
Zhadlt
77
Zdi
72
88
Zhdlt-a (l)
Zdi
Qal
Zhft (l)
79
Qal
Qal
Zhat (l)
Zhablt
71
Zhe Zhablt
67
Zhdlt (l)
36
Diabase dike - Dashed where inferred,
dotted where concealed.
70
Zhablt
74
Zhp/e
76
74
79
Zhp/e
87
Zhablt
Zhat (l)
Zhablt
Qal
87
78
Qal
Faults- Dashed where inferred, dotted where concealed.
U indicates upthrown block, D indicates downthrown block.
54
79
55
70
ASSORTED LINES
Qal
73
84
Zhablt
En
o
Zhadlt
Zhat (l)
73
Zdi
Zefg-4 – East Farrington pluton gray granitoid: Unfoliated to foliated, light gray to light greenish-gray, medium-grained granite to granodiorite. White-colored feldspar content is greater than pink feldspars. Foliated specimens have visible white mica growth and less pink feldspars than unfoliated specimens. Foliated rock is present along portions of Pokeberry Creek, Pritchards Mill
Creek and Cumbo Branch.
Zefmd – East Farrington monzodiorite porphyry of Terrells Creek area: Light gray to dark grayish-green where fresh, olive drab weathering, plagioclase-phyric monzodiorite and diorite, typically with very low color index. Fine- to medium-grained groundmass, with phenocrysts to 8 mm. Quartz phenocrysts very rare. Commonly has a cloudy, splotchy, or mottled appearance. Locally
contains salmon-colored feldspar phenocrysts and/or orange ovoids interpreted as cavity filling or weathered phenocrysts. May have a thin light beige outer weathering rind. Weathered surface may be pitted. Locally sulfide-bearing, saussuritized, or streaked with tiny epidote veins. Fine-grained near margins.
Zhft (l)
Jd
Qal
Zhadlt
Zdi
Zhdlt-a (l)
Zdi
81
79
Zhablt
Zhe
85
Qal
72
70
Miles
21,000
Feet
North Carolina State Plane NAD 83 meters coordinate system,
Lambert Conformal Conic projection
Base Map Information: Base map is a composite of the USGS
GeoPDF 7.5-minute quadrangles covering the County from 2010 and 2011.
Air photographs, map collars and select features removed.
This geologic map was funded in part by the
USGS National Cooperative Geologic Mapping Program.
5
Kilometers
A
0'
Zhe/p
Pdad Dike
CZtgd
-1271'
CZtgd
Padid Dike
Padid Dike
Zgd-gb
no vertical exaggeration
Zhe/p
Zhft (l)
Zhft (l)
DRAFT
Zgd-gb
Zgd-gb
Zhft (l)
Zhft (l)
Zhe
Zhablt
Ze/p-d
Zhablt
Ze/p-d
Zhablt
Zhdlt (l)
Zhft (l)
Zhadlt
Zhft (l)
Zhdlt (l)
Bald Mountain
Zdi
Zhdlt (l)
Zgb
Zhft (l)
Zhft (l)
Trq-breccia
Zhdlt (l)
Zgd-gr-p
Zhdlt (l)
Zhft (l)
Zhft-b
(l)
Zhdlt (l)
Zhe/p
Zhe/p
Zdi
-3271'
Zhft (l)
Zgd
Zhe/p
Zt-qdi
Zhe-m2
Trcs/si1
Zgr-ch
Zgr-ch
Zhft (l)
Zhft (l)
Zgd-ch
Zhdlt (l)
Zgd
Zgr-ch
Zhft (l)
GEOLOGIC MAP OF ORANGE COUNTY, NORTH CAROLINA
By Philip J. Bradley, Heather D. Hanna, Norman K. Gay, Edward F. Stoddard, Randy Bechtel, Cindy M. Phillips, Stephen J. Fuemmeler
Map preparation and editing by Philip J. Bradley, Heather D. Hanna and Michael A. Medina Digital representation by Michael A. Medina, Philip J. Bradley and Heather D. Hanna
2012
-1271'
B'
Zgd
Zhft-b (l)
0'
Zhat (l)
Zgd-di-b
Zhe Zhe/p
Zdi
729'
Zhft (l)
Zdi-gd-b
Zhablt
-1263'
-3263'
elevation in feet
Zhadlt
Zhdlt (l)
Zhdsi (l)
cross section scale: 1:50 000
Zhablt
Zhat (l)
Zhft (l)
Padid Dike
B
Zhe/p
Zhe/p
Zhe/p
Zhablt
Zhft (l)
Zhdlt (l)
-3271'
0'
A'
Zdi-gd-b
729'
737'
Zefg-2 – East Farrington pluton porphyritic granite: Gray, fine-grained groundmass with pink- and white-colored phenocrysts (1 mm to 4 mm) of orthoclase and plagioclase, granite. Anhedral to acicular-shaped, dark green, amphiboles (less than 1mm to 4 mm long) present in groundmass of quartz and orthoclase and as intergrowths with orthoclase and plagioclase phenocrysts.
