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 2 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 3 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$t-eentral AICJlka. • .. 9· I.LLUST.RATJ.ON flg~re .1.. Skete~ map of the Eagle di-strict, Alaska • •. .. ..... .. ·.• ~ 5 OFFlC.IAL USE ONlY OJFIC1AL USE ONLY 4 RAO.!OACTlVlT'l AT THE COPPER CREEK COPPER LODE PROSPECT, EAGLE DtSTRLCT;~ _ EASI:-CENTRAL ALAS.KA By Helmuth VVedo,w, Jt .. and Gene E ... Tolbert ABSTRACT lnvestlgcatloq of radioactivity ,QRomalles .a:t the Coppe.r Creek .copper lode pr.O$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 ~ \ \ ~ «"') ~ ~ \ '' "' I / / ~ c I I Q:' {-I J w /~ .... ~ .... U) \ /\ / \ ~ / ... _ ~ c1 I a. / - Q\S 'TR\ I 0 \__\ 0 ( // fQRi'<t-'ILE. 0 \ (!) ) ( ( / \ EXPLANATION I ~- 3725-L Sample from lode prospect ( -\ \ ( 0- 3688 Stream concentrate '\__ /'-- ' --- - '\._,...-\ .... ) "-1 -- 10 0 10 20 30 Miles 1 I 1410 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 <Jbout the first 40 feet of the adi,t. Lack of understanding of a complex strueture 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. $., Atomi(: Ener:gy Commiss-ion. OFFlCaAL USE ONLY I OFFICIAL USE 'ONLY 7 GEOLOGY The bedrock at the Copper Creek Olode prospe~t, pre~lou~ ly mapped in reconnal5Sance as Meso~oic(?) g J ~anite (Prindle, 1913, pl. 2; Jv\ertie, 1937, pL. 1), consi·sts of highly metamorphosed sedimentary rocks,. These _. rocks are apparently 11 part of a small (sever.al ~' mi~ TOC)f pendant in the 11 Charley River batholith and ae,ted as .a host .for the depos-ition of the metallic minerals found in the p!l"ospect. Ten~ative !dentlficaticins . :show lime:-•silicate rock and amphibolite as the' two main lithologi~ types at the prospect: . ' The bufk of th.e metallic. minerals is in the Urne:~i licate r.ock, mainly along a conta.et wlth the amphibolite, although minor amounts,of the metal'lic minerals are dls.seminated through both rock types but in· dlmminis~ing amounts away from 'the contact. ChalcopyrHe, malachlte and azurite are the chief metallic minerals at the prospect.. Minor amounts of ga.lena ' ' are present and tr.aces of gold, s.il-ver and tungsten have been .reported in assay~. RADIOACTIVITY STUDIES The radioactivity of the rocks at the Copper Creek prospect was meas~red wi.th Q commercial model of a portable SL.Jrvey meter modified to accept both the standard 6-in. beta""'9amrna probe and a probe consi.sting of six 1..- by 14-i.n. copper-walled gamma tubes connected in paroll~el • The variation .ln radioactivity ln the adit, as measured with the large gomma probe, is .summarized as .follows: OFFICIAL. USE ONLY OFFICIAL USE ONLY 8 Distance (ft) into adlt Radioactivity from portal (dlv b lon~ on 2,.0 scale) Rock type 0-2 12 Li.me :~il icate ~rock end amphibolite ... 2 .-18 10 Do. 1.8-32 8 Amphibolite 32-.40 10 Lime-'""'$ 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 .