gold mineralizatton, and tin, base metals, and thorium anomalibs at ...

VIRGINIA DIVISION OF MINERAL RESOURCES

PUBLICATION 112

GOLD MINERALIZATTON, AND TIN, BASE METALS, AND THORIUMANOMALIBS AT YANKBE HORSE RIDGE, IRISH CREEK TIN AREA,

ROCKBRIDGE COUNTY, VIRGINIA

Richard S. Good

COMMONWEALTH OF VIRGINIA

DEPARTMENT OF MINES, MINERALS AND ENERGYDIVISION OF MINERAL RESOURCES

R. C. Milici, State Geologist

CHARLOTTES VILLE, VIRGINIAt99l


PUBLICATION 112

GOLD MINERALIZATION, AND TN, BASE METALS, AND THORIUMANOMALMS AT YANKEE HORSE RIDGE, IRISH CREEK TIN AREA,


Richard S. Good

COMMONVYEALTH OF VIRGINIA



CHARLOTTES VILLE, VIRGINIAt99l


PUBLICATION 112

GOLD MINERALIZATION, AND TIN, BASE METALS, AND THORIUMANOMALIES AT YANKEE HORSE RIDGE, IRISH CREEK TIN AREA,


Richard S. Good

COMMONWEALTH OF VIRGINIA



CHARLOTTES VILLE, VIRGINIAr991

DEPARTMENT OF MINES, MINERALS AND ENERGYRICHMOND, VIRGIMAO. Gene Dishner, Direcor

Copyright 1991, Commonwealth of Virginia

Portions of this publication may be quoted if credit is given !o the Virginia Division of Mineral Resources.

CONTENTS

Trenching and drilling on the Yankee Horse Ridge anomalyOrigin of mineralization and exploration targets

AppendicesAppendix I: Results of the geochemical analysis of soil samples from Eaverse F, Yankee Horse RidgeAppendix Il Gold and silver assays of vein material from the Buck Mountain gold mine, Amherst County ........Appendix ltr: Results of the geochemical analysis of soil samples from the Buck Mountain gold mine,

Appendix IV: Whole-rock Rb/Sr ratios in granitoid plutons and dikes ...........Appendix V: Background and anomaly statistics for soil geochemisryAppendix VI: Results of the geochemical analysis of soil samples from the Irish Creek tin mine, references

Appendix VII: Resuls of the geochemical analysis of soil samples from the Irish Creek tin mine reference,

Appendix VIII: Results of the geochemical analysis of soil samples from reconnaissance traverse C, Nettle

Appendix IX: Results of the geochemical analysis of soil samples from reconnaissance traverse C, Yankee

Appendix X: Results of the geochemical analysis of soil samples from traverse D, Yankee Horse RidgeAppendix XI: Results of the geochemical analysis from ftaverse E, Yankee Horse RidgeAppendix XII: Geochemical soil values, detailed soil grid at anomaly Y, Yankee Hone RidgeAppendix XIII Results of the geochemical analysis of soil samples, for gold and silver at anomaly Y, Yankee

Appendix XIV: Whole-rock analyses for gold and silver, Yankee Horse Ridge

ILLUSTRATIONS

Figure1. Regional geological setting of hish Creek tin mine, Buck Mountain mine, and other nearby mines ..........2a. Location and topography of the geochemical soil traverses across Nettle Mountain and Yankee Horse Ridge ......2b. Location and topography of ttre geochemical soil traverses across Irish Creek tin mine............3. Parts per million beryllium in stream sediments....4. Parts per billion fuoride in stream5. Geology of the area of investigation with the location of the geochemical soil traverses6. Parts per million beryllium in soil, traverses on Nettle Mountain and Yankee Horse Ridge7. Parts per million beryllium in soil in the vicinity of kish Creek tin mine............8. Whole-rock Rb/Sr ratios for selected Blue Ridge province, Virginia, granitoid plutons compared with some

9. Modified A-K-F diagram for granites and felsic volcanic rocks ...........10. Alpfiqo + Ilo vs Ato/Cao + Nap + Iqo11. Gamma specfrometer and geochemical fraverse across Grapevine Ridge.....

Page1

1

666

10T2

t2l6t7t7182020

2525

262728

32

5J

34

35363637

393940

)3J3

J455

999ll

12. Soil ThAJ ratios for the traverse across Irish Creek tin mine ............ 1213. Soil Th/U ratios for the traverse across Nettle Mountain and Yankee Horse Ridge 1214. Parts per million tin in soil mverses on Nettle Mountain and Yankee Hone Ridge 1215. Parts per million tin in soil traverses at and near Irish Creek tin mine....... 1316. Parts per million lead in soil traverses on Ne$le Mountain and Yankee Horse Ridge 1317. Parts per million lead in soil in the vicinity of hish Creek tin mine............. 1318. Parts per million zinc in traverses on Nettle Mountain and Yankee Horse Ridge 1319. Parts per million zinc in soil in the vicinity of hish Creek tin mine ........... 1420. Geochemical soil profile for tin, lead, and zinc atanomaly Y, Yankee Horse Ridge 1421. Parts per million rubidium in soil in traverses on Nettle Moun[ain and Yankee Horse Ridge 1422. Pafis per million rubidium in soil in the vicinity of Irish Creek tin mine ........... 1423. Pafis per million arsenic in soil traverses on Nettle Mountain and Yankee Horse Ridge 1424. ParA per million arsenic in soil in the vicinity of kish Creek tin mine............ 1525. Parts per million of gold in soil travenes on Yankee Honse Ridge tin-lead-zinc anomaly....... 1526. Parts per milliun of fluorine in soil traverses on Nettle Mountain and Yankee Hone Ridge 1527. Parts per million fluoride in soil in the vicinity of Irish Creek tin mine ........... 1528. Parts per million lithium in soil traverses on Nettle Mountain and Yankee Horse Ridge 1529. Parts per million lithium in soil traverse in the vicinity of hish Creek tin mine............ ...................... 1630. Parts per million copper in soil in the vicinity of Nettle Mountain and Yankee Horse Ridge 1631. Parts per million copper in soil in the vicinity of Irish Creek tin mine ........... 1632. Bulldozed mineralized qurtz monzonite at Yankee Horse Ridge l733. Mireralized bedrock, geochemical anomaly, Yankee Horse Ridge 1734. Micropho0ograph of cataclastic leucoquartzmonzonite, anomaly Y, Yankee Horse Ridge 1835. Microphotograph of felsite (rhyodacite dike) showing radiated, devitrified spherulite, anomaly Y, Yankee

36. Bedrock in Nettle Creek showing rhyodacite and Catoctin(?) metabasalt xenoliths in hornblende granite 19

37. Bedrock in Nettle Creek showing Catoctin(?) metabasalt xenoliths in hqnblende granite 1938. Bedrock in Nettle Creek showing Catoctin(?) metabasalt xenoliths in hornblende granite 1939. Bedrock in Nettle Creek showing Caoctin(?) metabasalt xenoliths in hornblende granite 19

TABLE

Whole-rock chemical signature of Nettle Mountain granite compared with average mineralized and average

Average major ctrcmical and mineral differences between Nettle Mountain granite and Mobley Mountain

l.

2.8

10

GOLD MINERALIZATION, AND TIN, BASE METALS, AND THORIUMANOMALIES AT YANKEE HORSE RIDGE,IRISH CREEK TIN ARBA,


Richard S. Good

ABSTRACT

Gold mineralization was identified by soil geochemistryon Yankee Horse Ridge three miles southwest of the aban-doned Irish Creek tin mines in the central Blue Ridge prov-ince of Virginia. The highest concentrations of gold in thesoil samples ranged from 0.33 to 0.51 ppm. Anomalous tin(44 ppm),lead (521 ppm), zinc (457 ppm), copper (59 ppm),anenic (25 ppm), rubidium (70 ppm), and thorium (45 ppm)are also present in the soil samples. Samples of myloniticbedrock, exposed by shallow trenching, have whole-rockassays of up to 0.17 ounces/short ton (5.8 ppm) of gold. Thebedrock is hydrothermally altered and sheared, gray to green-ish-gray, aphanitic, felsic quartz monzonite witl sparse,limonitic and hematitic vugs with sparse boxworks, andcontains disseminated relict pyrite, jarosite, and beudan-tite(?). The slightly deformed bedrock is leucocratic quartzmonzonite, which in places is felsic enough to be classed as

an alaskite. Some highly sheared rock contains smoky-quartzclasts. Subvolcanic rhyodacite and basalt dikes occur at andnear the anomaly. About 700 feet north-northwest of theanomaly is an occurrence of pyrrhotit€, arsenopyrite, chal-copyrite, and fluorite mineralization with anomalous arsenic(600 ppm) and fluorine (5495 ppm) in the soil.

The Yankee Horse Ridge prospect is less than 800 feetfrom a fluorite-bearing biotite granite on Nettle Mountain(informally called the Nettle Mouncain granite). This biotitegranite is intruded into a Grenville-age clinopyroxene-hyper-sthene-hornblende granulite gneiss with a contact zone con-raining felsic dikes and xenoliths. The Nettle Mountaingranite contains a chemical signature, including a Rb/Sr ratioof 5.05, characteristic of highly differentiated, volatile-richintrusives similar to those associated with tin districts inEngland, Nigeria, Australia, and Canada. The Nettle Moun-tain granite has generated enrichments of up to 14.5 ppmberyllium in soil and 6 ppm in nearby stream sediments. Thestream sediment values are similar to those found in sedi-ments downstream from the Irish Creek tin mines.

The rocks enclosing the mineral deposit are part of acomplex allochthonous imbricate tectonic thrust sheet, wit}a northeast trend and southeast low-angle dip, that lies overlower Paleozoic-age clastic sedimentary rocks. Thrust sheetsin the area are characterized by anastomosing, catackNticzones west of the Rockfish Valley fault. Gold mineralizationon Yankee Horse Ridge may have been generated frompaleo-hot springs associated with subvolcanic rhyolite dikespresent in thelate hecambrian-age, Crossnore-related NettleMountain fluorite-biotite plulon. The gold mineralizationcould also have been controlled by metal-rich brines orpossibly much younger, metal-rich solutions that were remo-bilized following reactivated paleo-rift faults. These faultsare now mapped as low-angle mylonitic thrust zones.

INTRODUCTION

This study describes the results of a geochemical inves-tigation for tin and precious metals in the Irish Creek area ofRockbridge County. Except for negligible placer deposits inAlaska there is no significantprimaryproduction of tin in theUnited States (Carlin, 1988). The only tin mine in Virginia isat Irish Creek, Rockbridge County. This small operation has

been inactive for more than 70 years (Figure l).The recorded occurrences of gold and silver in the

vicinity of the Irish Creek mines indicate that the area has thepotential for precious metals as well as tin. Hotchkiss (1883)reported values of 0.1 ta7.36 ounces/short ton of gold (3.4 -252 ppm) and 38 to 73.73 ounces/short ton (2528 ppm) ofsilver in the arsenopyrite in the vicinity of Irish Creek. Brown(1885) also noted auriferous arsenopyrite occurring withwolframite and cassiterite. A recent assay for gold on an

arsenopyrite sample from the #2 dump at hish Creek indi-cates 7.8 ounces/short ton (267 ppm) of gold and I 1. 1 ounces/short ton (381 ppm) of silver (Virginia Division of MineralResources samples, 1985).

Sulhde mineralization (pynhotite) occurs about 3 milessouthwest of ttre Irish Creek tin mines along Nettle Creek, atibulary of Irish Creek (Herbertl. Grow, penonal commu-nication, 1985; Figure 24, traverse F). Assay records at theVirginia Division of Mineral Resources indicate tlnt pynhotitefrom this locality contains negligible gold and silver. Thereare stories of a small gold mine or gold prospect that wasworked by Hubbard near the headwaters of Nettle Creek inthe late 1800s or early 1900s (Herbert Clark, personal com-munication, 1985). This prospect might be the sulfide occur-rence, F, on Nettle Creek. However, tlte Hubbard prospec(?)was never located with certainty by the writer. On the east

bank of Neule Creek at the pyrrhotite locality (Figure 2A,traverse D, the writer identified white fluorite, arsenopyrite,and chalcopyrite in a mafic granulite gneiss. There is novisible evidence of an adit or shaft in the area, but severalcylindrical marks that indicate very limited drilling andblasting can be observed on a rock face along the creek.Analysis on one of three soil samples taken near the site(traverse F) indicates 600 ppm arsenic, 5495 ppm fluorine,49Zppmcopper, and I32 ppm lead (Appendix I, sample 3W-1). There is a series of very shallow, barely visible, 5 feetlong, 1 to2 fent deep exploration trenches about 800 feet upslope from the Nettle Creek sulfide-fluorite occurrence. Thetrenches are on a spur on the west slope of Yankee HorseRidge (Figure 24, traverse C-C'). The Nettle Creek sulfide-fluorite occurence is located along the eastern contact of asmall, fluorite-bearing biotite granite that is intrusive intoGrenville-age granulites (Figure 2A). The granite at NettleMountain has been described by Hudson (1981). Fordham(1978) analyzed stream sediments from this same area and


ALBEMARLE/,couNTY/

i-e.so*r, ,,COUNTY 1-tt, ui

Figure 1. Regional geologic setting of the Irish Creek tin mine, Buck Mountain gold silver mine, and other nearby mines andprospects.

EXPLANATION

I - kish Creek mine (Sn)2 - Yankee Horse Ridge prospect (Au)3 - BuckMormtainmine (Ag, Au)4 - Jack's Hill mine (Au, Ag)5 - Colleen prospect (Au, Ag, Pt)6 - Ivy Creek prospect (Au)7 - Fabermine (Pb Zn, Ag)8 - Allenmine (Cu)9 - Roseland anorthosite titanium deposits (Ii)10 - kon, manganese, and iron-manganese mines

Triassic-Jurassic JTrsiltstone, feldspathic sandstone, and conglomerate of the Scottsvillerift basin

Cambrian Crsemarine limestone, dolomitg shale, and sandstone of the Valley andRidge province; Rome, Shady, and Erwin Formations

Cambrian CchChilhowee Group: arenitic shelf to slrore face sedimentary roclqphyllite, metasilstone, feldspathic sandstone, with aminor arnountof basalt at the base

Late Precanbrian ctCatoctin Formation: rift-related metabasalt and minor arnormts ofsedimentuy rock

Late Precambrian LYLynchburg Group (Ashe Formation, Alligator Back Formation):rift-related oceanic metasediment, generally deeper water depositsof the continental slope withsome shallow water deposits; turbidite,submarine conglomerate, and includes greenstone which may rep-resent a partial ophiolitic sequence

Late Precambrian LY(?)deep watetmetasediment, dominantly schist with quartzite, marble,amphibolite, and felsic gneiss, mapped as the Evington Group,Paleozoic metasediment

Late Precambrian cnCandler Formation: phyllite with quartzite and marble

Late Precamb,rian mrMechum River Formation: rift-rela&ed shallow water arkose withconglomerate and conglomerate with coalescing fans of conglom-erate

Late PrecambrianCrossnore Suite pluton: biotite granitc and granodiorite with fluo-rite and accessory rare earth minerals

NM-Nettle Mountain granite, 637 mry. Q)MM-Mobley Mountain granite, 652 m.y.WM-Woods Mountain pluton age not determinedRF-Rockfish 573 m.y.

Precambrian PcPedlar Complex' Grenville (-1 lfi) m.y.) and Pre-Grenville (-17fi)m.y.) age massive and layered chunockite, massive and layeredgranulite gneiss, leucocratic quartz monzonite an! alaskite; domi-nantly pyroxene and pyroxene with homblende-bearing granulitefacies rocks characterizedby anastomosing, narrow mylonite zonesand bands which pervade a southeast-dipping, northeast-uendingstack of thrustplates; steeply dipping to verticalnorthwest-trendingtransverse faults,

kecambrian Irl,ovingston Complex: Grenville (-1100 m.y.) and pre-Grenville(-1700 m.y.) biotite augen gneiss, granulite gneiss, minor char-nockite, granite, ferrodiorite, anorthosite and nelsonite; dominantlybiotite-and homblende-bearing rocks with minor pyroxene; sepa-rated from the Pedlar Terrane by the Rockfish Valley mylonitethrust zone

RA-Roseland anorthosite

I

I'I

I arrt A or rNVrsllcATtoN

ILoI ta

-100 lokM I t0/ ,ta /r------r I '" 1.. I

|/'k *rRrsH .REEK ,r,". / 6to

BUCK MOUNTAIN

l7r''V-?t'Z;,N,r

PUBLICATION 112

a.x2aa5

Figure 24. Location and topography of the geochemical soiltraverses across Nettle Mountain and Yankee Horse Ridge,Montebello 7.5- minute quadrange, Rockbridge County, Vir-ginia.

Figure 28. Location and topography of geochemical uav-erses A-A and B-B across and close to Irish Creek tin mine,#1 working, Montebello 7.5-minute quadrangle, RockbridgeCounty, Virginia.

found an anomalously high beryllium signature similar toanomalous valuesdownstream from the Irish Creektin mines

(Figure 3). There are also slightly elevated fluoride values(180 and 240 parts per billion) in the stream water near theNettle Creek showings, but not as high as fluoride valuesdownsream from the tin mines (9l0partsperbillion) (Figure4). Fresh lvaters average 100 ppb (Rose and others, 1979).

Figure 3. Parts per million beryllium in stream sediments,hish Creek tin mine vicinity, Rockbridge County, Virginia.

PPB FLUORIDE

o <200

o 200-900

O >900

ta abandoned mine

(Oata, R.S.Good)

0^t-.j

KILOMETERS

Figure 4. Parts per billion fluoride in stream water in vicinityof Irish Creek tin mine and Nettle Mountain granite.

Penick and Sweet (1984) noted a previously unrecordedgold andsilvermine (now called the BuckMountain mine) onstrike with the Nettle Creek sulfide-fluorite occurrence inAmherst County. This locality is about l0 miles southwest ofthe Irish Creek tin mines. The Buck Mountain mine is withinhost rocks similar to tlose at Irish Creek (Figure 1). Assayson adit samples from a quaravein in a shear zone from Buck

CR€€K MINE

NI

I'

I

It

\

N

./)

-I

,#1

180

VIRGINIA DIVISION OF MD.IERAL RESOURCES

.t !'><1

zfa;)/

Figure 5. Geology of the portion of the Montebello Quadrangle of investigation with location of the geochemical soil traverses,designated A-A', B-B', C-C', D-D', and E-E (Geology modified from Hudson, 1981).

PUBLICATION I12

T-A__A'

tnt,l_l

EXPLANATION

Cataclastic zone.

Fault.

Geochemical soil and spectrometer traverse.

Irish Creek mine, Pantler Run #1, mainworkings, 2 accessible adits and trenches.

Irish Creek mine, Panther Run #2, workingsinaccessible except for pits.

Chilhowee Group: metasediment sandmetavalcanics; phyllite, feldspathic sand-stone and meta basalt.

Catoctin metabasalt feeder dikes.

Crossnore Group pluton: Nettle Mountainfluorite-bearing biotite granite with accessoryflorencite.

lr Porphyritic leucocratic quartz monzonitewith blue qaartz,locally alaskitic; with dis-seminated, anastomosing, thin mylonitezones separated by undeformed or slightlydeformed rock.

Poikiloblastic clinopyroxene, hypersthene,hornblende granulite gneiss; layer hornblede,clinopyroxene, hypersthene granutite gneiss;quartzofeldspathic granulite gneiss; char-nokite facies of Pedlar terrance characterizedby local, thin, anastomosing mylonite zones,often wittr little or no displacement.

