Radioactivity at the Copper Creek Copper Lode Prospect, V Eagle

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I Radioactivity at the Copper Creek 1 Copper Lode Prospect, V Eagle District, East-Central Alaska

Trace Elements ln'Vestigations Report 195

/ UNITED STATES DEPARTMENT OF.THE INTERIOR 1 L\. GEOLOGICAL SURVEY ") \l\

'I Fi ~ c~oo)

T~'1 ~ OfFJCIAL USE ONLY ~.' lq5 Geology ·""'' Mineralogy

Thl$ document .COA$;b;ts of 10 page$o Serie~ A

UN-ITED SlATES DEPARTMENT ,O.FTHE INTERIOR

/ \A .S • GEOLOGICAL SURVEY ---·~ ~,.~ ..~

~ RADJOACTJVITY AT THE COPPER CREEK ,COPPER LODE P,RQSPECT1

EAGLE DISTRICT 1 EAST~ENTRAL ALASKA* By Helmuth WedoJ~ l1..-;,.,d Gene · . Tolbert) ftj),$"-

September 1952

Trace Elements Jnve~.tigc;~tions Repod 195

This preliminary _report is dls;tribut.ed without edltorial and technlca.l rev.lew {Qr ,conformity with official standard$ and nomenclature. lt is not fo~r pub llc inspection or qu9tatlon"

*This report concerns wowk done on behalf of the Divi:sJon of Raw Materials .of the U. S. Atomic Energy CommtS5Jon

OFF.I.CIAL USE ONLY OFF~ClAL USE ONLY

US'GS: ""' TEl Report 195

GEOLOGY ·~ MJN.ERALOGY

.Db3tdbutlo.n ~Sede$ A) No. of eopies

AmeJr.ican Cy_onamid Company 1 Waiedown , ., ., ~ " .• "" ., .., .., ·. ~ • ]

Argonne National Labor.at.oey • .• · Q · " " .o ,., " ... "" ,. " o _., o <> .• . "' " .1

Atomic Energy Comml~ion, W~hington o o .., ,., .o • ..... o o _., ..._ ., 2

Carbide and Carbon Chemicals Company I v~;12 Area 0 o_ 0 " ·o 0 1

Colorado Raw Material$\ OJfice (F o ·H o MacPherson) o ...... , " , 1

Oiv.i$ion of Raw Materials; Grand Junction .. . · ~ ...... 0 • • • • 1

DivJ$ton .of Raw Mat~rJals ., Gr.ant$ -o .. .. • o o . ... • 1 Dtvh>Jon of Raw Mateda-lsJ Denver • ., . .. .•• .., .. • .. .. 1

D i vi% ion -ef .Raw Mated als1 Hot Springs Q • , o o • .• .. • 1

Divlsjon of .Raw Material$-, New York .~ ., ~- • " o 6

DivisJon of Row Matedal$, :Salt Lake City o •.• 1

Di.vbJQn of .Raw Materials, Rlchfleld A ... • • <> o. 1

Divbion of Raw Mate.riaJs,~ Butte o • ... .• . •.• .• •• - ~ •. ·!lc •• ...... o 1

