Geologic map of the southeastern corner of the Liberty 7.5-minute quadrangle, Randolph, Chatham and Alamance Counties, North Carolina

North Carolina Department of Environmental Quality Energy Group Jenny Kelvington, Executive Director Kenneth B. Taylor, State Geologist This Geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program Qal Za Zhe/plim Zhe/pl Zhablt-dcp Qal CORRELATION OF MAP UNITS Metamorphic Rocks Aaron Formation Youngest detrital zircons of ca. 578 and 588 Ma (Samson etal., 2001 and Pollock et al., 2010, respectively) Za Hyco Formation - upper member metamorphosed vo lea ni clastic sedimentary and pyrodastic rocks (stratigraphic relations uncertain) ca. 612 - 616 Ma (Wortman et al., 2000; Bowman, 2010; and Bradley and Miller, 2011) Zhe/plim Zhe/pl Zhablt-dcp E Я2 | <L SI iff i-3-g- INTRODUCTION The Liberty 7.5-minute Quadrangle lies in the east central portion of the North Carolina Piedmont. The headwaters of the Rocky River are present in the quadrangle; the Randolph - Chatham County line crosses the quadrant from north to south. The Chatham - Alamance - Randolph County iines are present in the northeast of the quadrangle. The Town of Liberty (population approximately 2,600) occupies the north-central portion of the quadrangle. The Town of Staley (population approximately 400) is located in the southern portion of the quadrangle. The quadrangle is crossed by northwest-southeast US Highway 421. US Highway 64, a major east-west corridor for the central Piedmont, is located immediately to the south of the quadrangle and crosses into the quadrangle for approximately 0.75 miles. Approximately half of the quadrangle drains to the Rocky River along drainages that include the North Rocky River Prong and the unnamed headwater creeks and tributaries of the Rocky River. A small portion of the quadrangle, immediately north of Town of Liberty, drains to the Haw River. The western portion of the quadrangle drains to the Deep River along drainages that include Boodom Creek, Mount Pleasant Creek, Reed Creek, Brush Creek and Reedy Fork. In the southeast corner of the quadrangle, 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 810 feet above sea level northeast of the Town of Liberty, to less than 540 feet along Reed Creek and one of it’s unnamed tributaries near the southwestern corner of the quadrangle where US Highway 64 enters the quadrangle. Geologic Background and Past Work Pre-Mesozoic crystalline rocks in the Liberty Quadrangle 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 et al., 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 (2013). 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 and adjacent quadrangles. 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 area, however, diabase was not encountered during mapping activities in the Liberty Quadrangle. Additionally, Burt et al. (1978) indicates the presence of a through-going diabase dike inferred from aeromagnetic data or stream patterns in the map area. Quaternary aged alluvium is present in most major drainages. Mineral Resources There are no active mining activities currently in the quadrangle. The central portion of the quadrangle is on strike with a large zone of high-sulfidation alteration as described by Schmidt et al. (2006). This alteration zone has the potential for pyrophyllite and gold resources. The abandoned Staley Pyrophyllite Mine is located in Randolph County, approximately 3.5 miles west of the Town of Staley, on Soapstone Mountain Road. Stuckey (1967) indicates that the Staley pyrophyllite deposit was, at one time, the second largest pyrophyllite mine in the State with an estimate 400,000 tons of material mined. The Staley deposit is also discussed in Broadhurst and Councill (1953) and Espenshade and Potter (1960). According to the USGS MRDS database, the former Staley quartz crushing plant was located within the Town of Staley. 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. A preliminary review of the area geology is provided in Bradley (2013). Unit descriptions common to Hanna and Bradley (2016) and Bradley and Hanna (2016) from the Crutchfield Crossroads and Coleridge 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 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 SEDIMENTARY UNITS 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. 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 et al., 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 Quadrangle. Hyco Formation - Upper Portion 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. 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. Environmental Quality 35 52' 30" 79 37' 30" AkM ( 79 37' 30 35 45' 00" 79 30' 00" 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 Imagery . NAIP, May 2012 Roads . 02006-2012 TomTom Names . GNIS, 2012 Hydrography. . National Hydrography Dataset, 2012 Contours . National Elevation Dataset, 2008 Boundaries . Census, IBWC, IBC, USGS, 1972 - 2012 Bounds of GeoPDF based on 7.5-minute grid projection in UTM 17S; North American Datum of 1983 (NAD83). Geologic polygons tied to 7.5-minute grid projection in State Plane coordinates for edge-matching with legacy GIS data, as such some overlap and underiap of map unit polygons occur around edge of map. T 8' 29' • 151 MILS cN 05 SCALE 1:24 000 0 KILOMETERS ROAD CLASSIFICATION 1000 500 O' 50 15 MILS UTM GRID AND 2013 MAGNETIC NORTH DECLINATION AT CENTER OF SHEET 0.5 METERS 0 1000 1000 1000 20M MILES 3000 4000 5000_ 6000_ 7000 8000 2000 9000 10000 Expressway Secondary Hwy Ramp Local Connector Local Road 4WD I Interstate Route QUADRANGLE LOCATION a US Route О State Route U.S. National Grid 100,000-m Square 10 PV Grid Zone Designation 17S FEET 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 Climax Kimesvillc Snow Camp Grays Chapel Liberty Crutchfield Crossroads Rantseur Cbleridge Siler «tv LIBERTY, NC ADJOINING 7.5' QUADRANGLES Research supported by the U.S. Geological Survey, National Cooperative Geologic Mapping Program under STATEMAP (Award - 2015, G15AC00237). This map and explanatory information is submitted for publication with the understanding that the United States Government is authorized to reproduce and distribute reprints for governmental use. 