PPM BERYLLIUM

o <5o 56o >6

-'a7 L)'a'- == =27

ooA'

0 1000lt..'.'rr.l

Feel

Figure 7. Parts per million beryllium in soil Eaverses in thevicinity of Irish Creek tin mine, #1 working.

Mountain range from 0.04 to 1.3 1 ounces/short ton of goldand from 1.82 to 5.4 ounces/short ton of silver (Appendix II).The mineralogy of the quartz vein is pyrite, arsenopyrite,scorodite, fluorite, and gypsum. The writer also found highlyelevatedtinvalues inthe soil around theadit (20 to416 ppm),but no cassiterite has been identified. Additional anomal-ously high metal values in the soil are lead (400 to 607 ppm),beryllium (6.1 ppm), arsenic (12,500 ppm), and silver (2to 5ppm); fluorine in the soil is 1195 ppm (Appendix III). Threeottrer small precious metal mines or prospects (Jack's Hill,Colleen prospect, Ivy Creek, Figure 1) have been identifiedby SweetandLovett(1985),but there is no dataregarding thehistory or grade of ore from these mines.

The Irish Creek mine sites and the Yankee Horse Ridgeprospect are both within a 5500 acre tract of private landowned by Dr. Laurie Landeau of New York. The tract wasformerly owned by Owens-Illinois Company, Forest Prod-ucts Division, which became the Nekoosa Packaging, Inc. inthe 1980s.

GEOLOGIC SETTING

IRISH CREEK TIN DEPOSITS

The Irish Creek tin mines are located in the centralVirginia portion of the Blue Ridge physiographic and geo-logic provinces @gure 1). The mines are located on a smalltribuary of Irish Creek @anther Run on l5-minute topo-graphic map) that is unnamed on the 1965 edition of theMontebello 7.5-minute topographic map. The sites arelocated on the 7.5-minute Montebello quadrangle (Figures 1

and 2B). The mines were active from 1884 to 1886, 1890 to1892,and,1918 to 1919 @erguson, 1918). However, total

o

B'd

"o o-oa B

""t,,u

o

PPM AERYLLIUt\,1o <5o -^oa a^

oooa

.\e s^\.,4-l",rs'

o\-

9.,...,..1.q00Feel

Figure 6. Parts per million beryllium in soil traverses onNettle Mountain and Yankee Horse Ridse.

q^-q\\ > (

\*\3N-.-Nh\ \$r\\ \ro

VIRGIMA DIVISION OF MINERAL RESOURCES

production has been estimated at only 3200 short tons of orewith an average grade of 1 percent. This ore produced anestimated 17 short tons of tin metal (Koschmann and others,1942). The grade estimate was lowered to 0.49 percent basedon data obtained from drilling by Bethlehem Steel (Adair,1942; French, 1956). Several exploration companies includ-ing International Nickel and Billiton Metals did additionaltrenching and assaying in the 1970s and 1980s.

Tin occurs at Irish Creek in cassiterite that is formed ingreisenized gay-quartz veins that inrude clinopyroxene-hypersthene-hornblende granulite gneiss. These regionalhost rocks were formerly all grouped within the Pedlar For-mation (Bloomer and Werner, 1955) (in ilris study calledPedlar complex), but Hudson (1981) recognized mappablelithologic units locally that included quafrz monzonite, andfelsic and mafic granulites. All of these lithologies as well asLovingston complex rocks are intruded by younger LatePrecambrian-age granites (NM, WM, RF, Figure l) and LatePrecambrian- to Cambrian-age Catoctin basalt feeder dikesand flows (Figure l). Minerals reported from Irish Creekinclude arsenopyrite, pyrite, hematite, pyrrhotite, galena,galenobismutite, aikinite, beryl, phenakite, scheelite, wolf-ramite, sphalerite, siderite, apatite, scorodite, parisite, and ti-tanomagnetite (Glass and others, 1958). I-esure and others(1963) described tfie beryllium mineralization associatedwith the deposits. Fordham (1978) notes anomalous beryl-lium values (above three standard deviations) in stream sedi-ments downsEeam from the mines and at one other locationin Nettle Creek (Figure 3). Hudson ( 1 98 I ) mapped a fl uorite-biotite granite in the vicinity of Fordham's stream sedimentanomaly and concluded that this granite was the Irish Creek"tin granite." Soil geochemisry done for this investigationindicates elevated beryllium values in the bedrock over bothHudson's fluorite-biotite granite and near the tin mines(Figures 6 and 7).

PETROLOGY AND TECTONICS

A simptfiedregional geologic map showstheareaof in-vestigation to be within Pedlar complex rocks (Figure 1 ) . Theterm Pedlar was established by Bloomer and Werner (1955)in the mapping of an area that included the Yankee HorseRidge-Nettle Mountain-Irish Creek areas. They combinedpre-Grenville-, Grenville-, and post-Grenville-age granites,granodiorites, syenites, quartz diorites, anorthosites, andunakite of the Blue Ridge Mountain into the Pedlar Forma-tion. Bartholomew and others (1981) and Sinha andBartholomew (1984) retained the term Pedlarin describing alarge complex tectonic block consisting of a stack of alloch-thonous plates west of the Rocldish Valley fault (Rockfishmylonite zone, Figure l), as Pedlar massif. The RockfishValley fault was first described and defined by Gathright andothers ( I 977) and Bartholomew ( I 977) in an area northeast ofthe area of investigation.

Northwestof the Rockfish Valley fault (Rockfish mylonite zone, Figure 1) lithologies are dominantly Grenville-(1lCI m.y.) and pre-Grenville-age (1700 m.y.) massive andlayered charnockites, massive and layered felsic and maficgranulite gneisses, and leucocratic, quartz monzonites par-

tially reflecting different degrees of deformation. A Gren-ville age of 1075 m.y. wzrs obtained from zircons extractedfrom Pedlar complex charnockite by Pettingill and others(1984). Mapping of an individual fault may be misleading.The local scale tectonic style consists of anasbmosing faultswhich pervade a southeast-dipping, northeast-trending stackof thrust sheets which appears !o form a duplex.

Southeast of the Montebello quadrangle Herz andForce(1987) used the term "Pedlar massif'as an informal term todescribe rocks northwest of the Rockfish mylonite zone.Within the Montebello quadrangle, Hudson (1981) droppedthe term Pedlar and mapped four granulite gneiss units:massive ilmenite-hornblende granulite gneiss, massive clino-pyroxene-hypersthene hornblende granulite gneiss, poikilob-lastic ilmenite-homblende granulite gneiss, and layered granu-lite gneiss. Within the area of this investigation @gure 5),Hudson (198 1) mapped most of the bedrock as poikiloblasticclinopyroxene-hypersthene-hornbende granulite, layeredhornblende-clinopyroxene- hypersthene granulite gneiss withsmall amounts of quartzofeldspathic gneiss and a large areaof porphyritic,leucocratic quartz monzonite (Figure 5). Thewriter indicates all of these rocks as Pedlar complex (Pc) intheregional map @gwe 1).

Rocks that occur to the southeast of the Rockfish mylo-nite zone (Figure l) are Grenville- (1100 m.y.) and pre-Grenville-age (f700 m.y.) biotite augen gneiss, granulitegneiss, minor chamockite, granite, ferrodiorite, anorthosite,and nelsonite (Herz and Force, 1987; Evans, 1984). Theserocks are dominantly biotite and hornblende-bearing rockswith minor pyroxene. The rocks are shown informally as

Lovingston complex (Figure 1). The term hvingston origi-nated with (Jonas, 1928), was continued by Bloomer andWerner (f955), and was retained informally by Herz andForce (1987) as "Lovingston massif."

The Rockfish mylonite zone (Figure 1) marks lithologicdifferences but its significance is undergoing reevaluation.The zone is about I to 3 miles in width and contains mylonitesalong with rocks less intensely deformed. It is considered bymany workers to be part of a major fault system, the Hay-esville-Fries-Rockfish Valley fault" extending on strike to thesouthwest and northeast. The fault system also extends as

subparallel fractures to the northwest and southeast of thetrace indicated in Figure l.

The Rockfish mylonite zone @MZ) has been consideredone of dominantly ductile deformation and was called theductile deformation zone @DZ) by Bartholomew and others(1981). The assumed Ordovician-age Taconic deformationof the Rockfish mylonite zone through arc-continent colli-sion (proto-Atlantic Ocean,Iapetus of Wilson (1966), clos-ing) is now open to question. Evans (1984) found evidenceof both ductile and brittle deformation in his detailed map-ping across the RldZ. The Rocldish mylonite zone is consid-ered the trace of a reactivated hinge zone (Wehr and Glover,1985; Evans, 1984) marking the uplift and stretching of acontinental margin which developed rift grabens on each

flank in Late Precambrian time. Late Precambrian- to EarlyCambrian-age rift-related faulting occurs along the entireBlue Ridge geologic province from Alabama to Pennsylvania(Costello and Hatcher, 1985). The driving force causinguplift is widely viewed as a mande plume convection cell

PUBLICATION 112

(Wehr and Glover, 1985; Seyfert, 1987). Based on stratigra-phic evidence Fichter and Diecchio (1986) have suggested630 m.y. as the beginning date for rifting. Odom and Fullager(1984) believe rift-related events started earlier at 690 m.y.with felsic intrusions of the Crossnore plutonic-volcanicsuite. The Crossnore group was originally defined to describelate Precambrian- to Eady Cambrian-age igneous rocks in-cluding the Catoctin, MountRogers, and Grandfather Moun-tain volcanic rocks (basalts andrhyolites) plus the Crossnore,Beech, Striped Rock, Brown Mountain, and Iansing plutonsof northernmostNorth Carolina and southwest Virginia. Onstratigraphic, mineralogic, and isotopic-geochronologicalgrounds, Rankin, 1968a, 1968b; Rankin and ottrers, 1969;Rankin, L97 5, 197 6,presented evidence tlat these rocks con-stitute a single bimodal suite and an orogenic magmatic suite,the Crossnore complex. The Crossnore plutonic suite, a sub-division of the Crossnore complex, is characterized by felsicmembers which have mildly to distinctly peralkaline affini-ties. The Crossnore plutonic-volcanic suite is characterizedby enrichments in niobium, yttrium, thorium, uranium, rare-earth elements, potassium, and depletions in strontium andbarium (Rankin, I 975). The plutons are fl uorite-bearing andbiotite rich granitoid rocks. A few are truly peralkaline, thatis, the sum of Nap and Kp exceeds Alpron a molecularbasis (Bailey, 1989) and contain small amounts of alkalipyroxenes (aegirine) and alkali amphiboles (riebeckite)

@ankin, 1976). Felsic extrusives (rhyolite) are associatedwith some of the Crossnore felsic plutons.

In the Blue Ridge province of central Virginia there arefour known small, fluorite-bearing, rare earth-enriched, tho-rium and uranium-enriched biotite granitoid plutons whichintrude the Pedlar Complex and Lovingston Complex rocks.Because of their intrusive relationships, their lithology, andages, they are called Crossnore plutons in this investigation.Granitoid Crossnore plutons indicated in Figwe 1 are: NettleMountain granite, NM; Mobley Mountain Granite, MM;Woods Moun[ain pluton, WM; and Rockfish pluton, RF.Two of these plutons have been dated as Late Precambrian,the Nettle Mountain Granite indirectly at637 m.y. (Hudsonand Dallmeyer, 1982) and the Mobley Mountain Granite at652 m.y. (Brock, 198 1). The locations of theplutons and agesof intrusion are evidence for melting accompanying domingor uplift prior to, or during, earliest rifting. The other biotitefluorite-bearing granitoid plutons intrusive into Grenville-age rocks, the Rockfish (RF, Figure 1) and the Woods Moun-tain (WM, Figure l) have been described briefly but notdated: Woods Mountain by Smith and others (1981); andRockfish by Evans (1984). Three of these Crossnore plutons(MM, RF, and WM) occur southeast of the Rockfish mylonitezone and the Nettle Mountain granite (NM) occurs to thenortiwest (Figure l).

Within the Montebello quadrangle, Hudson (198 1) iden-tified a small (1900 feet by 600 feet) fluorite-bearing biotitegranite on the east flank of Nettle Mountain, 2.84 milessouthwest of the Irish Creek tin mines (Figure 5). This granitewas described but never formally named by Hudson (1981).In this study, this granite is informally referred to as ttre NettleMountain granite. Hudson and Dallmeyer (1982) obtained anageof 637 m.y. (by AflA3e) from muscovitetaken from hishCreek tin mine greisen samples. They concluded that the

nearby (2.84 miles) Nettle Mountain granite and its associ-ated aplites are the source of Irish Creek tin mineralization,even though no rock similar to ttre Nettle Mountain granitehas been identified at or close to the tin mines. Compared tothe "average granite" (2485 samples from Le Maire, 1976)the Nettle Mountain granite shows a depletion in barium andenrichment of rubidium, yttrium, niobium, uranium, tho-rium, zirconium, and zinc (fable 1). Rankin (1975) noted en-richmens in niobium, yttrium, thorium, uranium, rare earths,potassium and depletion of stnontium and barium in theCrossnore plutonic suite. Additionally, the average of threeNettle Mountain granite samples tends to match the distinc-tive signature of the average mineralized granite of S temprokand Skvor (L974). Their data shows a signature of a highSiO' low TiO, low MgO and CaO, high IlO and NqO, andenrichment in a number of trace elements including beryl-lium (Table l). Further evidence to support the NettleMountain granite, or a very similar pluton as the source of tinmineralization, is shown by the Rb/Sr value of 5.05 (range

3.6 1 to 7.4 8) which places the Nettle Mounain granite withinlhe lower range of mineralized plutons of various tin districtswhen compared to barren granitoid rocks. All other granitoidbodies fall well below a Rb/Sr ratio of 5.0 (Figure 8).

Other evidence that supports a genetic relationship be-tween the Nettle Mountain granite and Irish Creek minerali-zation is Fordham's (1978) beryllium data from streamsediments. The stream sediment values for beryllium showthat the only anomalies in the area surveyed are downstreamfrom the tin mines and from the Nettle Mountain granite(Figure 3). Elevated geochemical values in soil forberyllium(this study) over tle Nettle Mountain granite strengtlensFordham's data (1978) (Figure 6).

A plot of the Nettle Mountain granite on a modified A-K-F diagram shows that it is close to the Crossnore plutonic-volcanic goup, and that although none of the samples are

ruly peralkaline, one sample plots very close to the peralka-line divide at the base of the diagram @igure 9). One trulyperalkaline Crossnore granite from Rappahannock County,northern Virginia Blue Ridge province, is shown in Figure 9but others are not included (Mount Rogers felsic volcanicrocks).

Alkalic and peralkaline rocks are well known in theirassociation with tensional or rifting environments as opposedto a subduction setting. Early studies by Martin and Piwinski(1972) on relating the chemistry of rocks to tectonic settingwere noted byRankin ( 1975) who observed thatthe Crossnorevolcanic and plulonic rocks matched rifted areas rather thansubducted settings. Later refinements using discriminantfunctions with whole rock chemistry by Maniar and Piccoli(1989) clearly places the Crossnore plutonic suite within arift-related setting (RRG in Figure 10).

As uplift continued and grabens deepened on each flankof the hinge zone @ockfish mylonite zone, Figure l) elon-gated basins were formed. On the ocean (east) side elongatedbasins were filled with turbidite-dominated sediments andmafic and ultramafic oceanic intrusives shown asLynchburgGroup, Ashe Formation, and Alligator B ack Formation (Figure1). Lynchburg Group rocks occur in narrow, subparallelbasins both northeast, southwest, and east of, as well as withinthe area shown in Figure 1 (Conley, I 985, I 987). Some of the

8

Table 1. Whole-rock chemicalunmineralized granites.


signature of Nettle Mountain granite compared with average mineralized and average

sior7oTiO"VoTotal Fe asFe"O"VoMgOVoCaOVo

\ovoNarOToRb/SrRbEauppmTh ppmZr ppmNb ppmBeppm

Lippm

Sn ppm

Rare earths ppm

mafic rocks within Lynchburg Group rocks are greenstonesand may represent partial ophiolite sequences (Conley , I 98 5 ,1987). Ulramafic rocks (Figure 1) now altered to soapstonealso occur within the Lynchburg Group. In places close to hotspots within the Lynchburg-Ashe basins, warm and hotmetal-rich and silica-rich brines deposited the syngenetic,sEatiform, massive sulfides of iron, copper, zinc, and lead ofthe Gossan Lead of southwest Virginia (Gair and Slack,1984), and also the strataboundbarite, manganese oxide, andbanded iron formations of the westem Piedmont of Virginia(Sweet and others, 1989). The Faber lead-zinc mine (number6, Figure I ) and the Ivy Creek gold prospect (number 7, figure1) are excellent examples of rift-related mineralization withinthe Lynchburg Group rocks. Saline brines are known to havean important role in the mylonitization process (Kirby andothers, 1989). Saline brines generated in Iate Precambrian-age Lynchburg rift basins may have augmented the faultingprocess. With or wittrout brines, however, the Late Precam-brian-age rift faults are believed to be favored sites forrepeated faulting through Paleozoic and perhaps even Meso-zoic time. Metamorphism altered but did not completelyobliterate these paleofractures. Mesozoic-age rift basins of

Average ofmineralized granites3

73.020.2r2.270.52r.244.573.28highhighhighhighhighhighhigh

high

highvariable>15-20

high

the Triassic and Jurassic (Figure 1) follow the trend of LatePrecambrian-age rifts" It is not clear whether these arereactivatedolder faults or acombination of newer faults witholder ones.

On the landward (west) side of the hinge line fluvial con-glomerates and arkoses were deposited in narrow elongatedrift basins coeval orpartially coeval with Late Precambrian-age Lynchburg deposition as the Mechum River Formation(Frgure 1). Otherrift-related deposits coeval with theMechumRiver, butnot shown, are the SwiftRun and Fauquier Forma-tions. Some of the Mechum River deposits are subaerialconglomerates with some shallow-water clastics.

As rifting continued from Late hecambrian time intoearliest Cambrian time, rift-related fractures directed basalticflows which follow thenortheasttrendof theMechum River-Lynchburg basins. Basalts (now greenstones) directly over-lie the riftgraben clastics (Catoctin Formation, Figure 1) andhave a chemical signature of continental margin rifting, notsubduction (Moseandothers, 1985; Badgerand Sinha, 1988).The Catoctin Formation also contains some minor sedimen-tary and volcaniclastic beds. Catoctin feeder dikes are shownin Figure 2.

Averagegraniter

7r.300.313.030.7r1.844.073.682.760.333.9

20.0175.020.0

3.0

40.0

3.0

41.0Y

Nettle Mountarngranite2

74.50.082480.110.784.924.765.052.r87.7

24.r391.0r57.0

(anomalous, in soil overgranite, up to 14.5)(anomalous, in soil overgranite, up to 67)

(anomalous, in soil overgranite, up to 16-19)

r79.0Y, Nd, CE

rAverage granite, whole-rock analyses of major element oxides from 2485 samples (Le Maitre, 1976); trace element average frodrTurekian (1977), in Rose and others (1979).2Average of three whole-rock analyses of fluorite-biotite granite which crops out on Nettle Mountain (Hudson, 1981) and isinformallycalledNettleMountaingraniteinthisinvestigation. Thisgraniteis2.8milesfromthelrishCreektinmineandisthoughtto be the "tin granite." Soil data on Be, Li, and Sn over the granite me from this study.3Average for specialized granitoid host rocks in mineralized areas Stemprok and Skvor (1974) in Taylor (1979).