Dlvi~lon of Raw Material~ 1 . Washington o .• • • • .. 8 -

Dow Chemical .Company, Pittsburg p • • , .o o...... 1

Jechni.cal Information Service, Oak JUdge ., ...... o ... o .• 6

Battelle tv\emoJJ".ialln$titute1 Columbus' .. .. o • o o. 1

Tenne~e Valley Authority, WU$0n ()am , ...... o ., ...... •• • 1

U. S. Geologic;:(]l Su. wvey~

Mineral Depo~ihi Btaru:h,· Washington ... ., ...... o o • 1

Geochemi~twy _and Petrology Btan.ch, Wclshington • "'· .. 4>. o "' 1

Geoph.ysiC$ B.r:an.cb, WO$hington . ~ . " ...... " o " " ...... , ~ - 1

Al~kan Geology 1\raAc:h,~ Washington o , ...... "*·. .. • ...... 10

Te:1r.r .. Dept.. Mines 1 Juneau (P. H ~ Hold$worth, Jr ..;) . .. . 1

Ten o . Dept .. Mlne~, Ketchika~ -(A... E, Glover) o ...... , .. ... ,.. .. 1

Ten. DepL Mine$, AAehorage (P. 0. Sandvik) ...... o .. 1

Terw ... Dept o _ .Mlnes, College (L... l .. Patton) o ... ,.. 1

Ten .. Dept ... Mines, Nome (D ... Jones) •. .•. -o .. ~· .. .. • .. o 1

G .. 0 .. G.ate%, San Froru:h~.co ...... " . .o .. "' .• .. .. •• 1

E.. A. Youngberg 1 Juneau .... .o ...... , ...... - ~ ...... •• • .. .• 1

_R.., M .• Chapman, FalrbQnks <0 .. ., " ..... " ... "" .. _, ~ - ~ ...... · ~ 1

V. E. Me.Kelvey 1 _ WO$.hington . , ...... - ~ _., .._ ...... _ •• .o- 1

_L .. R.. . Page, Denver."; o ...... , .. , ... ""' -o .. o .• · ·4 ...... 1

.It, P~ Fi$cher , _Gran -d Junction .• , .. o .. • • ...... o ...... 1

A .. E ~ WeiMeAborn, Spokan.e •. ., ...... - ~ ...... o . .. ·" ...... o 1

TEPCO -' · Wa~hi.ngton • • .. ., ~ ...... "0 ...... , .... • • • ...... 5 {inel.uding master)

OF.FJC!AL USE ONLY OFFlClAL USE ONLY

CONTENTS

•- • · ••o ~ ._ ,...... ,_ .•.. . 4

lntroduetion 4 ....

.,. ~ Geology ••. ••, ...... • Cl' · • - ~ • · - .,... 7

Radioactivity $tud.ies 7

A,_ ·.. .. • .. • • Con . clu~Jons "' . ,...... , ·~ ._ 10

.Refe.ren .Ce$-.. cjted • .• .. ·'!· .. • • .. • • • ...... '"· ...... " .• • • • .• ...... 4 10

TABLE

Table .1 .. Data on selected $0Mples from the Copper Creek copper lode ,pros.pect, Eagle dl$trict, eCI$t-eentral AICJlka. . • .. 9·

I.LLUST.RATJ.ON

flg~re .1.. Skete~ map of the Eagle di-strict, Alaska • •...... ·.• ~ 5

OFFlC.IAL USE ONlY OJFIC1AL USE ONLY

RAO.!OACTlVlT'l AT THE COPPER CREEK COPPER LODE PROSPECT,

EAGLE DtSTRLCT;~ _ EASI:-CENTRAL ALAS.KA

By Helmuth VVedo,w, Jt .. and Gene E ... Tolbert

ABSTRACT

lnvestlgcatloq of radioactivity ,QRomalles .a:t the Coppe.r Creek .copper lode

pr.O$pect 1 Eagl~ dl$trlct, eCJ$t,..,·eentr.aJ Aluska 1 _ eluting 1949 dbcJo~d that the radioactivity i$ .asso.clated wllh coppeJ m.ineralizadon in highly metamorph~d

SedimentaJny -rocks. The~e 1ocks .are a. roof pendant in the Meso:zoie ••Charley

-Rjve:J• batholi.th. The fQdloactivity ~.s probably all due to urani.um qsociated

wlth bornite an.d mctlachite e

JNJRODUCTlON

The Copper .Creek coppE~r lode prospect b located iA t.he sout-hwe$_tern pcu:t of the Eagl~ di'striet, eCQto-centroJ Alaska.1_ Qbout 60 mile5 west .of the t.own

neG¥ of Eagle 1 which lSc the in lternotlonaJ boundary (fig~ l) . .The protpect i.s on the right bank of Copper Creelk ,about 6 miles above the creek•$ confluence with the. Charley R1-ver.,"

The Copper Creek prospect ha' n.ever been reported in G.eologi.eaJ Sur:vey literature although know.l.eclge of Jt ts widespread. among pros.pectors. in interior

AICJSka.. It was .staked and p_artiaJJy developed by the Hudson. btothe.rs in the ecn:ly

19001.5, but since then has cha1rtged hands several times. The owner .of the cJcd m in

1'949, Howard Sparb of F . airbanks:~ restsked the prospect ln 1946, pdmat:ily on _the

<)fFIClAL USE ONL. Y UNITED STATES TRACE ELEMENTS INVESTIGATIONS DEPARTMENT OF THE INTERIOR REPORT 195 GEOLOGICAL SURVEY FIGURE I 22"f2 1

