Bedrock geologic map of the Pisgah Forest 7.5-minute quadrangle, North Carolina

NORTH CAROLINA DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES DIVISION OF ENERGY, MINERAL, AND LAND RESOURCES Tracy E. Davis, Director Dr. Kenneth B. Taylor, State Geologist This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program 42'30" 40' NORTH CAROLINA GEOLOGICAL SURVEY OPEN FILE MAP 2012-05 910 000 FEET c n Z) О CL Ш О CO oc < о о > ш Q MAP UNITS Brevard Zone Sericite phyllite bzsp bzgs bzggp Graphitic schist Mylonitic granitic gneiss/phyllonite < о > О Q CL О Devonian intrusives Pink Beds trondhjemite Granitoid gneiss Henderson Gneiss Augen gneiss Mylonitic augen gneiss О О N О ос ш о ос 0_ о ш Ashe Metamorphic Suite/Tallulah Falls Formation Metagraywacke Zag Zagsi Zambs Schistose metagraywacke Muscovite-biotite schist Zaa Zua Amphibolite Altered ultramafic ROCK DESCRIPTIONS Brevard Zone Sericite phyllite (bzsp) - Dark gray to light olive gray, to greenish gray; fine- to coarse-grained; lepidoblastic to porphyroblastic; strongly foliated; mylonitic. Com¬ posed of sericite, quartz, feldspar, and accessory graphite, chlorite, and opaque minerals. Lenticular muscovite-aggregate porphyroblasts flattened in the mylonitic foliation planes impart a distinctive “fish scale” or “button" appearance. Locally inter- layered with mylonitic metagraywacke and schistose metagraywacke, sericite- chlorite phyllonite and sulfidic graphitic schist. Graphitic schist (bzgs) - Medium gray to dark gray; fine-grained; inequigranular; lepidoblastic; thinly foliated; consists of quartz, graphite, muscovite, biotite, and opaques. Interlayered with phyllite, mylonite, marble, meta-arkose and sericite schist. Thickness of layering ranges from centimeters to meters. ROCK DESCRIPTIONS (continued) Mylonitic granitic gneiss/phyllonite (bzggp) - Medium light gray to yellowish gray; fine- to medium-grained; inequigranular; locally porphyroclastic; strongly foliated; mylonitic, locally protomylonitic. Consists of plagioclase, quartz, potassium feldspar, sericite, muscovite, biotite, epidote and trace accessory minerals. Rounded to elongated feldspar porphyroclasts are common. Interpreted to be fault slices of mylonitic Henderson Gneiss interlayered with sericite phyllite by Brevard Zone deformation. Devonian intrusives Pink Beds trondhjemite (Dpbt) - Light gray to very light-gray; non-foliated to weakly foliated; medium- to coarse-grained; equigranular; occurs as massive outcrops. Consists of 45-55% plagioclase, 30-40% quartz, 0-10% potassium feldspar, 0-3% biotite, and 1% opaques. Locally migmatitic and foliated to mylonitic near the contact with Ashe Metamorphic Suite/Tallulah Falls Formation rock types. Granitoid gneiss (Dgg) - White to very light-gray, non-foliated to mylonitic; medium- to coarse-grained; equigranular; granoblastic; occurs commonly as thin layers and lenses (thickness of layering ranges from centimeters to meters) within and cross-cutting Ashe Metamorphic Suite/Tallulah Falls Formation rock types and as mappable bodies; typically trondhjemitic to granitic in composition and consists of 1-60% potassium feldspar, 5-55% plagioclase feldspar, 15-30% quartz, 5-15% muscovite and sericite, and minor biotite and opaques. Granitoid gneiss is possibly related to Pink Beds trondhjemite (Dpbt). Henderson Gneiss Augen gneiss (Ohg) - Medium-gray to medium-bluish-gray to mottled black and white; inequigranular; medium- to coarse-grained matrix with large megacrysts (augen) of microcline variable in size and abundance; protomylonitic to mylonitic to granoblastic to lepidoblastic; massive to well foliated; dominantly biotite granite that ranges to tonalite; consists of approximately 1 to 35% potassium feldspar, 28 to 35% plagioclase, 10 to 33% quartz, 1 to 20% biotite, 1 to 20% muscovite, 