PUBLICATION T12

I nHcnon nN MINE GRANTTE, tnsultta ! za

Tlil GBANITES W|TH OrHER M|NERAL|ZATIOH, ttCeRtlf ZZ

I rrl GRANrrEs, rteeRtr f zeI

MT. PLEASANT TIN GRAI.IITE PORPHYRY (w.uo,gI-sH) MINE, NEw gnuNswlcx (D zs

KEY

rsf rtn-ernnrNc : orHER MtNERALtzATtoN

roQ eanRrH oR AppARENTLy BARREN

NUMBERS REFER TO

REFERENCE SOURCES

GIVEN IN APPENDIX I!!

zr I arotrte GRANITE, NEw Ross PLUToN, NovA scortAzs Q eeRnel cRANrrEs, N|GERTA

zzf eoneHvnrrrc Lr MrcA GRANTTE, sr. AUsTELL, coRNwALL sN Dlsrnlcr21 O eLtzaeErH cREEK GRANITE, QUEENSLAND (sN, Mo, w, PB, cu+AU, Ac, sB)

zo ! reW ROSS PLUTON, ALASKITE/LEUCOGRANITE, NOVA SCOTIA

rs Qnllsxrre, HALIFAX pLUToN, NovA sconAtef rtHlevsoN TrN GRANTTE, 0UEENSLAND170rsO sr. AUSTELL BrorrrE Muscovl-rE TrN GRANTTE, coRNwALL DtsrRlcr, ENGLAI{D

rsO HoRNeLeNDE GRANlrEs. NTcERTAN Trir DrsrRrcrs

rtf ilEttte ntr'rtuoRtte glottte eRA,xtte. tnlsH cReex rlr otstntct. vtRctlterr! clRtuerElLts ADAMELLTTE TtN GRAN|TE, coRNwALL DtsrRtcr, ENGLAND

rzQ eoReHvRrlc BrolrE GRANITE-ADAMELLTTE, TAsMANTA

rrQ storrre GBANITE, wEST DALHousrE pLUToN, NovA scorAro O eveneeE GRANTTE RATro

s Q etortrr GRANTTE, HALIFAx pLUToN, NovA scorrAa Q sr. GEoRGE GRANITE, NEw BRutrtswlcK

z Q HtoH-x ALKALT GRANTTE, NEw MEXtco

6 O sHAEFFER HoLLow L

sO nogLEv nounllrn rLuonrre grottte cRlillte, vrnctxrl gtue RtoqE

c Q poRpxvnlrrc oulntz moilzoxtte, tRtsx cnerx rtr otstRtct, ytRclrte etue Rtoee3O uoBLEy HT. LEUcocRATrc DlKEs, vrRGtNrA BLUE RrpGE

z Q nlxelr cRANtrEs, cHARLorrE BELT eLUToNS, wEsrERN NoRTH cARoLINA eIEDMoNTt Q tuRxey ut. puutot, ytRewra-nost nocK FoR toBLEy MT. cRANtrE, cENTRAL ylncriltA BLuE RTDGE

rrlr10'1 100 101 102 103

Figure 8. Whole-rock Rb/Sr ratios for Blue Ridge province granitoid plutons ftom Virginia compared to graniroid plutons fromselected tin disticts of the world. Sources listed in Appendix I.

AvERAGE qrEB€cKlTE oneurr (ro)-r* Rrs€*rrc GiANtrE /AVERAGE PEFALKALIN€ enoUle 1,,1----*

"rBrRTsON RiVER GRANITE

\\ av€FAGE e€nerxeurne auvottre fz).,--* RAPPAHNoK co //\/

Figure 9. Modified A-K-F diagram in molecular percent forgranites and felsic volcanic rocks. (Data partly adapted fromRankin, 1975).

I'€TALUMINOUS

POG

CEUG

PERALUMINOUS

-/{^rn trom Maniar and Picola (1989)

0: I0.9 1. I l.3

AlrOa/(CaO + Na2O + K2O) (molar)

Figure 10. Shand indices of Nettle Mountain granite and otherCrossnore Intrusive Suite rocks (RRG) in relation to tectonicsettings as classified by Maniar and Piccoli (1989).

Further evolution of the Early Cambrian-age rift systemis describedby Simpson and Eriksson ( 1989). They examinedthe transition from rift to passive margin within the Unicoi and

3.0

(CHOPAWAMSIC CAFOLINA SLATE BELT]

FELSIC VOLCANIC ROCKS (1)

a 2.6oog 2.2

NY tg+-o

N6

i 14

{ ,^AVERAG€ GRANTTE (2)--*l

MOBL€Y MT GRANITE (6)

.--BIOTIT€ AEGIFINE

0.6

t txtrne IOTAL FE {FEO)

4L203-(NA20 + K20)

/- FELSIC VOLCANTC

ROCKS (7)

10 VIRGINIA DIVISION OF MINERAL RESOURCES

lower Hampton Formations (shown as Chilhowee, Figure 1).Rifting is indicated by thick alluvial fan sediments, basalts,abundant lithic clasts, and the feldspathic character of thesandstones in the lower and middle Unicoi. The overlyingupper Unicoi, quartzose sandslones, represents the incipientphase of passive margin sedimentation. Stratabound iron,manganese, and iron-manganese deposits were depositedwithin the sediments of the Chilhowee Group (Antietam,Harpers, and Weverton Formations) rocks and the overlyingCambrian carbonates and shales of the Shady and RomeFormations (Figure I ) . A regional reatrnent of current think-ing on Blue Ridge rifting and tectonics can be found in Glover(1989). Conley (1987) has suggested that a suMuctiory'oMuction event may have also occurred in Late Precambriantime in addition to rifting.

Although the evidence forlate Precambrian-age riftingis subslantial, any interpretation must be tempered with therealization that the entire Blue Ridge geologic province istectonically rootless. Seismic data indicates continuous hori-zontal reflectors at 3.7 to 5 mi beneath the Blue Ridge andwestern Piedmont province. These reflectors are interpretedas being flat-lying lower Paleozoic-age strata (Clark andothers, 1978; Cook and ottrers, 1979; Harris and others, 1982;Glover and others, 1982; Wehr and Glover, 1985). Thetectonic style is now seen by many workers to be affected byright lateral movement in late Paleozoic-time.

The Nettle Mountain Granite is one of four Crossnoreplutons indicated on the regional geologic map (Figure 1).Hudson (1981) considered the Nettle Mountain granite to bethe Irish Creek tin granite, but no granite was identified at ornear the mine, although Ferguson (1918) indicates ten other"veins" up to more than a mile away from Irish Creek #1 and#2 workings. This lack of a source granite may be because itis not prominently exposed or it may be because the kishCreek tin mineralization and the Nettle Mountain granite liewithin a very thin, southeast dipping thrust sheet. Hudson(1981) indicates an extensive cataclastic zone @gure 2) andthe writer noted parallel shearing on Yankee Horse Ridge.Evidence for the thinness of a Pedlar complex thrust sheet isthe comment of Ferguson (1918) who noted'purple slates"atthe#2 underground tin workirigs (now inaccessible). Thisobservation wouldtend to supportan interpretation of Pedlarcomplex granulite gneiss containing greisen lying overyounger Catoctin or Chilhowee rocks (Figure 2). }Jen andothers (1981) andBrock andothers (1987) postulated thattheNettle Mountain granite is a rootless roof pendant of theMobley Mountain Granite (Brock, l98l).

The Nettle Mounain granite according to these workersis a deached cupola of the Mobley Mountain granite, afluorite-bearing biotite granite 14.3 miles to the southeast ofNettle Mountain. The roof pendant is thought to have beentransported during Paleozoic-aged (probably Taconic) thrust-ing to the northwest. The geologic age determined for theMobley Mountain Granite, 652 m.y., by Brock (1981) ismarginallycompatible with Hudson and Dallmeyer's (1982)date for Irish Creek greisen mineralization, alttrough the 637m.y. age is only an inferred date for the Nettle Mountaingranite. The overall mineralogic and whole-rock chemicalevidence connecting the fwo granites is very weakandcannotentirely be explained by enrichment of volatiles. Table 2

shows that the Mobley Mountain granite does not meet any ofthe criteria for mineralized granites discussed earlier andshown in Table l. Furthermore, the Mobley Mountaingranite does not show a high Rb/Sr value (Figure 8). Brock(1981) and Brock and others (1987) underplay the chemicaland mineralogic discrepancy by postulating upper mantlemelting (possibly of a lherzolite) and fractional crystalliza-tion leading to a volatile-enriched pluton cupola. The frac-tional crystallization for Brock's model (1981) was derivedfrom computer modeling (XLFRAC, mass balance simula-tion). It is certainly reasonable to envision dismembermentof plutons in this allochthonous thrust belt setting, but itshould be noted that the data for the Rockfish pluton plotscloser to the Nettle Mountain granite than the Mobley Moun-tain gnnite on a modified A-K-F diagram (Figure 9).

Table 2. Average major chemical and mineral differencesbetween Nettle Mountain granite and Mobley Mountaingranite.

Nettle Mountain Mobley Mountaingraniter granite2

SiO.Vo 74..5TiO,Vo 0.08Total Fe asFerOr%o 2.48MgOTo 0.llCaOVo 0.78Rbppm 437.0Srppm 82.0Yppm 179.0Uppm 7.7Th ppm U.lRblSr 5.05

Quartz (modal%o) 27.5Albite (modal To) 5.2Epidote (mdal%o)

67.60.475.610.36L.t4

97.4190.022.0

0.577.20.59

24.8t2.l5.4

tNettle Mountain granite data from Hudson (1981), mean ofthree analyses.

2Mobley Mountain granite data from Brock (1981), mean of14 analyses.

THORIUM AND URANIUM

Anomalous thorium values may have a potential use inthe Blue Ridge province as a rapid guide to poorly exposed orburied mineralized pegmatite or pegmatoid zones, mineral-ized cataclastic zones, tin-bearing greisen, and surface ex-pressions of uranium at depth. Late Precambrian-age,Crossnore-type plutons (fluorite-bearing biotite granitoidrocks rich in thorium and rare-earth elemens) have beenproposed as prime exploration targets for uranium in igne-ous-metamorphic rock terranes @ogen and others, 1978).

Uranium mineralization is associated with tin deposits inEngland and Europe in geologic settings similar to IrishCreek. Mineralization is associated with granites containing

PUBLICATION I12 ll

more than 5 ppm uranium (Rich and others, 1977). In theeastern United States, exploration foruranium is difficultandmisleading because surface leaching, transportation, and re-deposition can easily remove all direct indications of unoxi-dized uranium mineralization at depth, or leave only shallowconcentrations ofsecondary uranium minerals at the surface.

Thorium, because of similar ionic radius and valencecharge compared to uranium and rare-earth elements, accom-panies these elements in magma evolution. Crossnore-typegranitoid plutons are enriched in these elements as well as ru-bidium, beryllium, lithium, tungsten, tantalum, and tin, andthus might be considered rift-related because of the knownassociation ofalkalic/peralkalic felsic rocks in tensional set-

tings. Upper mantle plune melting during uplift precedingrifting is the most probable source.

Uranium (U{) separates from thorium (Th{) as it oxi-dizes to U*6and forms more soluble and mobile complexesduring the weathering cycle in humid climates. The Th{remains unoxidized in rock and soil as a stable compound.One example in Virginia where the surface radioactivity isnot superficial, or due to disseminated thorium minerals, isthe Marline Uranium Corporation's Swanson ore body inPittsylvania County. This deposit consists of an estimated3O-million pounds of UrOrin coffinite-pitchblende-uraniniteore averaging 0.20 percent QO, (Chenowith, 1983). Themineralizedzone is contained in a sheared late Precambrian-age augen gneiss in contact with a younger granite along aborder fault of the Danville Triassic basin. This deposit mightrepresent mineralization along a reactivated late Precam-brian-age rift fault

Deformation of accessory uranium and thorium-bearingminerals is known to markedly enhance radioactivity in my-lonite zones because of redistribution of the oxidized andsoluble U{ cation and radon gas movement within morepermeable cataclastic textures. In studying sources of radonenrichment in Virginia and Pennsylvania, Gunderson andGates (1988) noted that uranium content could be positivelycorrelated with shear strain as determined by the angle be-tween C and S bands. In the l^ate Precambrian-age Readinghong allochthon of Pennsylvania, uranium was found hostedin allanite, titanite, and monazite in unsheared rocks, but wasredistributed in association with hematite in the foliation ofmylonite at levels of 25 to 50 ppm uranium (Gunderson andGates, 1988).

Allanite and chevkinite/perrierite are common in smallamounts in the Blue Ridge province of Virginia (Mitchell,1966a). Thorium always substitutes in varying small amountsfor cerium in allanite (Ce, Ca, Y) (Al, Fed), (SiO), (OlD,penierite (Ca,Ce,Th)o(Mg,Fe'2)r(fi,Fe'3)rSip, monoclinicperrierite (chevkinite), florencite (Ce,AQ@O.)r(OlI)u, andbastnaesite (Ce,I^a) (CO3)F,OFD, all of which are known tooccur in the Crossnore plutons and the Robertson Riverplutons andpegmatites (Hudson, 1981; Brock, 1981; Lukertand Halladay, 1980). Complications in interpretation couldoccur because allanite is also found in association with peg-matoid intrusion zones near older charnockites. Allanite andchevkinite may be related to late Precambrian-age Crossnorepegmatoids. Hudson (1981) notes a radioactivity anomalyassociated with dark-gray quartz veins containing iron oxides(200 ppm thorium, 7 ppm uranium) about 0.6 mile from the

fluorite-biotite granite along Nettle Mountain. Whole- rockanalyses by Hudson on the Nettle Mountain granite showed

a range of 13.5 ppm to l7 .9 ppm for thorium and an averageof 7 ppm for uranium . His mapping indicates aplites and gre-

isen in theperipheral zone of the fluorite-biotite granite, one

of which ourcrops on the west slope of Yankee Horse Ridge.Hudson noted thorium enrichment along a cataclastic zone onGrapevine Ridge in the southwest corner of the Montebelloquadrangle (Figure 1) and reported thorium values of I94ppm and only 3.4 ppm uranium. A southem projection ofHudson's mapping of a radioactive cataclastic zone was

checked by the writer. Gamma-ray spectrometry indicatedthorium and uranium values similar to Hudson's data (Figure1 1).

WEST O 1OO 2OO 3OO 400 500 600 700

FEET

Figure 11. Gamma-ray spectrometer and geochemical rav'erse across a projection of the cataclastic zone mapped byHudson (1981) on GrapevineRidge, Montebello 7.5-minutequadrangle, Rockbridge County, Virginia.

B

EAST

-

THORIUM PPM GS

-._. LEAO PPM AAS

- - - URANIUM PPM GS

'--------'+---+- . - . -i

t2 VIRGINIA DIVISION OF MINERAL RESOURCES

Ames ( 1 98 1 ) noted thorium enrichments of 275 ppm and15.3 ppm uranium in the felsic mylonites of the Rockfishmylonite zone southeast of the Irish Creek mines @gure l).This area is northeast of the Montebello quadrangle. Valuesof 50,000ppm thorium and4800ppm uranium werereportedin saprolites of shearzones with enrichments of tin, tungsten,lanthanum, scandium, titanium, vanadium, zinc, and yttriumin the Lovingston Formation southwest of Charlottesville(Baillieul and Daddazio, 1982). The radioactivity in thiscataclastic zone is generated primarily from monazite, ura-nothorite, and thorogummite. A strong north-northeast trend-ing thorium and uranium anomaly is indicated by streamsediments in the National Uranium Resouces Evaluation(I{URE) survey (Herz, 1982). This anomaly is south of theMontebello quadrangle in the adjacent Forks of Buffaloquadrangle. A low-level thorium emichment is noted (Ih/ugreater than 4.0, 1 3.4 ppm thorium, 3. 3 ppm uranium: Appen-dix VI) at kish Creek tin mine (Figure 12\ and, in an areaperipheral to the Nettle Mountain granite (6f ppm thorium,7.5 ppm uranium: Appendix IX:44.7 ppm thorium, 7 ppmuranium: Appendix X; Figure 13).

THORIUM / URANIUMo <4.0

< 4.0

> 40

g. . . , , , . .1.q00Feel

Figure 13. Soil Tty'U ratios for the gamma spectrometertraverse across Nettle Mountain and Yankee Horse Ridge,Montebello 7.5-minute quadrangle, Rockbridge County.

r-

oo

El *u,,,"

oo

oo

"..i.$-

Figure 14. Parts per million tin in soil traverses on NettleMountain and Yankee Horse Ridge.

at Irish Creek mine (traverse A-A' in Figures 15, 17, and 19)

and apparently uncon[aminated and unmineralized soil (trav-erse B-B', figures 14, 16, and l8). Traverse B-B' is 250 feetnortheast of the mine and parallel to the Eaverse across themine adis. The values are listed in Appendices VI, VIL VIII,and IX. Background values were computed from geochemi-cal soil values from Eaverse B. Additional geochemical soildata from the literature helpful for establishing or evaluatinganomalies for tin" lead, and zinc as well as for other metalsanalyzelin this investigation are given in Appendix V.

A topographic-geochemical profile of the southqstpor-tion of reconnaissance traverse C-C' across Nettle Mountain(Figure 20) shows elevated tin,lead, and zinc values. In theother traverses @gures 14,16, and 18) detailed sampling atlO-foot intervals along three, 200-foot sample Faverses isindicated within in the large rectangle representing an en-larged view of anomaly Y on Yankee Horse Ridge. Addi-tional short north-south and east-west traverses with 100-footintervals, D, E, andF have metal values listed in AppendicesX, XI, and XII.

THORIUMo

URANIUM

ooo

o >4.0

1='2tttt= =

^ lrish Creek'o Mineo'l

-a

9,.......10p0Feel

Figure 12. Soil fiy'U ratios fm the gamma spectrometertraverse across Irish Creek tin mine, #l working" Montebello7.5-minute quadrangle, Rockbridge County.

RESIJLTS OF INVESTIGATION

GEOCIIEMICAL SOIL TRAYERSES

A geochemical soil traverse with 100-fooa intervals wasdesigned to cross the fluorite-biotite granite on Nettle Moun-tain (described by Hudson, 1981) and intersect a smallgreisen and aplite area on Yankee Horse Ridge. The initialreconnaissance soil traverse clearly indicates a tin, lead, andzinc anomaly (Figures 14, 16,18, and 20). Reference soiltravgrses were made over mineralized and concaminated soil

oo o

.\o .{^\. . a'

+:nc'$'

ooo

o

N

\\\\:

PUBLICATION II2 13

PPM TINo <16o 16-19. >19

PPM LEADo <42o 4247a >47

t---*-i900Feel

Figwe f 5. Fafls per million tin in soil traverses at and nearkish Crcek tin mine, #l working.

co

'=-- --= 2tt2?s"-

-

ooooo

o oo lrish cCreek.oo Min9o

oo

o,-****--i-9ooFeel

Figure 17. Para per million lead in soil in the vicinity of theIrish Crcek tin mine, #l wo*ing.

vo

l.

'==--= 2t?tt?= -

o

t*r(I,

"s

\"'\ oo^o"oA,.no

oB'

N

YY

..*;ilJ''.(II

tI

oooo

oooo

oB,

o-o

oo

PPM LEADo <42

9.., .rr-. .l,o.oo

Figue f6. Parts per million lead in soil traverses on NettleMountain and Yankee Horse Ridge.

