A A' A A' A A'
N ort h Caroli na G eolog i calS urv ey O pen Fi le R eport201609
Thi s G eolog i c map w as funded i n partby th e U S G S N ati onalCooperat i v e G eolog i c Mappi ng P rog ram
Jenny Kelv i ng ton,Executi v e Di rector Kenneth B.T aylor,S tate G eolog i st
Mesozoi c– P aleozoi c
Mesozoi c
Quaternary
IN T R O DU CT IO N
CORRELATI ON OFMAPUN I TS
Qal
Met amorph i c R ock s
T h e majori ty of th e quadrang le drai ns to th e R ock y Ri v eralong drai nag es t h ati nclude Lacy’ s Creek,N i ckCreek ,N ort h P rong ,G reenbri erCreek,Joh nson Creek,Mud Li ckCreek,V arnellCreekand unnamed creeks.T h e nort h eastporti on ofth e quadrang le drai ns t ot h e Haw R i v eralong drai nag es t h ati nclude S outh Fork,R eedy Branch and P i ne Hi llBranch . Asmall area i nt h e south w estcorner of t h e quadrang le drai ns to t h e Deep R i v er. T h e drai nag e di vi de bet w een t he R ock y and Deep R i v ers i s locally cont rolled by a ri dg e th at mark s a major g eolog i c contact ( Hyco and Aaron Format i ons) .N at ural exposures of crystalli ne rocks occur mai nly along t h ese and numerous unnamed creeks.R ock exposure at road cuts,ri dg es,resi stant fi nnedsh aped outcrops and pav ement out crops occur locally out si de of drai nag es.T h e elev ati ons i nt h e map area rang e from about740feetabov e sea lev elnort h ofth e i ntersect i on ofP i ney G rov e Ch urch road and Fellow sh i p Ch urch R oad ( on t h e ri dg e t h atdefi nes t h e drai nag e di vi de betw een th e R ock y and Deep R i v ers)i n t h e south w est corner of t h e quadrang le,to less th an 500 feet along P i ne Hi ll Branch near th e nort h east ern cornerofth e quadrang le.
Aa r on For m at ion
G eolog i c Backg round and P astW ork
Jd
MP zg b
Young estdet ri talzi rcons ofca.578and 588Ma ( S amson etal. ,2001and P ollocket.al. ,2010,respect i v ely) .
Met amorph osed v olcani clast i c sedi mentary and pyroclast i c rocks ( st rati g raph i c relat i ons uncert ai n)ca.612-616Ma ( W ort man etal. ,2000; Bow man,2010;and Bradley and Mi ller,201 1)
Zh asi
Zh el Zh dlt( u)
Zh e/ pl Zh e/ pli m
5004
5003
533
U ni di recti onalR ose Di ag ram ofJoi nts N =157 O uterCi rcle =8% Mean v ector=267deg rees Max v alue =7% betw een 341deg rees and 350deg rees
Zh asi
Zh ablt dcp
O bserv ati on st ati on locat i on Di abase stat i on locati on Indi cat es locat i on ofv ug g y quart z orsli ceous brecci a float
7057
Indi cat es locat i on ofZh abltdcp boulders oroutcrop
533
1882 5030 6096
79
6136
46
85 77 82
66
81
83
84
88
P rospect( pi torsmallopen cut ) 2Hi nsh aw P rospect( pyroph ylli te)-abandoned 4S now Camp S outh P rospect( pyroph ylli te)-abandoned
88
quarry ormi ne -abandoned 1quarry ( flag stone)-abandoned 5S now Camp P yroph ylli t e Mi ne
84
78
86
75 84
81
84
80 80
84
88
Zh e/ pl
76
87
84
88
84
86
79
84
78
80
82
Qal
81
61 85 88 80 85
88 79
76
87
74
Zh e/ pl
77
77
77
89
79
81 71
47 85
86
89 59
84
82
83
80
56
86 59
79 88 81
MPzgb – Ga b b r o:Melanocrati c( CI g reaterth an 50) ,fi neg rai ned g abbro.Di st i nct i v e brow n w eat h eri ng .O ccurs as a small map scale body closely associ ated w i t h a di abase di ke,and as i solated boulders along th e trend of a di abase di ke.Appears unmetamorph osed.P urple st ati on locat i ons i ndi cate out crop orboulders ofMP zg b.
Zh e/ pli m
78
78
78
72
69 84 89
Za
Zh e/ pl
78
84
Z hel-Epic la st ic r oc ksa n d la va s:Metamorph osed cong lomerat e,cong lomerat i c sandst one,sandstone,si ltst one and mudstone.S i ltstones and mudstones t ypi cally di splay beddi ng rang i ng from mmscale up to 10cm,beddi ng layers t raceable for sev eral feetlocally,may exh i bi tsoftsedi mentdeformat i on.Locally t uffaceous w i th a reli ctv i t ri ct exture. Locally contai ni nterbedded daci ti c to basalti c lav as.Cong lomerates and cong lomerati c sandstones t ypi cally contai n subrounded to ang ularclasts of daci te i n a clasti c matri x.Deposi t i on i nterpret ed as di stalfrom v olcani c center,i n deep w at er( ?) ,and v i a turbi di t e flow s.
74
74
68
Za
81
89 84
69
89
85
89
78
87
87
72
79
83
66
88
Z he/ pl -Mixed epic la st ic pyr oc la st ic r oc kswit h in t er la yer ed da c it ic la va s:G rayi sh g reen t o g reeni sh g ray,locally wi t h di sti nct i v e reddi sh g ray or maroon t o lav ender colorati on;met amorph osed: cong lomerat e,cong lomerati c sandst one, sandstone, si ltst one and mudstone. Li th olog i es are locally bedded; locally tuffaceous w i th a cryptocrystalli neli k e g roundmass.S i ltst ones are locally ph ylli ti c.Locally cont ai ni nt erbedded daci ti c lav as i denti calt o Zh dltuni t .Cont ai ns lesser amounts of fi ne-t o coarse t uff and lapi llituff w i th a crypt ocrystalli neli ke g roundmass. P yroclasti cs,lav as,and epi clasti cs are mai nly felsi ci n composi t i on.Mi norandesi t i ct o basalti c lav as and tuffs present . Si li ci fi ed and/ orseri ci t i zed altered rockare locally presentand i ncrease i n occurrence tow ard th e nort h .Cong lomerates and cong lomerati c sandst ones typi cally cont ai n subrounded to ang ular clasts of daci t e i n a clasti c mat ri x. Fi ne-to medi umg rai ned di ori t ei s locally present .P orti ons oft h e Zh e/ pluni tare i nterpreted to h av e been deposi t ed proxi malt o act i v e v olcani c cent ers represented by t h e Zh dltuni tbutare also i nt erpret ed to record t h e erosi on of proxi malv olcani c cent ers aftercessat i on ofact i v e v olcani sm.
84
Z hdlt( u)– Da c it ic la va s a n d t uffsof t he upperpor t ion of t he Hyc o For m at ion : G reeni sh g ray to darkg ray, si li ceous,metamorph osed:aph ani t i c daci te,porph yri t i c daci te w i t h plag i oclase ph enocrysts,and flow banded daci te. Daci t ewi t h h yaloclast i ct extures are common.W elded and nonw elded tuffs associ ated w i th th e lav as i nclude:g reeni sh g ray t o g rayi sh g reen,fi ne tuff,coarse plag i oclase crystal t uff and lapi llituff.Locally,i nterlayers of i mmat ure cong lomerate and cong lomerati c sandst one w i t h abundantdaci t e clasts are present.T h e daci t es are i nterpreted to h av e been coh erentext rusi v es or v ery sh allow i nt rusi ons associ ated w i t h dome format i on.T h e t uffs are i nterpret ed as epi sodi c pyroclast i c flow deposi t s,ai r falltuffs or rew orked tuffs g enerated duri ng format i on of daci t e domes.T h e uni t occurs as map scale pods surrounded by clasti c rock s of Zh e/ pl uni t .W ortman et al.( 2000)reports an ag e of 615. 7+3. 7/ 1. 9Ma U P b zi rcon date fora daci t i c tufffrom t h e uni ti nt h e R oug emontquadrang le.
68
84
56
74
Za
84
Za
82 87
78
85
88
J d
81 84
60
82
84
88 87
J d
MP zg b
60
80
81 82
Qal80
82 87
1
77 88 88
86 87
83 9
81
86 84
87
J d
80
76
79
79 80 72
77 74
75
Qal 49 74
85
74
86
78
Zh e/ pli m 86 80
84
Zh dlt( u)
89
78
82
78 80
46
74
78 88
86 49
80
70 84
84
49
84 79
68
72
81
Zh e/ pl
74
Zh asi
59 89 88
82
84 87
74 86
Zh e/ pl
83
79
86
70
62
59
71
64
89
84
70
80
84
80
83 64
74
71
85
89
64
85
88
65
86
73
84
60
79
88
Qal
78
84
71
J d
75
80 88
82
84
82
86 88
84 65
88
89
Qal
81
88
87
82
82
88
82
82
78
86
84
78
64
79 76 76
70
72
84
85
76
86
75
89
76
82
Zh e/ pli m
82
77
84
Zh e/ pli m
65
86
85
84
75
56 74 79
72
87
88
80
81
78
Zh ablt dcp
77
80
84
81
Zh e/ pli m
Z he/ plim -Mixed epic la st ic pyr oc la st ic r oc kswit h in t er la yer ed in t er m edia t et ob a sa lt ic la va s:G rayi sh g reen to g reeni sh g ray,locally w i th di st i ncti v e reddi sh g ray or maroon to lav ender colorati on;met amorph osed: cong lomerate, cong lomerati c sandst one,sandstone,si lt stone,mudstone,and felsi c fi ne-t o coarse t uff and lapi llit uff. S i ltstones are locally ph ylli t i c.Locally cont ai ni nt erbedded andesi ti c to basalti c lav as i dent i calto Zh abluni t .S i li ci fi ed and/ orseri ci ti zed altered rockare locally present. Interpreted t o be i n g radati onal cont actw i t h uni tZh e/ pl and i denti fi ed by i ncrease i n i ntermedi ate to mafi c lav as and decrease and/ orabsence ofdaci tes.