0 to 10% epidote group minerals, 0 to 5% opaques and trace amounts of titanite, zircon and apatite; locally pegmatitic and migmatitic. Locally microcline augen exceed one inch in length. The augen structures are produced by a high temperature protomylonitic overprint. Makes up the largest granite pluton in western North Carolina and is approximately 447 million years old (Moecher et al., 2011). Mylonitic augen Gneiss (Ohgmy) - Light-gray to medium-gray, fine- to medium-grained, inequigranular, mylonitic, consists of microcline, quartz, plagioclase, muscovite, biotite with minor epidote group minerals, and seric¬ ite. The sericite is a product of mylonitization associated with faulting and is derived from feldspars. Ashe Metamorphic Suite/ Tallulah Falls Formation Metagraywacke (Zag) - Medium-light-gray to medium-dark-gray; weakly foliated to well foliated; medium- to coarse-grained; equigranular to inequigranular; granoblas¬ tic to lepidoblastic; locally migmatitic; consists of plagioclase, quartz, biotite, musco¬ vite, minor opaques, epidote and apatite; thickness of layering ranges from several decimeters to several meters. Interlayered at all scales with schistose metagray¬ wacke, garnet-mica schist, and conglomeratic metagraywacke. Schistose metagraywacke (Zagsi) - Medium-gray to dark-gray; foliated; fine- to medium-grained; equigranular to inequigranular; lepidoblastic to weakly granoblas¬ tic to porphyroblastic; locally migmatitic; consists of quartz, plagioclase, muscovite, biotite, epidote, chlorite and trace opaque minerals; thickness of layering ranges from several millimeters to several centimeters to several meters; commonly inter¬ layered with metagraywacke and minor garnet-mica schist. Muscovite-biotite schist (Zambs) - Light-gray to medium-dark-gray; medium- to coarse-grained; foliated; consists of muscovite, biotite, quartz, garnet, and chlorite, with accessory staurolite, kyanite, and pyrite. Amphibolite (Zaa) - Dark-green to black; foliated to strongly foliated; fine- to medium-grained; equigranular to inequigranular; consists of hornblende, plagio¬ clase, quartz, epidote group minerals, garnet, chlorite, pyroxene, titanite, and opaques. Amphibolite occurs as minor interlayers within other Ashe Metamorphic Suite/Tallulah Falls Formation map units and as small mappable bodies. Altered ultramafic (Zua) - Small body of uncertain extent comprised of talc chlorite schist and metagabbro. The lithologic variations within the altered ultramafic could not be mapped at 1 :24,000 scale. Talc chlorite schist: green to silvery-grayish green; foliated; lepidoblastic; consists of 45-55% chlorite, 35-45% talc, 0-7% serpentine, 5-7% opaques including magnetite and chromite, and 0-3% anthophyllite. Metagab¬ bro: coarse-grained; weakly foliated; granoblastic; consists of 65-75% hornblende, 15-25% plagioclase, 3-8% quartz, 4% opaques including magnetite; observed at the contact of the altered ultramafic body and surrounding metasedimentary rocks of the Ashe Metamorphic Suite/Tallulah Falls Formation. ’Mineral percentages are based upon visual estimates of selected samples. References Cited Moecher, D., Hietpas, J„ Samson, S., and Chakraborty, S., 2011, Insights into southern Appalachian tectonics from ages of detrital monazite and zircon in modem alluvium: Geosphere; v. 7; no. 2; p. 1-19. 