Compiled geologic map of Durham County, North Carolina

MAPUNITS Qal Qt alluvium(Qal) QUATERNARY terracedeposits(Qt) QUATERNARY/ K/Tu post-ChathamGroupundiffferentiatedsediments Jd Jd-recon a ase(Jd) MEZOZOIC diabase-reconnaissance(Jd-recon) TriassicSedimentaryRocks DeepRiverBasin:DurhamSub-basin MESOZOIC ChathamGroup ChathamGroup ChathamGroup Trfb Faultbreccia LithofaciesAssociationI LithofaciesAssociationII LithofaciesAssociationIII Trcs/si1 Trcs/si2 Trcsi/s Trcs Trcs/c Trcsc Trcc Conglomeratesofthewestern Trccw borderoftheChathamGroup CarolinaTerrane EasternmostCarolinaTerraneVirgilinaSequence-AaronFormation MetaintrusiveRocksReedyCreekmetagranodiorite(Zrg); Zrg Zbdi Zbgb metasedimentaryrocksassociated eaver amdiorite(Zbdi); NEOPROTEROZOIC with ZA a aronFormation can BeaverdamGabbroandmetapyroxenite(Zbgb)Metavol icandMetasedimentaryRocks Zbr1 BigLake-RavenRockschist1(Zbr1)? HycoFormation metantrusiverocksassociatedwithHycoFormation:upperportion (stratigraphicrelationsuncertain) ca.612-614Ma(Wortmanetal.,2000) Zmpf Zgms Zagms Zdim PMolurtoniahicPrlouctonksfaeslssioccpiahtaesdew(iZthmpthfe);FglraanotRidvieorricteomptonalelxitearoeafthoefMStcemConneandllMoanrdiaGhlopvluetron(1s9(8Z2gm): s); alteregranodioriteandgraniteoftheMoriahpluton(Zagms);dioriteoftheMoriahpluton(Zdim); granodioriteandgraniteoftheMoriahPlutonfromMcConnellandGlover,1982andMcConnell,1974(Mpf); Mpf Mpm Mpd tonalite,quartzdacite,anmnorgabbrooftheMoriahPlutonfromMcConnellandGlover,1982and McConnell,1974(Mpm);daciteoftheMoriahPlutonfromMcConnellandGlover,1982andMcConnell,1974(Mpd); Zgd Zgd-gr-p fine-grainedgranodiorite(Zgd);granodioritetograniteofPineyMountainCreekarea(Zgd-gr-p) Zdi diorite(Zdi) foliatedtohighlyfoliatedzonesindicatedwithhatchedoverlay metamorphosedvolcaniclasticsedimentaryandpyroclasticrocks associatedwithHycoFormation:upperportion(stratigraphicrelationsuncertain) ca.613-616Ma(Wortmanetal.,2000;Bowman,2010;andBradleyandMiller,2011)Zq Zhat(u) quartzbodies(Zq);alteredtuffs(Zhat(u))Zhe/p Zhe/pl mixedepiclastic-pyroclasticrocks(Zhe/p);mixedepiclastic-pyroclasticrockswithinterlayereddaciticlavas(Zhe/pl)Zhablt andesitictobasalticlavasandtuffs(Zhablt) Zhdlt-a Zhadlt Zhdlt(u) altereddaciticlavasandtuffs(Zhdlt-a);andesitictodaciticlavasandtuffs(Zhadlt); Zhdsi(u) daciticlavasandtuffs(Zhdlt(u));daciticshallowintrusive(Zhdsi(u))A1 Z intermediatevolcanicrocksfromMcConnellandGlover,1982andMcConnell,1974(A1); FelsicpyroclasticrocksfromMcConnellandGlover,1982andMcConnell,1974(Z)foliatedtohighlyfoliatedzonesindicatedwithhatchedoverlay ? metamorphosedvolcaniclasticsedimentaryandpyroclasticrocks associatedwithHycoFormation:lowerportion(stratigraphicrelationsuncertain) ca.629-633Ma(Wortmanetal.,2000andBradleyandMiller,2011) Zhat(l) Zhft(l) alteredtuffs(Zhat(l));felsictuffs(Zhft(l)) Zhdlt(l) Zhdsi(l) daciticlavasandtuffs(Zhdlt(l));daciticshallowintrusive(Zhdsi(l)) 7852'30" 8671 82 Zhe/plZhe/pl 87 Zhdlt(u) 78 74 SC-16 83 Zhe/p84l Zhe/pl 88 88 78 8775 A1K-116 K-14 K-55 Mpf C-5Zhdsi(u) 88 76 SC-11 88 87Za 82 68 Zhdlt(u) 74 Q8a7l Zhe8/4pl Z Zhdlt u 75 8880 Zhe/pl 79 84 C-4 8189 8188 Zhdlt(u) 77 5 75 88 Zhd8s6i7(u6) 87 Z Zgms C-3 80 88 83 89 88 8886 85 84 6882Zhat(u) SC-22andSC-22A 80 82 Zhdsi(Cu-)277 81 81 Zfgms 70 7849 79 74 Zhdlt(u) Zhablt 85 K-10 SC-12 48 85 88 Zmpf43 7887 Qal Zhfdlt-a 8665 81 Zhe/pl Jd K-58 Zgms SC-4 88367686 86 Zhdlt(u) 78 79 K-98 Zfgms Zhe/pl 86 Zhdlt(u) 68 8784 Mpf K-96 Zfgms Zhdlt-a 72 88 78 80 Zhdlt(u) 81 K-1 84 Zfagms 76 7784 8478 5575 72 77 8881 K-3 ZagmsZhdlt(u) 8688 88 80 76 Zhdlt(u) 77 40 K-87Zhablt 79 88 77 K-71 K-70 Zgm6 s 8 Zfagms Zhdsi7(0 u)8481 80 Zhdlt(u)88 88 71 8488 81 K-72 K-68 Zhfdlt 7Z0fgms 75 8774 Zgms K-50 62 Zhfdsi 51 81 Zhdlt(u) K-39 70 K-51 Zhablt 74 74 8777 9 72 Zhfdsi Zgms 82 8884Q88al 8287 8125 K-7 Zhdlt(u) Zagms 71Zfgms 66 84 Zhdlt(u) Zhe/pl 81 75 Zgms 72 80 Zhfdlt Zhdlt(u) 8435 78 55 66 77 Zhdlt(u) 85 Jd 77 88 Zdim 5066 82 82 81 Zhdlt(u) 77 8480 73 Zhe/p 65 Zdim Zdim 680582 72 43 808284 7784 A1 Zhe/pl 80 86 7888 88 75 Zgms 85Qal 15 8344 86 Zmpf Zfgms 84K-48 82 Zhfe/pZdi 21 80 Zhdlt(u) 72Zdi 84 F Zhe/pl 77 60 82 65 Zhe/p 8Q6al 82 7986 Zhdlt(u) Zagms 70 83 Zhdlt(u) Zhe/pl 75 89 88 Qal 81 Zhe/pl 82 8174 81 Zdim 85 Zhe/p 82 85 Zhdsi(l) Zhdlt(l) 85 Zhdlt(u) 88 81 Zhfe/p 84 Mpm K-32 80 85 8886 70 Zfdim Trcs/si1 Trcs/si2 83 74 76 79 Zmpf 8Mpf Zhe/p 10 5 86 MpdK-36 K-40 Jd-recon Qal 83 Zhe/p 86 Zhdlt(l) 74 3607'30" 3607'30" 83 77 Zdi Zhds7i4(u) 88 69 Qal Zgd Trcs/si1Zh 7 d 1 lt(l)88 7776 73 81 Zhdsi(l) Qal 73 81 Zq Qal 81 89 58 71 Qal 70 79 A Zhe/ p 80 74 Zdi Zhe/ p 86 Zhdlt(l) Q a Qal l Zhdlt(l) Zhdsi(l) Qal 83 64 Qal Zhft(l) Q 72 l 34 a 81 84 78 7786 Z7h1dlt(l)4 83 60 NWD-115 Qal 76 82 Z LOCATIONOFDURHAMCOUNTY CONTACTS Lithologiccontacts-Distributionandconcentraton ofstructuralsymbolsindicatesdegreeofreliability. Contactdashedwhereinferred. Contactdotedwhereconcealed.gradationalcontact DU REFERENCES EqualAreaSchmidtNetProjectionsandRoseDiagramAllmendinger,R.W.,Cardozo,N.C.,andFisher,D.,2013,StructuralGeologyAlgorthms:Vectors&Tensors:Cambrdge,England,CambridgeUniversityPress,289p. PlotsandcalculationscreateusingStereonetv.8.6.0basedon ain,G.L.,andHarvey,B.W.,197,FieldguidetothegeologyoftheDurhamTriassicbasin:CarolinaGeologicalSociety,FortiethAnnualMeeting,October7-9,1977,GeologyandMineralResourcesSection,Raleigh,84p. Allmendingeretal.