Geologic map of the Chatham County portion of the Crutchfield Crossroads 7.5-minute quadrangle, Chatham and Alamance Counties, North Carolina

North Carolina Department of Environmental Quality Policy and Innovation Group Mary Penny Kelley, Senior Advisor - Policy and Innovation Kenneth B. Taylor, State Geologist Metamorphic Rocks Aaron Formation CORRELATION OF MAP UNITS Youngest detrital zircons of ca. 578 and 588 Ma (Samson et al., 2001 and Pollock et. al., 2010, respectively). Za Hyco Formation - upper member Metamorphosed plutonic rocks ca. 613 and 614 Ma (Wortman et al., 2000' Zgr Za Zqmd Metamorphosed volcaniclastic sedimentary and pyroclastic rocks (stratigraphic relations uncertain) ca. 612 - 616 Ma (Wortman etal., 2000; Bowman, 2010; and Bradley and Miller, 2011 ) Zhe/pl Zhel Zhabl Zhablt-dcp Zhasi ■ Zhe/plim Zhdasi •'.Zh'dtyu f. Zhft (I) m Ш (5' m ■o =r o' 5. m o' з о Ф INTRODUCTION The Crutchfield Crossroads 7.5-minute Guadrangle lies in the east central portion of the North Carolina Piedmont. The Rocky River crosses the southwestern corner of the quadrangle; the Chatham - Alamance County line crosses the quadrangle from west to east. Portions of the Town of Siler City (population approximately 8,200) occupies the southwest corner of the quadrangle. Impounded portions of the Rocky River within the quadrangle serve as the water supply source for the Town of Siler City. The quadrangle is crossed by northwest-southeast US Highway 421. Hwy 64, a major east-west corridor for the central Piedmont, is located immediately to the south of the quadrangle. The majority of the quadrangle drains to the Rocky River along drainages that include Lacy's Creek, Nick Creek, North Prong, Greenbrier Creek, Johnson Creek, Mud Lick Creek, Varnell Creek and unnamed creeks. The northeast portion of the quadrangle drains to the Haw River along drainages that include South Fork, Reedy Branch and Pine Hill Branch. A small area in the southwest corner of the quadrangle drains to the Deep River. The drainage divide between the Rocky and Deep Rivers is locally controlled by a ridge that marks a major geologic contact (Hyco and Aaron Formations). Natural exposures of crystalline rocks occur mainly along these and numerous unnamed creeks. Rock exposure at road cuts, ridges, resistant finned-shaped outcrops and pavement outcrops occur locally outside of drainages. The elevations in the map area range from about 740 feet above sea level north of the intersection of Piney Grove Church road and Fellowship Church Road (on the ridge that defines the drainage divide between the Rocky and Deep Rivers) in the southwest corner of the quadrangle, to less than 500 feet along Pine Hill Branch near the northeastern corner of the quadrangle. Geologic Background and Past Work Pre-Mesozoic crystalline rocks in the Siler City Cuadrangle are part of the redefined Hyco Arc (Hibbard et al., 2013) within the Neo proterozoic to Cambrian Carolina terrane (Hibbard et al., 2002; and Hibbard et al., 2006). In the region of the map area, the Carolina terrane can be separated into two lithotectonic units: 1) the Hyco Arc and 2) the Aaron Formation of the redefined Virgilina sequence (Hibbard et al., 2013). The Hyco Arc consists of the Hyco Formation which include ca. 612 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 may be divided into lower (ca. 630 Ma) and upper (ca. 615 Ma) members (informal) with an apparent intervening hiatus of magmatism. In northeastern Chatham 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 consists of metamorphosed layered volcaniclastic rocks with youngest detrital zircons of ca. 578 and 588 Ma (Samson et al., 2001 and Pollock, 2010, respectively). The Hyco Arc and Aaron Formation lithologies were folded and subjected to low grade metamorphism during the ca. 578 to 554 Ma (Pollock, 2007; Pollock et al., 2010) 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 Hyco and Aaron Formation lithologies are interpreted to range from shallowly to steeply dipping due to open to