Geologic map of the Garner 7.5-minute quadrangle, Wake and Johnston Counties, North Carolina

North Carolina Department of Environmental Quality This Geologic map was funded in part by the usgs National Cooperative Geologic Mapping Program North Carolina Geological Survey Energy Group Open File Report 2016-14 Jenny Kelvington, Executive Director Kenneth B. Taylor, State Geologist 78°37' 30" 78°30' 00" 35°45' 00" 35°37' 30" Tia**' Ha-S Tphms Tphms Tphms GA215 \ l +k Tphms Tphms 1 phms Tphms GA 069 Tphms GA 091 CZrbg Tphms u GA 055 Tpfms Tphms. Tphms Tphms Tphms Tphms 1 1 1 й \ A 1 Ту - V л \ y---' - * 35°45' 00" 35°37' 30" Qal Ql Tphms Tpfms Plbg PzZng CZrgn CZrbg PzZg CZqfg CZgn UNIT DESCRIPTIONS Qal - Alluvium: Unconsolidated, tan to light gray, stream deposits of sand and gravel, with occasional clay and silt; poorly to well sorted, poorly stratified. Qt - Terrace alluvium: Unconsolidated, tan to light gray, stream terrace deposits of sand and gravel, with occasional clay and silt; poorly to well sorted, poorly stratified. Interpreted to be present in one area along Swift Creek near the Wake/Johnson County line. Coastal Plain Units Tphms - Heavy mineral bearing sand: Sand, silty and clayey, reddish brown, yellow, and pink; fine to very coarse grained; typically fines upward; moderately well to moderately poorly sorted; subangular to rounded. Contains rare to trace heavy minerals, (dominantly dravite and rutile) rare to trace mica; rare to trace rose quartz; and rare to trace amethyst. Massively bedded with upper 5-feet typically having a strong pedogenic overprint which obscures sedimentary structures. Very coarse-grained and medium sand fraction is typically well-rounded and frosted. Lower contact has a sharp erosional contact. Basal portion contains pieces of reworked silicified limestone and lithified sandstone with common fossil impressions; these are presumed to be middle Eocene in age. Thickness ranges up to about 20-feet. Tpfms - Fine micaceous sand: Unit only recognized in cores. Sand, clayey and silty, yellow, light gray and pink to reddish pink. Contains two distinct lithofacies. The upper lithofacies is typically fine-grained sand, but contains coarse silt as well; moderately well to well-sorted; grains are subangular to subrounded. Contains rare to trace heavy minerals often in distinct laminations, trace to minor mica, and rare to trace white feldspar. Sedimentary structures include laminations, flaser bedding, and burrows. The lower lithofacies consists of coarse- to very coarse-grained quartz sand with distinct beds of coarse-grained silt; poorly to moderately sorted; grains are angular to subangular. Contains rare to trace heavy minerals, trace to minor coarse mica, rare to trace white feldspar, and rare rose quartz. Massively bedded, silt beds are laminated and contain lenticular beds. Contact between the upper and lower lithofacies is gradational. Intrusive Rocks Jd - diabase: fine to medium-grained, equigranular to locally plagioclase porphyritic diabase, typically olivine-bearing. Commonly weathers to black to tan-gray, spheroidal boulders and cobbles. Occurs in vertical to steeply dipping dikes. The traces of some of the dikes on the Garner quadrangle are inferred on the basis of linear magnetic highs. Other dike locations are inferred from the location of float. Refer to explanation for details. Plbg- Lake Benson Pluton: medium-grained, locally porphyritic biotite granite. May contain white mica, epidote, allanite, and zircon. Rolesville Batholith Prg - Rolesville main granite: medium- to coarse-grained biotite + muscovite monzogranite with a color index of 2-10 named by Farrar (1985). The Rolesville main granite varies in appearance, with a range in color index and grain size, development of a foliation, as well as the presence or absence of subhedral alkali feldspar megacrysts. This variation may result from a number of still unrecognized granitoid facies. It is notable for its friable nature. This granitoid is ubiquitous in the Rolesville pluton, and occupies the largest surface area at the present level of erosion. (Description from Speer, 1994) The southern portion of the Garner quadrangle may have local occurrence of the Archers Lodge phase of the Rolesville Batholith. Archers Lodge granitoid: a coarse-grained biotite monzogranite with alkali feldspar megacrysts up 3 cm long. (Description from Speer, 1994) Raleigh Terrane PzZng - Nottingham granitoid orthogneiss: streaky to weakly banded, generally moderately well foliated, locally porphyritic, tan, light brown, or brownish -orange biotite granitic orthogneiss. Contains local biotite-rich enclaves which may be xenoliths; epidote, titanite, and white mica are interpreted as products of metamorphic and/or low-temperature alteration. CZrgn - Raleigh gneiss: mixed unit consisting mainly of fine- to coarse-grained, well foliated, compositionally layered, and locally lineated biotite granitoid gneiss, and lesser amounts of biotite + hornblende gneiss, biotite schist, white mica +/- sillimanite schist, metagabbro, and amphibolite. The unit is locally intruded by dikes of pink to gray granitic pegmatite and white to gray graphic granite. CZrbg - Biotite granitic orthogneiss: medium-grained, weakly banded, weakly porphyritic, well foliated granitic gneiss. Phenocrysts are alkali feldspar; also contains white mica, epidote, and titanite. Rocks of Uncertain Affinity PzZg - granitoid: medium- to coarse-grained, light gray to pale pink, massive to slightly foliated granitoid composed of quartz, plagioclase, k-feldspar, muscovite, biotite, epidote, chlorite, and garnet. Locally, contains clusters of biotite and muscovite. CZqfg - quartzofeldspathic gneiss and schist: fine- to coarse-grained, white to light gray, well foliated, quartzofeldspathic gneiss. Contains interlayers of light gray to pale pink felsic gneiss, white to gray, fine¬ grained muscovite schist, quartz- muscovite schist, biotite schist, and greenish-black to black amphibolite. CZgn - felsic gneiss: pinkish-gray to tan-white, fine- to medium-grained poorly to well foliated, weakly banded microcline-plagioclase-quartz-white mica gneiss and leucogneiss, locally with magnetite. REFERENCES: Clark, T.W., Blake, D.E., Stoddard, E.F., Carpenter, P.A., III, and Carpenter, R.H., 2004, Preliminary bedrock geologic map of the Raleigh 30’ x 60' quadrangle, North Carolina: North Carolina Geological Survey Open-file Report 2004-02, scale 1:100,000, in color. Farrar, S.S., 1985, Stratigraphy of the northeastern North Carolina Piedmont: Southeastern Geology, v. 25, p. 159-183. Speer, J.A., 1994, Nature of the Rolesville Batholith, North Carolina, in Stoddard, E.F. and Blake, D.E., eds., Geology and Field Trip Guide, Western Flank of the Raleigh Metamorphic Belt, North Carolina, Carolina Geological Society Guidebook for 1994 Annual Meeting, p. 57-62. EXPLANATION OF MAP SYMBOLS CONTACTS, FAULTS, AND OTHER FEATURES - contact - location inferred . contact - location concealed - brittle fault - location inferred . brittle fault - location concealed f 58 Strike and dip of biotite foliation ^ Strike of biotite foliation, dip unknown [ 78 Strike and dip of inclined joint surface <j> во Strike and dip of schlieren т Strike of schlieren, dip unknown - diabase dike - location inferred diabase dike - location concealed diabase - inferred from aeromagnetic data or stream patterns ^ 72 Strike and dip of inclined regional foliation Strike of inclined regional foliation, dip unknown ^ Strike of vertical regional foliation 45 Trend and plunge of lineation Trend of oriented inclusion Ы Coastal Plain mapping station location • Diabase station location 0 Bedrock mapping station location GA 1 91 + Coastal Plain hand auger location and number Locations with multiple symbols (present as elongate or wider-than normal symbol clusters) indicate collection of hand auger data from multiple depths. ^ Crushed stone quarry - active Base topographic map is digital raster graphic image of the Garner 7.5 minute USGS quadrangle (1993). 61/2 116 MILS 1 27' 26 MILS UTM GRID AND 1981 MAGNETIC NORTH DECLINATION AT CENTER OF SHEET SCALE 1:24 000 1 _ 05 _ 0 _ 1 I I I I I I I I I I I I Miles 1 , 000 500 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 III I I I I - I I - IFrrI 1 0.5 0 1 I — I I — I I — I I — I I — I I 3 Kilometers CONTOUR INTERVAL 10 FEET RALEIGH WEST RALEIGH EAST KNIGHTDALE LAKE WHEELER GARNER CLAYTON ANGIER EDMONDSON POWHATAN ADJOINING 7.5' QUADRANGLES Rolesville Batholith geology mapped 1992 - 1994. Supported by the U.S. Geological Survey under assistance award #1434-93-A-1165 through the North Carolina Geological Survey. Geologic units in the Raleigh terrane portion of the quadrangle from Clark and others (2004). Johnston County portion mapped 1993 - 1994 by Edward F. Stoddard. Coastal Plain mapped by John G. Nickerson and Norman K. Gay in 2000 - 2001 with partial support from USGS Statemap program award #00HQG148 (2000). Data entry of A. Speer field notes by Anna Katerina Pascht Compiled Geologic Map of the Garner 7.5-minute Quadrangle, Wake and Johnston Counties, North Carolina Geology by J. Alexander Speer (Rolesville Batholith portion) Edward F. Stoddard (Johnston County portion of map area) John G. Nickerson and Norman K. Gay (Coastal Plain) Digital representation by Michael A. Medina, Philip J. Bradley and Heather D. Hanna 2016 (Version 9/30/2016) 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. 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 Garner 7.5-minute Quadrangle, Open File Report 2016-14