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EAGLE DISTRICT, ALASKA OFF~CIAL USE ONLY

po$£lbU ity that the gold, l$1lve ~ r 1 lead., and tung$ten content in addition to the

copper might wall;rant furthew exploration Q

The workings at the Coppe.r Creek pr.~pect con~h;t of an adlt in a eLiff'-$t.Jrface

showing of copper ore.. The portal i$ 10 to 15 .feet above the level o.f Coppe.r Creek

and the working~ extend 114 feet underground~ The ore showing$ cx::cur only in

apparently c.au$ed the earlie.r pro$pectors to wander off the t)rend of the ore.,..,bearing

zone with the res:ult that the hut 60 feet of the adlt isenHrely in e~ntially barren

rock.._

The radiometric examination of the Copper Creek prospect was made 0$ a ~ide

trip in con.nection with othe.r radioactivity studie$ in the adi<:~cent part of the Fotty.-

mile dis.twict (Wedow and Tolbert, in preparation)~ Traruspo~rtation to the pro~pect'

w.as by a Sikorsky Model H5G helicopter furnished by Detachment B, Tenth Re~cue

Squ~dron, U .• S. Air Jorce, based at Ladd Field, Fairbanks.

The examination was made on August 17, 1949~ The author.$ were accompanied

by Geor.g_e 0 ~ Gates of the Geological Suwvey and Howard Sparks, owner of the

pll'O$.pect. The statement below on the geologie setting .of the prospect ha! been t.aken mainly from field notes by Gate'$.

Thi~ -work was done on behalf of the Division of Raw Materials of the U. $.,

Atomi(: Ener:gy Commiss-ion.

OFFlCaAL USE ONLY I

OFFICIAL USE 'ONLY

GEOLOGY

The bedrock at the Copper Creek Olode prospe~t, pre~lou~ ly mapped in reconnal5Sance as Meso~oic(?) g J ~anite (Prindle, 1913, pl. 2; Jv\ertie, 1937, pL. 1), consi·sts of highly metamorphosed sedimentary rocks,. These _. rocks are apparently

11 part of a small (sever.al ~' mi~ TOC)f pendant in the 11 Charley River batholith and ae,ted as .a host .for the depos-ition of the metallic minerals found in the p!l"ospect.

Ten~ative !dentlficaticins . :show lime:-•silicate rock and amphibolite as the' two main lithologi~ types at the prospect: . ' The bufk of th.e metallic. minerals is in the

Urne:~i licate r.ock, mainly along a conta.et wlth the amphibolite, although minor amounts,of the metal'lic minerals are dls.seminated through both rock types but in· dlmminis~ing amounts away from 'the contact. ChalcopyrHe, malachlte and azurite are the chief metallic minerals at the prospect.. Minor amounts of ga.lena

' ' are present and tr.aces of gold, s.il-ver and tungsten have been .reported in assay~.

RADIOACTIVITY STUDIES

The radioactivity of the rocks at the Copper Creek prospect was meas~red wi.th

Q commercial model of a portable SL.Jrvey meter modified to accept both the standard

6-in. beta""'9amrna probe and a probe consi.sting of six 1..- by 14-i.n. copper-walled gamma tubes connected in paroll~el •

The variation .ln radioactivity ln the adit, as measured with the large gomma probe, is .summarized as .follows:

OFFICIAL. USE ONLY OFFICIAL USE ONLY

Distance (ft) into adlt Radioactivity from portal (dlv b lon~ on 2,.0 scale) Rock type

0-2 12 Li.me :~il icate ~rock end amphibolite ... 2 .-18 10 Do. 1.8-32 8 Amphibolite 32-.40 10 Lime-'""'$ ilicat:e Jr:ock.Q 4 o ~ - 44 16-18 Lime~i Iicote ro.ck with iron ~tained fracture zone$.,

44- 48 12 Lime~i Iicate Jr.ock o . 48 ... 54 10 Doo 54~ - 114 8 Do.

Te~ting with the 6-in. beta-gamma probe lndicated th.at the radioactivity ai. the 11 portal" anomaly ts JocaUz.ed around eertain mineral groupin.gs in the ore zone •.

At the ''4044" anomaly the mdloactivity _appears to be confined to iron~~tai . ned surface ~ or zones along low--angle fractures _Q_r fault-s :in the ltme:1Hicate .ro.c:k .,. Data. on rel_ected samples from both anonlQUes are summarized i.n table I .

As .reen in table l the uranium in the sample$ from the Copper Creek pr~ct is concentrated mainly in mat:erial of less :t han about 3.-0 specific g_ravity._ This mater.ial consbti mo$tly _of w•llastonlte and .reddish or yellowJ~h cal~ite ~ it aim

contain$ minor .amounts of galena and bornite1 mostly _as inc:lusJons in some of the

wollast.onit.e-gr-ains. The bor.nlte is .slight ly altered to malachite 9 The uranium appcuen~ly _occurs as an impurity in the bornite and malachite ..