84
86
78
59
87
71
Zh e/ pli m
75
88
68
68
72
82
Zh dlt( u)
85
Zh e/ pli m
88
85
72
72
82
60
80
85 84
Qal
84
79
81
86
84
62
74
74
72
78
78
83
83
79
74 70
86 82
87
84
78
74 76
86
84
75
88
Qal
48
80
76 88
81
MP zg b
84
76
84
Z a – Aa r on For m at ion : Di st i nct i v e met asedi mentary packag e th atrang es from fi neg rai ned si lt stones to coarseg rai ned sandst ones,pebbly sandst ones and cong lomerates. S i lt stones are si mi lar i n appearance to Hyco Formati on li th olog i es.T h e sandstones,pebbly sandst ones and cong lomerat es ( classi fi ed as li th areni te,feldspath i c li th areni t e and li th i c feldsareni te by Harri s ( 1984) )are di st i nct i v e and commonly contai n rounded to subrounded clasts of quartz rang i ng from sand-to g rav elsi zed.In th e sandst ones,feldspari s th e mostpromi nentmi neralg rai n;quart zv ari es from sparse t o abundanti n h and sample.Li th i c clasts are t ypi cally promi nentand rang e from sand-to g rav elsi ze.Harri s ( 1984) ,performed a det ai led sedi mentary st udy of t h e Aaron Formati on t ot hei mmedi ate w estof th e map area.Harri s ( 1984)i nt erpreted t h e Aaron Formati on t o h av e been deposi ted by turbi di ty current si n a ret rog radat i onalsubmari ne fan set ti ng .P ollocketal.( 2010)i nt erpret s an approxi mate 35mi lli on yearunconformi t y betw een t h e Aaron and underlyi ng Hyco Format i on. T h i si nterpretati on i s based i n parton detri t al zi rcon ag e date data from an Aaron cong lomerate sample collect ed i n th e nearby Li bert y Quadrang le.
85
84
76 88
79
81 84
87
83
79
56
88
73
68 72
80
78 84
88
88
76
74
84
6782
72
89
Jd – Dia b a se:Blackt o g reeni sh black,fi ne-t o medi umg rai ned,dense,consi sts pri mari ly of plag i oclase,aug i t e and may cont ai n oli vi ne.O ccurs as di kes up to 100ftw i de.Di abase t ypi cally occurs as sph eri odally w eath ered boulders wi t h a g rayi sh brow n w eat h eri ng ri nd.R ed stat i on locati on i ndi cat es outcrop orboulders ofdi abase.
85
84 83
89
A
86
75
80
Qa l – Alluvium : U nconsoli dat ed poorly sorted and strat i fi ed deposi t s of ang ular to subrounded clay,si lt,sand and g rav el-t o bouldersi zed clast s,i n stream drai nag es.May i nclude poi ntbars,terraces and natural lev ees along larg er stream floodplai ns.S tructural measurements depi cted on th e map w i th i n Qal representoutcrops of cryst alli ne rock i nli ers surrounded by alluv i um.
St ri ke ofv ert i calJ oi ntsurface ( multi ple observ at i ons atone locati on)
PROSPECTSAN DQUARRI ES
78 85
St ri ke and di p ofi ncli ned joi ntsurface ( multi ple observ at i ons atone locati on)
3
1923
82
70
79
mi ne sh aft-abandoned
88
72
88
St ri ke and di p ofi ncli ned reg i onalfoli ati on ( multi ple observ at i ons atone locati on)
R EFER EN CES :
80
76
St ri ke ofv ert i calJ oi ntsurface
3" O re Hi ll"sh aft( Iron?)-abandoned
85
81
St ri ke and di p ofcleav ag e ( multi ple observ at i ons atone locati on) St ri ke and di p ofi ncli ned joi ntsurface
81
St ri ke and di p ofcleav ag e
84
84 83
80
St ri ke and di p ofi ncli ned reg i onalfoli ati on
78
655
87
St ri ke and di p ofpri mary beddi ng and/ orlayeri ng ( multi ple observ at i ons atone locati on)
83
72 76
S ch mi dtetal.( 2006)g eoch em locati on
St ri ke and di p ofpri mary beddi ng and/ orlayeri ng
65
87 77
Indi cat es locat i on ofMP zg b boulders oroutcrop
PLAN ARFEATURES
76
Hyco Formati on – U pperP ort i on
Zh able
4
74
Aaron Format i on
Zh dlt( u)
2
6128
MET AV O LCAN ICAN DMET AV O LCAN ICLAS T ICU N IT S
Zh e/ pl
MP zg b di ke -i nferred
6611
To Be Mapped 2016-2017 81
Inferred di abase di ke; dott ed w h ere concealed
Cross secti on
6441
6903
Int erpret ed fold h i ng e ofov ert urned anti cli ne
1603
6244
IN T R U S IV EAN DMET AIN T R U S IV EU N IT S
Zh e/ pli m
Int erpret ed fold h i ng e ofsyncli ne; quest i on markw h ere exi st ence i s questi onable;dott ed w h ere concealed
6955
6468
S EDIMEN T AR Y U N IT
EqualArea S ch mi dtN etP roject i on of Contoured P oles to P ri mary Beddi ng and Layeri ng ContourInterv al=2si g ma N =30
A'
5072
A preli mi nary rev i ew of th e area g eolog y i s prov i ded i n Bradley ( 2013) . U ni tdescri pt i ons common to Hanna etal. ( 2014)and Hanna and Bradley ( 2016)from t he S i lkHope and S i ler Ci ty g eolog i c maps,respecti v ely,w ere used for conformi ty w i th on st ri k e uni ts i n nei g h bori ng quadrang les. U ni t descri pt i ons and strat i g raph i c correlat i ons w ere mai nt ai ned from adjacent mappi ng i n O rang e County Bradley ( Bradley et al. ,2016) . T h e nomenclat ure of th e Internati onalU ni on ofG eolog i calS ci ences subcommi ssi on on i g neous and v olcani c rocks ( IU G S )afterLe Mai tre ( 2002) i s used i n classi fi cati on and nami ng of th e uni t s.T h e classi fi cat i on and nami ng of t h e rock si s based on reli cti g neous t extures,modal mi neral assemblag es,or normali zed mi neral assemblag es w h en w h olerock g eoch emi cal data i s av ai lable.P yroclasti c rocktermi nolog y follow s t h atofFi sh erand S ch mi nk e( 1984) .
Zh el
Int erpret ed fold h i ng e ofant i cli ne, dott ed w h ere concealed
5055
All preMesozoi c rock si n th e map area h av e been met amorph osed to atleastt h e ch lori t e zone of t h e g reensch i st metamorph i c faci es. Many of th e rocks di splay a w eak or strong met amorph i c foli ati on. Alth oug h subject ed t o metamorph i sm,t h e rock s retai n reli cti g neous,pyroclasti c,and sedi ment ary text ures and st ructures th atallow for th e i denti fi cati on ofprotoli th rocks.As such ,th e prefi x “meta”i s noti ncluded i nt h e nomenclature oft h e preMesozoi c rocks descri bed i nt h e quadrang le.Jurassi c di abase di kes are unmetamorph osed.
Za
1599
5074
DES CR IP T IO N O FMAP U N IT S
MP zg b
1568
A
6254
S ch mi dtetal.( 2006)i denti fi ed “O re Hi ll”as a locati on of a small sh aftatth e top of a knob. T h e rocki s mag net i t e beari ng and i ti s speculat ed t h atth e sh aftw as sunki n search of i ron ore. T h e Hi nsh aw pyroph ylli te prospecti s descri bed by S t uckey ( 1967)and S ch mi dtetal.( 2006) . T h e S now Camp P yroph ylli t e Mi ne i s abandoned. S ch mi dt ( 1985)descri bed t h e mi ne as an i mportantformerproducerof h i ghg rade pyroph ylli t ei n N orth Caroli na acti v e from th e mi d1930’ st o th e mi d1960’ s.Addi ti onaldescri pti ons of th e S now Camp Mi ne are prov i ded i n Broadh urstand Counci ll ( 1953) ,Espensh ade and P ott er ( 1960) ,S t uckey ( 1967) ,and Hug h es ( 1987) . T h e S now Camp S outh pyroph ylli te prospecti s located on th e south ern end ofth e ri dg e t h ati ncludes th e S now Camp Mi ne locat i on.
J d
6494 5
5028
1515
5071
T h ere are no act i v e mi ni ng act i vi t i es currently i nt h e quadrang le. O ne h i stori c flag st one quarry associ ated w i th an abandoned g ri stmi llsi t e w as i denti fi ed along th e R ock y Ri v eri n th e sout h of th e quadrang le.T h e north ern port i on of t h e quadrang le w as mapped atreconnai ssancescale as partofth e S ch mi dtetal.( 2006)st udy.T h e area w as i dent i fi ed as cont ai ni ng larg e zones of h i ghsulfi dati on alterat i on w i t h t h e potenti al for pyroph ylli te and g old resources. T h e quadrang le h as 4i denti fi ed prospectand/ or mi ne areas i ncludi ng :1)“O re Hi ll”,2)Hi nsh aw pyroph ylli t e prospect,3) S now Camp P yroph ylli t e Mi ne,and t h e 4)S now Camp S outh pyroph ylli t e prospect.
Qal
6446
6889
Mi neralR esources
EqualArea S ch mi dtN etP roject i on of Contoured P oles to Foli ati on and Cleav ag e ContourInterv al=2si g ma N =215
Concealed cont act
Inferred bri t tle fault ; dott ed w h ere concealed
Abundantev i dence of bri tt le faulti ng atth e outcrop scale and larg escale li neaments ( as i nterpreted from h i llsh ade Li DAR data)are presenti n th e map area. T h e bri ttle faulti ng and li neaments are i nt erpret ed to be associ ated w i th Mesozoi c extensi on. T h e Colon crossstruct ure ( R ei nemund,1955) ,locat ed to t h e sout h eastof th e st udy area,i sa const ri cti on zone i n th e Deep R i v er Mesozoi c basi n and i s ch aracteri zed by cryst alli ne rock s ov erpri nted by complex bri t tle faulti ng .Di k es of J urassi c ag ed di abase i ntrude th e crystalli ne rocks ofth e map area.Quaternary ag ed alluv i um i s presenti n mostmajordrai nag es.