Present as several map scale bodies and as outcrop scale enclaves surrounded by East Farrington pluton main facies rock.Zefg-3 – East Farrington pluton fine-grained granite: Orange pink, fine-grained granite. Similar texture and mineralogy to East Farrington pluton main facies but with an overall finer-grained texture. White feldspar phenocrysts compose less than 5% of rock.
81
87
Jd
76
70
66
Zdi
Qal
Zgr-di
Zhdlt (l)
Qal
Zhdsi (l)
Zhablt
Qal
88
Zhdlt (l)
86
Qal
Zhablt
Qal
Zhablt
Zhablt
Zhdlt (l)
85
Qal
76
Interpreted fold hinge of large
scale doubly plunging syncline.
44
60
Zhablt
87
87
Zgd
76
Zdi
72
Zefg-m1 – East Farrington pluton main facies variety 1: Identical to main facies but with dark green, chlorite masses up to 4 mm diameter. In thin section, the chlorite masses are intergrowths of chlorite and dark green, fibrous amphibole.
36 07' 30"
Zefg-6 – East Farrington pluton satellite granitoid: White, creamy, pale pink, or pale greenish; fine- to medium-grained, locally plagioclase-porphyritic granite, granodiorite, leucogranite, leucogranodiorite, and quartz monzodiorite. Contains distinctive prismatic amphibole crystals, locally acicular and up to one cm. Amphibole-rich enclaves to 2 cm are present locally. At western contact
in Heron Pond subdivision, contains enclaves of and cuts fine-grained gray diorite and monzodiorite porphyry of the Zefmd unit.
Zhadlt
84
Jd
Zhdsi (l)
83
24
Zhft (l)
Zq
Zefg-m – East Farrington pluton main facies: Unfoliated, orange pink to pinkish-gray to gray, medium- to coarse-grained, equigranular to slightly porphyritic, amphibole (va. hornblende?) granite. Amphibole content varies from approximately 5 to 10% by volume and occurs locally as dark green, elongate crystals up to 1.5 cm long and amorphous intergrowths with feldspar and quartz up
to 0.5 cm diameter. Dark gray xenoliths/enclaves up to 8 cm in diameter are common. Grain size becomes finer and xenoliths/enclaves larger near the pluton edge. Cavities, less than 1mm in diameter, with euhedral terminating crystals are common in some specimens. In thin section the main facies can be separated into two groups: 1) rocks with a porphyritic texture with orthoclase and
plagioclase phenocryts in a groundmass of intergrown orthoclase, plagioclase and quartz with a granophyric texture (micrographic texture) and 2) porphyritic and equigranular rocks consisting of orthoclase, plagioclase and quartz without a granophyric texture in matrix. The two varieties appear to be intermingled throughout the study area and within the adjacent Farrington Quadrangle
(Bradley et al., 2008).
82
Jd
Trq
breccia
Zhablt
Zdi
Qal
East Farrington pluton: The East Farrington pluton is composed of several distinct granitoid facies based on mineral and textural characteristics. U-Pb zircon geochronologic data (Tadlock and Loewy, 2006) indicate that the East Farrington pluton is ca. 579 Ma.
88
Zgd-di-b
Zq
Zhdsi (l)
81
Zhat (l)
72
70
Zhablt
Zgd
77
Qal
78
72
77
75
85
Zhat (l)
84
Equal Area Schmidt Net Projection of Contoured Poles to
Primary Layering, Bedding and Welding/Compaction Foliation.
