Bedrock geologic map of the Pea Ridge 7.5-minute quadrangle, Polk and Rutherford Counties, North Carolina

North Carolina Department of Environmental Quality Energy Group Jenny Kelvington, Executive Director Kenneth B. Taylor, State Geologist CORRELATION OF MAP UNITS V Pzgg Poor Mountain Formation Pzgg < о > о о СЕ о stratigraphic relations uncertain unnamed meta-igneous rocks I I ol 81 z g|E Ш. cc tl m o" 2 op I < Q-* о 0| lill "I I Age relations uncertain Opmq Tallulah Falls Formation Opms Opma INTRODUCTION The Pea Ridge 7.5-minute Quadrangle is located in the southwestern portion of the Piedmont physiographic province in Polk and Rutherford counties, North Carolina. The quadrangle lies southwest of Rutherfordton, NC and northeast of Columbus, NC. It is located within the Rutherfordton-Spindale-Forest City metropolitan projected growth area, and southern Pea Ridge is home to the Tryon International Equestrian Center. Major transportation corridors include U.S. Highway 74 and N.C. Highway 108. Total elevation relief is 459ft with a low of 705ft and a high of 1164ft. Major rivers include the Green River, Broad River, and Mountain Creek. GEOLOGIC OVERVIEW The Pea Ridge quadrangle comprises the following units of the Tugaloo terrane (Hatcher and others, 2007). Neoproterozoic to early Cambrian Tallulah Falls Formations (TFF); Ordovician Poor Mountain Formation (PMF); and intrusive unnamed meta-igneous rocks (UMIR) of uncertain correlation. The TFF and PMF are interpreted to lie within the Six Mile Thrust Sheet (Griffin, 1974). The PMF contains sillimanite-grade meta-sedimentary units interlayered with mafic and felsic meta-volcanic rocks. The PMF structurally overlies all other units on the quadrangle by a ductile thrust fault evidenced by associated sheared and mylonitic rocks. The TFF consists of meta- sedimentary and meta-igneous rocks thought to have been deposited in a distal marine basin outboard of the Laurentian rifted margin (Hatcher and others, 2007). TFF rocks on the quadrangle have been metamorphosed to upper amphibolite facies and are migmatitic. Structural and textural relationships indicate that the UMIR intrude into the TFF, but not into the PMF. Age of the UMIR are uncertain, but cross¬ cutting relationships constrain them be post-TFF deposition and pre-fault emplacement of the PMF. Several resistant and less deformed granitoid gneiss bodies intrude the UMIR and TFF. Foliations trends are variable and most dip less than 35 degrees. A prominent ENE-WSW joint set and a less prominent ESE set exist on the quadrangle. ENE-trending quartz breccias on the quadrangle are likely associated with the Tryon-Marietta fault zone of Garihan and Ranson (1992). REFERENCES Garihan, J. M., and Ranson, W. A., 1992, Structure of the Mesozoic Marietta- Tryon graben, South Carolina and adjacent North Carolina, in M. J. Bartholomew, D. W. Hyndman, and R. Mason (editors), Basement Tectonics 8: Characterization and Comparison of Ancient and Mesozoic Continental Margins: Proceedings of the Eighth International Conference on Basement Tectonics, Kluwer Academic Publishers, Dordrecht, p.539-555. Griffin, V.S., 1974, Analysis of the Piedmont in Northwest South Carolina, Geological Society of America Bulletin, v.85, p. 