P lot s and calculat i ons created usi ng S t ereonetv .8. 6. 0based on Allmendi ng eretal.( 2013)and Cardozo and Allmendi ng er( 2013) .
Li nearg eomorph i c feat ure i nt erpret ed from h i llsh ade Li DAR -ori gi n uncert ai n
Quaternary alluv i um cont act
Map uni ts of metav olcani c and met av olcani clasti c rocks i nclude v ari ous li th olog i es t h atw h en g rouped t og et h er are i nterpret ed to i ndi cat e g eneral env i ronments of deposi t i on.T h e daci t i c lav as and tuffs uni ti si nt erpret ed to represent daci ti c domes and proxi mal pyroclast i cs. T h e andesi t i c to basalti c lav as ( wi t h tuffs or cong lomerates)uni ts are i nterpret ed to represent erupt i on of i nt ermedi at e t o mafi c lav a flow s and associ at ed pyroclasti c and/ or epi clasti c deposi ts.T h e epi clast i c/ pyroclasti c uni ts are i nterpreted t o representdeposi ti on from t h e erosi on ofdormantand acti ve v olcani chi g h lands.S ome of t h e met av olcani clasti c uni ts w i t hi n th e map area di splay li th olog i c relati onsh i ps si mi larto dat ed uni t s present i n north ern O rang e and Durh am Count i es. Due to t h ese si mi lari t i es,th e metav olcani c and metav olcani clasti c uni ts h av e been tentat i v ely separated i nt o upper and low er port i ons of t h e Hyco Formati on; g eoch ronolog i c dat a i n th e map area i s needed to confi rm th i si nt erpret ati on. A rev i ew of t h e reg i onal li th olog i es i s summari zed i n Bradley ( 2013) .
Equa lAr ea Sc hm idtN etPr ojec t ion s a n d Rose Dia gr am
Inferred cont act
G radat i onalcontact-i nferred; dott ed w h ere concealed
T h e Hyco Arc and Aaron Formati on li t h olog i es w ere folded and subjected t o low g rade met amorph i sm duri ng t h e ca. 578to 554Ma ( P ollock,2007;P ollocketal. ,2010)V i rg i li na deformati on ( G lov er and S i nh a,1973;Harri s and G lov er, 1985;Harri s and G lov er,1988;and Hi bbard and S amson,1995) .In t h e map area,ori gi nallayeri ng of Hyco and Aaron Format i on li t h olog i es are i nt erpret ed t o rang e from sh allow ly t o steeply di ppi ng due to open t oi socli nal folds th atare locally ov ert urned t o th e sout h east .
St rat i g raph i c relat i ons uncert ai n
N eoprot erozoi c
Hyc oFor m at ion – upperm em b er
Zh abltdcp
CON TACTS,FAULTS,AN DOTHERFEATURES
P reMesozoi c crystalli ne rocks i nt h e Crutch fi eld Crossroads Quadrang le are partofth e redefi ned Hyco Arc ( Hi bbard et al. ,2013)w i th i n th e N eoproterozoi c to Cambri an Caroli na terrane ( Hi bbard etal. ,2002;and Hi bbard etal. ,2006) .In t h e reg i on ofth e map area,t h e Caroli na terrane can be separated i nto t w o li t h ot ectoni c uni ts:1)t h e Hyco Arc and 2)t he Aaron Formati on of t h e redefi ned V i rg i li na sequence ( Hi bbard etal. ,2013) . T h e Hyco Arc consi sts of th e Hyco Format i on w h i ch i nclude ca.612 to 633 Ma ( W ortman et al. ,2000;Bow man,2010;Bradley and Mi ller,201 1) metamorph osed layered v olcani clast i c rock s and plutoni c rocks.Av ai lable ag e dat es ( W ortman etal. ,2000;Bradley and Mi ller,201 1)i ndi cat et h e Hyco Format i on may be di vi ded i nto low er( ca.630Ma)and upper( ca.615Ma)members ( i nformal)w i t h an apparenti nterv eni ng h i at us of mag mat i sm.In north eastern Ch ath am County,Hyco Formati on uni t s are i ntruded by t h e ca.579Ma ( T adlockand Loew y,2006)EastFarri ng t on pluton and associ ated W estFarri ng ton pluton.T h e Aaron Format i on consi sts of met amorph osed layered v olcani clast i c rocks w i th young estdetri t alzi rcons of ca.578and 588Ma ( S amson etal. ,2001and P ollocketal. ,2010,respect i v ely) .
Za
Zh able
EXPLAN ATI ON OFMAPSYMBOLS
T h e Crutch fi eld Crossroads 7. 5mi nute Quadrang le li es i n th e eastcentralporti on of th e N orth Caroli na P i edmont.T h e R ock y Ri v er crosses th e south w estern corner of th e quadrang le;t h e Ch at h am – Alamance Count y li ne crosses t he quadrang le from w estto east .P orti ons ofth e T ow n ofS i lerCi t y( populat i on approxi mately 8, 200)occupy th e south w est corner of t h e quadrang le. Impounded porti ons of t h e R ocky R i v er w i th i n th e quadrang le serv e as th e w ater supply source fort h e T ow n ofS i lerCi t y.T h e quadrang le i s crossed by north w est south eastU S Hi g h w ay 421.Hw y 64,a major east w estcorri dorforth e centralP i edmont,i s locat ed i mmedi at ely to t h e south oft h e quadrang le.
78 84
Zh e/ pl
89
68 81
82
72
Zh e/ pl
88
81 70
86
81
?
84
64
78
79
?
81 81
?
?
?
Zh el 76
82
Zh able
76
?
? Qal
?
A'
Allm en din ger ,R.W . ,Ca r dozo,N .C. ,a n d Fisher ,D. ,2012,S truct uralG eolog y Alg ori th ms:V ect ors and T ensors: Cambri dg e,Eng land,Cambri dg e U ni v ersi ty P ress,289pp. Bowm a n ,J. D. ,2010,T h e Aaron Formati on:Ev i dence fora N ew Li t h ot ectoni c U ni ti n Caroli ni a,N orth Cent ralN orth Caroli na,unpubli sh ed mast ers t h esi s,N orth Caroli na S t at e U ni v ersi ty,R alei g h ,N ort h Caroli na,1 16p. Br a dley,P. J. ,a n d Miller ,B. V. ,2011,N ew g eolog i c mappi ng and ag e constrai nts i n th e Hyco Arc of th e Caroli na t errane i n O rang e County,N ort h Caroli na:G eolog i calS oci et y ofAmeri ca Abst racts w i th P rog rams,V ol.43,N o.2. Br a dley,P. J. ,2013,T h e Caroli na terrane on t h e w estflankof th e Deep R i v er Basi ni nt h e north ern P i edmontof N ort h Caroli na – AS t atus R eport ,i n Hi bbard,J. P .and P ollock,J . C.edi t ors,2013,O ne arc,tw o arcs,old arc,new arc:T h e Caroli na terrane i n centralN ort h Caroli na,Caroli na G eolog i calS oci ety fi eld tri p g ui debook,pp.139151. Br a dley,P. J. ,Ha n n a ,H. D. ,Ga y,N . K. ,St odda r d,E. F . ,Bec ht el,R. ,Phillips,C. M. ,a n d Fuem m eler ,S.J,2016, G eolog i c map ofO rang e Count y,N ort h Caroli na:N orth Caroli na G eolog i calS urv ey O penfi le R eport201605,scale 1: 50, 000,i n color. Br oa dhur st ,S. D. ,a n d Coun c ill,R. J. ,1953,Apreli mi nary reporton h i g h alumi na mi nerals i nt h e V olcani cS lat e seri es,N orth Caroli na: N orth Caroli na Depart mentof Conserv at i on Dev elopment,Di vi si on of Mi neral R esources, Informat i on Ci rcular10,22p. Ca r dozo,N . ,a n d Allm en din ger ,R.W . ,2013, S ph eri cal projecti ons w i t h O S XS t ereonet: Computers and G eosci ences,v .51,no.0,p.193-205,doi :10. 1016/ j. cag eo. 2012. 07. 021. Espen sha de,G. H. ,a n d Pot t er ,D. B. ,1960,Kyani t e,si lli mani t e,and andalusi te deposi ts ofth e S outh eastern S tat es: U . S .G eolog i calS urv ey P rofessi onalP aper336,121p. Fisher ,R. V. ,a n d Sc hm in c ke H. U. ,1984,P yroclasti c rocks,Berli n,W estG ermany,S pri ng erV erlag ,472p. Glover ,L. ,a n d Sin ha ,A. ,1973,T h e V i rg i li na deformati on,a late P recambri an to Early Cambri an ( ?)orog eni c ev ent i nt h e centralP i edmontofV i rg i ni a and N ort h Caroli na,Ameri can JournalofS ci ence,Cooperv .273A,pp.234251. Ha n n a ,H. D. ,a n d Br a dley,P. J. ,2014,G eolog i c Map of th e Ch ath am County P orti on of t heS i lkHope Quadrang le, Ch ath am and Alamance Count i es,N ort h Caroli na: N orth Caroli na G eolog i cal S urv ey O penfi le R eport201402, scale 1: 24, 000,i n color. Ha n n a ,H. D. ,a n d Br a dley,P. J. ,2016,G eolog i c Map of th e N orth ern T h i rd of th e S i lerCi t y Quadrang le,Ch ath am County,N ort h Caroli na:N ort h Caroli na G eolog i calS urv ey O penfi le R eport201608,scale 1: 24, 000,i n color. Ha r r is,C. W . ,1984,Coarseg rai ned submari nefan deposi ts of mag mati c arc affi ni t yi n th e lat e P recambri an Aaron Format i on,N orth Caroli na,U . S. A. ,P recambri an R esearch ,26,pp.285306. Ha r r is,C. ,a n d Glover ,L. ,1985,T h e V i rg i li na deformati on:i mpli cat i ons of strat i g raph