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 express or implied, of the U.S. Government. Geologic Map of the Southeastern Corner of the Liberty 7.5-minute Quadrangle, Randolph, Chatham and Alamance Counties, North Carolina By Philip J. Bradley and Heather D. Hanna Geology mapped from July 2015 to May 2016. Map preparation, digital cartography and editing by Michael A. Medina, Heather D. Hanna and Philip J. Bradley. 2016 North Carolina Geological Survey Open File Report 2016-10 79 30' 00" 35 52' 30" EXPLANATION OF MAP SYMBOLS CONTACTS, FAULTS, AND OTHER FEATURES - - Inferred contact _ Linear geomorphic feature interpreted from hillshade LiDAR - origin uncertain . Concealed contact . . . "i" Gradational contact - inferred - Quaternary alluvium contact Inferred brittle fault; dotted where concealed Interpreted fold hinge of anticline, dotted where concealed Interpreted fold hinge of syncline; - 1 - question mark where existence is questionable; dotted where concealed - - - * - Interpreted fold hinge of overturned anticline © Observation station location д Indicates location of vuggy quartz or sliceous breccia float _ Indicates location of Zhablt-dcp ^ boulders or outcrop ^ Detrital zircon date (Pollock et al., 2010) 2 . Former Staley quartz crushing plant 3. X Staley Mine (pyrophyllite) PLANAR AND OTHER FEATURES 68 88 И Strike and dip of primary bedding and/or layering Strike and dip of primary bedding and/or layering (multiple observations at one location) Strike and dip of inclined regional foliation Strike and dip of inclined regional foliation 65 Strike and dip of cleavage (multiple observations at one location) Strike and dip of inclined shear foliation (multiple observations at one location) 81 Strike and dip of inclined joint surface ь qq I Ollll\c ctl IU UlfJ Ul IMUIIIIcU IcyiUllal IUIIcUI 1 85 (multiple observations at one location) Г I l ^ so Strike and dip of cleavage 65 | Trend and plunge of mineral lineation Strike and dip of inclined joint surface 84 (multiple observations at one location) Strike of vertical Joint surface (multiple observations at one location) REFERENCES: 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 and Hanna, H.D., 2016, Geologic map of portions of the northeastern quadrant of the Coleridge 7.5-minute Quadrangle, Chatham and Randolph Counties, North Carolina: North Carolina Geological Survey Open-file Report 2016-11 , 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. Burt, E.R., Carpenter, P.A., III, McDaniel, R.D., and Wilson, W.F., 1978, Diabase Dikes of the Eastern Piedmont of North Carolina: North Carolina Geological Survey Information Circular 23, 12 p. text plus map compilation. 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., 2016, Geologic map of the southern third of the Crutchfield Crossroads Quadrangle, Chatham and Alamance Counties, North Carolina: North Carolina Geological Survey Open- file Report 2016-09, 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. 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. Pollock, J.C., Hibbard, J.P., and Sylvester, P.J., 2010, Depositional and tectonic setting of the Neoproterozoic-early Paleozoic rocks of the Virgilina sequence and Albemarle Group, North Carolina: in Tollo, R.P, Bartholomew, M.J., Hibbard, J.P, and Karabinos, P.M., eds., From Rodinia to Pangea: The Lithotectonic Record of the Appalachian Region: Geological Society of America Memoir 206, p. 739-772. Reinemund, J.A., 1955, Geology of the Deep River coal field, North Carolina: U.S. Geol. Survey Prof. Paper 246, 159 p. Samson, S.D., Secor, D.T, and Hamilton, M.A., 2001, Wandering Carolina:Tracking exotic terranes with detrital Zircons, GSA Abstracts with Programs Vol. 33, No. 6, p. A-263. Schmidt, R.G., Gumiel, P., and Payas, A., 2006, Geology and mineral deposits of the Snow Camp- Saxapahaw area, Central North Carolina: United States Geological Survey Open-file Report 2006-1259 (http://pubs.usgs.gov/of/2006/1259/index.html). Stuckey, J.L., 1967, Pyrophyllite deposits in North Carolina: North Carolina Division of Mineral Resources Bulletin 80, 38 p. Tadlock, K.A., and Loewy, S.L., 2006, Isotopic characterization of the Farrington pluton: constraining the Virgilina orogeny, in Bradley, P.J., and Clark, T.W., editors, The Geology of the Chapel Hill, Hillsborough and Efland 7.5-minute Quadrangles, Orange and Durham Counties, Carolina Terrane, North Carolina, Carolina Geological Society Field Trip Guidebook for the 2006 annual meeting, pp. 17-21 . Wortman, G.L., Samson, S.D., and Hibbard, J.P., 2000, Precise U-Pb zircon constraints on the earliest magmatic history of the Carolina terrane, Journal of Geology, v. 108, pp. 321-338. TRAVERSE MAP Hillshade derived from a 20 foot LiDAR digital elevation model. Red and blue lines show paths of field traverses. Г:.:> Ш ьш by car by foot 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. Acknowledgements: Field assistance provided by Randy Bechtel and members of the Energy Group - Oil and Gas Program: Ann Shields, Ryan Channell, Katherine Marciniak, and Walt T. Haven Geologic Map of the Southeastern Corner of the Liberty 7.5-minute Quadrangle, Open File Report 2016-10