isoclinal folds that are locally overturned to the southeast. Map units of metavolcanic and metavolcaniclastic rocks include various lithologies that when grouped together are interpreted to indicate general environments of deposition. The dacitic lavas and tuffs unit is interpreted to represent dacitic domes and proximal pyroclastics. The andesitic to basaltic lavas (with tuffs or conglomerates) units are interpreted to represent eruption of intermediate to mafic lava flows and associated pyroclastic and/or epiclastic deposits. The epiclastic/pyroclastic units are interpreted to represent deposition from the erosion of dormant and active volcanic highlands. Some of the metavolcaniclastic units within the map area display lithologic relationships similar to dated units present in northern Orange and Durham Counties. Due to these similarities, the metavolcanic and metavolcaniclastic units have been tentatively separated into upper and lower portions of the Hyco Formation; geochronologic data in the map area is needed to confirm this interpretation. A review of the regional lithologies is summarized in Bradley (201 3). Abundant evidence of brittle faulting at the outcrop scale and large-scale lineaments (as interpreted from hillshade LiDAR data) are present in the map area. The brittle faulting and lineaments are interpreted to be associated with Mesozoic extension. The Colon cross-structure (Reinemund, 1955), located to the southeast of the study area, is a constriction zone in the Deep River Mesozoic basin and is characterized by crystalline rocks overprinted by complex brittle faulting. Dikes of Jurassic aged diabase intrude the crystalline rocks of the map area. Guaternary aged alluvium is present in most major drainages. Mineral Resources There are no active mining activities currently in the quadrangle. One historic flagstone quarry associated with an abandoned grist mill site was identified along the Rocky River in the south of the quadrangle. The northern portion of the quadrangle was mapped at reconnaissance-scale as part of the Schmidt et al. (2006) study. The area was identified as containing large zones of high-sulfidation alteration with the potential for pyrophyllite and gold resources. The quadrangle has 4 identified prospect and/or mine areas including: 1) "Ore Hill”, 2) Hinshaw pyrophyllite prospect, 3) Snow Camp Pyrophyllite Mine, and the 4) Snow Camp South pyrophyllite prospect. Equal-Area Schmidt Net Projections and Rose Diagram Plots and calculations created using Stereonet v. 8.6.0 based on Allmendinger et al. (201 3) and Cardozo and Allmendinger (201 3). Qal Equal Area Schmidt Net Projection of Contoured Poles to Foliation and Cleavage Contour Interval = 2 sigma N =396 Zqmd Zdi Zgr Zhat (u) Zhel Zhe/plim Equal Area Schmidt Net Projection of Contoured Poles to Primary Bedding, Layering, and Welding Compaction/Foliation Contour Interval = 2 sigma N = 39 Zhe/pl . Zhdil (u)' Unidirectional Rose Diagram of Joints N = 329 Outer Circle = 7% Mean vector = 253.2° ± 21 .3° Max value = 5.2% between 121° and 130° Zhft Schmidt et al. (2006) identified "Ore Hill" as a location of a small shaft at the top of a knob. The rock is magnetite bearing and it is speculated that the shaft was sunk in search of iron ore. A site visit to "Ore Hill" in 2016 did not encounter the shaft; several shallow (prospect-like) openings are present. The reported shaft may have collapsed. The Hinshaw pyrophyllite prospect is described by Stuckey (1967) and Schmidt et al. (2006). The Snow Camp Pyrophyllite Mine is abandoned. Schmidt (1985) described the mine as an important former producer of high-grade pyrophyllite in North Carolina active from the mid-1930’s to the mid-1960's. Additional descriptions of the Snow Camp Mine are provided in Broadhurst and Councill (1953), Espenshade and Potter (1960), Stuckey (1967), and Hughes (1987). The Snow Camp South pyrophyllite prospect is located on the southern end of the ridge that includes the Snow Camp Mine location. DESCRIPTION OF MAP UNITS All pre-Mesozoic rocks in the map area 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. A preliminary review of the area geology is provided in Bradley (2013). Unit descriptions common to Hanna et al. (2014) and Bradley et al. (2017) from the Silk Hope and Siler City geologic maps, respectively, were used for conformity with on strike units in neighboring quadrangles. Unit descriptions and stratigraphic correlations were maintained from adjacent mapping in Orange County Bradley (Bradley et al., 2016). 