1123-1138. Hatcher, R.D., Jr., Bream, B.R., and Merschat, A.J., 2007 Tectonic map of the southern and central Appalachians: A tale of three orogens and a complete Wilson cycle, in Hatcher, R.D., Jr., Carlson, M.P., McBride, J.H., and Martinez Catalan, J.R., eds., 4-D Framework of Continental Crust: Geological Society of America Memoir 200, p. 595-632. GZhqf GZhg GZa eztfb STREAM SEDIMENT HEAVY MINERAL ANALYSIS Stream sediment heavy mineral analysis was conducted from March 2015 through June 2016 to aid geologic mapping, better define conditions of metamorphism, and inventory minerals of potential economic significance. Procedure: In the field, approximately 13.6 kg of stream sediment material is panned to approximately 300 g of heavy mineral concentrate at each sample locality. In the laboratory, concentrate is washed and passed through heavy liquid separation using tetrabromoethane, and scanned with short- and long-wave ultraviolet illumination using an Ultra-violet Products Inc. Model UVGL-48 Mineralight Lamp. Magnetite is removed with a hand magnet. A sample split is grain mounted on a standard 27x46 mm glass slide and approximately 200 grains are identified and counted with the aid of a petrographic microscope and 1.67 index of refraction oil. Results of stream sediment heavy mineral analysis are tabulated below. Mineral abbreviations used in table: Mg-magnetite; Gt-garnet; Zr-zircon; Bt-biotite; Rt-rutile; Czo- clinozoisite; Ep-epidote group minerals; quartz; llm-ilmenite and other black opaque minerals; Hem-hematite and other red opaque minerals; Lx-leucoxene; Ud-unidentified. Sil - sillimanite; Hbl-hornblende;Ttn-titanite;Tur-tourmaline; Mnz- monazite; Ap-apatite; Qtz- 'Sample numbers correspond to stream sediment heavy mineral sample localities shown on geologic map 2Up to three most dominant map units contributing to the drainage basin, listed in decending order of map area Percentage of heavy minerals in 13.6 kg stream sediment sample Point count percentages of heavy minerals from processed samples WHOLE ROCK ICP ANALYSIS1 OF SELECTED SAMPLES This Geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program 35°22'30" DESCRIPTION OF MAP UNITS Breccia — Linear-trending cataclastic fault breccias and silicified microbreccias form resistant outcrops and concentrations of characteristic quartz float. Breccia is typically white to very light-gray; fine- to medium¬ grained; massive to weakly foliated; quartz crystal growth locally present in void spaces and along joint surfaces; consists of quartz, trace biotite, and opaque minerals. Granitoid gneiss — white to pinkish-gray to light-gray; fine- to medium-grained; massive to weakly foliated; equigranular to locally inequigranular; consists of plagioclase feldspar, potassium-feldspar, quartz, biotite, and muscovite. Locally observed to cross-cut and intrude foliated and migmatitic gneisses. Many small bodies are not mappable at this scale. Poor Mountain Formation Undivided — Heterogeneous unit of metagraywacke, schist, amphibolite, quartzite, metasandstone, meta- arkose, quartzo-feldspathic gneiss, and calc-silicate. Metagraywacke — medium-light-gray to medium-dark-gray; medium- to coarse-grained; foliated; locally mylonitic; equigranular to inequigranular; granoblastic to