COPPER-NICKEL DEPOSITS, NORTH DUNDAS FIELD,

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1 . ' 1 " 1'1 (..l '" COMMONWEALTH OF' AUSTRALA DEPARTMENT OF NATONAL DEVELOPMENT BUREAU OF MNERAL RESOURCES. -GEOLOGY AND CtEOPHYSCS RECORDS 1952 N 71 NTERM RE_PORT GEOPHYSCAL NVESTGATON OF THE COPPER-NCKEL DEPOSTS NORTH DUNDAS FELD NEAR ZEEHAN TASMANA '- by 0 KEUNECKE

2 .. '.: COMMONWEALTH OF AUSTRALA DEPARTMENT OF NATONAL DEVELOPMENT BUREAU OF MNERAL RESOURCES. GEOLOGY AND GEOPHYSCS RECORDS 1952 N 71 NTERM REPORT GEOPHYSCAL NVESTGATON OF THE COPPER-NCKEL DEPOSTS NORTH DUNDAS FELD NEAR ZEEHAN TASMANA by O. KEUNECKE

3 ~ 1 NTRODUCTON GEOLOGY. ~ ~ GEOPHYS CAL METHODS.$. 2 "'" ) 4. RESULTS AND NTERPRETATON fl 3 (a) Self-ptental Results. 3 (b) Magnetc Results e 4 51; SUMMARY REC OMVlE ND AT OTS. 'll RE FERE r::es.~ 6

4 1; Plan shwng pstn f cpperwnckel feld. 2. Self-ptental prfles. 3. Self-ptental cnturs~ 4. Magnetc vertcal ntensty prfles ~ - - ~

5 v NTER Th ~ REPORT NTRODUCTQN~ The Bureau f Mneral Resurces has cmmenced a gephyscal nvestgatn f the cpper-nckel depsts n the Fve-Mle dstrct near Zeehan at the request f the Tasmanan Department f Mnes Hbart. The cpper-nckel feld s stuated abut fve mles t the nrth-east f Zeehan and s reached by branchng ff the rad frm Zeehan t Rensn Bell (Plate 1). Prspectng and mnng have been carred ut n ths area at ntervals durng the past sxty years. Ths has shwn that hgh-grade cpper-nckel re ccurs n an area abut 1~ mles lng by apprxmately 1000 feet wde. Gephyscal wrk was carred ut n the nrthern part f the area by the mperal Gephyscal Expermental Survey n ~ The results were reprted by Edge and Laby (1931)~ The survey btaned ndcatns and sme f these were subsequently prved by drllng t be caused by rch cpper-nckel re. The Department f Mnes Tasmana n ts Summary Reprt (1952) has ndcated the pssblty that further rebdes f ecnmc value exst n the area.. Therefre the Bureau was asked t carry ut a gephyscal nvestgatn f the whle area. The Department f Mnes lad ut the lnes ncludng cuttng and peggng the traverses. The area s manly flat and swampy. The prtn suth f the Vaudeau shaft s farly pen and nly partly cvered wth bush but the area nrth f t s cvered wth thck bush. The wrk f layng ut the traverses thrugh ths thck bush was very greatly helped by the use f a bulldzer suppled by Eagle Metal & ndustral Prducts Pty. Ltd. The gephyscal survey was begun n May 1952 wth a prgramme ncludng self-ptental magnetc and electrmagnetc measurements. The members f the feld party were Dr. O. Keunecke and Mr. P. B. Tenn. Surveyng cmmenced near the ld Vaudeau shaft n the suthern prtn f the area. Because f bad weather t was necessary t dscntnue the survey n June Up t that tme self-ptental measurements had been made alng 22 traverses cverng 2100 feet alng the baselne and magnetc measureme~ts alng 15 traverses. N electr-magnetc measurements had been made. The survey s therefre as yet ncmplete even ver the suthern prtn f the area cvered s far. Hwever t s expected that mnng explratn wll be taken up agan sn n the cpper-nckel dstrct~ Therefre ths nterm reprt has been prepared t present the gephyscal results btaned t date and t dscuss ther sgnfcance. The nterpretatn f the results s necessarly restrcted by the lack f electr-magnetc measurements e Such measurements have been fund by experence t gve the best ndcatns n the case f sulphde mneralzatn f the type beleved t exst n the cpper-nckel dstrct.