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. Pyroclastic rock terminology follows that of Fisher and Schminke (1984). SEDIMENTARY UNIT Qal - Alluvium: Unconsolidated poorly sorted and stratified deposits of angular to subrounded clay, silt, sand and gravel- to boulder-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. INTRUSIVE AND METAINTRUSIVE UNITS 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. MPzgb - Gabbro: Melanocratic (Cl greater than 50), fine-grained gabbro. Distinctive brown weathering. Occurs as a small map scale body closely associated with a diabase dike, and as isolated boulders along the trend of a diabase dike. Appears unmetamorphosed. Purple station locations indicate outcrop or boulders of MPzgb. Zqmd - Quartz monzodiorite: Composite pluton of mesocratic, coarse- to medium-grained, equigranular, quartz monzodiorite, diorite and granodiorite. Major minerals include plagioclase and amphiboles with lesser amounts of quartz. Amphiboles appear altered to chlorite and actinolite masses. Feldspars have a light pinkish-hue locally. Includes a distinctive plagioclase porphyritic granodiorite to diorite on South Fork Cane Creek. Unit identified as the Lindley Farms Quartz Monzonite by Schmidt et al. (2006). Schmidt et al. (2006) whole rock and modal analyses were replotted on IUGS ternary diagrams and plot in the quartz monzodiorite field. Zdi - Diorite: Mesocratic (CI-50), greenish-gray to grayish-green, fine- to medium-grained, metamorphosed, 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. Gabbro intermingled locally. Zgr - Granite: Leucocratic, medium- grained, equigranular metamorphosed, granite ortonolite METAVOLCANIC AND METAVOLCANICLASTIC UNITS Aaron Formation Za - Aaron Formation: Distinctive metasedimentary package that ranges from fine-grained siltstones to coarse-grained sandstones, pebbly sandstones and conglomerates. Siltstones are similar in appearance to Hyco Formation lithologies. The sandstones, pebbly sandstones and conglomerates (classified as litharenite, feldspathic litharenite and lithic feldsarenite by Harris (1984)) are distinctive and commonly contain rounded to subrounded clasts of quartz ranging from sand- to gravel-sized. In the sandstones, feldspar is the most prominent mineral grain; quartz varies from sparse to abundant in hand sample. Lithic clasts are typically prominent and range from sand- to gravel-size. Harris (1984), performed a detailed sedimentary study of the Aaron Formation to the immediate west of the map area. Harris (1984) interpreted the Aaron Formation to have been deposited by turbidity currents in a retrogradational submarine fan setting. Pollock (2010) interprets an approximate 35 million year unconformity between the Aaron and underlying Hyco Formation. This interpretation is based in part on detrital zircon age date data from an Aaron conglomerate sample collected in the adjacent Liberty Quadrangle. Hyco Formation - Upper Portion 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. Zhel - Epiclastic rocks and lavas: Metamorphosed conglomerate, conglomeratic sandstone, sandstone, siltstone and mudstone. Siltstones and mudstones typically display bedding ranging from mm-scale up to 10 cm, bedding layers traceable for several feet locally, may exhibit soft sediment deformation. Locally tuffaceous with a relict vitric texture. Locally contain interbedded dacitic to basaltic lavas. Conglomerates and conglomeratic sandstones typically contain subrounded to angular clasts of