(2013)andCardozoandAllmendinger(2013) ae,..,chronce,A.G.,Smith,B.C.,andKendall,J.M.,2009,GeologicmapoftheStem7.5-minutequadrangle,GranvilleCounty,NorthCaroina:NorthCarolnaGeologicalSurveyOpenfileReport2009-02,scale1:24,00,incolor. 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ContouredPolestoPrimaryBedding, ilson,W.F.,andCarpenter,P.A.,197,SuperconductingSuperCollider:Location,geology,androadlo.Open-filereport97-2.NorthCarolinaGeologicalSurvey:Raleigh. Layerng,andWelding/Compaction Meanvector=325degrees ortman,G.L.,Samson,S.D.,andHibbard,J.P.,200,PreciseU-PbzirconconstraintsontheearliestmagmatichistoryoftheCarolinaterrane,JournalofGeology,v.108,p.321-338. FoliationinMetamorphicRocks. Wright,J.E.,1974,GeologyoftheCarolinaslatebeltinthevicinityofDurham,NorthCarolina,unpublishedM.S.thesis,VirginiaPolytechnicInstituteandStateUniversity,78p. ContourInterval=2sigmaN=91 COMPILEDGEOLOGICMAPOFDURHAMCOUNTY,NORTHCAROLINA Compiledby:HeatherD.HannaandPhilipJ.BradleyGeologyby(inalphabeticalorder):RandyBechtel,DavidE.Blake,PhilipJ.Bradley,TimothyW.Clark,PatriciaG.Gallagher,N.KennyGay,HeatherD.Hanna, CharlesW.Hoffman,KeithI.McConnell,CindyM.Phillips,DanielL.Rhodes,AmyN.Ward,MaryE.Watson,ChannaWitanachchi. Fieldandlogisticalsupportby:JoshuaD.April,AmyL.Gross,JacobM.Kendall,RobertH.Morrow. MappreparationandeditingbyHeatherD.Hanna,PhilipJ.BradleyandMichaelA.Medina DigitalrepresentationbyMichaelA.Medina,HeatherD.HannaandPhilipJ.Bradley 2016 74 hdlt(l)Ql 88 81 a Trcs/si Q 82 al Tr 70 Tr ccw Trcs/si 1 Q t Qal Jd Trcs/si 2 66 72 Trcs/si 1 ccw 82 1 82 18 Zhdlt(l) Trcs/si 1 QQ t Qal a l Trcs/si 2 Tr ccw Zhf t (7l)0 85 62 83 Qal Qal 75 79 Jd 7770 987 8555 Qal 88 8 Zhadlt Zgd 89 Zhadlt Qal Qal75 10 Jd d dlQ8a0 Z 67 684 86 Zh NWD-49si(u) 50 76 7 Zhat(l) 73 66Q Jd 75 Qal 73 p Zhe/ Qal 65 68 655 5 Q 77 l 8 4Qal 77 78 68 Trcs/si 79 a 75 Z 71 78 76 76 85 76 Zhd i(u) hdsi(u) 79 81 Q a l 69W -12 84 Trc 17 N s/ s i 75 D 1 3 7 Qal 76 h 2 Z1 7 a t l 86 63 s a l 65 Zgd� gr-p 83 Trcs/si Qal Qal 85 Z Jdh Jd T 63 rcc Z 76 ds h e/pl (u 75 83 10 B-2 67 i ) Z Trh cs adl /sit 69 6 79B Qal 409 - 1 Jd Jd Jd 1 82 J hadl t d w 1 56 47 Z Trcs hdsi /si 1 Trcs/siJd 79 Jd 1 Qal Qal Trcs/si 2 ThisgeologicmapwasfundedinpartbytheUSGSNationalCoperativeGeologicMappingProgram. INTRODUCTIONPre-MesozoiccrystallinerocksinnortheasernandnorthernDurhamCountyareparoftheredefinedHycoArc(Hibbardetal.,3withintheNeoproterozoictoCambrianCarolinaerraneoftheCarolinaZone(Hibbardetal.,2002;andHibbardetal.,2006;Hibbardetal.,2013).Withinthemaparea,theCarolinaterranecanbeseparatedntotwolithotectonicunits:1)theHycoFormationoftheHycoArcand2)theAaronFormatonoftheredefinedVirgilinasequence(Hibbardetal.,2013).AgedatesfromDurhamandOrangeCounty havedfferentiatedtheHycoFormationintoaca.633-629Malowermember(Wortmanetal.,200;andBradleyandMiller,201)andaca.616-612Mauppermember(Wortmanetal.,2000;Bowman,2010;andBradleyandMiller,201).InDurhamCounty,theHycoFormationconsistsoflayeredmeta-volcanicasticandmeta-plutonicrocks.TheAaronFormation,whichiscomposedofmetamorphosedlayeredvolcaniclasticrocks,yieldsdetritalzirconagesasyoungas578and588Ma(Samsonetal.,201andPollock,207, respectively).Deformationandlow-grademetamorphismofboththeHycoArcandtheAaronFormationoccurredduringtheca.578to554Ma(Pollock,207)Virgilinadeformation(GloverandSinha,1973;HarrisandGlover,1985;HarrisandGlover,1988;andHibbardandSamson,1995).Inthemaparea,originallayeringofHycoandAaronFormationlithologiesareinterpretedtorangefromshallowlytosteeplydippingduetoopentoisoclinalfoldsthatarelocallyoverturnedtothesoutheast.HycoFormationunitsofmeta-volcaniclasticrocksincludevariousithologiesthataregroupedtoethertorepresentinterpretedenvironmentsofdeposition(orlithofacies).Thedaciticlavasandtuffsunitisinterpretedtorepresentdaciticdomesandproximalpyroclastics.Thefelsictuffsunitisinterpretedtobedistallydepositedairfalltuffsandassociatedvolcanosedimentaryrocks.Theandesitictobasalticlavasandtuffsunitisinterpretedtorepresenteruptionofintermediatetomaficlavaflowsandassociatedpyroclastics.The epiclastic/pyroclasticunitsareinterpretedtobedepositsofactivevolcanicsanderodedvolcanichighlands.TheVermiformaantiquafossillocalityreportedbyCloudetal.(1976)ispresentwithintheHycoFormation(uppermember)alongtheSouthForkoftheLitleRiver.Seilacheretal.(200)indicatesthefeaturemaybeatectographinsteadofatruefossil.AsmallsectionoftheCarysequence(Parker,1979;Farrar,1985)oftheEasternmostCarolinaterrane(Blakeetal.,2012)islocatedinthesoutheasternsectionofthemap.Azirconagedateofca.575MawasreportedbyGoldberg(194)fortheBigLake-RavenRockschistunit.ThisdatemayindicatethattheEasternmostCarolinaterraneisequivalenttotheAaronFormationoftheredefinedVirgilinasequence(Hibbardetal.,2013).InDurhamCounty,theCarysequenceiscomposedofuppergreenschistfaciesmetaplutonicrocksof theBeaverdamComplexandmeta-volcaniclasticrocks.ThecentralandsouthernportionsofDurhamCountyarepartoftheTriassic-agedDurhamsub-basinoftheDeepRiverMesozoicbasin.Lithologiesinthebasinincludevariouslyinterlayeredmudstones,siltsones,sandstones,andconglomerates.GenerallythebasinisdominatedbyinterlayeredconglomeratesandsandstonesproximaltotheJonesboroFaultandincrementallyfinesawayfromthefault.Jurassic-ageddiabasedikesandsillsintrudebasinsediments.DiabasedikesalsointrudethecrystallinerocksoftheCounty.The