Geologic map of the northwest Durham 7.5-minute quadrangle, Durham and Orange Counties, North Carolina

DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES DIVISION OF LAND RESOURCES NORTH CAROLINA GEOLOGICAL SURVEY Description of Map Units JAMES D. SIMONS, DIRECTOR AND STATE GEOLOGIST This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program OPEN FILE REPORT 2004-03a Revision - 01 (2010) 36° 07' 30' 36° 00' 00' - Zgd- porphyritic NWD-1154 NWD-49 : 1 R*dlo ■Vit-teWK; FJfWN нйьуог П Н h : ' .. CON T ; -V - PUnt, tjCe- Courrt Radio sSabstttion? All pre-Mesozoic rocks of the Northwest Durham quadrangle 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. The nomenclature of the International Union of Geological Sciences subcommission on igneous and volcanic rocks (1UGS) after Streckeisen (1973 and 1 979) 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 Units Qal - alluvium: Unconsolidated clay, silt, sand and gravel to cobble-sized clasts, subrounded to angular, deposited in drainages. Acs/sh Acs/sii - Chatham Group Lithofacies Association I: Pinkish-gray, light-gray, and light-tan; fine- to coarse-grained, micaeous. slightly clayey, moderately poor to moderately well sorted, subangularto subrounded arkose and lithic arkose; maroon, very silly, micaeous, moderately well sorted, fine-grained sandstone; and maroon, 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 1 of Hoffman and Gallagher, 1989 and Watson. 1998. The clastic rocks of Lithofacies Association 1 are interpreted to have been deposited in a braided stream fluvial system. Accw *ccw - Chatham Group western border conglomerates: Reddish-brown to dark brown, matrix to clast supported, pebble to cobble conglomerate; clasts are subrounded to rounded consisting of primarily of quartz and foliated and unfoliated felsic volcanic rocks; matrix consists of coarse- to very coarse-sand. Intrusive and Meta-Intrusive Units Zgd-gr-p Jd - Diabase: Black to greenish-black, melanocratic, fine- to medium-grained, dense, consists primarily of plagioclase, augite, and may contain olivine. Occurs as sills and dikes up to 100 ft wide. Locally gabbroic in sills. Typically occurs as dense, spheriodally weathered boulders with a grayish-brown weathering rind. Red station location indicates outcrop or boulders of diabase. Whole rock geochemistry data for several samples in the Durham area are presented in Gottfried et. al. ( 1 991 ) and Brown et. al. (1985). 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. 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. Locally contains pinkish-hued feldspars. Plagioclase grains are often sericitized and saussuritized and may exhibit a greenish color. Zdsi Zgd-porphyritic - Porphyritic granodiorite: 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 the Buckwater Creek Pluton of Newton (1983). Zdsi - Dacitic shallow intrusive: Gray-green, light green to green; plagioclase porphyritic dacite with a granular-textured groundmass to very fine-grained granodiorite (with intrusive texture visible with 7x hand lens). Contains lesser amounts of fine- to medium grained granodiorite. Fine to medium grained diorite locally present. 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 luffs. Enclaves of dark gray, plagioclase poiphyritic dacite are common and at times give rock a psuedo-clastic appearance. Locally xenoliths of luffs are present. Generally equivalent to Unit В of Wright (1974). Zdi - Diorite: Greenish-gray to gray, fine- to medium-grained, hornblende diorite. Major minerals include plagioclase and hornblende. Plagioclase crystals are typically sericitized and saussuritized. Hornblende is typically altered to chlorite and actinolite masses. May be foliated. Metavolcanic Units Zq - Quartz bodies: White, beige, red. and tan; sugary to porcelaneous; very fine- to medium-grained massive quart 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 pryophy Hite 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. Ze/p Ze/p - Mixed epiclastic-pvroclastic rocks: Green, grayish-green to greenish-gray; siltstones. tuffaceous sandstones, conglomeratic sandstones and conglomerate. Minor phyllite. The siltstones typically are weakly phyllitic. Contains lesser amounts of fine to coarse tuff and lapilli tuff. Silicified and/or sericitized altered rock similar to Zat unit are present