The Yankee Horse Ridge anomaly shows elevafed val-ues ofrubidium @igure2l), arsenic @igure23), gold (Figure25),andsilver. A small thorium anomaly with a maximumvalue of 6l ppm thorium (Figure 13) is also presenL Metalvalues from samples along the FaversesareshowninAppen-dices VIII, D(, X, XI, and XII.

Comparison of the geochemical soil anomalies at Yan-kee HorseRidge with the reference travene A at Irish Creektin mine show ttrat there are elevated values of tin, lead,beryllium, lithium, zinc, copper, fluorine (Figure 27), rubid-ium @gure 22';, and silver very close to the mine adits (butnoton mine dump soil). No soil samples were taken for goldanalysis along the hish Creek mine traverse. Soil values withelevatedberyllium, tin, lead, lithium, zinc, andarsenic werefound over the Nettle Mountain granite in traverse C. Sometungsten values (apparently anomalous) are also present (Fig-

ao

9........1q00Feel

Figure 18. Parts per million zinc in soil traverses on NeuleMountain and Yankee Hone Ridge.

ures 7, 15, L7, 29, 19, and Vl). Traverses showing fl uorine,lithium, and copper :lre shown in Figures 26, 28, and 30 withreference traverses in Figures 26,28, and 31. In the detailedtraverse (10 foot intervals) on Yankee Horse Ridge anoma-lors iron, manganese, nickel, andcobaltvalues arealso rntedassociated with a Catoctin greenstone feeder dike.

Both gold and silver are identified in anomalous amountsin the soil at levels indicating the presence of gold minerali-zation in the bedrock. This non-visible mineralization isconfirmed by assays of the bedrock. The initial preciousmetal anomaly was suggested from ttre routine use of atomicabsorption for silver alone. Silver has been used as a "crude"pathfinder element forprecious mefals as well as base-metalmineralization. Silver has been demonstrated to be a useful,rapid, and inexpensive discriminator element even whenused with routine geochemical analyses with hydrochloric

aaaa

C

t4 VIRGINIA DIVISIOI{ OF MINERAL RESo(JRGS

PPM ZINCo <142o 142 160.>160

coooo

ooo

oo-====,t"t"- -

0 tooor+.t--....rFeel

Iigpre 19. hrts permillion zinc in soilin the vicinityoflrishCrceL tin mine, #l wutiqg.

Egue 20. Geochemical soil profile for tin,lea4 and zittcstheastern portion of C, location Y (Figure 2A), YankeeHaseRidge.

acid sample digestion. Enough silver remains in solutioneven thorgh silverin large amounts is precipitatedby chb-ridc, to provide low level silver anomalies with a detectionlim'tof I ppm silver.

AtYankee HoseRidge andNettle Mountain only twosil samples on traverses C, D, E, and F (Figrnes 2A, 5) showdetectable (more than detection l ppm limit) silver. Sample3-W-1 (traverseF, Apperdix I) contains 5 ppn silver. Oneolher sample contains detectable silver (l pm) @L onlravsseYC, detailed sampling, AppendixXtr). AII uhq

rfQt

ooo

."*{."*{,o-

ll

t

oo

(

l1a!I

'aoo

\oo

ooo

ooo

shtrMinC.

rishBlMinC,

irtooooo

eekI

oo

oo

fe(oo

toA

B *",tr" llounlain g.anile

oo o

o o

\F-

I

B n"nr,e rmtan gr.nitc PPT' RUBIDI,r.

Feel

Hgurc 2f. hc pa million nrtfdium in sil &av€rss @Nerle Itfiormain ed Yankee II6s Ridga

PPM RUBIDIUMo <68o 68-87

I r >87 ---====== =2?'

ooooq

ooo

B'

N

o roo0lJ-.J41

Feel

frgueZ,. krts lnmillion rubidium in soil trar,€rses fu lhevbinity of Irish Ge€k rin mirc, *l woting.

coooo^

-oo

oo

9.......-r.o.ooFeet

Flgure 23 . Parts pe million arsenic in soil traverses on NettleMountain and Yankee Horse Ridge.

o <68t 68lzo >87

34 PPM TIN

305 PPM ZINC

22 PPM I.EAD

lNett leCre ek

oaaooaooo

Y

Lo"tilir,?o'"*

g

o roo0rl-- ---.r-l

Feel

***. '.______---Y*qgue 25- ktslm million gdd in soil at tin-bd-zinc geo-chical zlfinaly Y (Figrrc 2a),localn Y (Figurc 5),YankecItusRidgc.

El *r,," rocilain grann€ PPT FLT'On|Eo <t73o i7t 72rt ut?t

g"---....10poFeel

Figure 26- hrts per million fluoride in soif traye{s€s onNe*[h ffiounain and Yankee Horse Ridgc.

L " i#i''Po

Figue 28. kts per milliorr lithium in soil traverses in lhevlfiity of kish Creek tin mine, #l worting.

rmine sfl smrples main no detectable silver excqr twosernlrles m trerderence traverse rross hish Creek (rarcneAnppendixVl). Thesevalues ae 13 and I ppn sihrcrattuftish Croek adit ard f00 feet soufteast of the adit. It is direreglonoethatfornsoilsamples from theBuckldomlainmirc (Egure l), ten miles southwest of the hish Creek minecmtain ftom 2 to 5 ppm silver (Appendix m). According toSnfttmdCmon (1977) therangeof silver in unminsalircdsils is 0.fi1 to 0.09 ppm. Even in mineralized soilq silwselilom cxaeds 1 14rn, althurgh the humic layers in mim-aNizrdrw may in exceptional cases rerch levels of 2 to 5p (Slucklwe and Boerngen, 1984).

Bcause of tlre cleuly anomalous silver values in fumil" additional soil samples were taken on a separate grid.These samples were malyzndfor gold and silverby fireassay(Figsre 25)" Three soil samples contained 0.326 ppm,0470

PT'BLICAIIOY 1I2 r5

PPM ARSENIC

o <5o >{ -

PPM FLUORINEo <573o 573-723o >723

'=--=-- ?t"t-'= = l

==--= 2"2t2"7

-

ooooo

ooA N

0 1000ll-- --.-..4

Feel

Egue 24- PaS permillip {3pafo in soil raverss in fu Fglua27- Prtspermillion fluaide in soil travenses in fuvLinity of kish Geet tin minq *f urc*iag- vicinity offtish Greek tin mine #l working.

cPPI' GOLD

6 < O.01

o o-01 _ 010

. (t.-t - o.5

rr: riletile ilbOlahDlJ qrarile

$f mractastic roc*rs

c@PPM ]I.ITN{IIJido <12o 425{}. >5o

$s";tt oo ooooooo

a/

tIl

I

-oo

Yn'

,,"o*;loS"*"

ooo@o I

-r&'^\"

oc'

co

oo

-ooo

oo

ET

El *.,,,. t ounraan granite

"" reiiiiii

r6

| ---= === == =t"'

0 1000f*-sf

Feel

figwe29. Parts permillion lithium in soil traverses on NettleMounain and Yarikee Horse Ridge.

c oo17.ooo tzlt Neille Mountain granite

"oo

a oa o

o

*$q

VIRGINIA DTVISION OF MINERAL RESOURCES

PPM COPPER

^ lrish Qreek-o Mindo

0 roo0Feel

Figre 31. kts per milion copper in soil traverss in tlrevicinity of kish Creek tin mine, #l working.

stage, gold can be p'resent in soil particulatas or in c&bles andpebbles. Gold is most often enriched in tlrc hrmus layersbecause itcan actas areductant and precipitatiur rnedium fumobile forms of gold. In mineralized areas Lakin ando&ss(197a) foundfca*mull (a special form of humus) to contain0.05 !o 5 ppm gold.

TRENCHING AI{D DRILLING ON T}IE YANKEEHORSE RIDGE ANOMALY

The soil anornaly on Yankee Horse Ridge was exposedby trenching. The rocks and soil in the tnench revealednussive, streee{ and mylonitized and hydrothermalty aI-tered leucocratic, quarg monzonite and alaskite bedrockbeneath a slrallow soil cover (Figures 5, ?fi,29,32, and 33).Inunsheaedquartz monzonite tlrc quartz is bluish gray andthin sections indicae that perthitic K-feldspar is abundant.The mylurite is a light gray to greenish gray, schislose,aphanitic rockwittr I to 3 millimeters elongated smoky gray,qaarlz, porphyroclasts. Mrrch of the uncrushed rock showsanasomosing, paper-thin, limonite or hematile-filled frac-tures in thin section. Mylonitic marerial contains quartz withmortar texture and Boehm lamellae, as well as sericite andchlorite leaves between the quartz clasts. Unweatheredmylonitic bedrock is shown in Figure 32.

A few samples contained visible hematitic vugs with dis-seminated pynte. Other rock fragments conlained isolatedlimonitic and lrematitic boxworks from2 to4 centimeters indiameter. Boxwork casts suggest both tetrahedra and cubes.Several fragments show traces of powdery yellow and yel-low-green films. X-ray diffraction indicates jarosite andpossibly beudantite, a lead arsenate mineral.

No definite greisen zone could be observed in the exca-vations. The exposed area indicated sparse, scattered miner-

PPMooa

LlTHIUM<4242- 50>50

PPM COPPER

o <34o 3438

f o > 38 ----- 2.

== == =t2'

ao

ooooo

tto

ooooo

aooB'

NN

Figure 30. Parts per million copper in soil traverses onNe$leMqptain and Yankee Horse Ridge.

ppm, and 0.5 I 2ppm gold. All of fhese values unambiguouslyindicate gold mineralization in urderlying or nearby bedrockAnomalous gold is indicated in 14 out of 39 soil samplesusing 0.01 ppm as the threshold (AppendixXltr). The resultsirrlicate gpical 1nechy anomalous ralues consistcnt withgoldmineralization elsewhere. In soils over oneof thelargestgold mines in Virginia's gold/pyrite belt, the Tellurium mine,arnmalous soil values range from 0.02 to 0.42 ppm gold withall background samples below 0.02 ppm (Good and others,1977). In abandoned South Carolina gold mines, Kinkel andI-eSure (1968) found soil values tro ftmge from 0.02 tfi 0.52ppm gold. Rose and others (1979) list 0.002 ppm gold asbackground for soils and Kabata-Pendias andPendias (1984)give 0.001 to 0.002 ppm gold as a background range for allunmineralized soils regardless of climate. Lakin and others(1974) studied gold disribution in soil profiles. They showthat depending on the origin of the soil and its weathering

PLTBLICATION I12 t7

Figure 32. Freshly bulldozed bedrock at geochemical soilanomaly Y (Figure 2a), location Y (Figure 5), Yankee HorseRidge, showing sparsely mineralized, sheared leucoquart-zmonzonite. Selected loose grab samples showed gold as-says up to 0.17 ounces of goldfter short ton.

Figure 33. Freshly bulldozed bedrock at geochemical soilanomalyY inFigure 2a,location Y (Figure 5), Yankee HorseRidge, showing sparsely mineralized leucoquartzmonzonite.Selected grab samples showed gold assays up to 0.17 ouncesof gold/per short ton but samples were not in place.

alization, not an obvious vein or dike. White aplite withpaper=thin, hematite-filled fractures occurs in the vicinity ofthe geochemical anomaly, away from the area of trenchingand about 500 feet down slope to the north of the trenchedarea.

Three mineralized grab samples were assayed from therenched geochemical soil anomaly (Figures 20 and 32). Theassays show marginal to ore grade values of 0.03, 0.05, and0.17 ounces/ong lon gold (assays 1,2, and l0; AppendixXIV) and up to 8.72 ounces/ong ton silver(assay 1, Appen-dix XIV). A fourth mineralizedbedrock sample from anom-aly Y showed0.002 ounces/ong ton gold (assay 12, Appen-dix XIV).

ORIGIN OF MINERALZATION AND E)PLORATIONTARGETS

TIN

Cunentgeologic evidence supports the association of tinmineralization with Late Precambrian- to Early Cambrian-age continental margin rifting as discussed earlier. Theidentification ofrift-generated felsic plutons as a potentialsource for tin and tungsten shouldfocus on any granitoid rockwith a specialized chemical signature, especially flubrite-bearing granites with biotite more abundant than muscovite.

Lithochemical or whole-rock chemical signatures ofpotential mineral-rich granitoid source rocks should showlow TiQ,low total Fe as FerO' low MgO,low CaO, highI!O, and enrichments in rubidium, fluorine, lithium, tin,beryllium, tungsten, and molybdenum witl or without ele-vated values of niobium, tantalum, caesium, uranium the,rare earths, and boron. Specific element values based on awide variety of mineralized areas of the world are summa-rized in Column 2 of Table 1. Additionally, elementpairs canbe used. A specialized signature would show low ratios forK/Rb, Mg1Li, and Ba/Rb.

Hudson ( I 98 1) and Rankin (197 5, I 976) did not includechemical data for tin, beryllium, or lithium, thus an evaluationof whole rock signature for the Irish Creek area is limited. Ifpossible, chemical analyses in a tin exploration programshould include tin, litlium, strontium, barium, selected rareearths, thorium, and uranium. Because of ttre limitations onchemical data for the Irish Creek area, aRb/Sr value of greaterthan 5.0 is tentatively suggested as a simple criterion foridentifying a potentially mineralized pluton. The basis forthis value is summarized in Figure 8. Where complete chemi-cal data is available, several chemical elements can be com-bined in a discriminant formula. Govett (1983) found one ofthe most useful to be: Rb2 x LdK x Mg x Sr with resultantdiscriminant numbers above 5ffi indicating apluton with fa-vorable mineralization. This figure was based on computa-tion from known mineralized and apparently banen rocks.

Theevaluation of areas containingplutons with aspecialchemical signature and exploration in areas without chemicalanalyses for granites, can be focused on areas surroundingstream sediment sample stations with values of more than 6ppm beryllium. Tin may or may not be anomalous in thesediment depending on tlte drainage. Values of tin in soilabove 20 ppm should be considered an indication of miner-

PUBLICATION II2 l7

Figure 32. Freshly bulldozed bedrock at geochemical soilanomaly Y (Figure 2a), location Y (Figure 5), Yankee HorseRidge, showing sparsely mineralized, sheared leucoquart-zmonzonite. Selected loose grab samples showed gold as-says up to 0.17 ounces of goldfuer short ton.

Figure 33. Freshly bulldozed bedrock at geochemical soilanomaly Y in Figure 2a, location Y @igure 5), Yankee HorseRidge, showing sparsely mineralized leucoquartzmonzonite.Selected grab samples showed gold assays up to 0.17 ouncesof gold/per short ton but samples were not in place.

alization, not an obvious vein or dike. White aplite withpaper-thin, hematite-filled fractures occurs in the vicinity ofthe geochemical anomaly, away from the area of renchingand about 500 feet down slope to the north of the trenchedarca.

Three mineralized gtab samples were assayed from the

trenched geochemical soil anomaly (Figures 20 and 32). Theassays show marginal to ore grade values of 0.03, 0.05, and0.17 ounceslong ton gold (assays 1,2, and 10; AppendixXIV) and up to 8.72 ounces/ong ton silver (assay 1, Appen-dix XIV). A fourth mineralized bedrock sample from anom-aly Y showed0.002 ounceslong ton gold (assay 12, Appen-dix XIV).

ORIGIN OF MINERALZATION AND EXPLORATIONTARGETS

TIN

Current geologic evidence supports the association of tinmineralization with Late Precambrian- to Early Cambrian-age continental margin rifting as discussed earlier. Theidentification of rift-generated felsic plutons as a potentialsource for tin and tungsten should focus on any granitoid rockwith a specialized chemical signature, especially fluorite-bearing granites withbiotite more abundant than muscovite.

Lithochemical or whole-rock chemical signatures ofpotential mineral-rich granitoid source rocks should showlow TiO' low total Fe as Fep' low MgO,low CaO, highK"O, and enrichmens in rubidium, fluorine, lithium, tin,bebllium, tungsten, and molybdenum with or without ele-vated values of niobium, tantalum, caesium, uranium the,rale earths, and boron. Specific element values based on awide variety of mineralized areas of the world are summa-rized in Column 2 of Table 1. Additionally, elementpairs can

be used. A specialized signature would show low ratios forK/Rb, M&/Li, and Ba/Rb.

Hudson ( I 98 1) and Rankin (197 5, I 976) did not includechemical datafor tin, beryllium, or lithium, thusan evaluationof whole rock signature for the Irish Creek area is limited. Ifpossible, chemical analyses in a tin exploration programshould include tin, lithium, strontium, barium, selected rareearths, thorium, and uranium. Because of ttre limitations onchemical data for the Irish Creek area, aRb/Sr value of greater

than 5.0 is tentatively suggested as a simple criterion foridentifying a potentially mineralized plulon. The basis forthis value is summarized in Figure 8. Where complete chemi-cal data is available, several chemical elements can be com-bined in a discriminant formula. Govett (1983) found one ofthe most useful to be: Rb2 x Lt/K x Mg x Sr with resultantdiscriminant numbers above 500 indicating a pluton with fa-vorable mineralization. This figure was based on computa-tion from known mineralized and apparently barren rocks.

The evaluation of areas containing plutons with a specialchemical signature and exploration in areas without chemicalanalyses for granites, can be focused on areas surroundingstream sediment sample stations wittr values of more than 6ppm beryllium. Tin may or may not be anomalous in thesediment depending on the drainage. Values of tin in soilabove 20 ppm should be considered an indication of miner-


alization. Northwest-southeast cross-striike reconnaissance

traverses can be followed by grids in anomalous areas.

COLD

The origin of the gold in the Blue Ridge province is less

clear than for tin. At the Irish Creek mines, gold occurs witharsenopyrite in the tin greisens and quartz veins that are close

to a cataclastic zone. The extent of the gold mineralization is

unknown. Ten miles southwest of 'Irish Creek, in rocks

similar to those at Irish Creek, gold and silver occur inamounts large enough to have been mined in a small opera-

tion at Buck Mountain. The precious metals occur in quartz

veins in association with arsenic minerals thatare confined toa narrow shear zone. In between these two occurrences, goldwas identified at Yankee Horse Ridge in sheared bedrock in

Creek, Montgomery County, Virginia, gold occurs withinmyloni @ilotgneiss iscoll,1989). Creeksamples from within the Fries mylonite zone showed that thegold is epithermal and ontinuousquartz veins. The ep distinctlYdifferent inclusion sig myloniticquartz. Driscoll concluded that the Brush Creek gold deposits

were controlled by brittle fracture tectonics and were there-

fore probably related to a tectonic event sometime after lateMississippian time (latest mylonitization associated with the

Fries fault).

Figure 34. Microphotograph of a sample of cataclastic leu-

coquartzmonzonite under cross-polarized light at 20x show-

ing hematite-filled fractures with traces of pyrite. From

bedrock at anomaly Y (Figure 2A), location G (Figure 5),Yankee Hone Ridge.

At Yankee Horse Ridge the precious metal anomalies are

associated with very sparse mineralization within cataclas-

tized, felsic,anomaliesaredikes (Figurewho considerNettle Mountainquartz monzonitage felsic plutonered to be rift-relanglandAnyand

clastic events. Gold is now lnown to be much more mobile

than previously thought so that caution must be shown ingenetic hterpretation s.

Figure 35. Microphoograph of a sample from therhyodacite

dile under cross-polarizbd light at 20x showing radiate

structure which may be a devitrification spherulite' From

felsite outcrop 150 feet from anomaly Y (Figure 2A).