Durhamsub-basinlacksmarkerbeds,makingtheidentificatonofformalformationsdifficult(Clarketal.,2001).Instead,analternatemethodofithofaciesassociationsisusedtogroupsedmentaryrocksoftheDurhamsub-basinbasedonlithologyandinterpreteddepositionalenvironment(HoffmanandGallagher,1989;Watson,1998;andClarketal.,201).LocationoftheLithofaciesAssociationIandIcontactintheNortheastDurhamQuadranglewasmodifiedfromSpencer(1987)toedgematchwithHoffmanandGallagher (1989)contacts.ThiscontactwasextendedintotheLakeMichieQuadrangletoedge-matchwiththeNortheastDurhamGeologicmap(Phillipsetal.,2004(revised2010).ExtentofdiabasesillsintheNorthwestDurhamQuadrangleweremodifiedfromSpencer(1987).TheformerTriangleBrickpitinsoutheastDurhamCountyisaworld-classTriassicfossillocalityintheTrcsi/sunit.Recoveredspecimensincludeplants,invertebrates,andvertebrates.Clarketal.(2001)andPeyeretal.(2008)provideadditionalinformationandreferencesrelatedtofossilsrecoveredfromtheTriangleBricksite.Allpre-MesozoicrocksinDurhamCountyhavebeenmetamorphosedtoatleastthechloritezoneofthegreenschistmetamorphicfacies.Manyoftherocksdisplayaweakorstrongmetamorphicfoliation.Althoughsubjectedtometamorphism,therocksretainrelictigneous,pyroclastic,andsedimentarytexturesandstructuresthatallowfortheidentificationofprotolithrocks.Assuch,theprefix�meta�isnotincludedinthenomenclatureofthepre-Mesozoicrocksdescribedinthequadrangle.Jurassicdiabaseisnotmetamorphosed.ThenomenclatureofheInternationalUnionofGeologicalSciencessubcommissiononigneousandvolcanicrocks(IUGS)afterLeMaitre(2002)isusedincassificationannamingoftheunits.Theclassficationandnamingoftherocksisbasedonrelictigneoustextures,modalmineralassemblages,ornormalizedmneralassemblageswhenwhole-rockgeochemicaldataisavailable.PastworkerswithintheCountyandadjacentareas(BainandHarvey,1977;Hortonetal.,1992;McConnell,1974;McConnellandGlover,1982; Spencer,1987;Wright,1974)haveusedvariousnomenclaturesystemsfortheigneousrocks.Therawdata,whenavailable,oftheseearlierworkerswasrecalculatedandplotedonternarydiagramsandclassifiedbasedonIUGSnomenclature.PyroclasticrockterminologyfollowsthatofFisherandSchminke(1984).TriassicunitsfollowthenomenclatureofClarketal.(2001)andHoffmanandGallagher(1989).ApreliminaryreviewoftheareageologyisprovidedinBradley(2013).ThismapisacompilationofmodifiedandediteddatafromtheDurhamCountyportionsoftheRougemont(Bradleyetal.,201),LakeMichie(Rhodesetal.,2012;McConnell,1974),NorthwestDurham(Bradleyetal.,204),NortheastDurham(Phillipsetal.,2004),Creedmoor(Clarketal.,2002),ChapelHill(Bradleyetal.,2004),SouthwestDurham(HoffmanandGallagher,1989),SoutheastDurham(HoffmanandGallagher,1989),Raleigh30�x60�(Clarket al.,2004),Farrington(Bradleyetal.,207),andGreenLevel(Watson,1998)geologicmaps. DESCRIPTIONOFUNITSSedimentaryUnitsQal�Alluvium:Unconsolidatedpoorlysortedandstratifieddepositsofangulartosubroundedclay,silt,sandandgravel-tocobble-sizedclasts,instreamdrainages.Mayincludepointbars,terracesandnaturalleveesalonglargerstreamfloodplains.StructuralmeasurementsdepictedonthemapwithinQalrepresentoutcropsofcrystallinerockinlierssurroundedbyalluvium.Qt�Quaternaryterracedeposits:Unconsolidatedclay,silt,sandandpebblesonflatplainabovecurrentfloodplainlevel;cobbleandboulderfloat(upto40cmdiameter)consistingofdiabase,granodioriteandvariousvolcanics(tuffsandlavas).K/Tu�post-ChathamGroupundifferentiatedsediments:Yellowish-orangetobrownish-yellowtoyellowish-gray,unconsolidatedofriableunitthatconsistsofdistincivesubroundedtowell-roundedgranules,pebblesandsmallcobblesofwhite-torose-coloredquartzinterlayeredwithclay,sandy-clayandclayey-sand.Lesseramountsofmoderatelyindurated,yellowish-white,medium-tocoarse-grainedarkosicsandstonepresent.UntismainyexposedonshoresofB.EveretJordanLake.Unitisinunconformablecontactwith Triassicsediments.Unitoutcropsinfewlocationsatoraboveapproximately250feetelevation.Assuch,unitextentinterpretedfromtopographywhenstationlocationdataaresparse.DistributionofunitintheSouthwestDurhamandChapelHillQuadranglesoftheCountywereinterpretedfromedgematchingwithgeologicmapsofGreenLevel(Watson,1998)andFarringtonquadrangles(Bradleyetal.,2007).AdetailedunitdescriptionisavailableinWatson(1998).TRIASSICBASINSEDIMENTSTrcs/si1�SandstonewithinterbeddedsiltstoneoftheChathamGroupLithofaciesAssociationI:Graysh-pink,pinkish-gray,andlight-gray;fine-tocoarse-grained,mcaeous,slightyclayey,moderatelypoortomoderatelywellsorte,subangulartosubroundedarkoseandlithicarkose;darkredtoreddish-brown,verysilty,micaeous,moderatelywellsorted,fine-grainedsandstone;anddarkredtoreddish-brown,massive,andthicklylamnated,bioturbated,micaeoustoverymicaeous,siltstoneandmudstone.Muscoviteflakesup to3mmdiameterarecommonespeciallyinthesiltstone.Fine-grainedflakesofbiotiteinthearkoseandlithicarkoseisadistinctiveaccessory.Randomlyorientedandvertical,cylindricalstructuresoftenfilledwithpale-green,fine-grained,quartzsandstoneareinterpretedasburrows.Bedding,whenobserved,isparalleltoslightlywavy,occurringasthicklaminationstothinlybedded(0.5cmto5cm).TheserocksareassignedtotheLithofaciesAssociationIofHoffmanandGallagher(1989),Watson(1998),andClarketal.