Contour Interval = 1 N = 804
81
Qal
71
Zhdlt (l)
Zhablt
Zhe/p-d
Zhat (l)
62
Zhat (l)
CZgb – Gabbro: Dark green to black, melanocratic, medium-grained gabbro to plagioclase porhyritic fine-grained gabbro. Present as a dike.
Zhft (l)
50
81
Zhft (l)
Zhdsi (l)
Zhft (l)
80
Qal
Zdi
64
Qal
30
Jd
Zgd-di-b
Zhablt
89
73
Qal
75
Zhablt
86
87
84
Zdi
Zdi
Qal
Zdi
23
Qal
79
70
86
88
Qal
Zhablt
88
67
Zq
Zhadlt
75
78
Zdi
Zgdporphyritic
Zhat (l)
CZgr-gd - Granite to granodiorite of the Prospect Hill pluton: Unfoliated, leucocratic (CI less than 10), pinkish gray hued, very light gray to yellowish gray, fine- to medium-grained, equigranular to locally plagioclase porphyritic, hypidiomorphic granular, metamorphosed granite to grano-diorite. Major minerals include white feldspars, quartz and ± pink feldspars. Mafic minerals
consist of fine-grained biotite/chlorite intergrowths that occur as amorphous masses and acicular shaped zones that resemble amphiboles in hand sample. Mafic mineral clots locally are aligned forming a weak (magmatic?) foliation.
88
69
86
Jd
Zdi
84
71
88
CZtgd – Prospect Hill tonalitic granodiorite pluton: Unfoliated to locally very weakly foliated, leucocratic (CI less than 10), very light gray to yellowish gray, medium- to coarse-grained, hypidiomorphic granular, metamorphosed tonalitic granodiorite to tonalite. Mafic minerals present in rock are most commonly biotite intergrown with chlorite and/or hornblende intergrown with
actinolite. Locally muscovite-bearing. Cross cutting pegmatitic dikes of similar mineralogy present in some areas. Locally biotite forms (magmatic?) foliation. Weathering of rock produces distinctive coarse quartz sand grains in soil. Andesite to diorite dikes (Zadid) are common throughout the pluton and typically occur as resistant spheroidal boulders. Pluton map pattern truncates
Virgilina sequence volcanics and pluton contains foliated xenoliths of volcanic rocks; as such, the pluton is interpreted to be related to the ca. 546 ma Roxboro pluton (Wortman et al., 2000).
14
Zhe/pl
79
Jd
75
60
76
75
85
Padid – Andesite to diorite dikes: Melanocratic to Mesocratic (CI ~50 to greater than 50), dark green to green gray, aphanitic to medium-grained, metamorphosed andesite to diorite. Andesites and diorites are locally plagioclase porphyritic. Typically occur in map area as resistant spheroidal boulders. Locally maybe basaltic to gabbroic. Dike trend lines indicated were strike of
dike measured in outcrop or interpreted from adjacent stations. Occur as infestation in Ztgd unit and are present in many more locations than displayed on map.
29
88
88
Pdad – Dacitic dikes: Dark gray to gray, finely crystalline, and locally weakly plagioclase porphyritic dacite dikes ranging from less than one foot to several feet wide.
Qal
75
Zhdlt (l)
Jd
83
Zdi
88
Zhdlt (u)
74
Zhablt
87
80
85
FAULTS
86
85
77
Interpreted fold hinge of large
scale overturned syncline. Arrow
indicates direction of plunge.
Zhft (l)
67
71
Zdi
80
81
Zhablt
Zhablt
77
Zhablt
Zhe/p-d
Qal
78
82
Qal
76
Metaintrusive Units
84
Zhdlt (l)
80
56
Zhat (l)
75
66
68
Zhablt
73
Zhat (l)
70
Qal
Zhat (l)
77
78
Zdi
Zhasi
Trq-breccia – Quartz breccia: White; massive to brecciated; vuggy quartz. Typically contains angular clasts of altered volcanic rock suspended in a quartz matrix. Some zones exhibit a lacey pattern of intersecting quartz veins with a matrix of altered wall rock.