lepidoblastic; migmatitic; consists of quartz, plagioclase feldspar, biotite, muscovite, potassium feldspar, garnet, and accessory minerals. Calc-silicate — light-gray; medium- to coarse-grained; weakly foliated; consists of quartz, feldspar, epidote group minerals, garnet, biotite, and trace chlorite. Metasandstone/Quartzite/Meta-arkose — Very pale-orange to grayish-orange to grayish-purple; dusky- yellowish-brown on weathered surfaces; fine- to medium-grained; foliated; locally mylonitic/sheared; equigranular; granoblastic; consists of quartz, potassium feldspar, plagioclase feldspar, garnet, biotite, muscovite, epidote, and opaque minerals. Interlayered with lesser amounts of metagraywacke, schist, quartzo-feldspathic gneiss, and amphibolite. Schist — Silvery-gray to light-reddish-gray; fine- to medium-grained; inequigranular; lepidoblastic and porphyroblastic; typically has a sheared (S-C) fabric; migmatitic; consists of muscovite, sillimanite, biotite, garnet, quartz, feldspar, and trace opaque minerals, tourmaline, and apatite. Interlayered with lesser amounts of metasandstone, meta-arkose, metagraywacke, and amphibolite. Amphibolite — Occurs as a mappable unit structurally beneath metasandstone, quartzite, and meta-arkose layers in places on the quadrangle, and as a minor rock type throughout other map units of the Poor Mountain Formation. Amphibolite is typically mottled white to dark-green to black; fine- to coarse-grained; foliated; equigranular to nematoblastic; consists of hornblende, plagioclase, biotite, epidote group minerals, quartz, and minor garnet, chlorite, pyroxene, titanite, and opaque minerals. Interlayered with lesser amounts of metasandstone, quartzite, meta-arkose, and sillimanite schist. Unnamed meta-igneous rocks Hornblende quartzo-feldspathic gneiss — Very light-gray to grayish-black, commonly weathers to dark- yellowish-orange; fine- to coarse-grained; foliated; well layered; equigranular; consists of quartz, plagioclase, potassium feldspar, epidote group minerals, biotite, muscovite, hornblende, chlorite, garnet, and trace apatite, rutile, monazite, and opaque minerals; interlayered with amphibolite and hornblende gneiss. Locally contains rotated enclaves (xenoliths?) of layered amphibolite and small pods of altered ultramafic rocks. Hornblende gneiss — Contains dominantly hornblende gneiss with lesser amounts of biotite gneiss. Hornblende gneiss is mottled white to greenish-black on fresh surfaces; weathered surfaces are mottled white to dark-reddish-brown; medium- to coarse-grained; foliated; massive to well-layered; equigranular; migmatitic; consists of hornblende, plagioclase, quartz, biotite, epidote group minerals, titanite, actinolite, magnetite, minor muscovite and opaque minerals, and trace apatite, monazite, chlorite, and zircon. Biotite granitic gneiss layers within hornblende gneiss are gray to grayish-black; medium- to coarse-grained; foliated; migmatitic; consists of plagioclase, quartz, biotite, muscovite, hornblende, minor epidote group minerals and sericite, and trace apatite. Amphibolite — Occurs as mappable and small unmappable bodies within the hornblende gneiss and hornblende quartzo-feldspathic gneiss units. Amphibolite is typically mottled white to dark-green to