i c correlati on i nt h e Caroli na slat e belt ,Caroli na G eolog i calS oci et y fi eld t ri p g ui debook,36p. Ha r r is,C. ,a n d Glover ,1988,T h e reg i onal ext ent of th e ca.600 Ma V i rg i li na deformat i on: i mpli cati ons of strati g raph i c correlati on i n th e Caroli na terrane,G eolog i calS oci ety ofAmeri ca Bulleti n,v .100,pp.200217. Ha uc k,S. A. ,1977,G eolog y and pet rolog y of t h e nort h w estquarter of t h e Bynum quadrang le,Caroli na slate belt, N ort h Caroli na,unpubli sh ed M. S .t h esi s,U ni v ersi ty ofN ort h Caroli na atCh apelHi ll,146p. Hib b a r d,J. ,a n d Sa m son ,S. ,1995,O rog enesi s exot i c t o t h e Iapet an cycle i n th e sout h ern Appalach i ans,In, Hi bbard,J. ,v an S t aal,C. ,Caw ood,P .edi tors,CurrentP erspect i v es i n th e Appalach i an– Caledoni an O rog en. G eolog i calAssoci at i on ofCanada S peci alP aper,v .41,pp.191–205. Hib b a r d,J. ,St odda r d,E. F. ,Sec or ,D. ,Jr . ,a n d Den n is,A. ,2002,T h e Caroli na Zone:O v erv i ew of N eoproterozoi c t o early P aleozoi c peri G ondw anan terranes along th e east ern flankof th e sout h ern Appalach i ans:Eart h S ci ence R ev i ew s,v .57,n.3/ 4,p.299339. Hib b a r d,J.P. ,va n St a a l,C.R. ,Ra n kin ,D.W . ,a n d W illia m s,H. ,2006,Li th ot ectoni c map of th e Appalach i an O rog en,CanadaU ni ted S tates ofAmeri ca,G eolog i calS urv ey ofCanada,Map2096A.1: 1, 500, 000scale. Hib b a r d,J. P. ,Polloc k,J. C. ,a n d Br a dley,P. J. ,2013,O ne arc,tw o arcs,old arc,new arc: An ov erv i ew of t he Caroli na terrane i n centralN ort h Caroli na,Caroli na G eolog i calS oci et y fi eld t ri p g ui debook ,265p. Hughes,E. H. ,1987,T h e g eolog y and alt erati on centers of t h e S now Camp mi neMajor Hi ll area,centralCaroli na slat e belt,Alamance and Ch at h am Counti es,N orth Caroli na:U . S .G eolog i calS urv ey O penFi le R eport87–180,29 p. Le Ma it r e,R. W . ,Ed. ,2002,Ig neous R ocks: A Classi fi cati on and G lossary of T erms: R ecommendat i ons of th e Internati onal U ni on of G eolog i cal S ci ences ( IU G S ) S ubcommi ssi on on th e S ystemati cs of Ig neous R ocks: Cambri dg e,Cambri dg e U ni v ersi ty P ress,252p. Polloc k,J.C. ,2007,T h e N eoprot erozoi cEarly P aleozoi c tect oni c ev oluti on of t h e peri G ondw anan marg i n of th e Appalach i an orog en: an i nt eg rat ed g eoch ronolog i cal,g eoch emi cal and i sot opi c study from N orth Caroli na and N ew foundland.U npubli sh ed P h Ddi ssert ati on,N ort h Caroli na S t ate U ni v ersi ty,194p. Polloc k,J. C. ,Hib b a r d,J. P. ,a n d Sylvest er ,P. J. ,2010,Deposi ti onal and tect oni c sett i ng of t h e N eoprot erozoi cearly P aleozoi c rocks of th e V i rg i li na sequence and Albemarle G roup,N orth Caroli na:i n T ollo,R . P. ,Bart h olomew , M. J. ,Hi bbard,J. P. ,and Karabi nos,P . M. ,eds. ,From R odi ni a to P ang ea: T h e Li t h ot ectoni c R ecord of th e Appalach i an R eg i on:G eolog i calS oci ety ofAmeri ca Memoi r206,p.739772. Rein em un d,J. A. ,1955,G eolog y of th e Deep R i v ercoalfi eld,N orth Caroli na:U . S .G eol.S urv ey P rof.P aper246, 159p. Sa m son ,S. D. ,Sec or ,D. T ,a n d Ha m ilt on ,M. A. ,2001,W anderi ng Caroli na:T racki ng exoti ct erranes w i th detri tal Zi rcons,G S AAbstracts w i t h P rog rams V ol.33,N o.6,p.A263. Sc hm idt ,R. G. ,Gum iel,P. ,a n d Pa ya s,A. ,2006,G eolog y and mi neral deposi ts of t h e S now CampS axapah aw area, Cent ral N ort h Caroli na: U ni ted S tat es G eolog i cal S urv ey O penfi le R eport 20061259 ( ht tp: / / pubs. usg s. g ov / of/ 2006/ 1259/ i ndex. h tml) . Sc hm idt ,R. G. ,1985,S now Camp pyroph ylli te mi ne,i n Fei ss,P . G . ,ed. ,V olcani ch osted g old and h i ghalumi na rocks ofth e Caroli na slate belt:S oci ety ofEconomi c G eolog i st s,p.37–47. St uc key,J. L. ,1967,P yroph ylli te deposi ts i n N orth Caroli na:N orth Caroli na Di vi si on of Mi neralR esources Bullet i n 80,38p. Ta dloc k,K. A. ,a n d Loewy,S. L. ,2006,Isotopi c ch aract eri zati on of th e Farri ng t on plut on:const rai ni ng t heV i rg i li na orog eny,i n Bradley,P . J. ,and Clark ,T . W. ,edi t ors,T h e G eolog y of th e Ch apel Hi ll,Hi llsboroug h and Efland 7. 5mi nut e Quadrang les,O rang e and Durh am Counti es,Caroli na T errane,N orth Caroli na,Caroli na G eolog i calS oci ety Fi eld T ri p G ui debookfort h e 2006annualmeeti ng ,pp.1721. W or t m a n ,G. L. ,Sa m son ,S. D. ,a n d Hib b a r d,J. P. ,2000,P reci se U P b zi rcon constrai nts on t h e earli estmag mati c hi st ory ofth e Caroli na terrane,J ournalofG eolog y,v .108,pp.321338.
TRAV ERSEMAP
Hi llsh ade deri v ed from a 20footLi DAR di gi t alelev ati on model.R ed and blue li nes sh ow pat h s offi eld t rav erses.
Bounds of G eoP DF based on 7. 5mi nut e g ri d project i on i n U T M 17S ;N ort h Ameri can Datum of 1983 ( N AD83) . G eolog i c polyg ons t i ed t o 7. 5mi nut e g ri d projecti on i n St at e P lane coordi nat es for edg emat ch i ng w i th leg acy G IS data,as such some ov erlap and underlap ofmap uni t polyg ons occuraround edg e ofmap.
Z ha b le – An desit ic t ob a sa lt ic la va swit h in t er la yer ed epic la st ic r oc ks: Li g h tg reen,g rayg reen,g ray,and dark g ray; t ypi cally unfoli ated, amyg daloi dal, plag i oclase porph yri t i c, amph i bole/ pyroxene porph yri t i c and aph ani ti c; metamorph osed:andesi t i c t o basalt i c lav as and sh allow i nt rusi ons.Hyaloclast i c texture i s common and i mparts a frag mental t exture on some outcrops and floatboulders.Cont ai ns lesser amount s of g rayi sh g reen,li g h tg reen,and li g h tg ray to w h i te;met amorph osed cong lomerate,cong lomerat i c sandstone,sandst one,si ltst one and mudstone.
A
Z ha si -An desit ic sha llow in t r usive: G rayi sh g reen t o li g h tg reen,metamorph osed:plag i oclase porph yri ti c andesi t e wi t h a g ranulartextured g roundmass to v ery fi neg rai ned di ori t e ( wi th i nt rusi ve t exture v i si ble w i th 7x h and lens) . Contai ns lesser amounts of fi ne-to medi um g rai ned di ori t e. P lag i oclase ph enocrysts t ypi cally rang e from 1mm to 4 mm.Darkg reen to blackcolored amph i bole,w h en present,occurs as ph enocrysts ( less th an 1mm t o 1mm)and as i nterg row t h sw i th plag i oclase.
660'
Z ha b lt dc p– An desit et ob a sa ltpor phyr y of t he Dr y Cr eek a r ea :Di st i nct i v e,g reen to darkg reen,met amorph osed andesi te porph yry w i th aph ani ti c g roundmass and euh edralph enocrysts ( up t o 10mm)of g reeni sh whi te plag i oclase; ph enocryst s typi cally consti t ut e 20 to 50% of th e rock;local ali g nmentof plag i oclase;lesser pyroxene/ amph i bole ph enocryst s.G reen to darkg reen basaltporph yry w i th abundantpyroxene ( alt ered t o amph i bole)ph enocrysts w i t h mi nor plag i oclase ph enocryst s.Andesi t e and basaltporph yri es locally amyg daloi dal ( up to 2cm) ,amyg dules i n fi lli ng i nclude calci t e,quart z,ch lori te,and epi dote. S ame as Dry CreekP orph yry complex of Hauck( 1977) . P resentas i solated outcrops orboulders as desi g nat ed by g reen st ati on locat i ons and as one mapscale body.
1340'
Siler City Water Supply Lake Number 3
Pi ney G rov e Ch urch R oad
Ed Clapp R oad
Si lerCi ty S now Camp R oad
Nick Creek Qal
J essi e Bri dg es R oad
Nick Creek
S mi th Hudson R oad
Si lkHope R oad
Varnell Creek
A' 660'
0'
0' Zh e/ pl Zh e/ pl Zh e/ pli m
Zh el
1340'
J d
Zh e/ pli m
3340'
In cross sect i on, g radati onalcont act-i nferred In cross sect i on, i nt erpret i v e fold form li nes
In cross sect i on, fold axi s -i nferred In cross sect i on,bri t t le fault, i denti ty orexi stence quest i oned, i nferred from Li DAR li neament
3340'
cross sect i on scale -1: 24000 no v ert i calexag g erat i on
by car
N.C.