82
88
Zhe/pl
Zq
73
Fault Rocks
73
83
Zhasi
19
85
Zhdlt (l)
MPzgb – Olivine gabbronorite: Unfoliated, black, medium- to coarse-grained gabbronorite. In thin section, olivine, plagioclase, orthopyroxene and clinopyroxene are present with no apparent metamorphic overprint. In field, rock is similar in appearance to coarse-grained diabase.
72
86
89
Zgd
BUS.
73
77
Qal
Zhe/p-d Qal
82
74
76
79
Zhft (l)
Zhablt
77
Zgd-fine
74
79
80
Zhablt
Zhft (l)
Zhdlt (l)
Interpreted fold hinge of large
scale overturned anticline.
Arrow indicates direction of plunge.
Zhablt
81
82
86
21
Qal
76
71
Zhe/p-d
Qal
88
59
81
Zhe/p-d
26
Zhablt
81
Zdi
76
Qal
Zhe/pl
84
Qal
64
75
57
Zq
Jd
Zdi
Zhablt
Qal
78
62
78
Zhablt
Zhablt
Zhe
82
67
Zhablt
Qal
Zhablt
76
Qal
Zhasi
75
Zhablt
Qal
Qal
Qal
Zhe/p-d
Zhdlt (u)
Qal
84
72
88
Zhablt
Zhasi
85
Qal
65
Jd
Zdi
Zdi
62
Zhe/p
Jd – Diabase: Black to greenish-black, fine- to medium-grained, dense, consists primarily of plagioclase, augite and may contain olivine. Occurs as dikes up to 100 ft wide. Diabase typically occurs as spheriodally weathered boulders with a grayish-brown weathering rind. Red station location indicates outcrop or boulders of diabase.
Zhdlt (u)
81
Jd
Zhablt
89
62
70
83
84
Qal
74
68
86
84
86
Mesozoic to Paleozoic(?) Intrusive Units
Zhablt
86
79
Zhdlt (l)
Zhe/p
Qal
75
76
Qal
Zagdfine
81
Zhdlt (u)
88
Zhe
dacitic lavas and tuffs (Zhdlt (l)); altered dacitic lavas and tuffs;
(Zhdlt-a (l)); porphyritic dacite associated with Zdlt (Zhdlt-p)
dacitic shallow intrusive (Zhdsi (l)); quartz dacite porphyry (Zhqdp);
andesitic to dacitic lavas and tuffs (Zhadlt)
Zhe/p-d
82
80
84
Qal
31
Zhablt
Zagd-fine
76
84
Zhe/p-d
84
87
Zgd-gb
Zgd-fine
Zhablt
Zhft (l)
Qal
57
Zhablt
Qal
76
76
Zdi
Zhe/p
Zdi
83
88
80
Zhe
Zhdlt (u)
Zhe
Zhablt
Qal
Zgd-fine
Zhdlt (u)
Zhablt
36 00' 00"
Zhdlt (u)
Qal
Zhdlt (u)
80
84
Zhablt
68
81
felsic tuffs (Zhft (l)); felsic tuffs of the Blackwood area (Zhft-b)
Zhadlt
Zgd-fine
Qal
67
88
82
82
80
55
73
Zmi
77
80
79
Qal
74
Zhe
84
Qal
Qal
79
76
Zhablt
Zdi 80
77
Qal
Jd
77
Zhdlt (l)
69
Qal
Zhe
Zhablt
Zhe
85
78
Zhe
84
79
78
Zhft-d (l)
73
Qal
61
48
gradational contact
74
Zgd-fine
79
Zhdlt (l)
Zgd-gb
Lithologic contacts - Distribution and concentration
of structural symbols indicates degree of reliability.
Contact dashed where inferred.
Contact dotted where concealed.