near contacts with other units. Minor andesitic to basaltic lavas and tuffs. Ziflt Ziflt - Intermediate to felsic lavas and tuffs with epiclastics: Green-gray to green; weakly foliated to well foliated, dacitic to andesitic volcaniclastic pyroclastic and sedimentary rocks interpreted as tuffs, reworked tuffs and volcanic sandstones to siltstones interlayed with dacitic to andesitic lavas. Zmst - 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. Zft-f - Felsic tuffs of the Few’s Ford area: Dominantly light-green to dark-green; massive to weakly foliated tuffs. Interlayered with light-gray to gray; massive to weakly foliated lapilli tuff; a distinctive purple-colored coarse tuff and dark-gray to black, andesitic to dacitic cryptocrystalline lava similar in appearance to the lavas present in the Zadlt unit in the Hillsborough quadrangle (Bradley et al. 2005). 1 -5% accessory sulfide minerals commonly present. Zft-c - Felsic tuffs of the Coile quarry area: Greenish-gray; massive to strongly foliated; dense; plagioclase crystal-fragment-rich coarse tuff's. Strong foliation is interpreted to be result of primary volcanic welding and/or compaction. 1 -5% accessory sulfide minerals commonly present. Outcrops and boulders typically display a white weathering rind. Zft-s Zft-s - Felsic tuffs of the St. Mary’s Church area: Grayish- green to greenish-gray, silvery-gray, and gray, massive to foliated, volcaniclastic pyroclastic rocks consisting of fine- to coarse tuffs, lapilli tuffs and minor welded tuffs. 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. Minor andesitic to basaltic lavas and tuffs. Distinctive plagioclase + quartz crystal tuff present in unit in higher stratigraphic zones near the Ze/p unit. Zat Zat - Altered tuffs: Very light-gray, light-greenish-gray to white, mottled red and yellow, altered tuffs. Alteration of felsic tuffs have produced sericite-quartz phyllite, pods of pyrophyllite, and quartz + pyrophyllite rock; all with common less than 1 mm to 2 mm diameter cubic pyrite aggregates and goethite-lined molds of pyrite crystals. Relict lithic clasts and kaolinitized feldspar crystal shards are visible in some outcrops. Relict structures are obliterated in heavily altered rocks. Zdlt Zdlt - Dacitic lavas and tuffs: Distinctive dark -gray to black; siliceous; cryptocrystalline lava, porphyritic lava with plagioclase phenocrysts. and flow banded dacitic lavas. Interlayered with gray to black; welded and non-welded coarse tuff and lapilli tuff. Tuffs often contain black-colored fiamme. up to 10 cm. interpreted as flattened pumice. Clast types include black cryptocrystalline lava and porphyritic lava with plagioclase phenocrysts. Differentiation between lavas and massive tuffs is difficult in hand sample in most cases. The lavas are inteipreted to have been coherent magma that were extrusive or very shallow intrusions associated with dacite domes. Tuff interlayers are interpreted as episodic pyroclastic flow deposits and air fall tuffs generated during eruption of domes. Includes portions of Wright (1974) unit C and Cp. Zadlt Zadlt - 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 anrygdules. Interlayed with the lavas are gray to black; welded and non-welded; coarse tuff, lapilli tuff, and tuff breccia. Lavas with relict hyaloclastic texture and amygdules are well exposed in the former Nello Teer Quarry south of the Eno River. References for map Bradley, P.J.. and Gay, N.K., 2005, Geologic map of the Hillsborough 7.5-minute quadrangle. Orange County, North Carolina: North Carolina Geological Survey Open-file Report 2005-02, scale 1:24.000. in color. Brown, Z.A.. Aruscavage, P.J., Brown. F.W., Mei, L.. Hearn, RP, and Philpotts. J.A, 1985, Some compositional aspects of Mesozoic diabase sheets from the Durham area. North Carolina, in Robinson, G.R., Jr., and Froelich. A.J., eds.. Proceedings of the 2nd U.S. Geological Survey Workshop on the early Mesozoic basins of the United States: U.S. Geological Survey Circular 946. p. 103-106. Fisher. R.V. and Schmincke H.