Hudson andDallmeyer (1982) mightbe incorrectin their

assumption that the from

IrishCleekgreiseni anite

because ttre Nettle d di-rectly and does not occur, or at least has not been observed,

at th; Irish Creek mines. There may be multiple inrusions ofdifferent ages at the Yankee Horse Ridge-Nettle Mountain

PUBLICATION T12 19

Figure 36. Bedrock in Nettle Creek showing rhyodacite andCatoctin(?) metabasalt xenoliths in hornblende granite, loca-tion F, Figure 2A.

Figure 37. Bedrock in Nettle Creek showing Catoctin(?)metabasalt xenolittrs in hornblende granite, location F, Fiugre21^.

Figure 38. Bedrock in Nettle Creek showing Catoctin(?)metabasalt xenolittrs in hornblende granite, location F, Fig-ure 24.

Figure 39. Bedrock in Nettle Creek showing Catoctin(?)metabasalt xenolittrs in hornblende granite.

lengttr, of Catoctin-like greenstone, felsic dikerock, and feld-spathic quartzite containing visible, rounded, clasts (Figures

36,37 ,38, and 39). The occulrence of the xenoliths in thehornblende granite at the periphery of the Nettle Mountaingranite supports the supposition of multiple intrusions as

noted in association with fluorite-biotite granites in Rap-pahannock County by Lukert and Halladay ( 1980) and Tolloand Arav (1987). It is possible that the xenolithic granite inNettle Creek could be Paleozoicin age and not Latehecam-brian. It is also possible that the granite is not a xenolitlticborder facies of different composition than the Nettle Moun-tain biotite granite. There is also no date on the rhyodacitedikes at Yankee Horse Ridge. The assumption is that thedikes are associated with the Nettle Mountain granite and are

I-ate Precambrian age, but the Nettle Mountain $anite has

never been directly dated. Similar felsic dikes are known tocut Lynchburg Group rocks.

It is possible that gold might also be associated withMiddle Cambrian-, Devonian-, Mississippian-, or even as

yet, unrecognized Mesozoic- or Eocene-age hydrothermalevents. Wittrout more data, the writer prefers a Late Precam-

brian-age gold-tin event with reactivation.At the Yankee Horse Ridge gold occurrence, no visible

gold has been observed. It is a reasonable assumption thatgold probably occurs in association with hematite-filledfractures cutting across mylonitic textures (Figure 34). It isknown from other Yankee Horse Ridge samples thatpyrite isoccasionally preserved as unoxidized cores with limonite orhematite husks as well as in rare boxworks (in a few places).

Additionally, typical oxidation minerals from pyrite, likejarosite, have been identified in fresh bedrock at YankeeHorse Ridge. The general association of gold with and inpyrite or arsenopyrite is well known. The time of minerali-zationhowever,remains uncertain until gold has been locatedand identified by microscopic and microprobe examinationand additional rock age dating is done.

Blue Ridge province gold is associated with cataclasticzones. Elevated thorium, uranium, and potassium values are

also associated with limited sections of a few cataclasticzones. High radioactivity might also be associated witl tinand gold mineralization as well as pegmatoid zones. Further

2A VIRGINIA DIVIS ION OF MINERAL RESOURCES

work is needed to establish anomalously high radioactivity asa reliable prospecting technique for other elements besidesuranium.

Discrimination of potentially mineralized cataclasticzones can be made by selective geochemical soil traversesacross ductile and brittle deformation zones using analysesfor gold (0.01 ppm or greater), silver (1 ppm or greater) andarsenic (5 ppm or greater) as guides. Tin values (greater ttran20 ppm) in soil may indicate either tin, base metal, or goldmineralization. The base-metal anomalies found in thisinvestigation may indicate apreviously unrecognized type ofmineralization in Virginia.

ACKNOWLEDGMENTS

The writer would like to thank the following individualswho aided in this projecu Jacqueline Kennamer, Division ofMineral Resources, for her assistance in the analyses of soilsamples for tin by X-ray emission, and for trace elementanalyses in soil, sEeam sediment, plant ash, and water samples;Carl Moses, formerly of the University of Virginia Environ-mental Science Department, now at the Department of Geo-logical Sciences, Irhigh University, for fluoride analyses onsfream water by ion chromatographic column procedures;Gary E. Harsh and other Owens-Illinois ForestProducts (nowNekoosa Packaging, Inc.) staff for help in road improvementand trenching in the Yankee Horse Ridge and Nettle Moun-tain area; Dave Wooley, Virginia Department of Highwaysand Transportation, for consultation and drilling of coreholes; John Allan and the late Dr. Robert S. Young, NorthAmerican Exploration, for assays on Buck Mountain mineand helpful discussions; Richard Duncan and Dr. Robert W.Luce, formerly of Billiton Metals for helpful discussions ontin exploration; Dr. Nicholas H. Evans, Virginia Division ofMineral Resources, for information on the Rockfish Riverand Wood's Mountain plutons and critical comments ontectonics; Dr. SandraClark, U.S. Geological Survey, and Dr.Charles P. Thornton, Departmentof Geosciences, ThePenn-sylvania State University, for critical review of the manu-script; and to local residents of the Irish Creek area forhistorical information and access to properties, particularlyHerbert Clark, Richard Montgomery, James Letcher, TroyPainter, Herbert L. Grow, and Wilson Grant.

REFERENCES CITED

Adair, G.L., 1942, Report on the Irish Creek tin prospect:unpublished Bethlehem Steel interoffice memorandum, inFrench, 8.L., 1956, interoffice memorandum of 9/L9/56 ofAtlantic Lumber Company, Boston, Massachusetts, summa-rizing drilling and assays by S. Lake on 1942 investigation byBethlehem Steel Company geologic staff: Virginia Divisionof Mineral Resources, Economic Section files.

Ames, R.M., 198 1 , Geochemistry of the Grenville basementrocks from the Roseland district, Virginia [M.S. $resis]:Athens, University of Georgia, 91 p.

Badger, R.L., and Sinha, A.K., 1988, Age and Sr isotopesignature of the Catoctin volcanic province: Implications forsubcrustal mantle evolution : Geology, v. 16, n. 8,p. 69249 5.

Bailey, D. K., 1989, Peralkaline igneous rocks, in Bowes, D.R., d., The encyclopedia of igneous and me[amorphic pe-trology: New York, Van Nostrand Reinhold, p.436-437.

Baillieul, T.A., and Daddazio,P.D., 1982, A vein type ura-nium environment in the Precambrian l,ovingston Forma-tion, central Virginia: Virginia Division of Mineral Re-sources Publication 38, 12 p.

Bartholomew ,M.I .,1977 ,Geology of the Greenfield and Sh-erando quadrangles, Virginia: Virginia Division of MineralResources Publication 4,43 p.

Bartholomew, M.J., Gatlright, T.M., II, and Henika, W.S.,I 98 1, A teconic model for the Blue Ridge in cenral Virginia:American Joumal of Science, v. 281, p. 1164-1183.

Bloomer, R.O., and Werner, H.J., 1955, Geology of ttre BlueRidge region in central Virginia: Geological Society ofAmerica Bulletin, v. 66, p. 579-ffi6.

Boyle, R.W., and Jonasson, I.R., 1973, The geochemistry ofarsenic and its use as an indicator element in prospecting:Journal of Geochemical Exploration, y . 2, p. 25 | -296.

Brock, J.C., 1 98 l, Petrology of the Mobley Mountain granite,Amherst County, Virginia [M.S. thesis]: Athens, Universityof Georgia, 130 p.

Brock, J.C., Herz, N., Mose, D.C., and Nagel, M.S., 1987,Geology of the Mobley Mountain granite, Piney River quad-rangle, Virginia Blue Ridge: Virginia Division of MineralResources Publication 7 4, p. 69-80.

Brooks, R.R., 1972, Geobotany and biogeochemistry inmineral exploration: New York, Harper and Row,290 p.

Brown, W.G., 1885, On cassiterite from lrish Creek, Rockbr-idge County, Virginia: American Chemical Journal, v. 6, p.185-187.

Bryant, B., and Reed, J.C., Jr., 1970, Geology of the Grand-father Mountain window and vicinity, North Carolina andTennessee: U.S. Geological Survey Professional Paper 615,190 p.

Butler, J.R., 1953, The geochemistry and mineralogy of rockweathering, l. The Lizard area, Cornwall: Geochimica andCosmochimica Acta, v.4, p. L57-178.

Butler, J.R., and Ragland, P.C., 1969, PeEology and chemis-try of meta-igneous rocks in theAlbemarle area, North Caro-lina slate belt American Journal of Science, v .267 , p. 700-726.

Carlin, J.F., Jr., 1988, Mineral and commodity summaries1988 Tin: U.S. Bureau of Mines, p. 168-169.

PUBLICATION 112 2l

Chapman, H.D., editor, l9l2,Diagnostic criteria for plantsand soils: Riverside, University of Califomia,793 p.

Chenowith, W.L., 1983, Developments in uranium in 1982:Bulletin American Association of PeEoleum Geologists, v.67,n. 10,p.2001.

Clark, H.B., Costain, J.K., and Glover, L., III, 1978, Struc-tural and seismic reflection studies of the Brevard ductiledeformation zone near Rosman, North Carolina: AmericanJoumal of Science, v. 278, p. 419-44I.

Condie; K.C., 1978, Geochemistry of Proterozoic graniticplutons from New Mexico, U.S.A. : Chemical Geology, v. 2 l,p. 131-149.

Condie, K.C., and Buddington, A.J., 1979, Geology and geo-chemistry of Precambrian rocks of central and south-centralNew Mexico: New Mexico Bureau of Mines and MineralResources Memoir 35, 58 p.

Conley, J.F., 1985, Geology of the southwestern VirginiaPiedmonc Virginia Division of Mineral Resources Publica-tion 59, 33 p.

Conley, J.F., 1987, Mafic rocks in the Alligator Back Forma-tion, the upper unitof the Lynchburg Group, in tle southwest-em Virginia Piedmonl An ophiolite sequence?, in Contribu-tions to Virginia Geology-V: Virginia Division of MineralResources Publication 7 4, p. 67 .

Connor, J.J., and Shacklette, H.T., 1975, Background geohem-istry of some rocks, soils, plants, and vegetables in the con-terminous United States: U.S. Geological Survey Profes-sional Paper 574f, 168 p.

Cook, F.A., Albaugh, D.S., and Brown, L.D., 1979, Thin-skinned tectonics in the crystalline southern Appalachians:COCORP seismic reflection profiling in the Blue Ridge andPiedmonu Geology, v. 7, n. 12,p.563-567.

Costello, J., and flatcher, R.D., Jr., 1985, Southern Appala-chian foreland-hinterland ransition and boundary conditionsfor duplex nucleation [abs.]: Geological Society of AmericaAbstracts with Programs, v. 17, p. 554.

Dagger, G.W., 1972, Genesis of the Mount Pleasant tung-sten-molyMenum-bismuth deposit, New Brunswick, Can-ada: Institute of Mining and Metallurgical Transactions,Section B, v. 81, p.73-102.

Debnam, A.H., and Webb, J.S., 1960, Some geochemicalanomalies in soil and stream sediments related to berylpegmatites in Rhodesia and Uganda: Institute of Mining andMetallurgical Transactions, v. 69, n. 7, p. 329-344.

Driscoll, A. J., Jr., 1989, Lode gold deposit characteristicsusing evidence from stream sediments: an example for BrushCreek, Montgomery County, Virginia, [M.S. thesis]:Blacksburg, Virginia Polytechnic Institute and State Univer-sity,71 p.

Evans, N.H., 1984, Lithofacies of the Virginia Blue Ridgeand Hardware terranes: evidence for pre-Middle Ordovicianvolcanic arc accretion in latest Precambrian to Ordovicianmetamorphism and orogenesis in the BlueRidge and westemPiedmont" Virginia Appalachians [Ph.D. dissert.] : Blacksburg,Virginia Polytechnic Institute and State University, 313 p.

Exley, C.S., 1958, Magmatic differentiation in the St. Austellgranite: Quarterly Journal Geological Society of London, v.114, p. 197-230.

Ferguson, H.G., 1918, Tin deposits near Irish Creek, Vir-ginia: Virginia Geological Survey Bulletin 15A, 19 p.

Fichter, L. S., and Diecchio, R. J., 1986, Stratigraphic modelfor timing the opening of the proto-Atlantic Ocean in north-em Virginia: Geology, v. 14, p. 307-3W.

French, 8.L., 1956, Interoffice memorandum of AtlanticLumber Company, Boston, Massachusetts, summarizingdrilling and assays of 1942 investigation by Bethlehem Steelfrom S.I-ake, Bethlehem Steel geologic stafl9/f9i56: Vir-ginia Division of Mineral Resources, Economic Section file.

Fordham, O. M., Jr., 1978, Stream sediment geochemistry ofthe Irish Creek tin district, Rockbridge County, Virginia: lnContributions to Virginia Geology-Ill: Virginia Division ofMineral Resources Publication 7, p. 75-85.

Furr, A.K., Parkinson, T.F., Bache, C.A., Gutenmann, W.H.,Pakt<ala,I., and Lisk, D.J., 1980, Multielement absorption bysoils amended with municipal sludges: Joumal of Agricul-tural Food Chemistry, v. 28, p. 660.

Gathright, T.M., II, Henika, W.S., and Sullivan, J.L., III,1977, Geology of Waynesboro East and Waynesboro Westquadrangles: Virginia Division of Mineral Resources Publi-cation 3, 53 p.

Glass, J.J., Koschmann, A.H., and Vhay, J.S., I 958, Mineralsof the cassiterite-bearing veins at Irish Creek, Virginia andtheir paragenetic relations: Economic Geology, v. 53, p. 65-84.

Glover, L., III, 1989, Tectonics of the Virginia Blue Ridgeand Piedmont: in, Melamorphism and tectonics of the East-ern and Central North America,2Sth International Geologi-cal Congress, Washington, D.C., FieldTrip GuidebookT363,p. 1-59.

Glover, L., III, Costain, J.K., and Coruh, C., 1982, VI-BROSEIS reflection structure along a Blue Ridge and Pied-mont James River profile, north central Virginia [abs.J:Geological Society of America Abstracts with Programs, v.14,n.7 ,p.497.


Good, R.S., Fordham, O.M., Jr., and Halladay, C.R., 1977,Geochemical reconnaissance for gold in the Caledonia andPendleton quadrangles in the Piedmont of central Virginia:Virginia Division of Mineral Resources, Virginia Minerals,v.23,p.13-22.

Govett, G.J.S., 1983, Regional scale exploration for depositsof plutonic association-identification of tin granites, in Govett,G.J.S., ed., Ilandbook of exploration geochemistry: Amster-dam, Elsevier Scientific Publishing Co., v. 3, p. 93-111.Groves, D.I., 1 972, The geochemical evolution of tin-bearinggranites in the Blue Tier batholith, Tasmania: EconomicGeology, v. 6'1, p. 445-457 .

Gunderson, L.C.S., and Gates, A.8., 1988, Redistributionand enrichment of uranium in mylonite zones as a function ofdeformation prccesses [abs.]: Geologicla Society of Amer-ica Abstracts with Programs, v.20, n. 7, p.A179-A180.

Harris, L.D., deWitt, J.W., and Bayer, K.C., 1982, Interpre-tation of seismic profile along Interstate I-64 from the Valleyand Ridge to the Coastal Plain in central Virginia: U.S.Geological Survey Report K,-123.

Herz, N., 1982, Exploration targets for metallic resources inthe Blue Ridge: tin, titanium, and U[h, in Allard, G.O., andCarpenter, R.H., eds., Exploration for metallic resources inthe southeasfi Invitational Conference, Department of Geol-ogy, Athens, University of Georgia, p.46-48.

Herz, N., and Force, 8.R., I 987, Geology and mineral depos-its of the Roseland district of cenral Virginia: U.S. Geologi-cal Survey Professional Paper 1371, 56 p.

Herz, N., Mose, D.G., and Nagel, M.S., 1981, MobleyMounain granite and Irish Creek tin disrict, Virginia: a ge-netic relationship [abs.]: Geological Society of AmericaAbstracts with hograms, v. 13, no.1 ,p.472.

Hotchkiss, J., 1883, Silver and gold in Virginia tin belc TheVirginias, v.4, p. 168.

Hudson, T.A., 1981, Geology of the kish Creek tin district,Virginia Blue Ridge [M.S. thesis]: Athens, University ofGeorgia, 144 p.

Hudson, T.A., and Dallmeyer, R.D., 1982, Age of mineral-ized greisens in the Irish Creek tin district, Virginia BlueRidge: Economic Geology, v. 77, p. 189-192.

Jonas, A. I., 1928, Preliminary edition of Geologic Map ofVirginia, Virginia Geological Survey.

Kabata-Pendias, A., and Pendias, H., 1 9 84, Trace elements insoils and plans: Boca Raton, Florida, Chemical RubberCompany Press, 315 p.

Kinkel, A.R., and LeSure, F.G., 1968, Residual enrichmentand supergene migration of gold, southeastern United States:

U.S. Geological Survey Professional Paper 600-D, p. I74-178.

Kirby, C.S., Driscoll, AJ., Jr., Bodnar, R.J., Law, R.D., 1989,Importance of fluid composition in the mylonitization proc-ess: a shear zone as conduit for CaCl-NaCl brines [abs.]:Geological Society of America Abstracts with Programs, linpressl.

Koschmann, A.H., Glass, J.J., and Vhay, J.S., l942,Tin de-posits of Irish Creek: U.S. Geological Survey Bulletin 936K,p.27r-296.

Lakin, H.W., Curtin, C.G., and Hubert, A.E., 1974, Geo-chemistry of gold in the weathering cycle, U.S. GeologicalSurvey Bulletin 1330, 80 p.

Le Maitre, R.W., 1976, The chemical variability of somecommon igneous rocks: Journal of Petrology, Part 4,v.17,p.589-637.

LeSure, F.G., Kiilsgaard, T.H., Brown, C.E., and Mtose,M.E., 1963, Beryllium in the tin deposits of Irish Creek,Virginia: U.S. Geological Survey Professional Pap er 47 5 -8,p. B-12 to B-15.

I-evinson, A.A., 1980, Introduction to exploration geochem-

istry: Second edition, The 1980 Supplernent, Wilmette,Illi-nois, Applied Publishing, Ltd., 924 P.

Maniar, P.D., and Piccoli, P.M., 1989, Tectonic discrimina-tion of granitoids: Geological Society of America Bulletin,v. l0l, p.635-643.

Martin, R.F., and Piwinski, A.1., 19'72, Magmatism andtectonic settings: Journal of Geophysical Research, v.77 ,n.26,p.49664975.

Mitchell, R. S ., 19 6q Virginia metamict minerals: allanite:Southeastern Geology, v. 7, P. 183- 195.

Mitchell, R.S., 1966b, Virginia metamict minerals: perrier-ite and chevkinite: American Mineralogist, v. 51, p.1394-1405.

Mose, D.G., Diecchio, R.J., DiGuiseppi, W.H., and Nagel,M.S., 1985, Conformation of a latestPrecirmbrian (6ffi m.y.)age for the Catoctin Formation in Virginia [abs.]: GeologicalSociety of America Abstracts with Programs, v. 17, n. 2, P.126.

Nockolds, S.R., 1954, Average chemical composition ofsome igneous rocks: Bulletin of Geological Society ofAmerica, v. 65, p. 1007 -1032.