FOLDS
Zhft (l)
84
Zgd-fine
CONTACTS
61
Qal
Zhe
Qal
Zgd-gb
Qal
Qal
87
Zhablt
Qal
78
70
Zhablt
81
84
Zgd-gb
Zhdlt (l)
Zhft (l) Qal
Zhdlt (l)
Qal
Zq
88
82
85
72
74
Zhft (l)
Qal
79
Zhft (l)
Zhablt
CZtgd
Qal
71
74
Zgd-gb
80
Zgd-gb
Qal
59
81
88
76
Zhft (l)
81
84
84
42
Zhdlt (l)
69
71
Zhablt
78
60
82
Zgd-gb
Zhdlt (l)
altered tuffs (Zhat (l)); matrix supported tuffs (Zmst)
Zhdlt-p
Qal
88
Zhablt
Zhablt
65
75
81
Zhat (l)
Zhat (l)
71
Zhdlt (l)
Zhft (l)
Zgd-gb
89
Jd
Qal
Zgd-gb
88
Zgd-gb
70
Zhft (l)
Jd
Qal
66
Zgd-fine
Zhft-b (l)
70
80
86
Qal
Zgd-ch
Zhmst
76
Zhft (l)
Zgd-gb
Zmi
82
78
metamorphosed volcaniclastic sedimentary and pyroclastic rocks
associated with Hyco Formation: lower portion (stratigraphic relations uncertain)
ca. 629 - 633 Ma (Wortman et al., 2000 and Bradley and Miller, 2011)
Zhft (l)
Qal
Zhe/p
metaintrusive rocks associated with Hyco Formation: lower portion
(stratigraphic relations uncertain)
ca. 630 Ma (Wortman et al., 2000)
Zhat (l)
Qal
78
76
77
12
Jd
78
70
88
48
Jd
Zhft (l)
88
Zgd-gb
Zgr-ch
Zhe/p
Zhablt
85
80
Trcs/si1 – Sandstone with interlayered siltstone of the Chatham Group Lithofacies Association I: Grayish-pink, pinkish-gray, and light-gray; fine- to coarse-grained, micaeous, slightly clayey, moderately poor to moderately well sorted, subangular to subrounded arkose and lithic arkose; dark red to reddish-brown, very silty, micaeous, moderately well sorted, fine-grained
sandstone; and dark red to reddish-brown, massive, and thickly laminated, bioturbated, micaeous to very micaeous, siltstone and mudstone. Muscovite flakes up to 3 mm diameter are common especially in the siltstone. Fine-grained flakes of biotite in the arkose and lithic arkose is a distinctive accessory. Randomly oriented and vertical, cylindrical structures often filled with
pale-green, fine-grained, quartz sandstone are interpreted as burrows. Bedding, when observed, is parallel to slightly wavy, occurring as thick laminations to thinly bedded (0.5 cm to 5 cm). These rocks are assigned to the Lithofacies Association I of Hoffman and Gallagher, 1989 and Watson, 1998. The clastic rocks of Lithofacies Association I are interpreted to have been
deposited in a braided stream fluvial system.
Zhdlt (u)
Qal
79
Qcv – Colluvium: Accumulations of angular cobbles and boulders . Possibly formed by Quarternary slope movements in some cases (rock slide, rock fall, etc).
89
Zhe/pl
82
71
Qal
Qal – Alluvium: Unconsolidated poorly sorted and stratified deposits of angular to subrounded clay, silt, sand and gravel- to cobble-sized clasts, in stream drainages. May include point bars, terraces and natural levees along larger stream floodplains. Structural measurements depicted on the map within Qal represent outcrops of crystalline rock inliers surrounded by alluvium.