82°37'30" 35°22'30'' WHOLE ROCK ICP ANALYSIS1 OF SELECTED SAMPLES SAMPLE2 COORDINATES (State Plane NAD 83 m) ROCK TYPE MAP UNIT Si02 AI203 Fe203 OXIDES IN PERCENT MqO CaO Na2Q K20 ТЮ2 P205 MnO Cr203 Ba Cu ELEMENTS IN PPM3 Zn Ni Co Sr Zr Ce Y Nb Sc LOI4 SUM5 BC94 179,125N; 279,267E mylonite bzggp 66.35 18.3 2.97 0.77 2.62 5.88 1.76 0.27 0.03 0.03 0.011 484 <5 68 <20 <20 499 138 72 6 16 4 0.8 99.99 BC313 178,609N; 277,165 E mylonite bzsp 64.74 16.23 7.11 1.83 0.24 1.07 4.54 0.99 0.19 0.09 0.012 918 27 92 44 29 99 389 75 17 18 15 2.7 99.99 BC331 178,671 N; 275 ,952 E hematite, limonite nodule bzsp 1.52 1.19 79.12 0.02 0.07 <0.01 0.02 <0.01 2.42 1.07 0.012 1572 14 1421 201 200 5 <5 <30 69 <5 2 13.9 99.95 BC378 182,816N; 270,534E talc chlorite schist Zua 44.31 6.57 15.54 23.4 2.06 0.03 <0.01 0.45 0.03 0.2 0.187 <5 110 125 1301 124 3 18 <30 9 <5 13 6.5 99.61 BC518 178,590N; 274,988E muscovite granitic gneiss Dgg 70.39 16.15 1.23 0.25 0.64 1.94 5.39 0.14 0.17 0.01 <0.002 1036 <5 12 <20 <20 251 88 <30 10 <5 3 3.5 100.01 BC597 183,600N; 279,927E protomylonitic quartz vein Zag 93.98 0.51 4.42 <0.01 <0.01 <0.01 0.08 <0.01 0.09 <0.01 0.01 10 69 127 22 <20 2 <5 <30 <3 <5 <1 0.9 100.03 BC601 183,333N; 279,826E mylonitic metagraywacke Zag 74.1 12.51 4.26 0.72 0.38 2.24 3.1 0.8 0.16 0.03 0.004 579 9 72 <20 <20 76 654 57 32 19 8 1.5 99.99 BC667 182,912N; 275,982E mylonitic trondhjemitic gneiss Zag 73.87 15.05 2.04 0.35 1.03 1.76 3.3 0.2 0.19 0.02 0.016 511 <5 16 <20 <20 118 94 53 17 17 5 2.1 100.02 BC707 179,117N; 275,991E mylonitic granitic gneiss Dgg 74.41 14.9 0.75 0.06 0.3 4.72 3.73 0.01 0.08 0.07 <0.002 37 <5 47 <20 <20 41 9 <30 4 18 1 1 100.02 RW31 186,573 N; 269,087E trondhjemitic gneiss Dpbt 74.84 14.97 0.63 0.07 1.86 5.22 1.85 0.03 0.02 0.01 0.012 941 <5 <5 <20 <20 274 46 <30 <3 7 1 0.4 100.05 RW63 178,468N; 279,679E mylonitic biotite granitic gneiss bzggp 71.34 14.53 2.59 0.48 0.57 3.06 5.15 0.33 0.12 0.05 0.008 681 6 35 <20 <20 204 411 169 18 32 8 1.6 100.01 RW143a 176,949N; 276,870E mylonite bzggp 50.14 14.76 10 7.76 11.41 1.69 0.23 0.9 0.06 0.16 0.044 29 84 66 76 41 173 45 <30 17 <5 41 2.6 99.84 RW143b 176,949N; 276,870E mylonite bzggp 65.85 15.85 5.89 1.98 0.58 1.69 3.89 0.85 0.13 0.09 0.01 610 17 96 48 22 73 238 38 25 18 14 3 99.97 RW144 176,823N; 276,812E mylonitic granitic gneiss bzggp 71.4 14.91 2.81 0.83 2.17 3.15 2.19 0.31 0.09 0.04 0.007 555 8 52 <20 <20 249 159 40 12 9 5 1.9 99.98 RW168a 177,899N; 277,431E mylonitic granitic gneiss bzggp 73.12 14.23 1.78 0.39 0.84 2.93 4.8 0.19 0.1 0.05 0.014 370 7 33 <20 <20 88 115 57 21 21 4 1.5 100 RW168b 177,899N; 277,431E mylonitic granitic gneiss bzggp 72.24 14.68 1.85 0.65 0.07 2.72 4.78 0.21 0.1 0.04 0.01 394 <5 24 24 <20 70 120 41 18 20 5 2.6 100.02 RW176 177,557N; 278,205E mylonitic biotite granitic gneiss bzggp 73.9 13.24 2.29 0.59 0.37 3.19 4.75 0.4 0.11 0.06 <0.002 493 <5 26 <20 <20 101 245 135 24 19 6 1 99.98 RW203 182,900N; 270/773E metagabbro (amphibolite) Zua 53.41 8.9 6.38 15.1 10.22 1.27 0.55 0.6 0.18 0.14 0.242 95 <5 67 903 46 501 101 60 17 <5 20 2.5 99.74 RW238 175,374N; 272,371E mylonitic granodioritic gneiss Dgg 73.36 15.02 1.3 0.26 0.89 2.31 5.05 0.11 0.32 0.03 0.008 426 <5 31 <20 <20 130 28 <30 23 12 6 1.3 100.01 RW405 179,128N; 275,956E mylonitic quartz vein Dgg 98.19 0.05 0.52 <0.01 0.02 <0.01 0.02 <0.01 0.02 <0.01 0.009 7 <5 13 <20 <20 <2 <5 <30 <3 7 <1 1.1 99.94 RW423 179,865 N; 269Д64Е mylonitic granitic gneiss Zag 69.31 15.59 1.74 0.41 0.78 1.9 8.33 0.29 0.09 0.03 <0.002 731 <5 28 <20 <20 138 306 92 86 <5 4 1.4 99.99 ’Whole Rock Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP) analysis conducted by Acme Analytical Laboratories, LTD., 852 E. Hastings St., Vancouver, BC 2Sample numbers correspond to thin section and whole rock sample localities shown on geologic map 3PPM = parts per million 4LOI = loss on ignition in percent 5SUM = Sum total in percent SCHMIDT EQUAL AREA STEREONET DATA 35°1 5 * *e * ; 82°45' Topographic base produced by the United States Geological Survey. Altered by the North Carolina Geological Survey for use with this map. North American Datum of 1983 (NAD83). World Geodetic System of 1984 (WGS84). Projection: Universal Transverse Mercator, Zone 1 7S 10 000-foot ticks: North Carolina Coordinate System of 1 983 Imagery