Odom, A.L., and Fullager, P.D., 1984, Rb-Sr whole rock andinherited zircon ages of the plutonic suite of the CrossnoreComplex, southern Appalachians and their implicationsregarding the time of opening of the Iapetus Ocean, inBartholomew, M.J., ed., The Grenville event in the Appala-

PUBLICATION 112 23

chians and related topics: Geological Society of AmericaSpecial Paper 194, p.255-261.Olade, M.A., 1980, Geochemical characteristics of tin-bear-ing and tin-barren granites, Northern Nigeria: EconomicGeology, v. 75, p. 7l-82.

Penick, D.A., Jr., and Sweet, P.C., 1984, Gold-silver redis-covered in old Amherst County mine: Virginia Division ofMineral Resources, Virginia Minerals, v. 30, n. 2,p.22-23.

Pettingill, H.S., Sinha, A.K., and Tatsumato, M., 1984, Ageand origin of anorthosites, chamockites, and granulites inCenral Virginia Blue Ridge: Contributions to Mineralogyand Perology, v. 85, n. 3, p.n9-291.

Presant, 8.W., 1971, Geochemistry of iron, manganese, lead,copper, zinc, antimony, silver, tin, and cadmium in the soilsof Bathurst area, New Brunswick Geological Survey ofCanada Bulletin no. 174,93 p.

Rankin, D.W., 1968a, Magmatic activity and orogeny in theBlue Ridge Province of the southern Appalachian Mountainsystem in northwestern North Carolina and southwesternVirginia: Geological Society of America, Annual MeetingAbstracts for 1967, Special Paper 115, p. 181.

Rankin, D.W., 1968b, Stratigraphic and structuralposition ofthe Upper Precambrian Mount Rogers Volcanic Group, Vir-ginia, North Carolina and Tenness@: Geological Socienty ofAmerica Abstracts for Annual Meeting 1967, p. SpecialPaper, p.495.

Rankin, D.W., 1975, The continental margin of eastem NorthAmerica in the southern Appalachians: The opening andclosing of the proto-Atlantic Ocean: American Journal ofScience, v. 27 5 - A, p. 298-336.

Rankin, D.W., 1976, Appalachian salients andrecesses: LatePrecambrian breakup and the opening of Iapetus Ocean:Joumal of Geophysical Research, v. 81, n.32,p.5605-5619.

Rankin, D.W., Stern, T.W., Reed, J.C., Jr. and Newell, M.F.,1969, Ztrcon ages of felsic volcanic rocks in the upperPrecambrian of theBlueRidge AppalachianMountains: Sci-ence, v. 166, p.741-744.

Rich, R. A., Holland, H.D., and Petersen, IJ., 1977, Hydroth-ermal uranium deposits: Amsterdam, Elsevier ScientificPublishing Co.,2flp.

Rogers, J.J.W., Ghuma, M.A., andNagy, R.M., 1978, Pluton-ism in Pan-African belts of northeastern Africa: Earth andPlaneary Science Iptters, v. 39, p. f09-117.

Rogers, JJ.W., and Greenberg, J.K., 1981, Trace elements incontinental margin magmatism: Part III, alkali granites andtheir relation to cratonization: Geological Society of Amer-ica Bulletin, Part 2, v. 92, p. 57 -93.

Rose, A.W., Ilawkes, H.E., and Webb, J.S., 1979, Geochem-

isry in mineral exploration: Second Edition, London, Aca-demic Press,635 p.

Sando, T.W., 1979, Trace elements in Hercynian graniticrocks of the southeastern Piedmont, U.S.A. M-S. thesisl:Chapel Hill, University of North Carolina, 91 p.

Seyfert" C. K., 1987, Mantle plumes and hot spots, iz Seyfert,C. K., ed., The encyclopedia of structural geology and platetectonics: New York, Von Nostrand Reinhold Co., p.412-427.

Shacklette, H.T., and Boemgen, J.G., 1 984, Element concen-trations in soils and other superficial materials of cotermi-nous United States: U.S. Geological Survey ProfessionalPaper 1270, 105 p.

Sheraton, J.W., and Black, L .P., 197 3, Geochemistry of min-eralized granitic rock of northeast Queensland: Joumal ofGeochemical Exploration, v. 2, p. 33 I -348.

Sillitoe, R.H., 1974, Tin mineralization above mantle hotspots: Nature, v. 248, p. 497 -a99.

Simpson, E.L., and Eriksson, K.A., 1989, Sedimentology ofthe Unicoi Formation in southern and cenftal Virginia: Evi-dence for late hoterozoic to Early Cambrian rift-to-passivemargin transition: Geological Society of America Bulletin,v. 101, p.42-54.

Sinha, A.K., and Bartholomew, M.J., 1984, Evolution of theGrenville terrane in the central Virginia Appalachians, inBartholomew, M.J., ed., The Grenville event in the Appala-chians and related topics: Geological Society of AmericaSpecial Paper 194, 175-186.

Smith, I.C., and Carson, 8.L.,1977,Trace metals in the en-vironment: Ann Arbor, Michigan, Ann Arbor Publications,v.2,469 p.

Smith, S.F., Frye, K., and Nagel, M.S., 1981, A Latest Pre-cambrian-Cambrian granite in the Virginia Blue Ridge [abs.] :

Geological Society of America Abstracts with Programs, v.13, n. 1, p. 35.

Smith, T.E. and Turek, A.,1976, Tin-bearing potential ofsome Devonian granitic rocks: Mineralium Deposita, v. 11,p.234-?A5.

Southwick, D .L., 1969,Crystalline rocks of flarford County,in Maryland Geological Survey, Geology of Flarford County,Maryland: Maryland Geological Survey, Baltimore ,p. l-76.

Southwick, D.L., Reed,J.C., Jr., andMixon, R.B., 1971,TheChopawamsic Formation - A new stratigraphic unit in thePiedmont, northeastern Virginia: U.S. Geological SurveyBulletin 1324-D,p. Dl-Dl 1.

Stemprok, M., and Skvor, P., 1974, Composition of tinbearing granites from tle Krusne Hory metallic province of


Czechoslovakia Sbornik, Journal of Geologic Science(Czechoslovakia), Economic Geology, v. 16, p. 7-87.

Taylor, R.G., 1979, Geology of tin deposits: Amsterdam,Elsevier Scientific Publishing Co., 544 p.

Sundelius, H.W., 1970, The Carolina slate belt, in Fisher,G.W., and others, editors, Studies of Appalachian geology-central and southern: New York, Interscience Publishers, p.35r-367.

Sweet, P.C., and Lovett, J.A., 1985, Additional gold mines,prospects, and occurrences in Virginia: Virginia Division ofMineral Resources, Virginia Minerals, v. 31, n. 4,p.41-52.

Sweet, P.C., Good, R.S., Lovett, J.A., Campbell, E.V.M.,Wilkes, G.P., and Meyers, L.L., 1989, Copper, lead, and zincresources in Virginia: Virginia Division of Mineral Re-sources Publication 93, 185 p.

Taylor, R.G., 1979, The geology of tin deposits: Amsterdam,Elsevier Scientific Publishing Co., 544 p.

Tischendorf, G.,1977 , Geochemical and perographic char-acteristics of silicic magmatic rocks associated with rare-element mineralization, in Stemprok, M., Burnol, L., andTischendorf, G., editor, Metallization associated with acidmagmatism: Geological Survey of hague, v.2,p.4I-46.

Tollo, R.P., and Arav, S., 1987, Petrochemical comparison oftwo plutons from the Robertson River Formation in nortlernVirginia: Geological Society of America Abstracts withhograms, v. 19, n. 2,p. 133.

Turekian, K.K .,1977 ,Gex.hemical distribution of elements,in Encyclopedia of science and technology: New York,McGraw-Hill Publishing Co., 4th Edition, p.627-630.Turekian, K.K., andWedepohl, K.H., 1961, Distribution oftlte elements in some major units of the earth's crusfi Geo-logical Society of America Bulletin, v.72,p.175-I9I.

Ure, A.M., andBacon, J.R., 1978, Comprehensive analysis ofsoils and rocks by spark source mass specEometry: Analyst,v. 103,p.807.

Wehr, F., and Glover, L., III, I 9 85, S tratigraphy and tectonicsof the Virginia-North Carolina Blue Ridge: Evolution of aLate Proterozoic- early Paleozoic hinge zone: GeologicalSociety of America Bulletin, v. 96, p. 285-295.

Werner, H.J., 1966, Geology of the Vesuvius quadrangle,Virginia: Virginia Division of Mineral Resources Report ofInvestigations 7, 53 p.

Wilson, J.T., 1966, Did the Atlantic close and then re-open?:Nature, v.2Il,n. 5050, p. 681.

25PI.}BLICATION 112

Iocasx.BeM.t

sa.eEEhqln

Eg,iE-g qtHJEE->o?E€€a'lgnfrdQlE=OEEe*:EEg0

E#a ai:>=.o'i8EoElrox.EE,UEE91=

=gqA

:'iOr;:48>'trEE.E<60E.=o>z.g -eIeqY.9

E;€eaB-(qFgof R-'trz<>, *tc!E

ftEtr

FF

b-oeE.9Paq|E'to<.t€q:q3FEs6'g96-?E-aeEbi€FEEi'ets-9A;E!t-bO99.=E-esE+(cas-a

O9ollr.E a xEI b€ ET* E d =,

E6296 {; E Fes:?,EE '5 ra2 €E E=>rLGlvo.{)E4cgE=EE.8 E2 'g

E E.s ts

T K g€ FE6 g E a fr;E .e € E ggE E .B E EAFl .E tr Eh.E € : R FEE F dr E 9is e g 2 E:F B € E O

{E' .9 !l :ag E 5 s3€!i;>i € € 3:E B E Eiai s E Fz.F = tsb E'#e a b sO.X H c\ e.)

.EE * * *

Lo

(J

E Ho\\oto\t<HdH

s EE€Rg

oOc-OOHi dH

clidO\O\

\s.09=qolcllaa

.:qc!\q6Ir7|{tc7l

dro!c!aclt\ c.r t\ co r7)

qqoqC.!-':*$$H(.!

dclg5oogJ'E()o

-sEavoloda

H?il6d3€ssiiF{gflfi;I !)q*E:r{ .AO

xHs4f,FF -lolE '9le

AE

HEct-c.HE

.g:H:.99gsEos€€

Ei=

.EgG'

Es(n

q

=l3q:?8Ktld c.l'd odIt€ \o tfr r-dfd -r

sJqr{ cI€Oa-q oe oe o!€\nHCflrndq

€dqcaqg'o$-

€1gJo \oHEEA4s::::olH Cl C.t s

c*qoqqq-cao€odHd(flH

Ho\C\r*(ficlHo\clH

$

t\S€H€t-O\SrnOH_Hdd

rn6lolr*€.qt$9ss

Ha-oo\*C\HHOCf|

dH

ooaoodi\o(tt<-otc.lH€c-l

\oHo6!r(\<-HHH

c.t o\ H co 6l\n \o rn ca (\l

-HVO-dvv vv3g$:8

rn

scaRrrtE

qqc']qn..| c.| 6l s c.l

Qco$€i.

i (\ c.t

>BFFFi(\cocoro

sat

,1

s

Xp5,-

;)

Ii(tt FFzrrl =trtJlrl E

N

E!.

LIA

al

5IxEO

,t

o

€)

.trv)

zot-Fat)

ztt VIRGINIA DI\NSION OF MINERAL RESIOT'RCES

APFE{IDIXItr

Remlrs of fte geochcmfouf mlysis of sil srylcs ftm fu Bd lilffito mld mine Ambs Cmtr- dala by RS- ffi

ppmAggm SnDtrnFpAsgmBeppmlbum7nppmCupBappRbplmLi%kpprtuppm}.IipmCoUmC.r

BM-I

258

4y5zm

3.4T2

l19n

r30&43

435zn

TLllr5

3l:t0!-gt

q5t21l14

BM-3

41494t5

r5(n4-7

,m16rr(BtnBrt3i4

55t6

157

BM4

54t6

I,195r2fl

6.rffT161r(Dr60:tty24.85

fr27

169

B,r'-2

In3ro7m

2!)r18ls,x160

BM-t resirhd sd *oe cnrrzre o rtrBM-} sdseqrrerrc(rffiBM-3: soil o Hedaea in ftmof ditBM4: sd a) fd&mslqleftom dit

Cmryoctrm6/iK

BMR-I: ffi) fs utftrrcsr dBuck lfuin mirc dBMR-2 25fsncttcr€$ddBMR-3: cnrretoafitBMR4: 30 fdinside drro* fr@BMR-S: l0t fs sdeast fi ffi.awBMR{: lfl)feffidfrr

pThDpmurh/Lt

BItIR{

r393243

BMR-5

7-65.Or5

BMR4

li3312

BMR-3

7.449r5

BMR-2

7889o-9

BMR-I

10-62.83-8

PTJBLICATIO{ IT2

APFENI}IXrY

Wholelo* RhlSr vals in grnir*l dms ad dftesThereftrence mmberis thepdntplffid m the grqlh in Figuc 8.

l. RhlSr = 0.f2 Tdey lfuain plm, ccnlxal Bhe Rfolep Fwire of Vnginia nsive funm.tire M tva,mangedbd horoctfaltfid@ lfimlainfluie-ffigriliq agpwtain,pobablyGrcnvilb; apd€ndybmeq tm uatpes (Bmck, l98l; Brock d derst fgBD.

2- RbAr = O-17 Alkati graites, five flms ftom (ladorc belt of wesem North Caolim pfrdmmg omse gnino4disoqdmt, ninm biodrc; rye abotlt 3m ny; bmen (Sado, grq Rqgcrs ad Cileenbsg; l98f)

3. RbAr= O3S Itfiobteyltfutainbuffiatfuaftes,@tralBlrcRi4egovircdYirgini4 avexageof 5 aalyseqbmon @rmk' l98l; Brock ad otrcrq fg8iD-

4. RbrSr=O-l9nrpnyritbquatzmwmiE(arlenrellite),hishGoefdnaea;gurimaltoNertelfioumin'tingruiE"age uwhi4 may be Grenvillq bdreq averge of 3 amlyses Cfubm, f98f)-

5. RbEr = 059 lfi6let' Itfufain fluie-biotite glanitc f43 niles soffiec of Netile Il4omsin $anite (Irish CroeLtingrmite?),centralBlueRidgpfvinccofvirginia;frithm€fbmcmof 14malyses(Brak, f98f;Brcckandottss,r987).

6. RblSr = 0.60 Shreftr Itrollow bureratfo granite in mrct with ltfiSley Itflomtain grmiE, centxal Blue RidgeItfiornains a pwince of Virginia bilren; (Bnch l98l; Brock d otrerc 1987)-

7- RhtSr= l.44lfg[potassiunaftaligrmie Nevltfiexicqbmeryagprygurimately 1400m.y.;avenagpdl5malyses(C.:mdie f97& Cutdb and Bddiagton" 1979; Rqgers and Clecnberg; 1981,p.62).

8. RbSr'= f SSaintGemgpgranite,NewBrunswiclqcanadavicinityoftinbeaingplutons;banenofallmineralization(Dagger, ln\, CfrYcfi" l9B).

9. RbAr = 224 Bfortite granite,Ilalifax plutm Nona Scotiq buren (referwe in Cover, 1983).

r0. RbtSr=2T6Averageftomahmdanedatafugrmiesofatlkinds(fuekim" l9l7);wlbrpublication(finekimandtrr@L 196f) indicabsRb6ris 025 in higb+atcium granirb rccks md 1.70 in low-calcium granitic rocks

ll. Rb/Sr = 3.(D Bbtilc graniie, West Dalbousie plutm, Nova Scoti4 Caad4 bdren (Govett, f9$).

lL RbAr = 4.9 Porphyritic bidite gradb-adame[ite, Arrchamine, Tasmania, austratia; average of 6 analyses; bercncountry-roc* pluton (Grove,s" lg'D).

13. RbfSr= 5.0Carnmenelliyadametlitetingruite,Cornwalltinrtistrict, SWEnglad; I sarple@utlu, 1953; Goveu,19rJ).

14. RbtSr= S.0sttreuleltfiormtainflruite-bir*itegnnito,3 milesfrom hishCheektinmine,centralBlueRidgeMountainsu province of Virgini4 average of 3 analyse.s ranging ftorn 3.61 b 7 .48 (Iludsoq 198 l).

f5. RbtSr = 7.45Brren htrnbknde granitq Nigeriar tin disrict (Olade, 1980).

f6. RbtSr = 8.6 St Ausrell biotite-muscovite tin granie, Cunwall dl*rbC SW EnglanG I analysis (Erley, 1958; Govets"re83).

17 - RbAr = 8.74 Yankee Horse Ridge grcisen, oenral Blue Ridge Mountains or province of Virgini4 I sample (Iludson,r98r).

f 8. RblSr = 9.1 Hnlayson tin granite, Queensland, Augralia; ecsromic mineralization; average of 6 analyses (Sheraonanil Black, 1973 in Govefi, 1983).

19. RblSr = f0.0 Alaskite, Halifax pluton, Nova Scotia, Canada; baren (Smith and Turek, 1976; Govetg 1983).

z7

28

20.

21.

23.

u.

25.

26.

27.

28.

VIRGINTA DIVISION OF MINERAL RESOURCES

RblSr= l4.9NewRossplutcr,elaskiteandbucograrite,NovaScotia,Cmada(SmithadTurek,1976;Goreu, f9B3).

RbAr = f6.0 Elizabeth Crcek graite, Qrleerrsland, Ausrali4 Sn, Mo,'W, Pb, Cu, and minu Arl Bl, Ag, ard SbmtuEralization (Slsaton and Bhct, f973 bGover, f9E3).

RUSr = 16.9 Porphyritic lithium-mica ganite, St Austell, C-ornwall tin disrict" SW England; mfuteralized (Exley,1958; Crovea,1983).

RtySr = 21.5 Baren gnnite ftom Jrnassic ring complex, Nig€dan tin districq avenage of 73 samples (Olade, f98O).

RbtSr = E9 Biotite granite, New Ross plutm, Nova Scotia Canda; mineralized (Smith and Tureh 1976; Goveu"le83).

R$Sr=i7.l MrPteasantmine,grariteporphyry,NewBrunswick,C.ana&;W,Mo,Bi,andSnmineralizafion(Dagger,1972; Gove$, 1983).

RbEr = 93 Mhenlized tin granite, Junassic ring corrpbx, Nigeria; arrerage of 73 sampbs (Olade, f980).

RbAr = 14O Graniie with other mineralization, Nigeria (Olade, f98O).

RblSr = A)7 Biotite-muscovite granite, Anclrc mine, Ta$nania, Arstralia (Groves, 1972).