71
59
76
81
86
75
84
Qal
Zhablt
72
88
85
Sedimentary Units
81
82
81
80
Zhablt
77
81
78
Zhft (l)
78
74
74
mixed epiclastic-pyroclastic rocks (Zhe/p);
mixed epiclastic-pyroclastic rocks of Neville Creek area (Zhe/p-n);
mixed epiclastic-pyroclastic rocks of Duke Quarry area (Zhe/p-d)
mixed epiclastic-pyroclastic rocks with interlayered dacitic lavas (Zhe/pl);
intermediate to felsic lavas and tuffs (Zhiflt)
andesitic to basaltic lavas and tuffs (Zhablt); andesitic shallow intrusive (Zhasi);
andesitic to basaltic shallow intrusive (Zhabsi)
mixed pyroclastic-epiclastics (Zhp/e); dacitic lavas and tuffs (Zhdlt (u));
dacitic shallow intrusive (Zhdsi (u))
Zhabsi
63
75
74
76
76
80
77
86
Qal
86
Zgd-gb
82
79
81
41
84
Zgd-gb
60
epiclastics (Zhe); Morgan Creek epiclastics (Zhe-m1 and Zhe-m2)
Zhe/p-d
Qal
Zgd-gb
74
diorite (Zdi); fine-grained diorite (Zdi-fine); diorite to gabbro (Zdi-gb);
gabbro (Zgb)
81
64
60
B
quartz bodies (Zq); altered tuffs (Zhat (u)); porphyritic mafic intrusive (Zmi)
Zhiflt
Zhe/pl
Zhp/e
62
80
Qal
86
metamorphosed volcaniclastic sedimentary and pyroclastic rocks
associated with Hyco Formation: upper portion (stratigraphic relations uncertain)
ca. 613 - 616 Ma (Wortman et al., 2000; Bowman, 2010; and Bradley and Miller, 2011)
Zhe/p
85
81
82
84
Qal
77
70
68
Zgd-gb
Qal
Jd
71
65
77
Zhat (l)
Zhft (l)
61
74
71
74
Zhdsi (l)
66
88
Qal
Zhe/p
Qal
75
51
82
75
Jd
82
82
Zhft (l)
87
78
Jd
Jd
77
85
79
85
ultramafic (Zum)
Zum
Zmi
84
Jd
87
Zhablt
74
Zhft (l)
81
54
79
86
76
Zhe/p
Zhdlt (l)
granodiorite to gabbro (Zgd-gb); tonalite to quartz diorite (Ztqdi);
quartz monzodiorite (Zqmd)
Zqmd
Zhat (u)
86
78
Buckwater Creek Pluton: granodiorite and diorite (Zgd-di-b);
diorite and granodiorite (Zdi-gd-b); porphyritic granodiorite (Zgd-porphyritic)
Zgdporphyritic
Zq
88
71
74
86
71
Jd
81
71
75
84
76
89
Qal
61
Zhft (l)
The nomenclature of the International Union of Geological Sciences subcommission on igneous and volcanic rocks (IUGS) after Le Maitre (2002) is used in classification and naming of the units. The classification and naming of the rocks is based on relict igneous textures, modal mineral assemblages, or normalized mineral assemblages when whole-rock geochemical
data is available. Past workers within the County and adjacent areas (Allen and Wilson, 1968; Black, 1977; Bland, 1972; Butler, 1963 and 1964; Chiulli, 1987; Clark, 1957; Hauck, 1977; Hayes, 1962; Kirstein, 1956; Mann et al., 1965; McConnell, 1974; McConnell and Glover, 1982; Newton 1983; Wagener, 1964 and 1965; and Wright, 1974) have used various
nomenclature systems for the igneous rocks. The raw data, when available, of these earlier workers was recalculated and plotted on ternary diagrams and classified based on IUGS nomenclature. Pyroclastic rock terminology follows that of Fisher and Schminke (1984). A preliminary review of the area geology is provided in Bradley et al., 2006a and b. This map is a
compilation of modified and edited data from the Orange County portions of the Farrington (Bradley et al., 2007), Bynum (Bradley and Stoddard, 2011), Chapel Hill (Bradley et al., 2004), White Cross (Bradley and Stoddard, 2008), Saxapahaw (Bradley et al., 2011a), Northwest Durham (Bradley et al., 2004), Hillsborough (Bradley and Gay, 2005), Efland (Bradley et al.,
2006c), Mebane (Bradley, 2011), Rougemont (Bradley et al., 2011b), Caldwell (Bradley et al., 2010), Cedar Grove (Hanna et al., 2010) and Burlington Northeast (Hanna and Bradley, 2010) geologic maps.
DESCRIPTION OF UNITS
Zhe/p
72
78
84
Qal
88
Zhdlt (l)
81
74
84
Qal
granodiorite to granite of Piney Mountain Creek area (Zgd-gr-p)
Zgd-gr-p
Zgd-di-b
Zhdlt (l)
82
84
71
Zhdsi (l)
Qal
Jd
68
Qal
Jd
62
Zhablt
87
88
65
80
All pre-Mesozoic rocks in Orange County have been metamorphosed to at least the chlorite zone of the greenschist metamorphic facies. Many of the rocks display a weak or strong metamorphic foliation. Although subjected to metamorphism, the rocks retain relict igneous, pyroclastic, and sedimentary textures and structures that allow for the identification of protolith
rocks. As such, the prefix “meta” is not included in the nomenclature of the pre-Mesozoic rocks described in the quadrangle. Jurassic diabase dikes are unmetamorphosed.