(201).Trcs/si2�SandstonewithinterbeddedsiltstoneoftheChathamGroupLithofaciesAssociationI:Cyclicaldepositonalsequencesofwhitish-yellowtograyish-pinktopalered,coarse-toverycoarse-grained,troughcross-beddedlithicarkosethatfinesupwardthroughyellowtoreddish-brown,medium-tofine-grainedsandstone,toreddish-brown,burrowedandrootedsiltstone.Bioturbationisusuallysurroundedbygreenish-bluetograyreductionhalos.Coarse-grainedportionscontainabundantmuscovite,andbasalgravellags consistofclastsofquartz,bluish-grayquartzcrystaltuff,andmudstonerip-ups.TheserocksareassignedtotheLithofaciesAssociationIofHoffmanandGallagher(1989)andClarketal.(2001).Trcsi/s-SiltstonewithinterbeddedsandstoneoftheChathamGroupLithofaciesAssociationI:Reddish-brown,extensivelybioturbate,micaceoussltstone;locallycalcareouswiththin,discontinuousstringersoflmestoneandchertorzonesofcalcareousconcretionsandironnodules.Interbeddedsandstoneistypicallyfine-tomedium-grained,micaceous,feldspathic,andusuallylessthanonemeterthick.Locallycontainssparselaminatedtothin-beddedreddish-brownshalewithconchostracansandostracods.Worldclass TriangleBrickfossillocalityfromunitinDurhamCountywithlocationindicatedonmap.SeeClarketal.(2001)andPeyeretal.(2008)foradditionalfossilinformation.TheserocksareassignedtotheLithofaciesAssociationIofHoffmanandGallagher(1989)andClarketal.(2001).Trcs�Interbeddedsandstone/pebblysandstoneoftheChathamGroupLithofaciesAssociationI:Reddish-browntodarkbrown,irregularlybeddedtomassive,poorlytomoderatelysorted,medium-tocoarse-grained,muddylithicarkoses,withoccasional,matrix-supportedgranulesandpebblesoras1-5cmthickbasallayers.Muscoviteiscommontoabsent.Occasionalbioturbationisusuallysurroundedbygreenish-bluetograyreductionhalos.Bedsaretabular,1-3metersthick,withgoodlateralcontinuity.Unitgrades eastwardintoTrcs/c.ThisunitdescriptionfromClarketal.(2001)combinestheTrcsandTrcscunitsofHoffmanandGallagher(1989).Trcs/c-SandstonewithinterbeddedconglomerateoftheChathamGroupLithofaciesAssociationI:Reddish-rowntodarkbrown,irregularlybedded,poorlysorted,coarse-grainedtopebbly,muddylithicsandstoneswithinterbeddedpebbletocobbleconglomerate.Muscoviteisraretoabsentinthematrix.Well-definedconglomeratebedsdistinguishthisunitfromconglomeratebasallagsofTrcs.Anarbitrarycut-offoflessthan50percentconglomeratedistinguishesthisunitfromtheTrccconglomeratefacies.Conglomerate bedsarechannel-shapedandscourintotheunderlyingsandstonebeds.UnitgradeseastwardintoTrcc.UnitdescribedbyClarketal,(201)andHoffmanandGallagher(1989).Trcsc-PebblysandstoneoftheChathamGroupLithofaciesAssociationI:Reddish-brown,pebbly,poorlysorted,coarse-grained,lithic,feldspathicsandstone;locallycontainslaterallydiscontinuouspebbleandcobbletrainsandconglomeraticchannellags.DescriptionfromHoffmanandGallagher(1989).Trcc�ConglomerateoftheChathamGroupLithofaciesAssociationI:Reddish-browntodarkbrown,irregularlybedded,poorlysorted,cobbletoboulderconglomerate.Muscoviteisraretoabsentintheverycoarse-grainedtogravellymatrix.Anarbitrarycut-offofgreaterthan50percentconglomeratedistinguishesthisunitfromtheTrcs/cfacies.Clastsarechieflymiscellaneousfelsicandintermediatemetavolcanicrocks,quartz,epidote,bluish-grayquartzcrystaltuff,muscoviteschist,andraremeta-graniticmaterial.Locally, maximumclastdiametersareinexcessof2m.TheserocksareassignedtotheLithofaciesAssociationIofHoffmanandGallagher(1989)andClarketal.(2001).Trccw�ConglomeratesofthewesternborderoftheChathamGroup:Reddish-browntodarkbrown,matrixtoclastsupported,pebbletocobbleconglomerate;clastsaresubroundedtoroundedconsistingofprimarilyofquartzandfoliatedandunfoliatedfelsicvolcanicrocks;matrixconsistsofcoarse-toverycoarse-sand. MesozoicIntrusiveUnitsJd�Diabase:Blacktogreenish-black,melanocratic,fine-tomedium-grained,dense,consistsprimarilyofplagioclase,augite,andmaycontainolivine.Occursasdikesupto100ftwideandsills.Locallyoccursascoarse-grainedgabbroinsills.Typicallyoccursasdense,spheriodallyweatheredJd-recon-Diabasereconnaissance:JurassicdiabasefromreconnaissanceandgeophysicaldataasdepictedinGotfriedetal.(191).Fal c TutRoks rfb-Faultbreccia:Silicifiedand/orhematite-stainedfaultbrecciacontainingangularclastsofTriassicandpre-TriassicrockmaterialalongJonesborofault.EASTERNMOSTCAROLINATERRANEBeaverdamComplexMetaintrusiveUnitsZrg-RedyCrekmetagranodiorite:leucocratic(CIlessthan10)lighttannish-gray,medium-grainedtoporphyritic,foliatedandlineatedtomassive,metagranodiorite.Locallywhitemicarichandorcontainsbluequartzphenocrystsandclotsofbiotiteandepidote.Zbdi-Beaverdamdiorite:Grayish-whitetogreenish-white,coarse-grained,unfoliatedtowell-foliated,mesocratic(CIlessthan40)biotitehornblendemetagranodioritetometadiorite.Zbgb-Beaverdamgabbroandmetapyroxenite:Blackandwhitetogreenishblack,fine-tomedium-grained,unfoliatedtowell-foliated,melanocratictohypermelanocratic(CIgreaterthan40)gabbrotometapyroxenite.MetavolcanicandMetasedimentaryUnitsZbr1-BigLake-RavenRockschist1:lighttantowhite,fine-tomedium-grainedwhitemicaquartziticschistcontainingabundantrelictphenocrystsofbluequartz\andplagioclaseorlocalwhitetograylapilliandrockclasts.Azirconagedateofca.575MawasobtainedbyGoldberg(194). CAROLINATERRANE AaronForma Za�AaronFotion rmation:Brown,graytograyishgreenorlightgray;typicallyfoliated,arkosicsandstones,siltysandstonesandphylliticsiltstones. HycoFormation MetaintrusiverocksassociatedwithHycoFormation:upperportionca.613and614Ma(Wortmanetal.,2000) Tr 7845'00" i 1 (u ) Trcs/si Trcs/si 2 1 Jd Jd Qal FallsLak cs/s 2 e Trcs/si 2 Qal Jd 17 FAULTS Faults-Dashedwhereinferred,dotedwhereconcealed.Decorationondownthrownblock. STRUCTURALSYMBOLS 56 77 strikeanddipofjoint strikeanddipoffoliation 62 strikeofverticaljoint strikeanddipofshearfoliation 74 strikeanddipofcleavage strikeofverticalfoliation strikeofverticalcleavage strikeofverticalshearfoliation 21 strikeanddipofprimary 75 beddingandlayering strikeanddipofprimaryvolcanic compactionfoliationand/orwelding 76 strikeanddipofoverturnedbedding OTHERPOINTS F FossillocalityofCloudetal.