black; fine- to coarse-grained; foliated; equigranular; nematoblastic; consists of hornblende, plagioclase, biotite, epidote group minerals, quartz, muscovite, and minor garnet, chlorite, pyroxene, titanite, and opaque minerals. Altered ultramafic — Interpreted to be an altered pyroxenite. Ultramafic is typically medium-gray-green to dark-gray-green; medium- to coarse-grained; weakly foliated; equigranular to inequigranular; nematoblastic. Bronze, coarse-grained, poikilitic hypersthene with green amphibole inclusions locally preserve a relict porphyritic texture. Consists of actinolite/tremolite, talc, hypersthene, enstatite, chlorite, and minor opaque minerals including magnetite. Lesser amounts of medium- to coarse-grained amphibolite and hornblende gneiss occur within this unit. Tallulah Falls Formation Undivided — The Tallulah Falls Formation is a thick, heterogeneous sequence of metamorphosed sedimentary and volcanic rocks. Sequences of metagraywacke, schistose metagraywacke, mica schist, and amphibolite are interlayered at all scales. Metagraywacke — medium-light-gray to medium-dark-gray; medium- to coarse-grained; foliated (ranges from massive to gneissic); equigranular to inequigranular; granoblastic to lepidoblastic; migmatitic; consists of quartz, plagioclase, biotite, muscovite, potassium feldspar, sillimanite, and minor garnet, opaques, epidote, and apatite; thickness of layering ranges from decimeters to meters. Interlayered at all scales with mica schist, schistose metagraywacke, amphibolite, and minor calc-silicate. Schistose metagraywacke — medium-gray to dark-gray; fine- to medium-grained; foliated; equigranular to inequigranular; lepidoblastic to weakly granoblastic to porphyroblastic; migmatitic; consists of quartz, plagioclase, muscovite, biotite, potassium feldspar, sillimanite, epidote group minerals, chlorite, garnet, and trace opaque minerals; thickness of layering ranges from several millimeters to meters; commonly interlayered with metagraywacke, mica schist, conglomeratic metagraywacke, amphibolite, and minor calc-silicate. Mica schist — silvery-gray to medium-dark-gray; fine- to medium-grained; equigranular; lepidoblastic to porphyroblastic; migmatitic; consists of muscovite, biotite, garnet, quartz, feldspar, and trace epidote group minerals, chlorite, and opaque minerals; interlayered with metagraywacke, schistose metagraywacke, amphibolite, and rare calc-silicate. Biotite gneiss — Heterogeneous unit consisting of interlayered porphyroblastic biotite gneiss, with lesser amounts of metagraywacke, schist, and hornblende-biotite gneiss. Biotite gneiss is typically gray to grayish- black; medium- to coarse-grained; well foliated; compositionally layered; locally protomylonitic; inequigranular; porphyroblastic to lepidoblastic; migmatitic; consists of plagioclase, quartz, biotite, potassium feldspar, muscovite, garnet, epidote group minerals, chlorite, opaques, and little to no hornblende. Mineral abundances are listed in decreasing order of abundance based upon visual estimates of hand samples and thin sections. North Carolina Geological Survey Open File Map 2016-07 COORDINATES MAP UNITS % TOTAL HM IN PERCENT HEAVY MINERALS IN SAMPLE4 SAMPLE1 (State Plane, NAD 83 m) DRAINED2 SAMPLE3 Mg