81
86
75
The southeastern corner of the County is underlain by Triassic-aged sedimentary rocks of the Durham sub-basin of the Deep River Mesozoic basin. Sills and dikes of Jurassic aged diabase intrude the Triassic sediments. Diabase dikes also intrude the crystalline rocks of the County. Quaternary aged alluvium is present in most major drainages throughout the County.
72
76
Zdi
63
Qal
86
86
Zhasi
75
The Vermiforma antiqua fossil locality reported by Cloud et al. (1976) is present within the Zhe/pl unit in adjacent Durham County along the South Fork of the Little River. Seilacher et al. (2000) indicates the fossil may be a tectograph and not a true fossil.
82
Zhdlt (u)
87
71
65
86
62
27
74
Zhdlt (u)
84
84
Zhe/p
78
57
84
62
59
54
81
88
86
Qal
83
79
88
86
77
56
Map units of meta-volcaniclastic rocks include various lithologies that when grouped together are interpreted to indicate general environments of deposition (or lithofacies). The dacitic lavas and tuffs unit is interpreted to represent dacitic domes and proximal pyroclastics. The felsic tuffs units are interpreted to represent air fall tuffs and associated volcanosedimentary
rocks deposited distal from a vent. The andesitic to basaltic lavas and tuffs unit is interpreted to represent eruption of intermediate to mafic lava flows and associated pyroclastic deposits. The epiclastic and epiclastic/pyroclastic units are interpreted to represent deposition from the erosion of dormant and active volcanic highlands.
88
84
81
77
Zhdlt (u)
78
76
Zhft (l)
84
Zhdsi (l)
88
73
Qal
75
74
72
81
84
74
81
88
88
Zhft (l)
Qal
78
69
71
86
85
78
fine-grained granodiorite (Zgd); fine-grained luecocratic granodiorite (Zgd-leuco);
fine-grained altered granodiorite (Zagd-fine)
Zagd-fine
72
CZtgd
Zhablt
The Virgilina sequence was folded and subjected to low grade metamorphism during the ca. 578 to 554 Ma (Pollock, 2007) Virgilina deformation (Glover and Sinha, 1973; Harris and Glover, 1985; Harris and Glover, 1988; and Hibbard and Samson, 1995). In the map area, original layering of Virgilina sequence lithologies are interpreted to range from shallowly to
steeply dipping due to open to isoclinal folds that are locally overturned to the southeast. The northwest corner of Orange County is underlain by the Prospect Hill pluton. The Prospect Hill pluton intrudes foliated and folded Hyco Formation units and is correlated with the ca. 546 Ma Roxboro pluton (Wortman et al., 2000).
Zhdsi (u)
84
83
86
Zhe/p
81
Qal
Qal
82
72
Qal
CZtgd
88
82
er
Riv
Zgd-leuco
77
Zhe/p
84
72
Zhdlt-p
74
78
74
77
Zhe/pl
78
Zhdsi (l)
71
80
76
Zhe/p
Pre-Mesozoic crystalline rocks in Orange County are part of the Virgilina sequence of the Neoproterozoic to Cambrian Carolina terrane of the Carolina Zone (Harris and Glover, 1988; Hibbard et al., 2002; and Hibbard et al 2006). In the vicinity of the map area, the Virgilina sequence can be separated into two lithotectonic units: 1) the Hyco Formation and 2) the
Aaron Formation. The Hyco Formation consists of ca. 615 to 633 Ma (Wortman et al., 2000; Bowman, 2010; Bradley and Miller, 2011.) metamorphosed layered volcaniclastic rocks and plutonic rocks. Available age dates (Wortman et al., 2000; Bradley and Miller, 2011) indicate the Hyco Formation in Orange and Durham Counties may be divided into lower
(ca. 630 Ma) and upper (ca. 615 Ma) members (informal) with an apparent intervening hiatus of magmatism. In southern Orange County, Hyco Formation units are intruded by the ca. 579 Ma (Tadlock and Loewy, 2006) East Farrington pluton and associated West Farrington pluton. The Aaron Formation (not present in Orange County) consists of metamorphosed
layered volcaniclastic rocks with youngest detrital zircons of ca. 578 and 588 Ma (Samson et al., 2001 and Pollock, 2007, respectively).