(1976) SC-2 SuperconductingSuperCollidercorelocation ofWilsonandCarpenter(1997)Claypit-abandoned NWD-49 GeochemicalsamplelocationinBradleyetal.(2004)ae Quarry-ctiv Locality1 LocalityreferredtoinHoffmanandGallagher(1989)Quarry-inactiveorabandoned K-1 QAPdataofMcConnell(1974) Zgd� gr-p 86 88 Zhe/p 70 8 Zhe/pl Trcs/si1 87 l 73 85 13 Zhe/pl Qal 85 Q a 13 72 51 Jd Jd Jd 89 Jd 59 Trcs/si 87 88 2115 2 7 Jd 75 78 Trcs/si 1 Trcs/si 1 32 Qal 83 Qal Jd Jd FOLDS Interpretedfoldhingeoflarge scaleoverturnedanticlne. Arrowindicatesdirectionofplunge.Interpretedfoldhingeoflargescaleoverturnedsyncline.Arrowindicatesdirectionofplunge.Interpretedfoldhingeoflargescaledoublyplunginganticline. ASSORTEDLINES Diabasedike-ashedwhereinferred, dotedwhereconcealed. primaryroad secondaryroad boundaryofMcConnell(1974)mapping incrosssection-inferredaxialtraceoflarge-scalefold incrosssection-interpretefoldformlineso noncylindricalasymmetricfolds 8 Zgd� 82 Qal 8 89 77 Trcs/si 1 Jd Jd 69 65 7 gr-p Qal Trcs/si1 81 Jd Jd 73 65 Qal Jd 14 68 Qal Zhe/ 9 Jd 4 p 78 21 76 66 Zgd� gr-p Qal 20 J 5Qal Trcs/si 1 13 6 Qal 24 Trcs/si 1 Qal Trcs/si 2 Q a l Qal 70 J d 85 80 Trcs/si 2 Qal 44 4 Trcs/si 2 80 Jd Trcs/si 2 19 86 d Jd Trcs/si 1 Jd 83 80 3600'00" Zdi Jd 75 Qal Jd Qal Trcs/si Jd 2 75 Qal 75 89 59 81 4 Trcs/si J 10 d 7 72 9 2 8 Jd 42 Jd PlutonicrocksassociatedwiththeFlatRivercomplexareaofGloverandSinha(1973),McConnell(1974),andMcConnellandGlover(1982).Wortmanetal.(2000)reporta613.4+2.8/2MaUPbzircondatefromagraniteanda613.9+1.6/-1.5MaU-PbzircondatefromadioritecollectedinthenortheastoftheCounty.Zmpf�MoriahPlutonfelsicphase:Dominantlyleucocratic(CI10-30)lightpinkishgraytogray,fine-tomedium-grained,equigranulartoporphyriticgranitetogranodiroite.Majormineralsincludeplagioclase,actinoliticamphiboles,alkalifeldspar,andquartz.Outcropslocallycontainenclavesoffine-grainedanddarkercoloredgranodioritetodiorite.Locally,melanocratic(CI40-50),grayish-green,fine-tomedium-grainedquartzdioritetodioritepresent.Mpf-GranodioriteandgraniteoftheMoriahPlutonfromMcConnell(1974)andMcConnellandGlover(1982).Zgms�GranodioritetonaliteoftheStemandMoriahplutons:Leucocratic(CI=5-15),lighttan-graywhite,bluish-graywhite,orpinkish-white,mediumtocoarsephaneritc,hypidiomorphictoxenomorpohcgranulargranodioriteandtonalite.ThisunitcombinesthepreviouslymapedZstgunitintheStem(Blakeetal.,2009)andeasternLakeMichieQuadranglesandtheMoriahplutonofMcConnell(1974)inthewesternportionoftheLakeMichie Quadrangle.Majormineralsincludeplagioclase,alkalifeldspar,andquartzwihlesseramountsofbiotiteandamphibole,inerpretedtobehornblende.Plagioclaseishighlysericitizedandinlesseramountsaussuritized,especiallyincalcic-richphenocrystcores.Alkalieldspartypicallydisplaysgranophyrictextureinthinsecton.Ifpresent,biotiteiscommonlyrecrystallizedtochloritewhilehornblendemayberecrystallizedochlorite,epidote,andactinolte� opaquemineral.Metamorphosedtrondhjemiteandmonzonitepodsarepresentandmarepresentdikesordifferentiatedportonsofthepluton.LocallybecomesgraniticinthewesternportionsurroundingLakeMichie.OutcropslocallycontainenclavesofmicrodioriteoftheZdimandZdibunits.Locally,mm-tocm-scalegranitedikescrosscutgranodiorite.Aggregatesofwhitemica,quartz,plagioclase,andorthoclasehighlightsteeplydippingfoliationanddip- parallellineationdomainsinferredtobehighlyfracturedand/orphylloniticandprotomylonitichighstrainzones(Zfgms).ThisunitiscorrelativetotheZmpfunitofBradleyetal.(201)intheadjacentRougemont7.5-minuteQuadrangle.Zagms�ateredgranodioriteandgraniteoftheMoriahpluton:Leucocratic(CI=10-30),lightpinkishgraytogray,fine-tomedium-phaneritic,equigranulartoporphyrticgranodioriteandgranitethatishighlyrecrystallizedandhydrothermallyandchemicallyaltered.Majormneralsformingarelctxenomorhicgranularphaneritctexturelikelyncludedplagioclase,alkalifeldspar,andquartzthatarenowcombnationsoffinetomediumcrystalline,foliated andnon-foliateddomainsofwhitemicaandrecrystallizedfeldsparandquartz.Outcrops,andmorecommonlyfloatcobblesandbouldersdisplayapparentsilicification,whileothersamplesdisplaychemicalweatheringthatdevelopspredominantlyclaymineralizationmixedwithsilica.SomerocksadditionallydisplayFe-oxide-hydroxidestaining.UnitinterpretedtobeahydrothermallyrecrystallizedandalteredportionofZgms.Domainsofhighlyfoliatedrocks