R esearch support ed by t heU . S .G eolog i calS urv ey,N at i onal Cooperati v e G eolog i c Mappi ng P rog ram underS T AT EMAP ( Aw ard -2015,G 15AC00237) . Thi s map and explanatory i nformati on i s submi t ted forpubli cat i on w i t h t h e underst andi ng th atth e U ni t ed S tat es G ov ernmenti s aut h ori zed t o reproduce and di stri bute repri nt s forg ov ernmentaluse.T h e v i ew s and conclusi ons contai ned i nt hi s documentare t h ose ofth e auth ors and sh ould notbe i nt erpret ed as necessari ly representi ng th e offi ci alpoli ci es, ei t h erexpress ori mpli ed,oft heU . S .G ov ernment.
Geologic Ma pof t he Sout her n Thir d of t he Cr ut c hfield Cr ossr oa ds7. 5m in ut e Qua dr a n gle, Cha t ha m a n d Ala m a n c e Coun t ies,N or t h Ca r olin a By Hea t herD.Ha n n a a n d PhilipJ.Br a dley G eolog y mapped from July 2015to May 2016. Map preparati on,di gi talcartog raph y and edi ti ng by Mi ch aelA.Medi na,Heat h erD.Hanna and P h i li p J.Bradley. 2016
by foot
Thi si s an O pen Fi le Map.Ith as been rev i ew ed i nternally for conformi ty w i th N orth Caroli na G eolog i calS urv ey mappi ng standards and w i t h t h e N ort h Ameri can S trat i g raph i c Code. Furt h errev i si ons orcorrecti ons t o th i s O pen Fi le map may occur. Acknow ledg ement s:Fi eld assi st ance prov i ded by R andy Bech t eland members ofth e Energ y G roup -O i land G as P rog ram:Ann S h i elds,R yan Ch annell, Kath eri ne Marci ni ak,and W altT .Hav en
G eolog i c Map ofth e S outh ern T h i rd ofth e Crutch fi eld Crossroads 7. 5mi nut e Quadrang le,O pen Fi le R eport201609
N ort h Caroli na DepartmentofEnv i ronment alQuali ty Energ y G roup
Thi s G eolog i c map w as funded i n partby th e U S G S N ati onalCooperat i v e G eolog i c Mappi ng P rog ram
Jenny Kelv i ng ton,Executi v e Di rector Kenneth B.T aylor,S tate G eolog i st
Mesozoi c– P aleozoi c
Mesozoi c
Quaternary
IN T R O DU CT IO N
CORRELATI ON OFMAPUN I TS
Qal
Met amorph i c R ock s
T h e majori ty of th e quadrang le drai ns to th e R ock y Ri v eralong drai nag es t h ati nclude Lacy’ s Creek,N i ckCreek ,N ort h P rong ,G reenbri erCreek,Joh nson Creek,Mud Li ckCreek,V arnellCreekand unnamed creeks.T h e nort h eastporti on ofth e quadrang le drai ns t ot h e Haw R i v eralong drai nag es t h ati nclude S outh Fork,R eedy Branch and P i ne Hi llBranch . Asmall area i nt h e south w estcorner of t h e quadrang le drai ns to t h e Deep R i v er. T h e drai nag e di vi de bet w een t he R ock y and Deep R i v ers i s locally cont rolled by a ri dg e th at mark s a major g eolog i c contact ( Hyco and Aaron Format i ons) .N at ural exposures of crystalli ne rocks occur mai nly along t h ese and numerous unnamed creeks.R ock exposure at road cuts,ri dg es,resi stant fi nnedsh aped outcrops and pav ement out crops occur locally out si de of drai nag es.T h e elev ati ons i nt h e map area rang e from about740feetabov e sea lev elnort h ofth e i ntersect i on ofP i ney G rov e Ch urch road and Fellow sh i p Ch urch R oad ( on t h e ri dg e t h atdefi nes t h e drai nag e di vi de betw een th e R ock y and Deep R i v ers)i n t h e south w est corner of t h e quadrang le,to less th an 500 feet along P i ne Hi ll Branch near th e nort h east ern cornerofth e quadrang le.
Aa r on For m at ion
G eolog i c Backg round and P astW ork
Jd
MP zg b
Young estdet ri talzi rcons ofca.578and 588Ma ( S amson etal. ,2001and P ollocket.al. ,2010,respect i v ely) .
Met amorph osed v olcani clast i c sedi mentary and pyroclast i c rocks ( st rati g raph i c relat i ons uncert ai n)ca.612-616Ma ( W ort man etal. ,2000; Bow man,2010;and Bradley and Mi ller,201 1)
Zh asi
Zh el Zh dlt( u)
Zh e/ pl Zh e/ pli m
5004
5003
533
U ni di recti onalR ose Di ag ram ofJoi nts N =157 O uterCi rcle =8% Mean v ector=267deg rees Max v alue =7% betw een 341deg rees and 350deg rees
Zh asi
Zh ablt dcp
O bserv ati on st ati on locat i on Di abase stat i on locati on Indi cat es locat i on ofv ug g y quart z orsli ceous brecci a float
7057
Indi cat es locat i on ofZh abltdcp boulders oroutcrop
533
1882 5030 6096
79
6136
46
85 77 82
66
81
83
84
88
P rospect( pi torsmallopen cut ) 2Hi nsh aw P rospect( pyroph ylli te)-abandoned 4S now Camp S outh P rospect( pyroph ylli te)-abandoned
88
quarry ormi ne -abandoned 1quarry ( flag stone)-abandoned 5S now Camp P yroph ylli t e Mi ne
84
78
86
75 84
81
84
80 80
84
88
Zh e/ pl
76
87
84
88
84
86
79
84
78
80
82
Qal
81
61 85 88 80 85
88 79
76
87
74
Zh e/ pl
77
77
77
89
79
81 71
47 85
86
89 59
84
82
83
80
56
86 59
79 88 81
MPzgb – Ga b b r o:Melanocrati c( CI g reaterth an 50) ,fi neg rai ned g abbro.Di st i nct i v e brow n w eat h eri ng .O ccurs as a small map scale body closely associ ated w i t h a di abase di ke,and as i solated boulders along th e trend of a di abase di ke.Appears unmetamorph osed.P urple st ati on locat i ons i ndi cate out crop orboulders ofMP zg b.
Zh e/ pli m
78
78
78
72
69 84 89
Za
Zh e/ pl
78
84
Z hel-Epic la st ic r oc ksa n d la va s:Metamorph osed cong lomerat e,cong lomerat i c sandst one,sandstone,si ltst one and mudstone.S i ltstones and mudstones t ypi cally di splay beddi ng rang i ng from mmscale up to 10cm,beddi ng layers t raceable for sev eral feetlocally,may exh i bi tsoftsedi mentdeformat i on.Locally t uffaceous w i th a reli ctv i t ri ct exture. Locally contai ni nterbedded daci ti c to basalti c lav as.Cong lomerates and cong lomerati c sandstones t ypi cally contai n subrounded to ang ularclasts of daci te i n a clasti c matri x.Deposi t i on i nterpret ed as di stalfrom v olcani c center,i n deep w at er( ?) ,and v i a turbi di t e flow s.
74
74
68
Za
81
89 84
69
89
85
89
78
87
87
72
79
83
66
88
Z he/ pl -Mixed epic la st ic pyr oc la st ic r oc kswit h in t er la yer ed da c it ic la va s:G rayi sh g reen t o g reeni sh g ray,locally wi t h di sti nct i v e reddi sh g ray or maroon t o lav ender colorati on;met amorph osed: cong lomerat e,cong lomerati c sandst one, sandstone, si ltst one and mudstone. Li th olog i es are locally bedded; locally tuffaceous w i th a cryptocrystalli neli k e g roundmass.S i ltst ones are locally ph ylli ti c.Locally cont ai ni nt erbedded daci ti c lav as i denti calt o Zh dltuni t .Cont ai ns lesser amounts of fi ne-t o coarse t uff and lapi llituff w i th a crypt ocrystalli neli ke g roundmass. P yroclasti cs,lav as,and epi clasti cs are mai nly felsi ci n composi t i on.Mi norandesi t i ct o basalti c lav as and tuffs present . Si li ci fi ed and/ orseri ci t i zed altered rockare locally presentand i ncrease i n occurrence tow ard th e nort h .Cong lomerates and cong lomerati c sandst ones typi cally cont ai n subrounded to ang ular clasts of daci t e i n a clasti c mat ri x. Fi ne-to medi umg rai ned di ori t ei s locally present .P orti ons oft h e Zh e/ pluni tare i nterpreted to h av e been deposi t ed proxi malt o act i v e v olcani c cent ers represented by t h e Zh dltuni tbutare also i nt erpret ed to record t h e erosi on of proxi malv olcani c cent ers aftercessat i on ofact i v e v olcani sm.
84
Z hdlt( u)– Da c it ic la va s a n d t uffsof t he upperpor t ion of t he Hyc o For m at ion : G reeni sh g ray to darkg ray, si li ceous,metamorph osed:aph ani t i c daci te,porph yri t i c daci te w i t h plag i oclase ph enocrysts,and flow banded daci te. Daci t ewi t h h yaloclast i ct extures are common.W elded and nonw elded tuffs associ ated w i th th e lav as i nclude:g reeni sh g ray t o g rayi sh g reen,fi ne tuff,coarse plag i oclase crystal t uff and lapi llituff.Locally,i nterlayers of i mmat ure cong lomerate and cong lomerati c sandst one w i t h abundantdaci t e clasts are present.T h e daci t es are i nterpreted to h av e been coh erentext rusi v es or v ery sh allow i nt rusi ons associ ated w i t h dome format i on.T h e t uffs are i nterpret ed as epi sodi c pyroclast i c flow deposi t s,ai r falltuffs or rew orked tuffs g enerated duri ng format i on of daci t e domes.T h e uni t occurs as map scale pods surrounded by clasti c rock s of Zh e/ pl uni t .W ortman et al.( 2000)reports an ag e of 615. 7+3. 7/ 1. 9Ma U P b zi rcon date fora daci t i c tufffrom t h e uni ti nt h e R oug emontquadrang le.