APPENDD(V

BrckFround and anomalv statistics for soil geochemisnvBackgrourd stdistics are based on 22 soil samples taken along trav€rse B 250 feet l.IE of, and parallel to, the NW-SE tnendingtraverse A acrcss kish Creek mhe adit #1 on Panther Creelc

Tin

Brckground soil valrrc, this shrdy, rithmetic meanBackground standard dpviation, ftis studyMean plus one standrd deviationItfiean plus two standad deviationsMean plus two-ald-qp-half standrd deviationsMean plus thee sadand deviationsBackground values from literature

Soil" average @ose and othen, 1979)Soil over granite and grrciss, mean(Shackleme and Boerngbn, 1984)Standard soil, England, mean (Ure andBrcon,1978)

Unmineralized soil, Bathurst tin disrict,Canda range (Presant, 1971)

Unmineralized soil, range (Chapman, 1972)Threshold soil valug in this studyAnomalous soil value, in this surdy

Tungsten BDln

Background soil valrc, this sbdy, arithmetic meanBackground standard &viation, this studyMean plus one standtrddeviationMean plus two standard deviationsMean plus three standard deviationsBackground value friom literature

Soil, average (Brooks, 1972)Two soils from the United States, mean (Furr and othen, 1980)

@!E

624.1

10.314.416.418.6

r0.0

r.2

4.5

1.r4.61-l Il620

2.362.875.238.r

10.97

I1.2,2.5

PUBLICATION 112

Beryllium

Background soil value, this study, arithmetic meanBackground strndard deviation, this studyMean plus one standard deviationMean plus two standard deviationsMean plus two-and-one-half standard deviationsMean plus three standard deviationsBackground values from literature

Soil over granite and gneiss, range (ShacHette and Boerngen, 1984)Soil over granite and gneiss, mean (Shacklette and Boerngen, 1984)Unmineralized soil near beryl pegmatite inRhodesia and Uganda, range @ebnam and Webb, 1960)

Threshold soil value, this studyAnomalous soil value, this study

Arsenic

Background soil value, this study, arithmetic meanBackground standard deviation, this studyMean plus one standard deviationMean plus two standard deviationsMean plus three standard deviationsBackground values from literature

Surface soil over granite and gneiss inthe United States, mean (Shacklette and Boerngen, 1984)Surface soil over granite and gneiss in theUnited States, range (Shacklette and Boemgen, 1984)Surface soil, uncultivated, median (Connor and Shacklette, 1975)Normal (unmineralized) soil, worldwide, 327 localities, range (Boyle andJonasson, 1973)Soil and till near an arseniferous deposit, 193 samples, worldwide,

range (Boyle and Jonasson, 1973)Arsenic content of granite and aplite, 116 samples, worldwide, range (Boyle andJonasson, 1973)


Fluorine

Background soil value, this snrdy, arithmetic meanBackground standard deviation, ttris studyMean plus one standard deviationMean plus two standard deviationsMean plus two-and-one-half standard deviationsMean plus three standard deviationsBackground values from literature

Soil, median value (Connor and ShacHette,l9T5)Soil over granite and gneiss, range (Shacklette and Boerngen, 19&4)

Threshold soil value, this snrdy

Rubidium

Background soil value, this study, arithmetic meanBackground standard deviation, ttris studyMean plus one standard deviationMean plus two strndard deviationsMean plus two-and-one-half standard deviationsMean plus three standard deviationsBackground values from literature

29

DPIII

2.81.1

3.95.05.56.1

<1

:'

t-21.6

0.5-445

pp!!!

3.6

0.7-157.5

0.1-55

2-8m0

0.18-1545

pp!!r

422r50573724800875

30020-540724

ppllt

49.718.668.386.996.2105.5

30 VIRGINIA DIVISION OF MINERAL RESOI.JRCES

Soil, uncultivated, median (Connor and Shacklere, 1975)Soil over granite and gneiss, range (Shacklette and Boerngen, 1984)

Threshold soil value, ttris sndyAnomalous soil value, this study

Lithium

Background soil value, this shrdy, arithmetic meanBackground standard &viation, this studyMean plus one standard deviationMean plus two standard deviationsMean plus two-and-one-half standard deviationsMean plus three standard deviationsBackground values from literature

Uncultivated soil, median (Connor and Shackleue,l9TS)Soil over granite and gneiss in the United States, mean (Shacklette and Boemgen, 1984)Range in soil over granite and gneiss Shacklette and Boerngen, 1984


Irad

Background soil value, this study, arithmetic meanBackground standard &viation, ttris studyMean plus one standard deviationMean plus two standard deviationsMean plus two-and-one-half standard deviationsMean plus three standard deviationsBackground values from literature

Uncultivated soil, median (Connor and Shacklette,l9T5)Surface soil over gnnite and gneiss in the United States, mean (Shacklette andBoemgen,1984)Surface soil over granite and gneiss, range Shacklette and Boerngen, 1984

Threshold soil value, this snrdyAnomalous soil value, this study

Zinc

Background soil value, this study, arithmetic meanBackground standard deviation, ttris studyMean plus one standard deviationMean plus two standard deviationsMean plus two-and-one-half smndard deviationsMean plus three standard deviationsBackground values from literature

Uncultivated soil, median (Connor and Shacklette,1975)Surface soil over granite and gneiss in the United States, mean (Shacklette andBoemgen, 1984)Surface soil over granite and gneiss, range (Shacklette and Boerngen, 1984)

Threshold soil value, this snrdyAnomalous soil value, this study

Copoer

Background soil value, this study, arithmetic meanBackground standard deviation, this studyMean plus one standard deviationMean plus two standatd deviationsMean plus two-and-one-half standard deviationsMean plus three standard deviations

2223.5l0-454250

35<20-2106887

DE

27.r7.534.642.r45.949.6

pulll

31.65.136.741.744.346.8

t7

2l10-504247

PBSI

10r.918.5123.4r41.9r5r.2160.4

36

73.530-r25r421CI

pp!I}

14.87.6

22.430.033.837.6

PUBLICATION I12

Background soil values from literatureUncultivated soil, median (Connor and Shackleue,1975)Surface soil over granite and gneiss, mean (Shacklese and Boerngen, 1984)Surface soil over granite and gneiss, range (Shacklette and Boemgen, 1984)


31

15247-703438

VIRGINIA DIVISION OF MINERAL RESOURCES32

i cQ € O C\ \O C- \O O\ i O\ t-- ca co rf,O Cl H cf) C.| F - H - (\l F F C.l Ctl C.}

c.) $ r- rn o \n \o € rar o\ o d F o o\(\.l - -

(\.l (\l H F (\ - - C\ (\l cl (\l d

\o \o f- $ cf) $ 6l rn € r- r- oo c\l o\ oinFFclcl- 6t-cn

F r- 0o * Q d ca oo f\ i l\ oo o\ € €ca ol cl ca rn cn $ s \.t \n $ s t $ $

h

U

z

f- c?t \n 6l O\ \O € $ C\l \a O O € € caE <l(\tinSc.|C\$t.l\Of\r<f \OOf .<r\t

€ siiddddcQHHdHdd-z. c\iS3) g $. v"l oq i -':<?q qq c'') c''! \ \ \E S$$ S$$$Stf :f .f $ sf \t\f

f; H ol c\NN N c.t d<. c.tC\l H cl s d

€ co \r) d € (\l cQ H co \o c\ i r,n o oD \o cd d -r.r + cd +d $ + r c.i\ci r-_ - t q a n -l c.l v? n Q oq n ol n clF od F od od oi cj c- \o co o\ € F- ooo €FiF

= $ s \n F*o\oo\aooo\o* tf, o\o\C) <Fd-ii-c.l\nNHHiHd-

9), - 1.r \o d f.- co (\ co6r\ a' o H \o a- H r.)*f! OC.f $ OOO$\O6.<f H _ H(\ _-Nr

F€-

rtl ^ o o t= \oeo€c.,o\ <f, \o rno F-o i=

F (\l eO (\l C\ C.l C\l ci c! $ c.l c.l c.| C\l eo c.)HE C'

o € € d rr s o\ rr) € - * \o \n o\ €tr co oo i f- € 6 o o\ \a o\ \al \o \r! \o \oAii

-:. H - \n s or n F oo € o\ l.- € o C.) o\= - -(\(\l-C\l $co -(\l F -(\lC!el

o\ c.l * co c, i \o H in eo o t-- tn o \od e{ cn ca <. <' \o r.- F- r- \o \o \o \o \.)

ddd*d*;(f)HH*Hdi#

V V V V V V Vi V V V V V V

$0,oQstc.l$€s€sctt€*sCn l.) !n !f, \0 \O f\ O OO f- t- f- \O f- \O6l

c\ c\ d (-l H i h d (\l ol co c.l cl - dVV

c''l ca oq n c''! \ -1 oq q n -1 c"l v? r.'l otC.l ca cO cr) cf| cn $ \n \n \n v1 \n <' tf, ta)

i d d d d (\l cn I \O c.| in l.l \O \O \nVVVV X

tl

oo

o

F

fl

H

g

HIEltrl

il'E.=g$EEI r!

! HEg

E HgE=l I c>ot(! !r

€g E

AEEfl=6flEI

H

flH

F-rI]a

tr <-€rn$ oOO!n-<' i<-ro\OC-O V c\ofsc.lcldiHH

4qoL,, \O\O\n*ca(lldtr3 E=EEEE=b;ilililil8- ZZZZZZZ<AAAAAv)'(t)

JJPUBLICATION 112

.\ cne qj F e oo H qJ € cn ra rn\o \t \o.<t f- s H !n \o \nv -(\tcaH(r)*-(\l - - ; J; ; ; ji{C.t-

.= o in rn $ o\ ln\o or F tt) o \orrr rn \rr ot o \o \o \n h \nv -(\(\{(\(\diddo{(\d

E O t- !! r* O\\Oc\f Y-t O\ - oO $ \O C\t H cn C\ O H oO O rnFF(r F(\F -C.lC.tF N

<'C\lr,-O\$drnr.)F-€6ril-OOS-cOrnS(nSFf-F-tacO\Oo|\r)c.)t\ldi

1 a 5l. vl \ q v? q v? v? s 9 v? .: c.) c''! oq q \ 9cn co ca cn $ co ce $ co ca cn cf} c.) cn (o cri j c.i Fi c.i .i j

lllttllltttttltttttl

Frrrrrrrrrrrrrtrl

L0

'i \ - n tt $ Of Of !O\Q \t C.l car* oO \O O\ t-- inO\ * (.l coFl c\l cncrtC\C\ C\cacnC! cac.tbcf)en N 6ii-ic.i=: I -

* { t> \t Ci t-- \o .+ $ c\ o\ ra s o\ cn N o r.) € o F- sC\r eo *if S ea C\ co r.) \i \n + S co co c.) + 6 o(t - - i- G

-ts---HHididi*ii-diddiiVVVVVVVVVVVVVVVVVVV V

q \ -t el a \ c.! c.l q n ce cl \q n n \ n c'.) q e n qcn cn co $ cf) co c.t tn ca $ m co ol c\ ct N c.i e.i Fi Fi ci Fi

An i-r Al Al a r_. C.l \O C.l cr) cf) * (\l N rn OO H C\ H - d iV VV V'-' H VVVV

A €6 =-o V = =oo=oo"V ---Vv V V V

E \ht--r\Oc.)nOr-\O6l< d cficQ€\ncn(\l c\ \ooo \nH

flq

.Hl &:I E

fuFr

EHgiiFE EE5#

€q E:AK: H

H ?Fdt .=

l9H.s.91 v)

EI

fl

H

Be(l)lz

.t g .n q1 $ $ co g qt co s $ c.1 H o co $ co oo .r, $ \o Nv --C\r (\t(\l-;FF-=;;6t- -co--

r i F € € H (\l (\l O xt - irr.€O\ O c.| - - t--cn - \O eaji oOO\O ts d - * - eil N J dO{ = or,cOot bi\O \b i<N iitsHdHHHi*ia F-F -

F A \a CJ \ q,! 9e n <a r41\o i d d co trr \o \oco o\ i irr( c.t c\ co cl e! ca c\ cn cn c\ d crr ctr co iri io - - iri * co co

I $ $ E $ fi R S + S g $fi $ 3 5 $ K'- \o $ co

Er=Fs3R3RR88R883R8$fi egd - ol cn N ct co c.) c\ co ot dt N cn N c.t cd N i a *'-

--ts-dHdiHHdHiidHdiHdiHVVVVVVVVVVVVVVVVVV VVV

N tr E tr X V6 V X V 5 6 X U H i< TJ ;d E U U :<c.) S in co $ $ ca rr S € + < + .+ + \O In r.) N N d c.i

6l

oo

(n

a)

B

o d cl ca$ rn\o ..- 6 - 9 =

S I : : I 5= 9 R Ft-rl !-r1 t4 !_! t! t4 tq El H t! H H II1 H rrl rIJ rI] lIJ H H H Elv) v) <t) v) v) v) (h tt) (t) v) v) u) q ri q q o o q o q v)

zrrF

F(t)


N O O (\l O O O O\ C.l (\l O\ ca F- € \O Or d O d (\ eo H' frdd-HF Hl H d ddlddd

d N \O co d O f- $ $ O \O !f, O F t-- \n i \O t-- \n \n C.l- d dolol d d(\l(\l(\lc.r id d dc.l d * H H d

A Cl € (\| !t cq d O ln \n OO O € O co O C.l d N cn $ O\vrHHHdddddd(\diiid#dd

-1 - c"'! q q \ n n c! -1 q 9 a *t \ c.: q oC q q oC nc\ ca c\l co crl C\l c.l N eo l(f en s co (\l rf s ca ca co $ cr) s

ol 9\nolqclqNooFc'lOiC.i.iC.ic.ie.i.iOCi1ri.j-f | | | | | | | | | |

tttlrrrtl

tttll

F O co (n € cl H O O\ r.- O\ O\ I-- d r- € $ f- O\ O r) c{ oo=

lir s oo$ cncnco(\l cl - - - (\l crl c\ cacncac.r..}cn (\l

o.<t i r- $ F- \n oo (\l N oo \o * o - ci r.) o\ o \n rn F-ca eO \O \O c.) N (\l C.l c.| cO C.l C.l tA C\ cO c.) eO (\l cf) m co (\l

fa \r) co $ S C.l € \.| C{ O tf, N N \O ca H O \O (\f O N $cn cO rt ca \n d cO cA * + Gl el |,r) d rn \() F \n |.A rr |.) cO

34

Stss$585Ee58Ee8tK$SX fi fff- c.| (\ c.) o\ Q co ln o\ $ H rat H o c.r s \n \o rn in (\l \ndFcoiHid

z

Bsq)f1

F

LU

(J

trN

I.rlH

g

34(.IdEo{ke:o^H$fs-:il-toxtr boqHEEI

= BlF Fg

; E€i*A HE€F-1

= Q o

H;-Eg

HEiiglE

d-FI

f,

€

H

eaoor.|v\o€\o\or-on;) od od od cd cd c.i r: od .f c.i vi c.i '

E c\ 9 v? a 0c c.l 9 v.l c.l n \q \k F-lncaf-OO\O\f-OOoOO I

O\ tn c.) rn - € OO C\ c.) i \O € \O $ S C..l # O co € \O dd c.l H c\ ol (\l i (\l cn \o \o o\ c.) - cQ co N N cl c.l c.l c.l

O\ 6l O \g oO C\l f- O 0O t't O \O d (l\ (\l cf} or\ € co oF\ t-- 0OOO n r.t O N t-- \O rn O\ c.) \O * \O O C\ C.l t-- \O 6 \O \n OH t\ C.l CO (\l H - d i i i i i C.l (\l (\l d i d - i i

- o c.l \o o oo o \o rat € r- d o\ \o l1- c.l o\ N d ra) 6 $c\ c\ $ \o rn * 6l co r+ ca c.l c.| ea $ o € t-- rn \o F r- ooi

cO O\ \O A F- Or O \O !+ ca Cl l/) -{- t- i Or $ ca e.l O\ O\ OOi d ci c.l ci c.l H c.l d c\ d d crl ca co ln co ca N cl rf,

L(h

?r{Z6r

F]J.-ari l

iHHHiHHHHHHddHii*ddHdH

VVVVVVVVVVVVVVVVVVVVVV

\0 oo € s oo € $ \o oo t\l $ € € € o o c.l oo !f, 6 o c\tco crt ra) cf| (\l (\l cn |.) cn rtr co (\l co N ca cn c{ c.l ol c\| o| ot

Z $ CO \OOO(\I C.l d H d d H i d i i C.l # H i ef)C.)C\l=i _ VV VVVVV V

o \ n n n v? q c.'!oq n q n el q 9 c.) oq el \ oc el q crlfq - to:l9:l9 € co \o cf) S cr) s

= - !n F + cn c.) c.l c.l

o i ..r c., $ \", \o f- € - I I S 9: 3 P = =

I R F

z z zz z z z z zzz z z zz z z z z z z z

(t)zFF

Fu)

oo

OrNelenc.)crtelc{e{\O

€o\ooo€oo\ooooNidi

c.l co ra, (.1 c.l c\ co s $ cr) ca s

o\d\o\o\n$$\n$$$c--d-v(t)

35PUBLICATION 1I2

\ n q c'') <? v? c'l -': e! € el q el og<\<.|co(fi(ocl(fl r ricli$.f (\l j

l\coH\ocac-\ad\o| ' ' I 'c.icdod+oit-ic.ic.id; I

rttl

ltrl

€o ooc\loor-caC-.tF ool-O\$\OOr | | | ,d;6t; ,1-i_.-.i6e;++ |

cr'l € o\ q\ \o s o I oo l,n \o I \o r- €

f-tfNNN-* . NO\\O6codOF cO(\-F

O\ d \O \ 6l O.l H € \O f- \n f- ot\ o.\vF

(\l€$so$\o alclco\r-.tl,asHC-€€|.nF*FO t-O\F(i<. F roc7|(\t (\l - - H (v) I a - - S t- -t fr

,1 €\O=O\\rtd\O c>dH\Ocln€9) v c.|r)(nH-d 'C\en(\l<-<.FHtrE € 988€cgR,SFESeRBrrIJ14 F n$c!9eHn\o c{clQoH\or-\opr cncaro6t c.t6t cf|' F-N r-co* N ot

a $$KRFnS'$F.iS5R9s ;6F=X:5EU,=VHXH=H-

FFFF (.l(\l H-(\l(\l

LL)

(J

ztr

sq)frs

X

F-

p

F

sga60

g

flb!g.EdlsgEa>l'9

flasUl 8€s.8 F9.E g

flEBE HgPE HH€

F flga? ElsgHe E'

H:EAEEEI.E <vrl E

€sfle

$5g$EI

gn

ftqr OOC.lHO\oO'+$rjF+.ri\ct+c.; I

oq-qq-.:-1oqa-loqr o.l\od(\o\ca\rlrnco I

-i\O(i HdH<

F-cnOhe\\OC\le\t+$cQ(n(frco

lnHdHO\\pO\co!tss\nln$

HH-iH-iVVVVVVV

!oolaho(o\n\ocn€rn6l --ca$$$cn\nco

-:0qqq9qqcl cn H C\l 6l (\l cf|

rttlttl

.<lFr*€c.loo\v d ddH

. Indl.AOo\HO'tnC.ld(\F(\(\l

. do\olscr$€'f-rt$v1co\O\O

rdH-ddidVVVVVVV

. r.lO\nrnOOO'\OO\O-h\Orn

| $\96$\ C.l $

, -l$.qA99q(frCil-idHi

tttttttl

. {$\o\oo*s'(\tc.)H d V

.l

I&

EO

tu

v2

q)

F

(t)

\r)H c.r co $ \n \o

"- r- - - I I S I It4 lr1 E rrl trl I! tI] rrl EI EJ rrt JI] rI] EI II]cr) v) q) q) v) ./) q) v) .n c) u) v) .h q it)

zFFr(/)

VIRGINIA DIVISION OF MINERAL RESOURCES36

E \O . dt.nol-t-tni

s€l'El € F 88=3SREgl a d ' \o -;.tr r.r o\ \n?1

El I q,\q-.'qqqqel fl c., Nc'rc'riHhe1C)l

4l.qE - q\>l.ed;F

=l .= l*r \O

Xf o) . ) r I r r \l^|\O r I r

1{l K G'-l .o FO\d:s. F ,,,,i\'*,flHEErt\t24tol.E boo. -? o\ r71c.l doc{\n1-"]E'ri3 {J 6'+NcrFa.jsi\F.lI EYXgl .t I - cn ooc\.roc.lo6*r- [ilb.q.9 S 9'R9X=I:S

X )le\.,rix El 6s'=E El ;EE r 3'?R:=F$src *l AH:3F 61 8;F ': o.*\oco$oc? El nEF a a co'coc\cnNd-d

El cid6E F;lleq a a 3 RRgRF=g;t€:;=l 915 > 14

.IlE:= d 5 s,AsKKR=s9;.9 -

EI.= EHl EE E 5,SaflnnssEl c.9t

='=! x eobt.5Et Eq

8ld;

3l tu 8,p€F8H8R€lbl { .r r \.,\o..,€o\ncaqnd

AEl g \q -':ctn\noqqel C.f ' *tr cn cr.) H C-.1 - H

olq\9\oq\q\-tc4\O66S(\l@$C-** *coi<-i

LIQ

z

sc)

BS

dv

F

F.