Gt Zr Bt Rt Czo Ep Sil Hbl Ttn Tur Mnz Ap Qtz Ilm Hem Lx Ud NB 246 177.584N; 329,824E Opmq, Opma 1.47 1.72 - 17.69 2.95 - 1.97 31.94 - 37.84 1.47 0.49 - - 1.97 1.47 - 0.49 NB 249 173,168N; 328,771 E Opm, Opmq 0.09 13.16 3.91 6.08 2.17 - - 35.17 0.43 19.97 - 0.43 - - - 18.24 0.43 - - BC 242 174,478N; 333,294E €Za,€Zhq 0.60 20.62 0.40 0.79 1.19 0.79 0.40 12.30 - 55.96 - 0.79 - - - 4.76 1.59 0.40 - NB 247 177.475N; 333,188E CZhq, CZhqf 0.04 6.25 0.47 13.13 - 0.94 2.34 1.41 2.34 16.41 0.47 2.81 1.41 - 36.09 14.06 1.88 - NB 251 172,439N; 331.997E CZtfb, Opmq 1.00 1.47 - 14.15 2.44 - - 39.02 - 38.53 0.49 - 0.98 - - 0.49 1.95 0.49 - NB 581 183.768N; 326,81 1E Opm 0.78 15.44 8.03 0.42 - 0.42 1.27 3.81 2.54 2.96 0.42 - - - 0.42 62.15 1.69 - 0.85 NB 582 184.333N; 330,736E CZtfb 0.69 86.83 - 0.72 - - 0.46 1.51 - 0.53 0.72 - - 0.46 - 3.03 1.51 4.08 0.13 NB 583 179,71 9N; 328.250E CZhq, Opmq, Opma 1.99 2.51 - 6.34 - - 1.46 35.58 - 42.41 0.49 - - - - 0.97 5.36 4.87 - NB 584 1 80, 1 43N; 334,904E CZhq, CZtfb 1.98 0.47 - - - - 1.99 4.48 - 85.10 2.49 - - - - 0.50 1.00 3.98 - NB 585 183,880N; 330,494E CZtfb, CZhqf 0.29 2.88 2.91 8.26 - - 1.94 2.43 - 68.47 9.71 - - - - - 0.97 2.43 - 82°7'30" 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: State Plane North Carolina FIPS 3200 (Meters) 4,000-meter ticks: State Plane North Carolina FIPS 3200 (Meters) MN 1 tsN "TlTHirr 0- 37' 11 MILS 05 SCALE 1 :24 000 NLCMEimS ROAD CLASSIFICATION 1000 ECO 05. METERS 10CD 3X0 NORTH -.CAROLINA* Expressway Secondary Hwy Ramp Local Connector Local Road 4WD 10CO =^= MILS ioco3XD3oai4cco6ca)eoco7oco8xo 9X0 10СОО QUADRANGLE LOCATION Roads . ©2006-2012 TomTom Names . GNIS, 2013 Hydrography . National Hydroyaphy Dataset, 2012 Contours . National Elevation Dataset, 2008 Boundaries . Census, IBWC, IBC, USGS, 1972 - 2012 UTM GRID AND 201 3 MAGNETIC NORTH DECLINATION AT CENTER OF SHEET SAMPLE2 COORDINATES (State Plane, NAD 83 m) ROCK TYPE MAP UNIT OXIDES IN PERCENT ELEMENTS IN PPM3 •Г О -J SUM5 Si 02 AI203 Fe203 MqO CaO Na20 K20 ТЮ2 P205 MnO Cr203 Cu Ba Zn Ni Co Sr Zr Ce Y Nb Sc PR 5 BC 170,869N; 332.755E sillimanite-qarnel schist Opm 58.34 18.90 11.13 0.26 0.04 0.45 3.58 1.30 0.16 0.06 0.018 46 789 34 22 <20 67 217 105 26 14 28 5.6 99.98 BC 562 PR 184.226N; 327,991 E biotite meta-arkose Opm 66.23 15.44 6.63 0.57 2.8 2.44 0.87 0.52 0.12 0.08 <0.002 3.2 274 82 <20 16.3 113.5 169.4 33.7 14.8 8.6 24 4.2 99.92 BC 504 PR 184.328N; 334.424E muscovite arkosic metasandstone Opm 85.17 8.63 1.44 0.22 0.01 0.08 1.5 0.36 0.02 <0.01 0.007 24.8 989 7 <20 3.2 4.3 82 53.4 32.9 6.7 12 2.3 99.87 BC 723 PR 183, 1 10N; 327,961 E biotite-qarnet metasandstone Opm 77.55 8.8 8.32 0.44 0.14 0.54 3.52 0.38 0.06 0.1 0.022 8.7 637 54 46 21.2 55.5 65.9 29.8 14.7 5.2 13 0 99.95 PR 37 NB 171 ,471N; 329.964E muscovite metasandstone Opmq 77.49 12.42 2.07 0.54 <0.01 0.05 2.53 0.20 0.02 0.02 <0.002 24 1166 23 <20 <20 2 119 <30 13 <5 10 4.5 100.01 PR 43 NB 170,958N; 329.155E kvanite-qamet metasandstone Opmq 78.92 5.53 11.99 1.20 0.51 <0.01 0.01 0.28 0.08 0.51 0.004 52 65 44 <20 21 5 56 84 19 <5 7 0.9 100.00 PR 12 BC 176,082N; 331.658E homblende-biotite quartz syenite orthoqneiss CZhqf 57.01 19.52 4.91 1.59 3.66 3.45 5.97 0.77 0.34 0.09 <0.002 24 2480 56 <20 <20 760 1520 107 25 13 9 2.1 99.98 PR 