dacite in a clastic matrix. Deposition interpreted as distal from volcanic center, in deep water (?), and via turbidite flows. Zhe/plim - Mixed epiclastic-pyroclastic rocks with interlayered intermediate to basaltic lavas: Grayish-green to greenish-gray, locally with distinctive reddish-gray or maroon to lavender coloration; metamorphosed: conglomerate, conglomeratic sandstone, sandstone, siltstone, mudstone, and felsic fine- to coarse tuff and lapilli tuff. Siltstones are locally phyllitic. Locally contain interbedded andesitic to basaltic lavas identical to Zhabl unit. Silicified and/or sericitized altered rock are locally present. Interpreted to be in gradational contact with unit Zhe/pl and identified by increase in intermediate to mafic lavas and decrease and/or absence of dacites. 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; metamorphosed: 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. Pyroclastics, lavas, and epiclastics are mainly felsic in composition. Minor andesitic to basaltic lavas and tuffs present. Silicified and/or sericitized altered rock are locally present and increase in occurrence toward the north. Conglomerates and conglomeratic sandstones typically contain subrounded to angular clasts of dacite in a clastic matrix. Fine- to medium-grained diorite is locally present. Portions of the Zhe/pl unit are interpreted to have been deposited proximal to active volcanic centers represented by the Zhdlt unit but are also interpreted to record the erosion of proximal volcanic centers after cessation of active volcanism. Zhdlt (u) - Dacitic lavas and tuffs of the upper portion of the Hyco Formation: Greenish-gray to dark gray, siliceous, metamorphosed: aphanitic dacite, porphyritic dacite with plagioclase phenocrysts, and flow banded dacite. Dacite with hyaloclastic textures are common. 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 abundant 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/pl unit. 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 in the Rougemont quadrangle. Zhdasi - Dacitic to andesitic shallow intrusive: Gray to greenish-gray; dacite to andesite. Aphanitic groundmass with plagioclase and acicular amphibole phenocrysts. Weak relict cryptocrystalline texture present (less than dacites). Aphanitic dacite to andesite clasts present locally likely indicating hyaloclastic texture. Zhabl - Andesitic to basaltic lavas: Green, gray-green, gray, dark gray and black; typically unfoliated, amygdaloidal, plagioclase porphyritic, amphibole/pyroxene porphyritic and aphanitic; metamorphosed: andesitic to basaltic lavas and shallow intrusions. Hyaloclastic texture is common and imparts a fragmental texture on some outcrops and float boulders. Conglomeratic rocks consisting of angular clasts of andesite and/or basalt occur locally and are interpreted as resedimented hyaloclastite. Map-scale body within Sheeprock alteration zone is siliceous and magnetic. Zhable - Andesitic to basaltic lavas with interlayered epiclastic rocks: Light green, gray-green, gray, and dark gray; typically unfoliated, amygdaloidal, plagioclase porphyritic, amphibole/pyroxene porphyritic and aphanitic; metamorphosed: andesitic to basaltic lavas and shallow intrusions. Hyaloclastic texture is common and imparts a fragmental texture on some outcrops and float boulders. Contains lesser amounts of grayish-green, light green, and gray to light gray; metamorphosed conglomerate, conglomeratic sandstone, sandstone, siltstone and mudstone. Zhqdp - Quartz dacite porphyry: 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. Foliated and likely altered. Present in a few outcrops and boulders in the vicinity of Johnson creek. Similar to quartz dacite porphyry unit within the Bynum Quadrangle (Bradley etal., 2013). Zhasi - Andesitic shallow intrusive: Grayish-green to light green, metamorphosed: plagioclase porphyritic andesite with a granular- textured groundmass to very fine-grained diorite (with intrusive texture visible with 7x hand lens - microdiorite-like). 