68
84
56
74
Za
84
Za
82 87
78
85
88
J d
81 84
60
82
84
88 87
J d
MP zg b
60
80
81 82
Qal80
82 87
1
77 88 88
86 87
83 9
81
86 84
87
J d
80
76
79
79 80 72
77 74
75
Qal 49 74
85
74
86
78
Zh e/ pli m 86 80
84
Zh dlt( u)
89
78
82
78 80
46
74
78 88
86 49
80
70 84
84
49
84 79
68
72
81
Zh e/ pl
74
Zh asi
59 89 88
82
84 87
74 86
Zh e/ pl
83
79
86
70
62
59
71
64
89
84
70
80
84
80
83 64
74
71
85
89
64
85
88
65
86
73
84
60
79
88
Qal
78
84
71
J d
75
80 88
82
84
82
86 88
84 65
88
89
Qal
81
88
87
82
82
88
82
82
78
86
84
78
64
79 76 76
70
72
84
85
76
86
75
89
76
82
Zh e/ pli m
82
77
84
Zh e/ pli m
65
86
85
84
75
56 74 79
72
87
88
80
81
78
Zh ablt dcp
77
80
84
81
Zh e/ pli m
Z he/ plim -Mixed epic la st ic pyr oc la st ic r oc kswit h in t er la yer ed in t er m edia t et ob a sa lt ic la va s:G rayi sh g reen to g reeni sh g ray,locally w i th di st i ncti v e reddi sh g ray or maroon to lav ender colorati on;met amorph osed: cong lomerate, cong lomerati c sandst one,sandstone,si lt stone,mudstone,and felsi c fi ne-t o coarse t uff and lapi llit uff. S i ltstones are locally ph ylli t i c.Locally cont ai ni nt erbedded andesi ti c to basalti c lav as i dent i calto Zh abluni t .S i li ci fi ed and/ orseri ci ti zed altered rockare locally present. Interpreted t o be i n g radati onal cont actw i t h uni tZh e/ pl and i denti fi ed by i ncrease i n i ntermedi ate to mafi c lav as and decrease and/ orabsence ofdaci tes.
84
86
78
59
87
71
Zh e/ pli m
75
88
68
68
72
82
Zh dlt( u)
85
Zh e/ pli m
88
85
72
72
82
60
80
85 84
Qal
84
79
81
86
84
62
74
74
72
78
78
83
83
79
74 70
86 82
87
84
78
74 76
86
84
75
88
Qal
48
80
76 88
81
MP zg b
84
76
84
Z a – Aa r on For m at ion : Di st i nct i v e met asedi mentary packag e th atrang es from fi neg rai ned si lt stones to coarseg rai ned sandst ones,pebbly sandst ones and cong lomerates. S i lt stones are si mi lar i n appearance to Hyco Formati on li th olog i es.T h e sandstones,pebbly sandst ones and cong lomerat es ( classi fi ed as li th areni te,feldspath i c li th areni t e and li th i c feldsareni te by Harri s ( 1984) )are di st i nct i v e and commonly contai n rounded to subrounded clasts of quartz rang i ng from sand-to g rav elsi zed.In th e sandst ones,feldspari s th e mostpromi nentmi neralg rai n;quart zv ari es from sparse t o abundanti n h and sample.Li th i c clasts are t ypi cally promi nentand rang e from sand-to g rav elsi ze.Harri s ( 1984) ,performed a det ai led sedi mentary st udy of t h e Aaron Formati on t ot hei mmedi ate w estof th e map area.Harri s ( 1984)i nt erpreted t h e Aaron Formati on t o h av e been deposi ted by turbi di ty current si n a ret rog radat i onalsubmari ne fan set ti ng .P ollocketal.( 2010)i nt erpret s an approxi mate 35mi lli on yearunconformi t y betw een t h e Aaron and underlyi ng Hyco Format i on. T h i si nterpretati on i s based i n parton detri t al zi rcon ag e date data from an Aaron cong lomerate sample collect ed i n th e nearby Li bert y Quadrang le.
85
84
76 88
79
81 84
87
83
79
56
88
73
68 72
80
78 84
88
88
76
74
84
6782
72
89
Jd – Dia b a se:Blackt o g reeni sh black,fi ne-t o medi umg rai ned,dense,consi sts pri mari ly of plag i oclase,aug i t e and may cont ai n oli vi ne.O ccurs as di kes up to 100ftw i de.Di abase t ypi cally occurs as sph eri odally w eath ered boulders wi t h a g rayi sh brow n w eat h eri ng ri nd.R ed stat i on locati on i ndi cat es outcrop orboulders ofdi abase.
85
84 83
89
A
86
75
80
Qa l – Alluvium : U nconsoli dat ed poorly sorted and strat i fi ed deposi t s of ang ular to subrounded clay,si lt,sand and g rav el-t o bouldersi zed clast s,i n stream drai nag es.May i nclude poi ntbars,terraces and natural lev ees along larg er stream floodplai ns.S tructural measurements depi cted on th e map w i th i n Qal representoutcrops of cryst alli ne rock i nli ers surrounded by alluv i um.
St ri ke ofv ert i calJ oi ntsurface ( multi ple observ at i ons atone locati on)
PROSPECTSAN DQUARRI ES
78 85
St ri ke and di p ofi ncli ned joi ntsurface ( multi ple observ at i ons atone locati on)
3
1923
82
70
79
mi ne sh aft-abandoned
88
72
88
St ri ke and di p ofi ncli ned reg i onalfoli ati on ( multi ple observ at i ons atone locati on)
R EFER EN CES :
80
76
St ri ke ofv ert i calJ oi ntsurface
3" O re Hi ll"sh aft( Iron?)-abandoned
85
81
St ri ke and di p ofcleav ag e ( multi ple observ at i ons atone locati on) St ri ke and di p ofi ncli ned joi ntsurface
81
St ri ke and di p ofcleav ag e
84
84 83
80
St ri ke and di p ofi ncli ned reg i onalfoli ati on
78
655
87
St ri ke and di p ofpri mary beddi ng and/ orlayeri ng ( multi ple observ at i ons atone locati on)
83
72 76
S ch mi dtetal.( 2006)g eoch em locati on
St ri ke and di p ofpri mary beddi ng and/ orlayeri ng
65
87 77
Indi cat es locat i on ofMP zg b boulders oroutcrop
PLAN ARFEATURES
76
Hyco Formati on – U pperP ort i on
Zh able
4
74
Aaron Format i on
Zh dlt( u)
2
6128
MET AV O LCAN ICAN DMET AV O LCAN ICLAS T ICU N IT S
Zh e/ pl
MP zg b di ke -i nferred
6611
To Be Mapped 2016-2017 81
Inferred di abase di ke; dott ed w h ere concealed
Cross secti on
6441
6903
Int erpret ed fold h i ng e ofov ert urned anti cli ne
1603
6244
IN T R U S IV EAN DMET AIN T R U S IV EU N IT S
Zh e/ pli m
Int erpret ed fold h i ng e ofsyncli ne; quest i on markw h ere exi st ence i s questi onable;dott ed w h ere concealed
6955
6468
S EDIMEN T AR Y U N IT
EqualArea S ch mi dtN etP roject i on of Contoured P oles to P ri mary Beddi ng and Layeri ng ContourInterv al=2si g ma N =30
A'
5072
A preli mi nary rev i ew of th e area g eolog y i s prov i ded i n Bradley ( 2013) . U ni tdescri pt i ons common to Hanna etal. ( 2014)and Hanna and Bradley ( 2016)from t he S i lkHope and S i ler Ci ty g eolog i c maps,respecti v ely,w ere used for conformi ty w i th on st ri k e uni ts i n nei g h bori ng quadrang les. U ni t descri pt i ons and strat i g raph i c correlat i ons w ere mai nt ai ned from adjacent mappi ng i n O rang e County Bradley ( Bradley et al. ,2016) . T h e nomenclat ure of th e Internati onalU ni on ofG eolog i calS ci ences subcommi ssi on on i g neous and v olcani c rocks ( IU G S )afterLe Mai tre ( 2002) i s used i n classi fi cati on and nami ng of th e uni t s.T h e classi fi cat i on and nami ng of t h e rock si s based on reli cti g neous t extures,modal mi neral assemblag es,or normali zed mi neral assemblag es w h en w h olerock g eoch emi cal data i s av ai lable.P yroclasti c rocktermi nolog y follow s t h atofFi sh erand S ch mi nk e( 1984) .
Zh el
Int erpret ed fold h i ng e ofant i cli ne, dott ed w h ere concealed
5055
All preMesozoi c rock si n th e map area h av e been met amorph osed to atleastt h e ch lori t e zone of t h e g reensch i st metamorph i c faci es. Many of th e rocks di splay a w eak or strong met amorph i c foli ati on. Alth oug h subject ed t o metamorph i sm,t h e rock s retai n reli cti g neous,pyroclasti c,and sedi ment ary text ures and st ructures th atallow for th e i denti fi cati on ofprotoli th rocks.As such ,th e prefi x “meta”i s noti ncluded i nt h e nomenclature oft h e preMesozoi c rocks descri bed i nt h e quadrang le.Jurassi c di abase di kes are unmetamorph osed.