-U., 1984. Pyroclastic rocks, Berlin, West Germany, Springer- Verlag, 472 P. Flanagan. F.J.. 1984, Three USGS mafic rock reference samples, W-2, DNC-1 and BIR-1 . USGS Bulletin 1 623, 54 pp. ; updated by Additions and Corrections for USGS Bulletin 1623, Open-File Report 86-220, issued in 1986. Gotterfied. D., Froelich, A. J. and Grossman, J.N., 1991, Geochemical data for Jurassic diabase associated with early Mesozoic basins in the Eastern United States: Durham and Sanford Basins, North Carolina. USGS Open-File Report 91-322-1, 21 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 ofAmerica Bulletin, v. 100, pp. 200-217. Hoffman. C. W., and Gallagher. P. E., 1989, Geology of the Southeast Durham and Southwest Durham 7.5-minute quadrangles. North Carolina Geological Survey Bulletin 92, 34 p. Newton. M.C.. 1983. A late Precambrian resurgent cauldron in the Carolina slate belt of North Carolina. U.S. A., unpublished M.S. thesis, Viiginia Polytechnic Institute and State University, 89 p. Phillips. C.M.. Witanachchi. C., Ward, A.N., Clark, T.W., 2004, Geologic map of the Northeast and Northwest Durham 7.5-minute quadrangles, Durham, Granville, Orange, and Wake Counties, North Carolina: North Carolina Geological Survey Open-file Report 2004-03, scale 1:24,000. in color. 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. Samson, S.D.. Secor, D.T., and Hamilton, M.A.. 2001. Wandering Carolina: tracking exotic terranes with detrital zircons. Geological Society of America Abstract with Programs, 33. p. A-263. MAP LOCATION SCALE 1 :24 000 1 0.5 0 1 I I I I I H I - 1 111 I Miles 1,000 500 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 I I I — I I - I HI I - 1 Feet 1 0.5 0 1 I — I I — I I — I I — I I — I I I Kilometers CONTOUR INTERVAL 1 0 FEET Geology mapped from August 2002 through September 2003 by Philips, Witanachchi, Ward and Clark. Additional field work, data collection and interpretation by Bradley and Bechtel in 2005 through 2009. PLEASE NOTE: This map replaces the Northwest Durham quadrangle portion of NCGS Open-File Report 2004-03 (Phillips et al., 2004). UTM GRID AND 2003 MAGNETIC NORTH DECLINATION AT CENTER OF SHEET Base topographic map is a digital raster graphic image of the Northwest Durham 7.5-minute quadrangle ( 1993), North Carolina State Plane NAD 83 meters coordinate system. Schmidt Equal Area Stereogram Data of Contoured Poles to Foliation and Cleavage Contour Interval = 1 N = 282 Unidirectional Rose Diagram of Foliations and Cleavage N = 282 Schmidt Equal Area Stereogram Data of Poles to Bedding of Triassic Sediments N = 20 Unidirectional Rose Diagram of Joints for Carolina Terrane Crystalline Rock Types N = 437 Unidirectional Rose Diagram of Joints for Unidirectional Rose Diagram of Joints Triassic Sediments Only (Trcs) N = 46 for Diabase Only (Jd) N = 92 (Woman** эхо (Ha: Kv*f со«гр.«Г') Schematic representation of relationships of geologic units in the Orange and Durham counties, NC area. Includes geologic units from the Chapel Hill, White Cross, Efland, Farrington, Caldwell and Cedar Grove geologic maps. Not all uniLs represented in the Northwest Durham quadrangle. Streckeisen. A.L.. 1973. Plutonic rocks: Classification and nomenclature recommended by the IUGS subcommission on the systematics of igneous rocks: Geotimes, v. 18, p.26-31. Streckeisen, A.L.. 1 979, Classification and nomenclature of volcanic rocks, lamprophyres, carbonatites, and melilitic: Recommendations and suggestions of the IUGS subcommission on the systemics of igneous rocks. Geology, v. 7, p. 331-335. 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. Watson, M. E., 1 998, Geology of the Green Level 7.5-minute quadrangle, Chatham, Durham, and Wake Counties, North Carolina, North Carolina Geological Survey Open-File Report 98-3, 28 p. 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 ofGeology. v. 108. pp. 321-338. Wright. J.E., 1974, Geology of the Carolina slate belt in the vicinity of Durham. North Carolina, unpublished M.S. thesis, Virginia Polytechnic Institute and State University, 78 p. EXPLANATION OF MAP SYMBOLS CONTACTS Lithologic contacts - distribution and concentration of station locations and structural symbols indicates degree of reliability. inferred geologic contact I 1 1 1 1 1 Nl/ inferred fold hinge of plunging overturned anticline, dotted where concealed concealed geologic contact < - - inferred fold hinge of plunging overturned syncline, dotted where concealed diabase dike trend in cross section, fold form lines A 1 1 1 1 1 1 N1/ inferred fold hinge of doubly plunging overturned anticline, dotted where concealed in cross section, inferred fold