The radioactivity _of the placer con-centrate (sample 3688, table I and fig _. I)

.from Copper Creek Is probably due most.ly to thorlum in trace amounts of monazite.

OFFICIAL USE ;ONLY Table l j).:-:-.Data on releeted ~ample ~ from the Copper Creek .copper. _lode p1Fo ~pect, Eagle di ~ t.rict, ea$t-central Ala$ka ~eqvlvalent . ut~nium analy_se~ by member~ of the Alc$kaa_Tt.ace Element$ UnH) ..

Eqyival.enJ ~rt:mium (percent) UnconcentrateC,{.. .Fraction le$$ than Frre1ctJon gFeater .than. Sample no o rock 3.3 ~p gr 3.3 sp gr Ren1orks

368S ------..,.~- - .. ~ ---- ~ ---~~0~ _ 013~ CL003C:! ____ Concentrate from about: 50 pounds of gravel in Copper Creek about 100ft up$tream from lode prospect. "Po.rtalnonomaly; .

0 3730-L 0.032 0.003!¥ Grab sample from mo$lt .radio~tive ~pot on .,0 ~ e · ~t side of podol" ~ n""" 3731-L 0.001 0.003 0.002 Grab £ample f-rom $1 ightly radioactive pa.rt n )> of ore zone on eel$t side of portal.. r- >r- -o c "40-4411 anomalt~ c V). ~m m . 0.002 Grab sample o.f rock adiacent to mo~t 0 0 3725-L 0 ...003 0 .. 010 z z radi.oective iron~t.alned fracture zone o r- !( 3726-L 0.006 0 .. 004 0 .. 003 CI:Up sample· of I'"-foot lay~r above mo.$t ~ mdioactive fracture. 3727-L 0.003 O.. Ol2ij 0.002 Chip sample of 1 - ~foot layer below mo$t

radloac:.tlve fract.llte 4 3728~L Oo004 Oa.006 0 .. 003 Grab ~ample of same. fracture zone 0$ ~ample 3725-l but about 6 ft down dip of fracture 3729!"'L ~.,-=---~not de term i ned--.--, --~--"""-""'-=---go .... Specimen of !rock tmmediate ly below fracture in sclmple 3725~L; radioactivity _appears to be confjned to 0.1 .ft of rock immediately adiacent to fracture .. _ a/ fraction le$S than 2 ,;.8 $p gr b/ .Fractioilll greater .than 2 o8 ~P gr c/ .Contain~ 0 "058 percent U - ~determined by F. S .. Gr·irnaldl, Wa~hlngton Trace Element$ Labo r.atowy ~ . Cont, ain$ Oo009 ~rcent U a~ determ·ined by F. S. GrirT)al.di, WO$hlngton Tr-aee Eleme~t ~ Labo.rator-y OFF.ICIAL USE ONLY

CONCLUS~ONS,

Mino!t amount$ of wadioactive mater..ial~ are a~ociated with copper. Oll"e~ at the

Copper Cll"eek pro~pect in .t.he Eagle di$_trht.t where a $ma.U roof pendant in the

11 Charley _River." batholith appear$ to be highly minerali~d., The r.adioaC,tive

· miner.al5 o1re bornite and malachi.te, ln which uranlum oc.cut$ .as an impurity, ..

Because of the l.imited time available for the examlna-tjon of the prospect~

reconnabsance of matt of the roof pendont area wa$ n:ot undedaken. Jt ls pou8ble

that gJr:eater .concentration~ of uronlum may occu.r. in or imme:di:ately adiacent: to

the area of the roof pen.dant..

REF~RENCE.S CIIED

.Mertie, J .. .89, Jr .. , 1937, The Yukon~Tanana region, Ala~ka: U. So GeoL Survey Bull • 872 ._

Prindle, L. M., 1913, A geologic reconnais5ance o.f the Circle q~c;sdrangle, Alaskca~ .U . S. Geol .. Sur.vey Bull " 538.

Wedow" Helmuth, Jr. ,1 Q.nd Tolbert, G" E •.1 in prepaf.otion, ReconnaiS$ance for radioactive de~~tb ~in .the FortymUe di$tJr..iet, . eCJ$.t~en,txa-l Al~k-a., 1949~ U .. So Geol. Survey Trace Elements .Investigations _Report 196; title $Ubject to change ,..

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