Za
1599
5074
DES CR IP T IO N O FMAP U N IT S
MP zg b
1568
A
6254
S ch mi dtetal.( 2006)i denti fi ed “O re Hi ll”as a locati on of a small sh aftatth e top of a knob. T h e rocki s mag net i t e beari ng and i ti s speculat ed t h atth e sh aftw as sunki n search of i ron ore. T h e Hi nsh aw pyroph ylli te prospecti s descri bed by S t uckey ( 1967)and S ch mi dtetal.( 2006) . T h e S now Camp P yroph ylli t e Mi ne i s abandoned. S ch mi dt ( 1985)descri bed t h e mi ne as an i mportantformerproducerof h i ghg rade pyroph ylli t ei n N orth Caroli na acti v e from th e mi d1930’ st o th e mi d1960’ s.Addi ti onaldescri pti ons of th e S now Camp Mi ne are prov i ded i n Broadh urstand Counci ll ( 1953) ,Espensh ade and P ott er ( 1960) ,S t uckey ( 1967) ,and Hug h es ( 1987) . T h e S now Camp S outh pyroph ylli te prospecti s located on th e south ern end ofth e ri dg e t h ati ncludes th e S now Camp Mi ne locat i on.
J d
6494 5
5028
1515
5071
T h ere are no act i v e mi ni ng act i vi t i es currently i nt h e quadrang le. O ne h i stori c flag st one quarry associ ated w i th an abandoned g ri stmi llsi t e w as i denti fi ed along th e R ock y Ri v eri n th e sout h of th e quadrang le.T h e north ern port i on of t h e quadrang le w as mapped atreconnai ssancescale as partofth e S ch mi dtetal.( 2006)st udy.T h e area w as i dent i fi ed as cont ai ni ng larg e zones of h i ghsulfi dati on alterat i on w i t h t h e potenti al for pyroph ylli te and g old resources. T h e quadrang le h as 4i denti fi ed prospectand/ or mi ne areas i ncludi ng :1)“O re Hi ll”,2)Hi nsh aw pyroph ylli t e prospect,3) S now Camp P yroph ylli t e Mi ne,and t h e 4)S now Camp S outh pyroph ylli t e prospect.
Qal
6446
6889
Mi neralR esources
EqualArea S ch mi dtN etP roject i on of Contoured P oles to Foli ati on and Cleav ag e ContourInterv al=2si g ma N =215
Concealed cont act
Inferred bri t tle fault ; dott ed w h ere concealed
Abundantev i dence of bri tt le faulti ng atth e outcrop scale and larg escale li neaments ( as i nterpreted from h i llsh ade Li DAR data)are presenti n th e map area. T h e bri ttle faulti ng and li neaments are i nt erpret ed to be associ ated w i th Mesozoi c extensi on. T h e Colon crossstruct ure ( R ei nemund,1955) ,locat ed to t h e sout h eastof th e st udy area,i sa const ri cti on zone i n th e Deep R i v er Mesozoi c basi n and i s ch aracteri zed by cryst alli ne rock s ov erpri nted by complex bri t tle faulti ng .Di k es of J urassi c ag ed di abase i ntrude th e crystalli ne rocks ofth e map area.Quaternary ag ed alluv i um i s presenti n mostmajordrai nag es.
P lot s and calculat i ons created usi ng S t ereonetv .8. 6. 0based on Allmendi ng eretal.( 2013)and Cardozo and Allmendi ng er( 2013) .
Li nearg eomorph i c feat ure i nt erpret ed from h i llsh ade Li DAR -ori gi n uncert ai n
Quaternary alluv i um cont act
Map uni ts of metav olcani c and met av olcani clasti c rocks i nclude v ari ous li th olog i es t h atw h en g rouped t og et h er are i nterpret ed to i ndi cat e g eneral env i ronments of deposi t i on.T h e daci t i c lav as and tuffs uni ti si nt erpret ed to represent daci ti c domes and proxi mal pyroclast i cs. T h e andesi t i c to basalti c lav as ( wi t h tuffs or cong lomerates)uni ts are i nterpret ed to represent erupt i on of i nt ermedi at e t o mafi c lav a flow s and associ at ed pyroclasti c and/ or epi clasti c deposi ts.T h e epi clast i c/ pyroclasti c uni ts are i nterpreted t o representdeposi ti on from t h e erosi on ofdormantand acti ve v olcani chi g h lands.S ome of t h e met av olcani clasti c uni ts w i t hi n th e map area di splay li th olog i c relati onsh i ps si mi larto dat ed uni t s present i n north ern O rang e and Durh am Count i es. Due to t h ese si mi lari t i es,th e metav olcani c and metav olcani clasti c uni ts h av e been tentat i v ely separated i nt o upper and low er port i ons of t h e Hyco Formati on; g eoch ronolog i c dat a i n th e map area i s needed to confi rm th i si nt erpret ati on. A rev i ew of t h e reg i onal li th olog i es i s summari zed i n Bradley ( 2013) .
Equa lAr ea Sc hm idtN etPr ojec t ion s a n d Rose Dia gr am
Inferred cont act
G radat i onalcontact-i nferred; dott ed w h ere concealed
T h e Hyco Arc and Aaron Formati on li t h olog i es w ere folded and subjected t o low g rade met amorph i sm duri ng t h e ca. 578to 554Ma ( P ollock,2007;P ollocketal. ,2010)V i rg i li na deformati on ( G lov er and S i nh a,1973;Harri s and G lov er, 1985;Harri s and G lov er,1988;and Hi bbard and S amson,1995) .In t h e map area,ori gi nallayeri ng of Hyco and Aaron Format i on li t h olog i es are i nt erpret ed t o rang e from sh allow ly t o steeply di ppi ng due to open t oi socli nal folds th atare locally ov ert urned t o th e sout h east .
St rat i g raph i c relat i ons uncert ai n
N eoprot erozoi c
Hyc oFor m at ion – upperm em b er
Zh abltdcp
CON TACTS,FAULTS,AN DOTHERFEATURES
P reMesozoi c crystalli ne rocks i nt h e Crutch fi eld Crossroads Quadrang le are partofth e redefi ned Hyco Arc ( Hi bbard et al. ,2013)w i th i n th e N eoproterozoi c to Cambri an Caroli na terrane ( Hi bbard etal. ,2002;and Hi bbard etal. ,2006) .In t h e reg i on ofth e map area,t h e Caroli na terrane can be separated i nto t w o li t h ot ectoni c uni ts:1)t h e Hyco Arc and 2)t he Aaron Formati on of t h e redefi ned V i rg i li na sequence ( Hi bbard etal. ,2013) . T h e Hyco Arc consi sts of th e Hyco Format i on w h i ch i nclude ca.612 to 633 Ma ( W ortman et al. ,2000;Bow man,2010;Bradley and Mi ller,201 1) metamorph osed layered v olcani clast i c rock s and plutoni c rocks.Av ai lable ag e dat es ( W ortman etal. ,2000;Bradley and Mi ller,201 1)i ndi cat et h e Hyco Format i on may be di vi ded i nto low er( ca.630Ma)and upper( ca.615Ma)members ( i nformal)w i t h an apparenti nterv eni ng h i at us of mag mat i sm.In north eastern Ch ath am County,Hyco Formati on uni t s are i ntruded by t h e ca.579Ma ( T adlockand Loew y,2006)EastFarri ng t on pluton and associ ated W estFarri ng ton pluton.T h e Aaron Format i on consi sts of met amorph osed layered v olcani clast i c rocks w i th young estdetri t alzi rcons of ca.578and 588Ma ( S amson etal. ,2001and P ollocketal. ,2010,respect i v ely) .
Za
Zh able
EXPLAN ATI ON OFMAPSYMBOLS
T h e Crutch fi eld Crossroads 7. 5mi nute Quadrang le li es i n th e eastcentralporti on of th e N orth Caroli na P i edmont.T h e R ock y Ri v er crosses th e south w estern corner of th e quadrang le;t h e Ch at h am – Alamance Count y li ne crosses t he quadrang le from w estto east .P orti ons ofth e T ow n ofS i lerCi t y( populat i on approxi mately 8, 200)occupy th e south w est corner of t h e quadrang le. Impounded porti ons of t h e R ocky R i v er w i th i n th e quadrang le serv e as th e w ater supply source fort h e T ow n ofS i lerCi t y.T h e quadrang le i s crossed by north w est south eastU S Hi g h w ay 421.Hw y 64,a major east w estcorri dorforth e centralP i edmont,i s locat ed i mmedi at ely to t h e south oft h e quadrang le.
78 84
Zh e/ pl
89
68 81
82
72
Zh e/ pl
88
81 70
86
81
?
84
64
78
79
?
81 81
?
?
?
Zh el 76
82
Zh able
76
?
? Qal
?