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. Zhablt-dcp - Andesite to basalt porphyry of the Dry Creek area: Distinctive, green to dark green, metamorphosed andesite porphyry with aphanitic groundmass and euhedral phenocrysts (up to 10 mm) of greenish-white plagioclase; phenocrysts typically constitute 20 to 50% of the rock; local alignment of plagioclase; lesser pyroxene/amphibole phenocrysts. Green to dark green basalt porphyry with abundant pyroxene (altered to amphibole) phenocrysts with minor plagioclase phenocrysts. Andesite and basalt porphyries locally amygdaloidal (up to 2 cm), amygdules in filling include calcite, quartz, chlorite, and epidote. Same as Dry Creek Porphyry complex of Hauck (1977). Present as isolated outcrops or boulders as designated by green station locations. Zhft - 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. This Geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program 79°22’30" 35°52'30" 35°45' 1 79-30’ 35°45‘ 79°22’30" Topographic base produced by the United States Geological Survey. Altered by the North Carolina Geological Survey for use with map. North American Datum of 1983 (NAD83) World Geodetic System of 1984 (WGS84). Projection and 1 000-meter grid: Universal Transverse Mercator, Zone 17S 10 000-foot ticks: North Carolina Coordinate System of 1983 ,-,,T 152 MILS GN 1000 0.5 500 O' 55 16 MILS 05 SCALE 1:24 000 0 KILOMETERS METERS 0 ROAD CLASSIFICATION 1000 2000 Expressway Secondary Hwy Ramp Local Connector Local Road 4WD 1000 1000 2000 MILES 3000 _ 4000 5000 I Interstate Route 6000 7000 8000 Imagery . NAIP, May 2012 Roads . ©2006-2012 TomTom Names . GNIS, 2012 Hydrography . National Hydrography Dataset, 2012 Contours . National Elevation Dataset, 2008 Boundaries . Census, IBWC, IB C, USGS, 1972 - 2012 Base map is from USGS 2013 GeoPDF of the Crutchfield Crossroads 7.5-minute quadrangle. Air photo, map collar and select features removed. Bounds of GeoPDF based on 7.5-minute grid projection in UTM 17S; North American Datum of 1 983 (NAD83). UTM GRIP AND 2013 MAGNETIC NORTH DECLINATION AT CENTER OF SHEET FEET 9000 10000 i -i QUADRANGLE LOCATION a US Route О State Route U.S. National Grid 100.000 m Square ID PV Grid Zone Designation 17S CONTOUR INTERVAL 10 FEET NORTH AMERICAN VERTICAL DATUM OF 1988 This map was produced to conform with the National Geospatial Program US Topo Product Standard, 2011. A metadata file associated with this product is draft version 0.6.11 Kimesville Snow Camp Saxapahaw Liberty Crutchfield Crossroads Silk Hope Coleridge Siler City Siler CityNF. CRUTCHFIELD CROSSROADS, NC ADJOINING 7.5- QUADRANGLES Piney Grove Church Road Siler City Water Supply Lake Number 3. Ed Clapp Road Siler City Snow Camp Road Nick Creek Jessie Bridges Road Smith Hudson Nick Creek Road Silk Hope Road North Carolina Geological Survey Open File Report 2017-10 EXPLANATION OF MAP SYMBOLS CONTACTS, FAULTS, AND OTHER FEATURES - inferred contact --I--?-* . concealed contact gradational contact - inferred; . . dotted where concealed — T - interpreted fold hinge of anticline; question mark where existence is questionable; dotted where concealed interpreted fold hinge of syncline; question mark where existence is questionable; dotted where concealed quaternary alluvium contact inferred brittle fault; dotted where concealed linear geomorphic feature interpreted from hillshade LiDAR - origin uncertain — ^ - interpreted fold hinge of overturned anticline ? i interpreted fold hinge of overturned syncline, existence questionable cross section inferred diabase dike; dotted where concealed - MPzgb dike - inferred iiraiiwiiiiiiiiiiiiiiiiiiiiiiiuin zone of alteration associated with the Sheeprock area (Schmidt, et. al. 2006) IN CROSS SECTION inferred contact inferred gradational contact interpretive fold form lines . brittle fault, identity or existence questioned, inferred from LiDAR lineament - inferred fold axis - diabase dike - inferred 65 PLANAR FEATURES Strike and dip of primary bedding and/or layering 87 79 I