ofthisunitareseparatedas(Zfagms).Mpm�Tonalite,quartzdacite,andminorgabbrooftheMoriahPlutonfromMcConnell(1974)andMcConnellandGlover(1982).Mpd�DaciteoftheMoriahPlutonfromMcConnell(1974)andMcConnellandGlover(1982).Zdim�dioriteoftheMoriahpluton:Mesocratictomelanocratc(CI=40-70),greensh-graytograyish-greentogreen,fine-tomedium-phaneriticdiorite,microdioriteandquartzdiorite.Texturesrangefromequigranulartoslightlyporphyriticwithhypidiomorphictoxenomorpohicgranularplagioclaseandhornbendephenocrystsrangingupto1-3mmintabularandprismaticlength,respectively.Majormineralsincludeplagioclaseandamphibole,interpretedto behornblende.Plagioclasecrystalsarehighlysaussuritizedandinlesseramountssericitized.Hornblendemayberecrystallizedtochlorite,epidote,andactinolite-opaquemineral.Locallycontains5-10%quartzhighlightingdifferentiatedoutcropsofquartzdiorite.Foliatedequivalentmappedas(Zfdim).TexturallyandmineralogicallyequivalenttoZdibinGranvilleCountyportionsoftheLakeMichieQuadrangle. Tr 5 6 83 Jd Trcs/si Jd Qal Qal 1 Qal Qal Jd Trcs/si 1 Qal Qal Jd Jd Jd 0 Trcs/si Qal Jd Tr / c J Trd cc 85 9 cs cs 16 15 Tr cc 2 11 Qal Jd Trcs/si 2 Trcs Jd 12 Zr 56 41 ONESBOROFAUL 50 3600'00" g 34 Jd Trcs/si 0 Jd Trcs/si2 Qal Locality9 0 Tr csc 1 Trcs/si Jd Trcs/si 1 1 Jd 1 10 Jd 4 Jd Qal Jd 5 00 Tr Qal 58 64 Z 72 rg cc 55 49 Jd 12 Tr cs Qal 62 4 40 47 55 62 41 Locality3 Jd Jd Jd Jd Jd Qal Jd Qal Locality7 Jd Jd Jd L9ocality6 Jd Jd 75 Tr Jd Jd Jd cs 60 L 78 oc lity19 6 i a 1 Local Trcsc Tr 57 60 58 Qal 77 Qal Jd Trcs/si1 Qal Jd Trcs/si 1 Jd Jd Jd ty 20 cc 45 Z 17 3 58 55 rg Jd Jd Lo ca Trcs/si1 Trcs/sili y5 2 Trcs/si 2 t 10 Locality18 5 2 Jd 8 Jd 7 8 Jd 195 0 Trf 2 Jd Jd Qal Locality10 7 Jd Jd 3 Tr 8 Locality23 2 35 641 Z 62 b Z Zbdibgb Zbdi 55 rg Z rg cs JdLo c Jd Jd Jd Jd Jd Trcs/si 1 Locality1 4 Jd Jd Jd Jd Jd Trcs/si 2 Qal Jd Qal Qal ality21 4 Jd Jd Locality22 Locality28 Tr cc Trcs/si 1 Jd 13 Qal Tr csc Trcs/ c 59 Zdi Zdi Trcs/si Jd Jd 1 0 Jd Jd Jd Qal Qal Qal 78 0 55 Z 68 br1 88 A' 45' 0" Jd Trcs/si Jd Q Qalal Qal Qal Ql a 2 409 USGScorehole-numberindicatesdepthto U-PbagedatelocationofW botomofdiabasesillinfeet. IdentifiedinSpencer(1987). OTHERPOINTSEXPLANATIONS 1. a-aanoneHooverRoadPit;HoffmanandGallagher,1989) 2. a-aanoneStoneRoadPit;HofmanandGalagher,1989) 3. a-aanoneHighway70Pit;HoffmanandGallagher,1989) 4. Claypit-abandoned(TriangleBrickPit) 5. uarr-active(RougemontQuarry) 6. uarr-inactive(DurhamQuarry) 7. Quarry-abandoned(Braggtown) 8. -aeaeca.4a 9. U-Pbagedateca.613Ma ortmanetal.(2000) 8 Zhft(l) Qal ThsgeologicmapwasfundedinpartbytheUSGSNationalCooperativeGeologicMappingProgram. Theviewsandconclusionscontainednthisdocumentarethoseoftheauthorsandshouldnotbeinterpreted asnecessarilyrepresentingtheofficialpolicies,eitherexpressedorimplied,oftheU.S.Government. Thismapandexplanatoryinformationissubmitedforpublicationwiththeunderstandingthatthe UnitedStatesGovernmentisauthorizedtoreproduceanddistributereprintsforgovernmentaluse. Dsclaimer: ThisOpen-Filereportispreliminaryandhasbeenreviewedinternally forconformitywiththeNorthCarolinaGeologicalSurvey editorialstandards.Furtherrevisionsorcorrectionsto thispreliminarymapmayoccur. NorthCarolinaStatePlaneNAD83meterscoordinatesystem, SCALE1:50000 LambertConformalConicprojection Basemapinformaton:Basemapisacomposieofthe USGSGeoPDF7.5-minutequadranglescoveringtheCounty.3,0001,500 0 3,000 6,000 9,000 12,000 15,000 18,000 21,0F0ee0 t Airphoto,mapcollarandselectfeaturesremoved. Thismapandexplanatoryinformationissubmitedforpublication withtheunderstandingthatheUnitedStatesGovernmentisauthorized toreproduceanddistributereprintsforgovernmentaluse. Jd Qal Qal Jd Tr Jd cs /si Trcs/si 12 10 Trcsi/s Qal 1 3 Tr cs 1 0 Jd Qal Jd Trcsi/s Jd Jd Qal Qal Trcs/si1 Locality2 12 Trcs/si 2 Trcs/si 2 Jd Locali1t1y13 Locality16 2 Jd 552'30" KTu KTu Trcs/si 1 L Jdoc ality4 Qal 10 4 10 4 Locality14 Qal Jd Trcs/si a79 Q Qal Jd KTu Jd Trcs/si 1 Trcs/ 20 si 1 Qal Trcs/si 4 Jd 1L0ocality12 Trcs Trcsi/s QalJd 3552'30" 2 15 6 Jd 3 00'00" 7852'30" 116 Jd 12 8 Caldwell Rougemont LakeMichie Stem12 Hillsborough NorthwestDurham3 NortheastDurham 4 Creedmoor 5 ChapelHill 7SouthwestDurham 8SoutheastDurham 9 Bayleaf 610Farrington 11GreenLevel 12 Cary RaleighWest 9.03 2010MAGNETICNORTH DECL9IdNegATrIeesONA1.T93CEmNinuTEtResOWesFSHtEET 10.50 1 2 3 4 Miles 10.50 1 2 3 4 5 Kilometers boulderswithagrayish-brownweatheringrind.WholerockgeochemistrydataforseveralsamplesintheDurhamareaarepresentedinGotfriedetal.(191). Otherplutonicrocks:Zgd�Granodiorite:Leucoractctomesocratic,fine-tomedium-grained,equigranulartoporphyriticgranodiorite.Maycontainquartzdioriteanddiorite.Typicallycontainsdarkgreentoblacklessthan1mmto4mmclotsofactinolitic(?)amphiboleandchloritemasses.Plagioclasegrainsareoftensericitizedandsaussuritizedandmayexhibitagreenishcolor.Locally,granodioriteispinkish hued,fine-tomedium-grainedwithdarkgreentoblacklessthan1mmto4mmclotsofmaficmineralsinterpretedtobebiotiteandamphibolemasses.Chloritegrowthonbiotiteandamphiboleispresent.Zgd-gr-p�GranodioritetograniteofPineyMountainCrekarea:Compositeplutonofdominantlymedium-grainedhornblendegranodioritewithlesseramountsofmedium-grainedhornblendegranite.Typicallycontainsdarkgreentoblacklessthan1mmto4mmclotsofactinolitic(?)amphiboleandchloritemasses.Locallycontainspinkish-huedfeldspars.Zdi�Diorite:Mesocratic(CI~50),greenish-graytograyish-green,fine-tomedium-grained,hypidiomorphicgranulardiorite.Majormineralsincludeplagioclaseandamphibole.Plagioclasecrystalsaretypicallysericitizedandsaussuritized.Amphibolesaretypicallyalteredtochloriteandactinolitemasses.Maybegabbroiclocally.MetamorphosedvolcaniclasticsedimentaryandpyroclasticrocksassociatedwithHycoFormation:upperportion(stratigraphicrelationsuncertain)ca.613-616Ma(Wortmanetal.,200;Bowman,2010;andBradleyandMiller,201)Zq�Quartzbodies:White,beige,red,andtan;sugarytoporcelaneous;veryfine-tomedium-grainedmassivequartzrockoquartzite-likerock.Outcropsareusuallymassive.Quartzite-likerockisoccasionallymixedwithsericiteand/orpyrophyllite.Theadditionofsericiteand/orpryophyllitegivestheotherwisemassivequartzite-likerockafoliation.Pyriteispresentascubiccrystalsand