A'
Allm en din ger ,R.W . ,Ca r dozo,N .C. ,a n d Fisher ,D. ,2012,S truct uralG eolog y Alg ori th ms:V ect ors and T ensors: Cambri dg e,Eng land,Cambri dg e U ni v ersi ty P ress,289pp. Bowm a n ,J. D. ,2010,T h e Aaron Formati on:Ev i dence fora N ew Li t h ot ectoni c U ni ti n Caroli ni a,N orth Cent ralN orth Caroli na,unpubli sh ed mast ers t h esi s,N orth Caroli na S t at e U ni v ersi ty,R alei g h ,N ort h Caroli na,1 16p. Br a dley,P. J. ,a n d Miller ,B. V. ,2011,N ew g eolog i c mappi ng and ag e constrai nts i n th e Hyco Arc of th e Caroli na t errane i n O rang e County,N ort h Caroli na:G eolog i calS oci et y ofAmeri ca Abst racts w i th P rog rams,V ol.43,N o.2. Br a dley,P. J. ,2013,T h e Caroli na terrane on t h e w estflankof th e Deep R i v er Basi ni nt h e north ern P i edmontof N ort h Caroli na – AS t atus R eport ,i n Hi bbard,J. P .and P ollock,J . C.edi t ors,2013,O ne arc,tw o arcs,old arc,new arc:T h e Caroli na terrane i n centralN ort h Caroli na,Caroli na G eolog i calS oci ety fi eld tri p g ui debook,pp.139151. Br a dley,P. J. ,Ha n n a ,H. D. ,Ga y,N . K. ,St odda r d,E. F . ,Bec ht el,R. ,Phillips,C. M. ,a n d Fuem m eler ,S.J,2016, G eolog i c map ofO rang e Count y,N ort h Caroli na:N orth Caroli na G eolog i calS urv ey O penfi le R eport201605,scale 1: 50, 000,i n color. Br oa dhur st ,S. D. ,a n d Coun c ill,R. J. ,1953,Apreli mi nary reporton h i g h alumi na mi nerals i nt h e V olcani cS lat e seri es,N orth Caroli na: N orth Caroli na Depart mentof Conserv at i on Dev elopment,Di vi si on of Mi neral R esources, Informat i on Ci rcular10,22p. Ca r dozo,N . ,a n d Allm en din ger ,R.W . ,2013, S ph eri cal projecti ons w i t h O S XS t ereonet: Computers and G eosci ences,v .51,no.0,p.193-205,doi :10. 1016/ j. cag eo. 2012. 07. 021. Espen sha de,G. H. ,a n d Pot t er ,D. B. ,1960,Kyani t e,si lli mani t e,and andalusi te deposi ts ofth e S outh eastern S tat es: U . S .G eolog i calS urv ey P rofessi onalP aper336,121p. Fisher ,R. V. ,a n d Sc hm in c ke H. U. ,1984,P yroclasti c rocks,Berli n,W estG ermany,S pri ng erV erlag ,472p. Glover ,L. ,a n d Sin ha ,A. ,1973,T h e V i rg i li na deformati on,a late P recambri an to Early Cambri an ( ?)orog eni c ev ent i nt h e centralP i edmontofV i rg i ni a and N ort h Caroli na,Ameri can JournalofS ci ence,Cooperv .273A,pp.234251. Ha n n a ,H. D. ,a n d Br a dley,P. J. ,2014,G eolog i c Map of th e Ch ath am County P orti on of t heS i lkHope Quadrang le, Ch ath am and Alamance Count i es,N ort h Caroli na: N orth Caroli na G eolog i cal S urv ey O penfi le R eport201402, scale 1: 24, 000,i n color. Ha n n a ,H. D. ,a n d Br a dley,P. J. ,2016,G eolog i c Map of th e N orth ern T h i rd of th e S i lerCi t y Quadrang le,Ch ath am County,N ort h Caroli na:N ort h Caroli na G eolog i calS urv ey O penfi le R eport201608,scale 1: 24, 000,i n color. Ha r r is,C. W . ,1984,Coarseg rai ned submari nefan deposi ts of mag mati c arc affi ni t yi n th e lat e P recambri an Aaron Format i on,N orth Caroli na,U . S. A. ,P recambri an R esearch ,26,pp.285306. Ha r r is,C. ,a n d Glover ,L. ,1985,T h e V i rg i li na deformati on:i mpli cat i ons of strat i g raph i c correlati on i nt h e Caroli na slat e belt ,Caroli na G eolog i calS oci et y fi eld t ri p g ui debook,36p. Ha r r is,C. ,a n d Glover ,1988,T h e reg i onal ext ent of th e ca.600 Ma V i rg i li na deformat i on: i mpli cati ons of strati g raph i c correlati on i n th e Caroli na terrane,G eolog i calS oci ety ofAmeri ca Bulleti n,v .100,pp.200217. Ha uc k,S. A. ,1977,G eolog y and pet rolog y of t h e nort h w estquarter of t h e Bynum quadrang le,Caroli na slate belt, N ort h Caroli na,unpubli sh ed M. S .t h esi s,U ni v ersi ty ofN ort h Caroli na atCh apelHi ll,146p. Hib b a r d,J. ,a n d Sa m son ,S. ,1995,O rog enesi s exot i c t o t h e Iapet an cycle i n th e sout h ern Appalach i ans,In, Hi bbard,J. ,v an S t aal,C. ,Caw ood,P .edi tors,CurrentP erspect i v es i n th e Appalach i an– Caledoni an O rog en. G eolog i calAssoci at i on ofCanada S peci alP aper,v .41,pp.191–205. Hib b a r d,J. ,St odda r d,E. F. ,Sec or ,D. ,Jr . ,a n d Den n is,A. ,2002,T h e Caroli na Zone:O v erv i ew of N eoproterozoi c t o early P aleozoi c peri G ondw anan terranes along th e east ern flankof th e sout h ern Appalach i ans:Eart h S ci ence R ev i ew s,v .57,n.3/ 4,p.299339. 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TRAV ERSEMAP
Hi llsh ade deri v ed from a 20footLi DAR di gi t alelev ati on model.R ed and blue li nes sh ow pat h s offi eld t rav erses.
Bounds of G eoP DF based on 7. 5mi nut e g ri d project i on i n U T M 17S ;N ort h Ameri can Datum of 1983 ( N AD83) . G eolog i c polyg ons t i ed t o 7. 5mi nut e g ri d projecti on i n St at e P lane coordi nat es for edg emat ch i ng w i th leg acy G IS data,as such some ov erlap and underlap ofmap uni t polyg ons occuraround edg e ofmap.
Z ha b le – An desit ic t ob a sa lt ic la va swit h in t er la yer ed epic la st ic r oc ks: Li g h tg reen,g rayg reen,g ray,and dark g ray; t ypi cally unfoli ated, amyg daloi dal, plag i oclase porph yri t i c, amph i bole/ pyroxene porph yri t i c and aph ani ti c; metamorph osed:andesi t i c t o basalt i c lav as and sh allow i nt rusi ons.Hyaloclast i c texture i s common and i mparts a frag mental t exture on some outcrops and floatboulders.Cont ai ns lesser amount s of g rayi sh g reen,li g h tg reen,and li g h tg ray to w h i te;met amorph osed cong lomerate,cong lomerat i c sandstone,sandst one,si ltst one and mudstone.
A
Z ha si -An desit ic sha llow in t r usive: G rayi sh g reen t o li g h tg reen,metamorph osed:plag i oclase porph yri ti c andesi t e wi t h a g ranulartextured g roundmass to v ery fi neg rai ned di ori t e ( wi th i nt rusi ve t exture v i si ble w i th 7x h and lens) . Contai ns lesser amounts of fi ne-to medi um g rai ned di ori t e. P lag i oclase ph enocrysts t ypi cally rang e from 1mm to 4 mm.Darkg reen to blackcolored amph i bole,w h en present,occurs as ph enocrysts ( less th an 1mm t o 1mm)and as i nterg row t h sw i th plag i oclase.
660'
Z ha b lt dc p– An desit et ob a sa ltpor phyr y of t he Dr y Cr eek a r ea :Di st i nct i v e,g reen to darkg reen,met amorph osed andesi te porph yry w i th aph ani ti c g roundmass and euh edralph enocrysts ( up t o 10mm)of g reeni sh whi te plag i oclase; ph enocryst s typi cally consti t ut e 20 to 50% of th e rock;local ali g nmentof plag i oclase;lesser pyroxene/ amph i bole ph enocryst s.G reen to darkg reen basaltporph yry w i th abundantpyroxene ( alt ered t o amph i bole)ph enocrysts w i t h mi nor plag i oclase ph enocryst s.Andesi t e and basaltporph yri es locally amyg daloi dal ( up to 2cm) ,amyg dules i n fi lli ng i nclude calci t e,quart z,ch lori te,and epi dote. S ame as Dry CreekP orph yry complex of Hauck( 1977) . P resentas i solated outcrops orboulders as desi g nat ed by g reen st ati on locat i ons and as one mapscale body.
1340'
Siler City Water Supply Lake Number 3
Pi ney G rov e Ch urch R oad
Ed Clapp R oad
Si lerCi ty S now Camp R oad
Nick Creek Qal
J essi e Bri dg es R oad
Nick Creek
S mi th Hudson R oad
Si lkHope R oad
Varnell Creek
A' 660'
0'
0' Zh e/ pl Zh e/ pl Zh e/ pli m
Zh el
1340'
J d
Zh e/ pli m
3340'
In cross sect i on, g radati onalcont act-i nferred In cross sect i on, i nt erpret i v e fold form li nes
In cross sect i on, fold axi s -i nferred In cross sect i on,bri t t le fault, i denti ty orexi stence quest i oned, i nferred from Li DAR li neament
3340'
cross sect i on scale -1: 24000 no v ert i calexag g erat i on
by car
N.C.
R esearch support ed by t heU . S .G eolog i calS urv ey,N at i onal Cooperati v e G eolog i c Mappi ng P rog ram underS T AT EMAP ( Aw ard -2015,G 15AC00237) . Thi s map and explanatory i nformati on i s submi t ted forpubli cat i on w i t h t h e underst andi ng th atth e U ni t ed S tat es G ov ernmenti s aut h ori zed t o reproduce and di stri bute repri nt s forg ov ernmentaluse.T h e v i ew s and conclusi ons contai ned i nt hi s documentare t h ose ofth e auth ors and sh ould notbe i nt erpret ed as necessari ly representi ng th e offi ci alpoli ci es, ei t h erexpress ori mpli ed,oft heU . S .G ov ernment.
Geologic Ma pof t he Sout her n Thir d of t he Cr ut c hfield Cr ossr oa ds7. 5m in ut e Qua dr a n gle, Cha t ha m a n d Ala m a n c e Coun t ies,N or t h Ca r olin a By Hea t herD.Ha n n a a n d PhilipJ.Br a dley G eolog y mapped from July 2015to May 2016. Map preparati on,di gi talcartog raph y and edi ti ng by Mi ch aelA.Medi na,Heat h erD.Hanna and P h i li p J.Bradley. 2016
by foot
Thi si s an O pen Fi le Map.Ith as been rev i ew ed i nternally for conformi ty w i th N orth Caroli na G eolog i calS urv ey mappi ng standards and w i t h t h e N ort h Ameri can S trat i g raph i c Code. Furt h errev i si ons orcorrecti ons t o th i s O pen Fi le map may occur. Acknow ledg ement s:Fi eld assi st ance prov i ded by R andy Bech t eland members ofth e Energ y G roup -O i land G as P rog ram:Ann S h i elds,R yan Ch annell, Kath eri ne Marci ni ak,and W altT .Hav en
G eolog i c Map ofth e S outh ern T h i rd ofth e Crutch fi eld Crossroads 7. 5mi nut e Quadrang le,O pen Fi le R eport201609
N ort h Caroli na DepartmentofEnv i ronment alQuali ty Energ y G roup