Strike and dip of primary bedding and/or layering г 46 (multiple observations at one location) [ 78 Strike and dip of inclined regional foliation ► 85 I Strike and dip of inclined regional foliation 1 77 (multiple observations at one location) Strike and dip of cleavage Strike and dip of cleavage 80 (multiple observations at one location) t Strike and dip of inclined joint surface Strike of vertical Joint surface Strike and dip of inclined joint surface 79 (multiple observations at one location) Strike of vertical Joint surface (multiple observations at one location) S2 Strike and dip of primary volcanic compaction and/or welding foliation PROSPECTS AND QUARRIES X Prospect (pit or small open cut) 2 Hinshaw Prospect (pyrophyllite) - abandoned 3 “Ore Hill" (Iron?) - abandoned 4 Snow Camp South Prospect (pyrophyllite) - abandoned quarry or mine - abandoned 1 quarry (flagstone) - abandoned 5 Snow Camp Pyrophyllite Mine И mine shaft - abandoned 3 "Ore Hill" shaft (Iron?) - abandoned - not found in 2016; location from Schmidt, et. al. (2006) OTHER FEATURES 0 Observation station location Diabase station location Indicates location of vuggy quartz or sliceous breccia float 533 Indicates location of Zhablt-dcp boulders or outcrop Indicates location of MPzgb boulders or outcrop () Schmidt et al. (2006) geochem location REFERENCES; Allmendinger, R. W., Cardozo, N. C., and Fisher, D., 2013, Structural Geology Algorithms; Vectors and Tensors: Cambridge, England, Cambridge University Press, 289 pp. Bowman, J.D., 2010, The Aaron Formation: Evidence for a New Lithotectonic Unit in Carolinia, North Central North Carolina, unpublished masters thesis, North Carolina State University, Raleigh, North Carolina, 116 p. Bradley, P.J., and Miller, B.V., 2011, New geologic mapping and age constraints in the Hyco Arc of the Carolina terrane in Orange County, North Carolina: Geological Society of America Abstracts with Programs, Vol. 43, No. 2. Bradley, P.J., 2013, The Carolina terrane on the west flank of the Deep River Basin in the northern Piedmont of North Carolina - A Status Report, in Hibbard, J.P. and Pollock, J.C. editors, 2013, One arc, two arcs, old arc, new arc: The Carolina terrane in central North Carolina, Carolina Geological Society field trip guidebook, pp. 139-151 . Bradley, P.J., Hanna, H.D., Gay, N.K., Stoddard, E.F., Bechtel, R., Phillips, C.M., and Fuemmeler, S. J, 2016, Geologic map of Orange County, North Carolina: North Carolina Geological Survey Open-file Report 2016-05, scale 1:50,000, in color. Bradley, P.J, Peach, B.T. and Hanna, H.D., 2017, Geologic Map of the Siler City Quadrangle, Chatham County, North Carolina: North Carolina Geological Survey Open-file Report 2017-XX, scale 1:24,000, in color. Broadhurst, S.D., and Councill, R.J., 1953, A preliminary report on high alumina minerals in the Volcanic-Slate series, North Carolina: North Carolina Department of Conservation Development, Division of Mineral Resources, Information Circular 10, 22 p. Cardozo, N., and Allmendinger, R. W., 2013, Spherical projections with OSXStereonet: Computers and Geosciences, v. 51.ПО.0, p. 193 - 205, doi: 10.1016/j.cageo.201 2.07.021 . Espenshade, G.H., and Potter, D.B., 1960, Kyanite, sillimanite, and andalusite deposits of the Southeastern States: U.S. Geological Survey Professional Paper 336, 121 p. Fisher, R.V., and Schmincke H.-U., 1984, Pyroclastic rocks, Berlin, West Germany, Springer-Verlag, 472 p. Glover, L., and Sinha, A., 1973, The Virgilina deformation, a late Precambrian to Early Cambrian (?) orogenic event in the central Piedmont of Virginia and North Carolina, American Journal of Science, Cooper v. 273-A, pp. 234-251 . Hanna, H.D., and Bradley, P.J., 2014, Geologic Map of the Chatham County Portion of the Silk Hope Quadrangle, Chatham and Alamance Counties, North Carolina: North Carolina Geological Survey Open-file Report 2014-02, scale 1:24,000, in color. Harris, C.W., 1984, Coarse-grained submarine-fan deposits of magmatic arc affinity in the late Precambrian Aaron