90 NB 170.859N; 334,371 E qabbroic orthoqneiss CZhq 52.32 16.10 8.71 7.02 11.00 2.64 0.73 0.17 <0.01 0.18 0.021 8 138 56 39 34 194 19 <30 6 <5 45 0.9 99.87 PR 114 NB 172.302N; 333.898E hornblende tonalite qneiss CZhq 67.36 15.64 4.02 1.20 5.29 2.54 0.23 0.26 0.04 0.06 <0.002 21 97 33 <20 <20 112 64 <30 15 <5 19 3.3 100.00 PR 242 NB 172.484N; 335,01 1E epidote-biotite tonalitic qneiss CZhq 74.24 13.32 2.80 0.72 3.63 2.56 0.80 0.18 0.03 0.03 <0.002 84 240 21 <20 <20 160 127 <30 <3 <5 4 1.6 100.01 BC 602 PR 178.729N; 328.747E biotite felsic qneiss CZhq 72.07 14.77 2.01 0.32 1.29 3.01 5.71 0.13 0.07 0.02 <0.002 3 1204 17 <20 2.1 281.4 113.7 38.8 7.2 4.9 2 0.4 99.95 NB 509 PR 184,492N; 332.755E biotite-muscovite felsic qneiss CZhq 71.29 14.9 2.04 0.36 0.2 3.3 5.31 0.31 0.49 0.02 <0.002 3.2 1586 23 <20 1.8 328.8 199.4 161.4 10.2 7.9 2 1.5 99.87 BC 457 PR 178.254N; 334, 402 E biotite-hornblende quartzofeldspathic qneiss CZhq 59.54 15.65 7.99 2.44 7.88 2.39 0.99 0.57 0.14 0.14 0.01 91.3 282 49 21 18.8 445 213.1 51.5 17.1 7.7 23 2.1 99.82 PR 196 NB 174.732N; 334, 420 E altered ultramafic CZau 45.00 7.30 11.66 23.09 4.60 0.25 0.03 0.53 0.04 0.18 0.336 42 39 85 957 82 7 26 <30 16 <5 20 6.4 99.62 NB 396a PR 184,492N; 330.457E altered meta-pvroxenite CZau 51.85 6.42 8.85 17.89 11.02 0.7 0.13 0.21 <0.01 0.16 0.296 68.2 24 6 278 51.6 29.8 14.6 5.3 8.4 0.5 52 2.1 99.66 PR 142 NB 175.037N; 327.725E biotite qneiss CZtfb 62.36 16.92 6.29 2.13 3.88 2.93 2.87 0.78 0.22 0.09 0.002 8 860 96 <20 <20 330 438 148 25 17 13 1.3 99.97 PR 252 BC 171.058N; 335.987E amphibolite CZtfb 47.64 14.29 17.67 5.01 7.15 3.12 0.67 2.37 0.06 0.27 0.002 28 43 115 <20 38 135 107 <30 41 <5 43 1.5 99.85 BC 761 PR 180.247N; 330.537E biotite qneiss CZtfb 63.08 16.84 6.47 1.89 3.3 3.46 2.75 0.72 0.19 0.1 0.003 7.7 549 104 <20 11.2 277 372 119.2 33.7 18.1 13 1 99.83 BC 592 PR 182,923N; 327.104E quartz amphibolite CZtfb 54.14 14.77 13.31 3.42 6.01 5.03 0.13 1.91 0.29 0.24 <0.002 56.8 29 21 <20 24.3 137.1 137.5 18.3 49.3 3.1 31 0.6 99.87 BC 767 PR 179.785N; 330. 776 E biotite meta-melaqabbro CZtfb 37.5 14.92 17.4 6.89 12.03 0.92 2.4 3.21 1.76 0.19 <0.002 42 3558 45 <20 56.3 1210.6 134.9 110.7 35.5 10.1 31 1.9 99.55 U.S. National Grid 100,000-m Square ID Grid Zone Designation 17S шг CONTOUR INTERVAL 40 FEET NORTH AMERICAN VERTICAL DATUM OF 1988 This map was produced to conform with the National Geospatial Program US Topo Product Standard, 2011 . Ametadata file associated with this product is draft version 0.6.11 Lake Lure Shingle Hollow North Mill Spring Pea Ridge it lllll :T 1 ' i 1: It . ' I *. South Landrum Fingerville West Fingerville East ф Interstate Route / US Route Q State Route □ FS Primary Route □ R P^r FS High Clearance Route PEA RIDGE, NC 2013 'Whole Rock Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP) analysis conducted by Bureau Veritas, 9050 Shaughnessy St, Vancouver, BC Canada V6P 6E5. 