NAIP. October 7009 Roads «7006-7010 lele Atlas Roads within us Foiest Seivice lands Fslopo Data with limited Forest Service updates, 7009 Names C.NIS 7010 42'30" 82°37'30" mn tJ SCALE 1 :24 000 ROAD CLASSIFICATION 108 MILS GM 0° 58' i 0.5 0 KILOMETERS 1 2 10CO 500 0 METERS 10(0 20(0 1 05 0 1 MILES 10CO 0 10(0 20CO 30CD 4X0 50CO 60(0 70(0 ЭСКО 50(0 TOO NORTH CAROLINA QUADRANGLE LOCATION Interstate Route US Route Ramp State R oute Local Road 4WD Interstate Route D US Route О State Route UTM GRID AND 201 MAGNETIC NORTH DECLINATION AT CENTER OF SHEET U.S. National Grid Hydrography . Contours National Hydrography Dataset 7009 National Elevation Dataset. 7008 100,000-m Square ID LV Grid Zone Designation 17S FEET CONTOUR INTERVAL 40 FEET NORTH AMERICAN VERTICAL DATUM OF 1988 This map was produced to conform with version 0.5 .1 0 of the draft USGS Standards for 7.5-Minute Quadrangle Maps. A metadata file associated with this product is draft version 0.5.12 + Trend and plunge of minor fold axes, n = 36 + Trend and plunge of mineral lineations. n = 60 + Poles to foliations, n = 558 Poles to mylonitic foliations, n = 862 Ashe Metamorphic Suite/Tallulah Falls Formation n = 341 Research supported by the U.S. Geological Survey, National Cooperative Geologic Mapping Program, under USGS award number G11AC20296. 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. Cruso Dunsmore Mountain Skyland Shining Rock Pisgah Forest Horse Shoe Rosma n Brevard Standmgstone Mountain PISGAH FOREST, NC 201 1 ADJOINING 7.5' QUADRANGLES Brevard Zone Lithologies Henderson Granitic Gneiss n = 391 n = 130 STRUCTURAL FEATURES CONTACTS Solid line - located in field to within 150 meters Short-dashed - location inferred: querried where uncertain Fault Thrust Fault with reactivated Strike-Slip motion (teeth on upper plate) (teeth on upper plate; arrows indicate relative motion) Stratigraphic Contact STRIKE AND DIP OF PLANAR FEATURES Gradational Contact BEARING AND PLUNGE OF LINEAR FEATURES Observation sites are centered on the strike bar, or at the intersection point of multiple symbols. t? сл' Ю 0) го a ■'-l СЛ 13 c CD о •О го ГО го го -а to о to 6 сл 15 \^52 Foliation f2g Mylonitic Foliation / У Vertical Foliation <\™ Axial Plane ($) Horizontal Foliation As joint Vertical Joint ,*34 Minor Fault / / Horizontal Mylonitic ^ Foliation Small Fold Axis Slickenlines Horizontal Lineation Breccia Trend Lineation Crenulation / jt 43 Cross Cutting Trend NON-STRUCTURAL FEATURES CROSS SECTION A-A O Float Location MINERAL RESOURCES ВС667Д Thin section sample site. X1 Mine or quarry X Prospect COMMODITY LETTER SYMBOLS: Au Gold Mn Manganese M Marble s/g Stone and gravel TECTONIC AND METAMORPHIC CONDITIONS A u П // // ' / / ■i 4 / / / f ///> I / pp X....// 7 A / и / f ш / iWf&A J). у I i У /ЛУ'п - .ж * / ///•" / /// / / 0'/f У/ /У Ж/ .«■<& /к Г'Ж jy ‘ / / У/ У хе. / о /у П // X К''/ У У BREVARD FAULT ZONE О motion towards viewer motion away from viewer x thrust movement ■4- Л* plunging plunging synform antiform Ashe Metamorphic Suite/Tallulah Falls Formation TRAVERSE MAP Red lines show paths of field traverses. + Contoured poles to joints with unidirectional Rose diagram inset, n = 101 1 Unit Contact Fault Contact -= — relative thrust motion ® relative motion away from viewer О relative motion towards viewer This Open-File Map is preliminary. 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. Gradational Contact Form Lines - Bedrock Geologic Map of the Pisgah Forest 7.5-minute Quadrangle, North Carolina By Bart L. Cattanach, Richard M. Wooten, G. Nicholas Bozdog, and Bradley D. Worley Geology mapped from August 1996 to May 1999 and August 201 1 to August 2012. Field Assistance by David Ward and Abigail Bullard. Map preparation, digital cartography and editing by G. Nicholas Bozdog and Bart L. Cattanach. 2012