Formation, North Carolina, U.S. A., Precambrian Research, 26, pp. 285-306. Harris, C., and Glover, L., 1985, The Virgilina deformation: implications of stratigraphic correlation in the Carolina slate belt, Carolina Geological Society field trip guidebook, 36 p. Harris, C., and Glover, 1988, The regional extent of the ca. 600 Ma Virgilina deformation: implications of stratigraphic correlation in the Carolina terrane, Geological Society of America Bulletin, v. 100, pp. 200-217. Hauck, S.A., 1977, Geology and petrology of the northwest quarter of the Bynum quadrangle, Carolina slate belt, North Carolina, unpublished M.S. thesis, University of North Carolina at Chapel Hill, 146 p. Hibbard, J., and Samson, S., 1995, Orogenesis exotic to the lapetan cycle in the southern Appalachians, In, Hibbard, J., van Staal, C., Cawood, P. editors, Current Perspectives in the Appalachian- Caledonian Orogen. Geological Association of Canada Special Paper, v. 41, pp. 191-205. Hibbard, J., Stoddard, E.F., Secor, D., Jr., and Dennis, A., 2002, The Carolina Zone: Overview of Neoproterozoic to early Paleozoic peri-Gondwanan terranes along the eastern flank of the southern Appalachians: Earth Science Reviews, v. 57, n. 3/4, p. 299-339. Hibbard, J. P., van Staal, C. R., Rankin, D. W., and Williams, H., 2006, Lithotectonic map of the Appalachian Orogen, Canada-United States of America, Geological Survey of Canada, Map-2096A. 1 :1, 500, 000-scale. Hibbard, J.P., Pollock, J.C., and Bradley, P.J., 2013, One arc, two arcs, old arc, new arc: An overview of the Carolina terrane in central North Carolina, Carolina Geological Society field trip guidebook, 265 p. Hughes, E.H., 1987, The geology and alteration centers of the Snow Camp mine-Major Hill area, central Carolina slate belt, Alamance and Chatham Counties, North Carolina: U.S. Geological Survey Open-File Report 87-180, 29 p. Le Maitre, R.W., Ed., 2002, Igneous Rocks: A Classification and Glossary of Terms: Recommendations of the International Union of Geological Sciences (IUGS) Subcommission on the Systematics of Igneous Rocks: Cambridge, Cambridge University Press, 252 p. Pollock, J. C., 2007, The Neoproterozoic-Early Paleozoic tectonic evolution of the peri-Gondwanan margin of the Appalachian orogen: an integrated geochronological, geochemical and isotopic study from North Carolina and Newfoundland. Unpublished PhD dissertation, North Carolina State University, 194 p. 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Red and blue lines show paths of field traverses. Varnell Creek Л -1340’ -1340’ -3340’ -3340’ cross section scale - 1:24 000 no vertical exaggeration Geologic Map of the Chatham County Portion of the Crutchfield Crossroads 7.5-Minute Quadrangle, Chatham and Alamance Counties, North Carolina By Philip J. Bradley, Heather D. Hanna and Brandon T. Peach Map preparation, digital cartography and editing by Michael A. Medina, Heather D. Hanna and Philip J. Bradley. 2017 Supersedes NCGS Open-file Report 2016-09 This is an Open File Map. It has been reviewed internally for conformity with North Carolina Geological Survey mapping standards and with the North American Stratigraphic Code. Further revisions or corrections to this Open File map may occur. Research supported by the U.S. Geological Survey, National Cooperative Geologic Mapping Program, under USGS award numbers G15AC00237 and G16AC00288. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government. This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under StateMap award numbers G15AC00237, 2015 and G16AC00288, 2016). Geologic data collected in July 2015 through May 2016 under award G15AC00237 and July 2016 through May 2017 under award G16AC00288. Acknowledgements: Field assistance provided by Randy Bechtel and members of the Energy Group - Oil and Gas Program: Ann Shields, Ryan Channell, Katherine Marciniak, and WaltT. Haven in January through May 2016. Geologic Map of the Chatham County Portion of the Crutchfield Crossroads 7.5-Minute Quadrangle, Open File Report 2017-10