axis A A' . , - cross section line 0 observation station location • diabase station location Q geochemical sample location PLANAR FEATURES OXIDES IN PERCENT SELECTED ELEMENTS IN PPM SAMPLE ID Rock Type Map Unit Si02 AI203 CaO MgO Na20 K20 Fe203 MnO ТЮ2 P205 Cr203 LOI Sum Ba Ce Co Cu Nd Ni Sm Sr Та Y Zn Zr NWD-49 plagioclase porphyritic dacite Zdsi 67.38 15.87 2.66 0.94 4.74 2.84 3.58 0.07 0.43 0.1 0.05 1.35 100.2 928 57 7.7 16 23.5 14 4 446.8 <0.5 14.4 60 207.4 NWD-1154 plagioclase porphyritic dacite Zdlt 67.94 15.7 1.53 0.9 6.31 2.53 3.67 0.08 0.46 0.11 0.04 0.75 100.2 921.9 55.7 7.4 7 23 12 3.9 327 <0.5 14.2 62 209.8 NWD-1382 plagioclase porphyritic granodiorite Zgd-porphyritic 69.99 13.79 3.19 0.27 4.29 2.51 2.66 0.08 0.27 0.05 0.04 3.2 100.5 1171.4 56.7 3.8 10 21.6 9 3.7 114.2 <0.5 15.7 48 223 NWD-3127 basaltic dike intruding Zdsi unit Zdsi 44.4 15.6 9.22 8.19 2.48 0.17 14.3 0.25 1.52 0.07 0.04 3.05 99.3 160 6.7 56.7 148 3 167 3.2 253 <0.5 26 NA 64 Quarry-B-1 (58) andesitic lava Zadlt 56.6 17.5 3.35 1.39 1.93 1.58 8.22 0.09 1.19 0.05 <0.01 5.95 97.9 NA 29.4 19 41 14.9 14 3.8 NA 0.8 21.1 NA 133 Quarry-B-1 (60) andesitic lava Zadlt 56.1 17 3.8 0.91 6.19 0.44 8.88 0.07 1.21 0.08 <0.01 4.05 98.7 NA 36.2 14.2 22 21.3 <5 5.1 NA 0.6 22.3 NA 105 Quarry-B-1 (70) andesitic lava Zadlt 54.7 16 6.8 3.4 3.9 0.8 8.84 0.19 1.16 0.29 <0.01 2.1 98.1 NA 26.5 19.5 33 18.6 12 4.8 NA 0.5 28 NA 109 Quarry-B-1 (90) dacitic lava Zadlt 62.9 15.2 5.09 1.54 5.64 0.58 5.34 0.11 0.79 0.23 <0.01 1.5 98.9 NA 32.5 9.5 32 21.4 5 5.4 NA <0.5 30.9 NA 148 Quarry-B-2 (100) diabase Jd 47.2 18.4 10.7 10.7 1.95 0.22 9.51 0.14 0.46 0.06 0.04 0.05 99.4 NA 7.5 54.9 119 4.8 276 1.4 NA 0.6 15.4 NA 30.6 Geochemical analyses completed by SGS Mineruls, Toronto, Cunuda for major and trace elements. Whole-rock unulyses by method codes XRF103 (NWD-1154, NWD-1382 and NWD-49), XRF78V (NWD-3127), XRF76Z (quarry samples) for major oxides and IMS95A (all samples). Analyses from quarry samples prov ided by CDM. Samples collected from two borings. Number in parentheses indicate depth of sample in boring. NA = No samnle analysis Observation sites are centered on the strike bar or are at the intersection point of multiple symbols. Planar feature symbols may be combined with linear features. V strike and dip of primary bedding and layering 77 / / strike and dip of vertical cleavage strike and dip of high strain foliation У strike and dip of overturned primary bedding and layering / strike and dip of vertical high strain foliation 79 у strike and dip of primary volcanic compaction and/or welding foliation У strike and dip of joint 64y strike and dip of foliation У strike and dip of vertical joint / strike and dip of vertical foliation ® horizontal joint У strike and dip of cleavage У strike and dip of slicken plane -1300' - Durham County St. Mary's fold axis Road / Zdlt -3300' A' fold axis Umstead Road Guess Road fold axis i- 700' Old Oxford Road l Eno River/Sennett Hole area I US HWY 501/Roxboro Rd 1 cs/sil LINEAR FEATURE trend of plunge of slicken line inactive quarry and abandoned quarries 1 - Abandoned quarry on Eno River State Park property. Known as Coile Quarry or Eno Quarry. 2 - Inactive former Nello Teer Quarry 3 - Abandoned quarry on Museum of Life and Sciences property - Location of mafic rock standard DNC-1 (Flanagan. 1984). Known a s Bra ggt own Quarry. Scan with smartphone for link to Geo PDF of map. Third party App required. GEOLOGIC MAP OF THE NORTHWEST DURHAM 7.5-MINUTE QUADRANGLE, DURHAM AND ORANGE COUNTIES, NORTH CAROLINA Disclaimer: This Open File map is preliminary. It has not been externally reviewed for conformity with the North Carolina Geological Survey editorial standards or with the North American Stratigraphic Code. Further revisions or corrections to this Open File map may occur prior to its release as a North Carolina Geological Survey map. By Philip J. Bradley, Cindy M. Phillips, Randy Bechtel, Channa Witanachchi, Amy N. Ward and Timothy W. Clark Digital representation by Michael A. Medina, Philip J. Bradley and Cindy M. Phillips This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program. 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. 2004 GEOLOGIC MAP OF THE NORTHWEST DURHAM 7.5-MINUTE QUADRANGLE, DURHAM AND ORANGE COUNTIES, NORTH CAROLINA NCGS OPEN FILE REPORT 2004 03a REVISION -01 (2010)