O

o\codo\c-er\oso\so\d*idd(\d

OIO\nO\co!n\n\nN*Hcoidd d ic\lsclO\ O \n O ca \.) cO \O c\l t-- \O h

dd#iHfr(f)H

\od\o\o$\oc.t<f,o\rn\ornc\€\ooo\o\orA-h(\lC.)- FOI

oc9ogel\q\oq9C\C.lN.tCladHCfi | | |

n9oc\v?olv?<?s..tr e{ cn c\ c.l ci co co c.l

n el oq c? n v''! q q c''lc.t ca C\l (\l c\ !n \o \o \f,

qq1\qqqnqtn\ncncO\n\Ocnt.-d ttl

ttl

oo F co tf O O\ ct\ <\ C.l d oO t--d\ocr-)cnciFii$\f,mN

€r.)o\F-ociF*oear-o\s \n oo e{ c) rn F N cl \t c.t t--C.rC\l- F(\{F--

C- \.) O O (\l s- or\ r'- C.l C..l c.l ral\n \f, t-- - C\ Q c.) \O O\ \O.tr ra)at-

O t'- V O\ oO oO C* C\ (\l ci c., oOsdca\oN icl(\l*

n \f, oQ q \9 \o \o ca co c- (n $O.ld(\(\e{H i-dC.)H

c?l 1.) o\ H o c-l o\ oo co \o s c.lC{e'le{coco(\ d(\IHHH

'\o(.)N+coco--oll \tooc.lc.)$$\O\nNF-\O | \nS

tsHHdiHHHiHiiVVVVVVVVVVVV

88€Re88€RBRsFFi\F

c.) lal c.) l.) tf, O f- cO cO cO $ cOdH

oc v.l c'') q - el q c.l q -.: c.l $.clis\acoeldii(.iol*

!f,ets\o\.leaFN€\noo(\tiH iiN HH Cn

2 wt,t> c) v) v) v) v) v) -829E(\.lco$\n\OC*oOO\dd

t-- O\OcOdO\t'-€H 'll i

-

tlll

tr t-- O\ O C.l t co \O c.llh ' ---c!

FIF>>FqHH\()\nSc.)C.lHdC.lc.)

N

stlg

H

qgl6sin.8e€l dov-

ds:El8E ?olgF 2x glg! H

E El€€ ta flgFI €l€F

flr0=lJr cso|Y aOI= C)*l= a"l- (n.91.= >

€lH =FI F

(cl'5otdFlrt>elHtEI

;t

EI

bD

F

U)zvFFv)

zt<

F(h

ah

37PUBLICATION 112

\.| $ \n \o \.) tf s s $ in \n \o - I F \o \o c- d o\ odd dF<

\o f- € r- \o \n \o \n \n rn r- F F o o @ o\ o - \o <>

-- sHH<i

\n \O \O \O rn co c\ \O \O \O \O r- r- €r\ or\ O\ d - $ r- QHHd-r{-

q q a q q'1 c! c''! \q \q',? \ n oq v? -q a a q q \- H (\ (\l d d H - i ts d i (\il H s i i ; ol cota

e! { A \Q oA Q rn !n O C- \O O \n oo C\ O\ O\ F \O O\ C\lc\ (\t (\l c\t r\ c.t 6t N 6l d d N N N N ; = ; ; d 6i

8€SSFSSS€SH*frSffTR$83S

lltttttttl

lttttttttttlttttl

rnoI | | | i(\ tltttl tl

-q\ne! 6l cr

(\lHa-cn to ci

${rn

\or-€

$\nr-

o\+cocaomH (\| (fl

\9\

s\.lica cl ca

\OOco$co$co co c.)

otNco! \o ci6t C\ C\

$$raNC\C.I

dQf-\OF€

ttl

C)

=q)slF(/)Rl

Eg€ea6ta -Q).EH

tq(!)r '; Fg dsH FEfl sqg 8En

I EBgH fif,?gHs if

i g*Ei A

H gagEi

H flFE€5{HEEg

€E se

H €Et

HgEgg F E'

Hcggs[i.gt a"

E ss8EE90 S'F.T E.EEieA€ e

pF8gs8=r8sEssE888ERrS- d (\ (\ (\ (\ (r) d i d d H d i H (\ i (\ a - R

\ € n OQ l.| OO rn O CO O\rr,) f* O O\OO \O O H t+ r.rQ C-61 O\-Frr-r(\F -FF(\I\O -(\l(\l

F F -A F e G C 3 i{ =

8 8 + r( =

GA;8 8 R 88C\FFFFcnF--

Oh€o\r Ci$ |

E E = =

E =

E =

F F ; g_r 14 !-u t-rl LrI rJ1 s1 '!r

sl sllea?ea4zKva3Ks3n€?sE8 zzz<d -coc.tH ---'=

a9a*

--i oQ co & \o € ea ca oo s co o\ r.n € N \n \o o $ $ r\C\ (\l $ ra l,.| S'<l cO : i * - * i N C{ F = ; C.l eri

Q8F8SS:€8*frFF5eSRSS58C\ CqCO(')S eaCf)C\ Cl H

- d F t\ F

- d F F ts

c.l S Cl Q9.t r- Q\ €.f <. r- rn o|\ O\ O\ $ r- O € r.l (\lF K X R S S ?

= s S

= P PP I

= - a !'r cn $

tr

BS

a).nkFzt4=HJ14E

N

€

La

c!

:.]

&

b0

ftl

(tt

a)

(n

\ a 9 oq 9 oq q q 9 d'! ..: n a q 9 n € q -c q qt\ c! (\1 (\l c| H (\| H H i ts d d i d * s ct d o crl

- O qr O $ S f- O - O\ in rr OO € € oO OO € <r !f, *CaCq(\lcn<l$rn(\lH -adCn(\l 6lF V

ztrF<v)

38

|rO \n\Orn\n i ra* l.}c'\ g€.O r*\Oc'\ gS€

€\o\o \o \o t r- \o€ €€ € o 6€ \oQ \ni iH(\cn

\o F ca c- * r- \o.+ \o \o \o € cl H € c{ co cjFFF(\Co\o

N @ O $ ot\ e.).+ ot\ cfl.f, d OO.+ H cO \.) * -- n cO cO \c) ra) \O (\l $ C.l co O F c.l S \O O \fC\(\e.)ciFF -F\ncO!f\O

c! cJ n q q t: oq \ 1..1',? n q -C \ ol n <?cl <\ d i d i ts H(\ o| i i H i i c\ cn tn

OO r.- H f- C- d o|\ cA \O co O O O F- or\ € i €c\l c\ c.) c.l c\ c.) or N c.l el c.l c.l (\ d * F et ot

\o c.t 9Q in co \n in oo c> \o c.} r- co o oo t-- $ d€ r- =

r- \O € € S \O \n S \O Cr t- f- \O \O r-


r- \o ro \o $ \.r \n \o n,o g : g I g =

s : F G fl

f- oo € € F- \O \O € € oo € O (\l g\ \n € r<r \O +<r \O O\FFC\TC\C\

oo \o \n \o r- r* \o \o r-,n € 3 I 3 I o. P E R S R

t\l o\ € c\ o\ \o cn o\ o o\ co \n o \n o € \o N \o o €O\ O\ O\ cO E $ \O rn \O \O \n F F F f- O\ O\ - co (\l \nddH<6lc-.1 dcld(\lol (\lclHd H<.1 c\enc.l

oq q oq oc q 9 9 \ q n -1 \ ol 9 og og og q,n q cJd d i i F i i d F d c.l (\.l cocl d s - - c\ co.tr

z

sIta[.

N

o \n s - \r.) $ o c.r s oo d \n o + N + r- \o o\o c\ rn oo rn o\\o st F s o e.)\n o r- cn F €c\ cn\n F*\O \n € \O \t cac\l i (\| crl (\ H i; c{ \i c.l $ $ in \n c- € =

s rn $ co c.i (\l co ol d H - $ !+

co $ cl o t\ t'- co o H co o o ocn * H \ -t C\l i o € o\ N cl o tr- c.) o co cnrn |- co v oo <' \o dN AA oO S \O O\ Oc\ oo co $ o\ ci€ + + r- $ o\ F- d oo s (f) n \r}\O oA OO oOO\ O - rf) $ $ \O \OS S !f cO cnc.|C\ C.f C.f -

F ts d -

d F ts ts cncnca\f c.)$ S S $ C! (\l C\ C.lC.l (\l (\.l - - - -

H

\ s ln \ I c- \O r- F |,n \o cn o\ \n(o s \o o\ i \o H o i s cr') d H s \tl oo o\(\1 oo o\ \o s caO of- F- - f- O ol\ OO f--\O <- o|\ r'1 s. \O\O si eA C{ - S r.}€ O r'.) \ON $ S \O \n $ \O $ \f1 $ $ cecO Hc.l c\cocl coc\t (\l cl H - d F - eo(\l c\ (\ caco sf rn $ cl - F - - (\l

\n r- s d i F- c- \noo o t-- 4.- o\ ooo \o rn s H cn \o coor o\ t--o\ d oo \al { F \o o o oo i qN 9acl..ldddr

\o c.l (\l $ o\ o o\ Foo - o o co H c.l rn c.lGt cl cl H d o o\ o\ - o\ F o - * c\ c.r t- a - s ca cniiHd H ddddd(\ldd(N idFHd i

-Hdddi -H-di

(a

:l

oq ci.) d? d') -.: oq n n \ $. n cl 9 n a q v? d')c.lc.lolNc\o HHidd(\(\i(\

\.1 c.) d $ r.) d lr) e.) O O \t € rn l.)\O B - -c.l c\ -t eo c\ eo N (.it c{ ca ca (\l ol i z

E E E >>Z E '1r,1 H 14 Er rr rq rrr Er Fr r'rZZZZZZZAAqoqqqqAAc)l- \ora $ c.r6l i d c.l cis r.)\oF\ooo\o

t.- o\ € o\ F- o t-- d (\l vo c.) c.l \o cn rn c- \n s \o $ eaC{ Crl C.l (\l C.l co (\l ca co (\l c.) c.t ca cO (\.l d H H d (\l (\l

O O\ e.) Cr O\ \O d f- rar Crl O\ $ - \O O CO - cn e.) C- O\oo o, o\ o\ oo o\ c- \o \o \o o\ o\ o\ t-- t-- \n \o \n \n lr) s

o0, VVV r

l.)ln\n'*O\O\r \h\f)t\ t

rr-)sril.)

ttrrl d | | | | t | | | | |

tttrlllll

n \Jq 9 \ q n n s. cl \ \ \q n q Q € oq q el oq clN c.l N 6t - ol N ol c.l i # F c.i c\l c.l o i H c.l d cl

$ rr) C.l ol d r.) \O * O\ € O\.itr F- co $ S O\ S C- \O O\co ca eo cn co cQ co r{- ca (\l - c.i ol s cn -

ZZ Z Z Z ZZZ Z Z A 6 6 A q q q q q q qo6i 60 i< \o r.) $ 6 N - d c.l c.) $ l.) \O t- €o\ o

Z\_

PUBLICATION I12

APPENDIX XIII

Results of the geochemical analysis of soil samples for gold. Yankee Horse Ridge

Geochemical soil travenes across Yankee Horse Ridge anomaly. Traverses trend NNW normal to the ENE mylonite rend.Traverses are 600 feet in length. Traverse YG-2 crosses area Y (with detailed soil geochemisnry for other metals). Traverse YG-1 is 200 feetWSWof YG-2andparallel oitandtraverseYG-3 is200feetENE andparallel o YG-2 @gwe29). Assays, inppm,were performed by Northeast Geochemical and Assay Company, Yarmouth, Maine.

YG-1

300l{w2s0l.{w 200Nw l50Nw l00Nw 50Nw 0 5OSE 100SE 150SE 200SE 25058 30058

0.0.16 0.006 0.006 0.016 0.005 0.005 0.004 0.004 0.m3 0.004 0.002 0.002 0.002

YG-2

3001.Iw250t\nv 200I{w l50Nw t00l{w 75Nw 50Nw ONw 25sE 50sE 75sE 100s8 l50sE

0.00s 0.002 0.003 0.005 0.002 0.003 0.470 0.007 0.02s 0.013 0.019 0.025 0.025

200sE 250s80.@r 0.003

YG-3

300NW250I.nV 200NW 150Nw 100Nw 50NW ONw 50SE l00SE l50SE 200SE

0.003 0.M2 0.025 0.015 0.036 0.512 0.003 0.002 <0.002 0.002 <0.002

250SE 30058

0.002 0.326

APPENDIX XIV

Whole-rock analyses for gold and silver. Yankee Horse RidgeAssays of samples I through 13 by Northeast Geochemical and Assay Company, Yarmouth, ldaine.

Values are in parts per million and Troy ounces per short ton.

1. Yarikee HorseRidge geochemical anomaly Y: mylonitic be&ock,disturbed by bulldozer, goethite @ with relict pyrite.

2. Yankee Horse Ridge geochemical anomaly Y: sheared felsicbedrock, disturbed by bulldozer, traces of yellow-green

ppm oy'short ppm ozlshortAL ton Au Ag ton Ag

r.03 0.03 299 8.72

39

mineral (beudantite?). n.d. nil

3. Yankee Horse Ridge geochemical anomaly Y: mylonitic alaskite,no obvious mineralization, bedrock disturbed by bulldozer. n.d. nil

4. Yankee Horse Ridge geochemical anomaly Y: sheared alaskite,bedrock disturbed by bulldozer, yellow jarositic boxworks. 1.7 0.05

5. Yarikee Horse Ridge geochemical anomaly Y: diamond drillhole #1, vertical, ground core from 0-l 1 feet, core recoveryvery poor,<S%o. 0.01 nil

15 0.44

19.7 0.57

10.2 0.30

0.80 0.023


6. Yankee Horse Ridge geochemical anomaly Y: diamond drillhole #1, ground core from l1-15 feet, core recovery verypor,<57o.

7. Yankee Horse Ridge geochemical anomaly Y: diamond drillhole #1, grcund core from 17 feet, felsic mylonitic rock,core recovery very poor, <57o.

8. Yankee Horse Ridge geochemical anomaly Y: diamond drillhole #1, bottom of hole at2l f*.t, felsic mylonite bedrock

9. Yankee Horse Ridge geochemical anomaly Y: panned concenfiatefrom drill cuttings from hole #1.

10. Yankee Horse Ridge: bedrock beside hole #1, iron-stained, vuggymylonite with limonitic and hematitic boxworks.

11. Yankee Horse Ridge: grab sample, bedrock disturbed by bulldozer,10 feet south of hole #1.

12. Yankee Horse Ridge geochemical anomaly Y: 125 feet ENE of hole #1,in mylonite zone, sheared sericitic, felsic mylonite.

13. Irish Creek tin mine, Panther Creek #2 workings: arsenopyrite withscorodite.

14. Irish Creek tin mine, Panther Creek # 2 workings, arsenopyrite, assayfrom Horchkiss (1883) listed in Glass and others (1958).

0.005 nil 0.4 0.012

0.005

0.004

0.286

5.85

0.10

0.057

267.3

252.3

nil 0.3 0.009

nil 0.5 0.015

0.008 31 0.901

0.r7r 7.3 0.213

0.003 5 0.146

0.002 56 1.63

7.796 382.6 11.16

7.36 2513 73.3

APPENDIX XV

Procedures

Soil sampleswerecollectedby shovel, nowel, orsoilaugurfrombeneaththehumic layerof forestlitter, thenoven-driedandsievedto-l00meshwithnylonscreenedsieves. One-halfgramsoilsamplesweredigestedwithhotl:lHClinTeflonbeakers,filtered, and then analyzr.;d, by atomic absorption spectroscopy. Analyses for lead, zinc, copper, iron, manganese, cobalt,chromium, lithium, strontium, barium, and rubidiurn were done at the Virginia Division of Mineral Resources laboratory with aTechtron AAS unit. Prior to analysis solutions for rubidium, strontium, barium, and lithium were spiked with potassium chloride.Tin values in soil were determined by X-ray emission using pressed pellets prepared by mixing one gram of soil and one gramof cellulose in a SPEX mixing unit. Measurements were made on a Diana X-ray emission unit which has a limit of detection fortin of 4 parts per million.

Gold concentration in whole-rock samples was determined by ttre fire assay technique by hon King, Inc., Laboratory,Humboldt, Arizona and by Northeast GeochemiCal Laboratory, Yarmouth, lvlaine. Gold and silver concentrations in soil sampleswere determined by fire assay followed by atomic absorption by Norttreast Geochemical I-aboratory.

Fluorine, arsenic, and tungsten values in soil were determined by Western Analytical, Inc., SaltLake City and by BlueRidge Analytical Laboratory, Charlottesville, Virginia. Some tungsten data are included in appendices V, VI, and VII. Fluorideconcentration in soils was determined by NaOH fusion and specific ion electrode; arsenic concentration was obtained by pyro-sulfate fusion followed by HCI leach, dithiol exFaction, and then determined colorimerically.

Water samples from strqlms were filtered in tfte field using a Schleicher and Schuell Antlia pneumatic hand pump witha0.45micronmilliporefilter. Watersamplesforfluorineandsulfatewerenotacidifiedpriortoionchromatographydeterminationat the University of Virginia Environmental Science laboratory. Stream water samples for analysis of lithium, iron, and othermetals were acidified and refrigerated prior to atomic absorption analysis at the Virginia Division of Mineral Resources labora-rcry.

Radioactivity measruements for potassium, uranium, and thorium were made in the field wittr a portable Geometric GR-310 gamma spectrometer with a 2 inch x 2 inch (1Ol cm3) thallium-doped sodium iodide detector and an intemal Bals3referenceisotope. All measurements were made at ground level using the average of three l00-second count periods. Reduction of count

PUBLICATION T12

averages to estimates of element concentration in whole-rock was made using empirical constants based on measurements of rockanalyzed by chemical techniques plus Compton snipping constants. Average counts per second (cps) were used in the elementconcentration estimates as:

qoY\G(r.20')(0.96XK cps - 1.32U cps - 0.1Th cps)ppm U=(13)(U cps - 0.83Th cps)ppm Th=(28)(fh cps - 0.089U cps)

4l

gold mineralizatton, and tin, base metals, and thorium anomalibs at ...

Documents

Transcript of gold mineralizatton, and tin, base metals, and thorium anomalibs at ...