Jd
88
81
77
CZtgd
Qal
74
74
o
En
Zgd-fine
74
81
Zhdlt (l)
Qal
Qal
Zhdlt (l)
84
86
82
Qal
81
66
Zhft (l)
88
64
Zhft (l)
Qal
72
Zgd
Qal
Zhdlt (l)
88
81
84
Zgr-di
81
Qal
Zhdlt (l)
CZtgd
Padid
CZtgd
87
76
Zhdlt (l)
Zhdlt (l)
Padid
Qal
metaintrusive rocks associated with Hyco Formation: upper portion
(stratigraphic relations uncertain)
ca. 613 and 614 Ma (Wortman et al., 2000)
Zgr2
67
Qal
East Farrington pluton main facies (Zefg-m)
East Farrington pluton main facies variety 1 (Zefg-m1)
East Farrington pluton porphyritic granite (Zefg-2)
East Farrington pluton fine-grained granite (Zefg-3)
East Farrington pluton gray granitoid (Zefg-4)
East Farrington pluton satellite granitoid (Zefg-6)
East Farrington monzodiorite porphyry of Terrells Creek area (Zefmd)
West Farrington pluton diorite (Zwfd)
East Farrington pluton is ca. 579 Ma (Tadlock and Loewy, 2006)
89
87
81
Hyco Formation
Zgr
70
Zhdlt (l)
Qal
Qal
Dike present in Farrington Pluton
gabbro (CZgb)
Zefg-m1
Qal
CZtgd
CZtgd
Qal
Qal
CZtgd
84
71
82
79
85
East and West Farrington Plutons
metaintrusive rocks
Zefg-m
Zhdlt (l)
Qal
metaintrusive rocks
tonalitic granodiorite (CZtgd)
CZtgd
CZgr-gd
granite to granodiorite (CZgr-gd)
related to ca. 546 ma Roxboro pluton
(Wortman et al., 2000)
CZgb
CZtgd
88
64
87
82
Zhdlt (l)
Pdad
Prospect Hill Pluton
CAMBRIAN (?)/
NEOPROTEROZOIC
Zhdlt-p
36 14' 30"
78
75
86
Qal
olivine gabbronorite
Padid
Qal
82
Zhdlt (l)
Zdi
Qal
84
86
Qal
78
73
Zhdlt (l)
Zhdlt (l)
Zdi
Metamorphic Rocks
PALEOZOIC (?)/
NEOPROTEROZOIC
Zdi
Qal
Zhft (l)
Zhdlt (l)
79
74
Deep River Basin: Durham Sub-basin
MESOZOIC/
PALEOZOIC (?)
CZgr-gd
Qal
quartz breccia (fault rock)
Triassic Sedimentary Rocks
Trcs/si1
Zdi
CZtgd
CZgr-gd
Zhdlt (l)
INTRODUCTION
79 00' 00"
Zhft (l)
Qal
Padid
Padid
Padid
diabase
Jd
MESOZOIC
79 07' 30"
Zhe-m2
Jd
737'
Trcs/si1
Zhe-m2
Zhft (l)
0'
-1263'
-3263'
Allen, E.P., and Wilson, W.F., 1968, Geology and mineral resources of Orange County, North Carolina: Division of Mineral Resources, North Carolina Department of Conservation and Development, Bulletin 81, 58 p.
Black, W.W., 1977, The geochronology and geochemistry of the Carolina Slate belt of north-central North Carolina, unpublished Ph.D. thesis, University of North Carolina, Chapel Hill, 118 p.
Bland, A.E., 1972, Geochemistry of the Meadow Flats Complex, Orange County, North Carolina, unpublished M.S. thesis, University of North Carolina at Chapel Hill, 49 p.
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GEOLOGIC MAP OF ORANGE COUNTY, NORTH CAROLINA
NCGS OPEN FILE REPORT 2012-XX
79 15' 00"
MAP UNITS
Qal
This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program