emptycubicmoldsofcrystals(upto12mm).Mapareascontainboulders(uptoseveralfeetindiameter)andoutcropsofwhitecoloredmassivequartz.Zhat(u)�Alteredtuffs:Verylghtgraytolightgreenishgray(whitishinareas)wthredandyellowmotling,alteredvolcaniclasticrocks.Alterationconsistsofsilicified,sericitizedandpyrophllitizedrock.Sericitephyllite,podsofpyrophyllite,andquartz+phyrophylliterockallwithlessthan1mmto2mmdiameterweatheredsulfidesarecommon.Relictlithicclastsandkaolinitized feldsparcrystalshardsarevisibleinsomeexposures.Relictstructuresareobliteratedinheavilyalteredrocks.Mapareacontainsboulders(uptoseveralfeetindiameter)andoutcropofmassivemilkyquartzandquartz+sericiterock.Zhdlt-a�altereddaciticlavasandtuffs:Whiteoredtotan,silicecious,hydrothermallyalteredaphaniticdacite,porphyriticdacite,anddacitelavasofZhdlt.Altereddaciteistypicallymassive,finelycrystallineandlocallycontainsrelictquartzandplagioclasephenocrystsrangingfrom2to5mminsize.Commonlysiliceousconcentratonsgivetherocka�chunky�appearance.Localized pyrophyllitemineralizatonoccurasradiatingcrystalsthatrangefrom0.25mmto1cminsize.CommonlyFe-oxidemineralizationgivestherockaredcolor.EquivalenttotheZadltunitofBlakeetal.(2009)intheStemQuadrangletotheEastandthetotheZhat(u)unitofBradleyatal.(201)intheRougemontQuadrangletotheWest.Silicification,sulfidemineralization,andaggregatesof whitemicaandquartzhighlightsteeplydippingandplungingfoliationandlineationdomainsinferredtobehighlyfracturedand/orphylloniticandprotomylonitichighstrainzones(Zhfdlt-a).Zhe/p-Mixedepiclastic-pyroclasticrocks:Grayish-greentogreenish-gray,tuffaceoussandstones,conglomeraticsandstones,siltstonesandminorphyllite.Thesiltstonestypicallyareweaklyphyllitic.Containslesseramountsoffine-tocoarsetuffandlapilltuff.Tuffsaredifferentiatedfromothervolcaniclasticrocksbythepresenceofzonesofcryptocrystallinetexturethatexhibit conchoidal-likefracturesinbetweenfoliationdomains.Minorandesitictobasalticlavasandtuffspresent.Silicifiedand/orsericitizedalteredrocksimilartoZhatunitarelocallypresent.UnitisinterpretedtogradeintoZhe/plunit.ContactwithZhe/pldesignatedatfirstoccurrenceofdaciticlavas.DomainsofhighlyfoliatedrocksofthisunitareseparatedasZhfe/p.Zhe/pl-Mixedepiclastic-pyroclasticrockswithinterlayereddaciticlavas:Grayish-greentogreenish-gray,locallywithdisinctivereddish-grayormaroontolavendercoloration;conglomerate,conglomeratcsandstone,sandstone,siltstoneandmudstone.Lithologiesarelocallybedded;locallytuffaceouswithacryptocrystalline-likegroundmass.Siltstonesarelocallyphyllitic.Locally containinerbeddeddacticlavasidenticaltoZhdltunit.Containslesseramounsoffine-tocoarsetuffandlapillituffwithacryptocrystalline-likegroundmass.Minorandesitictobasalticlavasandtuffspresent.Silicifiedand/orsericitizedalteredrocksimilartoZhatunitarelocallypresent.Conglomeratesandconglomeraticsandstonestypicallycontainsubroundedtoangularclastsofdaciteina clasticmatrix.Zhe/pldistinguishedfromZhe/pbypresenceofdacitesandisinterpretedtorepresentafacieschangetoanareamoreproximaltotheactivevolcaniccenterscomparedtoZhe/p.Cloudetal.(1976)fossillocalityfromunitinDurhamCountywithlocationindicatedonmap.Zhdlt(u)�DaciticlavasandtuffsoftheupperportionoftheHycoFormation:Greenish-graytodarkgray,siliceous,aphaniticdacite,porphyriticdacitewithplagioclasephenocrysts,andflowbandeddacite.Weldedandnon-weldedtuffsassociatedwiththeavasinclude:greenish-graytograyish-green,finetuf,coarseplagioclasecrystaltuffandlaillituff.Locally,interlayersofmmature conglomerateandconglomeraticsandstonewithdaciteclastsarepresent.Thedacitesareinterpretedtohavebeencoherentextrusivesorveryshallowintrusionsassociatedwithdomeformation.Thetuffsareinterpretedasepisodcpyroclasticfowdeposits,airfalltuffsorreworkedtuffsgeneratedduringformationofdacitedomes.Theunitoccursasmapscalepodssurroundedbyclasticrocksof Zhe/plunit.Wortmanetal.(200)reportsanageof615.7+3.7/-1.9MaU-Pbzircondateforadacitictufffromtheunit.RedMountain,aprominenttopographicfeatureoftheRougemontquadrangleisunderlainbythisunit.Silicification,sulfidemineralization,andaggregatesofwhitemicaandquartzhighlightsteeplydippingandplungingfoliationandlineationdomainsinferredtobehighly fracturedand/orphylloniticandprotomylonitichighstrainzones(Zhfdlt).Zhdsi(u)�DaciticshallowintrusiveoftheupperportionoftheHycoFormation:Gray-green,lightgreentogreen,greenish-graytolghtgray;dacite,plagioclaseporphyriticdacitewthagranular-texturedgroundmasstomicro-granodiorite(intrusivetexturevisblewith7xhandlens).Locallyfine-tomediumgrainedgranodioritepresent.Plagioclasephenocryss,whenpresent,rangefrom