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 ADJOINING 7.5' QUADRANGLES Equal area Schmidt Net projection of contoured poles to foliation. Foliation count 1036. Equal area Schmidt Net projection of contoured poles to mylonitic foliation. Mylonitic foliation count 26. Equal area Schmidt Net projection of contoured poles to joints and unidirectional rose diagram inset. Joint count 775. Equal area Schmidt Net projection of fold hinges in blue and mineral lineations in red. Fold hinge count 8. Mineral lineation count 13. Environmental Quality Unit Contact Fault Contact Form Lines arrows indicate relative motion along fault interpretive patterns of subsurface foliation orientations based upon surficial structural measurements Research supported by the U.S. Geological Survey, National Cooperative Geologic Mapping Program under STATEMAP (Awards - 2015, G15AC00237; 2014, G14AC00230). 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. Bedrock Geologic Map of the Pea Ridge 7.5-minute Quadrangle, Polk and Rutherford Counties, North Carolina By Bart L. Cattanach, G. Nicholas Bozdog, Sierra J. Isard, and Richard M. Wooten Geology mapped from November 2014 to May 2016. Map preparation, digital cartography and editing by G. Nicholas Bozdog, Bart L. Cattanach, Sierra J. Isard 2016 This map supersedes NCGS OFR 2015-04. 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. Some station data omitted from map to improve readability. Please contact the North Carolina Geological Survey for complete observation and thin-section data. EXPLANATION OF MAP SYMBOLS CONTACTS Contact — Identity and existence certain, location inferred Thrust fault — Identity and existence certain, location inferred. Sawteeth on upper (tectonically higher) plate 80 . H-.-j-...? . — j- •-?•••• Normal fault-identity or existence questionable, location concealed. Ball and bar on downthrown block PLANAR FEATURES (For multiple observations at one locality, symbols are joined at the "tail" ends of the strike lines) 64y Inclined metamorphic or tectonic foliation— Showing 7'y Small, minor inclined joint— Showing strike and dip strike and dip Inclined metamorphic or tectonic foliation, for multiple se/ Small, minor inclined joint, for multiple observations observations at one locality — Showing strike and dip У Inclined mylonitic foliation — Showing strike and dip 23y 46y Inclined mylonitic foliation, for multiple observations ' at one locality — Showing strike and dip LINEAR FEATURES у Inclined aligned-mineral lineation — Showing bearing and plunge , 18 Inclined slickenline, groove, or striation on fault / surface — Showing bearing and plunge j, 66 Inclined fold hinge of generic (type or orientation unspecified) / small, minor fold — Showing bearing and plunge NATURAL RESOURCES MIC - Mica STN..C - Stone, Crushed/Broken at one locality — Showing strike and dip P Small, minor vertical or near-vertical joint, for multiple ' observations at one locality — Showing strike OTHER FEATURES о Float station 36 A AA Thin section and whole rock analysis sample location t (•) Heavy mineral sample location X Prospect (pit or small open cut) 'K' Abandoned open pit, quarry, or glory hole lx? Open pit, quarry, or glory hole ? Inclined mine shaft GENERALIZED STRATIGRAPHY AND SEQUENCE OF TECTONIC EVENTS IN CROSS-SECTIONAL VIEW Devonian - Mississippian Peak metamorphism & deformation Breccia Brittle faulting & erosion TRAVERSE MAP Hillshade derived from a six meter pixel resolution LiDAR (Light Detecting And Ranging) digital elevation model. Red lines show paths of field traverses. Pea Ridge 7.5-minute Quadrangle, Open File Map 2016-07