lessthan1mmto4mm.Blackcooredamphibole,whenvisible,occursasphenocrysts(lessthan1mmto1mm)andasintergrowthswithpagioclase.Amphiboleintergrowthsdistinguishrockfromfine-grainedtuffs.Rockromtheactivequarryincludesgreenish-graytolightgray;aphanitctoweaklyplagioclaseporpyriticdacitetomcro-granodiorite.Relctpagioclasephenocryssare sausseritzedinamatrixofrecrystallizedfeldsparandquartzwithdarkcoloredclots(lessthan1mmto4mm)interpretedinhandsampeaschlorite(?)massesand/orrelictenclavesofdarkgraydacite.Containslesseramountsofdarkgray,aphaniticdacite.Interpretedasshallowlyemplaceddaciteprobablyco-magmaticwithZhdlt(u)unit.Silicification,sulfidemineralization,andaggregatesof whitemicaandquartzhighlightsteeplydippingandplungingfoliationandlineationdomainsinferredtobehighlyfracturedand/orphylloniticandprotomylonitichighstrainzones(Zhfdsi).Zhadlt�Andesitictodaciticlavasandtuffs:Distinctiveblacktodarkgray;porphyriticlavawithplagioclasephenocrysts(upto4mm),andflowbandedlavawithlocalamygdules.Interlayedwiththelavasaregraytoblack;weldedandnon-welded;coarsetuff,lapillituff,andtuffbreccias.Zhablt�Andesitictobasalticlavasandtuffs:Green,gray-green,gray,darkgrayandblack;typicallyunfoliated,amygdaloidal,plagioclaseporphyritic,amphibole/pyroxeneporphyriticandaphanitic;andesitictobasalticlavasandshallowintrusions.Hyaloclastictextureiscommonandimpartsafragmentaltexturesimilartoalithictuffonsomeoutcrops.Locallyinterlayeredwithmeta- sedimentsidenticaltotheZhe/plandZhe/punit.A1�IntermediatevolcanicrocksfromMcConnell(1974)andMcConnellandGlover(1982).Z�FelsicpyroclasticrocksfromMcConnell(1974)andMcConnellandGlover(1982).MetamorphosedvolcaniclasticsedimentaryandpyroclasticrocksassociatedwithHycoFormation:lowerportion(stratigraphicrelationsuncertain)ca.629-633Ma(Wortmanetal.,2000andBradleyandMiller,201)Zhat(l)�AlteredtuffsofthelowerportionoftheHycoFormation:Verylightgraytolightgreenishgray(whitishinareas)withredandyellowmotling.Alterationconsistsofsilicified,sercitizeandpyrophyllitizedrock.Sericitephyllite,podsofpyrophyllite,andquartz+phyrophylliterockallwithlessthan1mmto2mmdiameterweatheredsulfidesarecommon.Fine-grainedchloritoid porphyroblasts(lessthan1mm)arepresentinsomepyrophyllitebearingrocks.Relictlithicclastsandkaolinitizedfeldsparcrystalshardsarevisibleinsomeexposures.Relictstructuresareobliteratedinheavilyalteredrocks.Mapareacontainsboulders(uptoseveralfeetindiameter)andoutcropofmassivemilkyquartzandquartz+sericiterock.Zhft(l)-Felsictuffs:Grayish-greentogreenish-grayandslvery-gray;massivetofoliatedvolcaniclasticpyroclasticrocksconsistingoffine-tocoarsetuffs,lapillituffsandminorweldedtuffs.Tuffsaredifferentiatedfromothervolcaniclasticrocksbythepresenceofzonesofcryptocrystallinetexturethatexhibitconchoidal-likefracturesinbetweenfoliationdomains.Layeringrangesfrom massivetothinlybedded.Containslesseramountsofvolcaniclaticsedimentaryrocksconsistingofvolcanicsandstones,andgreywackeswithminorsiltstonesandphyllite.Zhdlt(l)�DaciticlavasandtuffsofthelowerportionoftheHycoFormation:Distnctivegraytodarkgray,siliceous,crytocrystallinedacite,porphyriticdacitewithplagioclasephenocrysts,andflowbandedacite.Weldedannon-weldedtuffsassociatedwiththelavasinclude:greenish-graytograyish-green,finetuff,coarseplagoclasecrystaltuff;lapillituff;andtuffbreccia.Thedacites areinterpretedtohavebeencoherentextrusivesorveryshallowintrusionsassociatedwithdomeformation.Thetuffsareinterpretedasepisodicpyroclasticflowdeposits,airfalltuffsorreworkedtuffsgeneratedduringformationofdacitedomes.Wortmanetal.(2000)reporta632.9+2.6/-1.9MazircondatefromasamplewithintheunitintheChapelHillquadrangle(OrangeCounty). - Zhdsi(l)�DaciticshallowintrusiveofthelowerportionoftheHycoFormation:Gray-green,lightreentogreen;plagioclaseporphyritcdacitewithagranular-texture amphibole,whenvisible,occursasphenocrysts(lessthan1mmto1mm)andasintergrowthswithplagioclase.Amphiboleintergrowthsdistinguishrockfromfine-grained OrangeCounty. groundmasstomicro-granodiorite(intrusivetexturevisiblewith7xhandlens).Containslesseramountsoffinetomediumgrainedgranodiorte.Plagioclasephenocryststypicallyrangefrom1mmto4mm.Blackcolored tuffs.Enclavesofdarkgray,plagioclaseporphyriticdacitearecommonandattimesgiverockapsuedo-clasticappearance.BradleyandMiller(201)reportanageof628.5�1Maforadacitefromthisunitinsouthern MapperIndex 1.Bradleyetal., 2.Rhodesetal.,12;McConnell,1974 3.Bradleyetal., 4.Phillipsetal.,2004 5.Clarketal.,2016 6.Bradleyetal.,2004 7.omananaaer, 8.HoffmanandGallagher,1989 9.0.CBlrarketal.,2004 adleyetal.,2007 12..CWatson,198 larketal.,2004 Exampleofdatadensityat :24,000-scalefor 1mile-widearea.Examplefromnorthern DurhamCountyalongtheLitleRiver intheRougemontQuadrangle (Bradleyetal.,201)Site-specificinvestigationsshould use1:24,000-scalemaps 640' A Qal NCHwy157 EnoRQivaelr U.S.Route501 Qal Trcs/si1 Qal EllerbeCQreeal k JdU.S.RouQtea1l 5 CQhun aClrkeeykPipe LiCttlreeeLQkic a kl NCHwy98 LickCrQeeakl (RoLcickkyCBrreeanQk aclh) LCaureerekl JQone aFlausbltoro A' 640' 0' Zhdsi(l) Trfb -1360' Zhdlt(l) Zhft(l) Zhdlt(l) Jd Zhdsi(u) Jd Jd Trcs/si1 Trcs/si2 Trcs TrcscTrcsc Trcc Zrg 0-1'360' Trcs/si2 Jd Jd Zhadlt Jd Zhadlt Trcs/si1 Trcs/c Zbr1 Zhadlt Trcs/si1 Trcsc -3360' -3360' Carolinaterrane TriassicBasin Easternmost Carolinaterrane PRELIMINARYCOMPILEDGEOLOGICMAPOFDURHAMCOUNTY,NORTHCAROLINA NCGSOPENFILEREPORT2016-23 10 Miles MAJORGEOLOGICFEATURES