6 21J GEOLOGY ~ -- The area cnssts f a seres f Cambran slates and breccas f purple grey green and black types. These rcks are ntruded by fur r mre basc dykes strkng nrth. These dykes cnsst f pyrxente nrte and gabbr and have a wdth rangng frm apprxmately 10 feet t 50 feet. At the surface the dykes dp farly steeply t the east but at a depth f abut 100 feet the dp s fund t have decreased t abut 45. Cpper-nckel mneralzatn s knwn t be clsely asscated wth ne f these basc dykes. The re whch has been mned at several places extendng ver a length f mre than 1t mles was fund ether n the ftwall f the dyke r wthn.- t. The re s massve and cnssts f pyrte pyrrhtte pentlandte and chalcpyrte. t has been xdsed at the surface t lmnte and nckel and cpper carbnates. t s stated n the Reprt (1952) f the Tasmanan Mnes Department that the are at a depth f abut 100 feet has been replaced by cellular quartz~ The very lmted extent f the ld wrkngs n the area shws that th~ cpper-nckel re ccurs nly ntermttently alng the strke that t des nt persst t any great depth and that the cppernckel rebdes fund s far have been small. Althugh the re appears t ccur nly n small pckets ts average metal cntent s reprted t have been' 5-6% cpper and 9-12% nckel. Besdes the cpper-nckel re there s galena mneralzatn f mnr ~ mprtance asscated wth quartz vens n the slates. The baselne was frst lad ut alng the western bundary f the area t be surveyed~ ts bearng s 1720 magnetc. The traverses whch le at rght angles t the baselne are each 1000 feet lng and are at ntervals f 100 feet. Three shrt traverses HCA" HDA and HEA; were added subsequently n rder t gve a better delneatn f an anmaly n the suth-west crner. Observatn pnts were spaced 25 feet apart n all traverses. The survey was started usng bth self-ptental and magnetc measurements. The self-ptental methd reveals anmales where sulphde mneralzatn s present extendng t grund-water level thus gvng rse t chemcal reactns. As a result f these reactns electrcal currents are set up prducng ptental dfferences whch can be measured. These measurements may shw a negatve centre f as much as several hundred mllvlts ver an xdsed sulphde bdy_ Hwever snce pyrtzed fault and shear znes graphtc slates etc. can cause anmales f the same rder the nterpretatn f self-ptental anmales has t be made very carefully partcularly where n ther type f electrcal measurements has been carred ut. Magnetc measurements usng the vertcal magnetmeter are used n the search fr magnetc re such as magnette pyrrhtte lmente etc. Als the methd may be used t nvestgate the general dstrbutn f rck types n an area partcularly f gneus rcks are present. These rcks are ften mre magnetc than sedments and wthn the gneus grup the mre basc types usually have a greater magnetc effect than the mre acd am s~ Therefre a magnetc survey can e:.ve very useful nfrmatn~

7 - 3 - (a) SeJJ.=.R~ntal_ Results." The results f the self-ptental survey have been pltted and are shwn as prfles n Plate 2. These results have been cmbned t prduce the cntur map f Plate 3 shwng cntur lnes f equal ptental. Each prfle shws the change f ptental frm pnt t pnt alng a gven traverse and sne f these ndcate dsturbances. The cnturs shw the extent and strke f each anmaly. The cntur map reveals several anmales wth negatve centres rangng frm 100 t 200 mllvlts. The anmales n the suthern prtn f the area ccur manly n the west whereas further nrth they ccur manly n the eastern prtn f the area. The anmales are nt unfrm n strke r shape~ t can be presumed therefre that they are prduced by dfferent gelgcal features. n the self-ptental ~rfles tw man types f _ndcatn can be ntced. One has qute a strng and dstnct character and the ther s rather weak. Frm such gelgcal evdence as s avalable t wuld seem that the strng anmales ma~t be asscated wth sulnhde mneralzatn r :lyr tzed fault r shear znes whereas the vleak anmales seem t be asscated wth cuper-nckel mneralzatn. As prevusly mentned self-ptental anmales are btaned f sulphde mneral~atn reaches the grund-water level and xdatn has taken place. The fact that n dstnct anmales appear near the knwn ld wrkngs des nt necessarly mean that n further cpper-nckel mneralzatn exsts there. t lnd cates nly that there s n xd 1.~ed re present. All the xdsed re rgnally present may have been remved by mnng.. Als t s pssble that the grund-water level was temprarly lwered n the ld wrkngs durng mnng peratns.. The level wuld then have rsen agan after mnng ceased and wuld have cvered the remanng re thus preventng further xdatn. n ths case n anmaly wuld be expectedl.~ Ths all means that the results f the self-ptental measurements alne taken n cnjunc tn v th the knwn gelgy are ndetermnate. n rder t determne mre cnclusvely whether r nt further cpper-nckel re exsts t wll be necessary als t make electr-magnetc bservatns as rgnally planned. The cpper-nckel re s asscated wth ne f the basc dykes n the area as s shwn n the ld wrkngs and n the Vaudeau shaft. Hwever nthng s knwn regardng the pssble cntnuatn f the dyke t the nrth and suth f the mne wrkngs. Ths s mprtant because a well defned selfptental anmaly wth a nrtherly strke s fund n traverses F G and H n a lne whch s apprxmately a sutherly extensn frm the Vaudeau shaft. t seems pssble that the basc dvke extends ths far suth and that the anmaly s therefre due t cpper-nckel mneralzatn. The farly unfrm shape and very steep ptental gr:j.dent f ths ndcatn shws that t s f lcal character and les clse t the surface. Als the unfrm shape ndcates that the bdy prducng the anmaly has a nearly vertcal atttude. Ths des nt crrespnd wth the general tendency f the cpner-nckel bdes n the area t have an easterly d:p. Therefre t s nt certan thtlt ths anmaly s caused by cpper-nckel re. Trenchng alng traverse G shuld help t determne.ts cause.

8 - 4 - Anther anmaly f lcal extent shwng a steep ptental gradent traverses the suth-western part f the area. t has been bserved n traverses He t HF. ts mst ntceable feature s that t has" a nrth-westerly strke whereas the knwn cpper-nckel mneralzatn n the area s asscated nly wth dykes havng a nrtherly strke. Ths anmaly mght therefre be due t qute a dfferent cause$ t seems prbable that there exsts a fault system wth a nrth-westerly strke and that ths has becme pyrt:tzed thereby gvng rse t the. anmaly. The area n whch the anmaly has been fund has s far receved lttle attentn frm prspectrs and there s therefre lttle surface expsur.e f the gelgy whch mght assst n the nterpretatn f the gephyscal result. Hwever snce the ptental gradents are steep the bdy gvng rse t the anmaly s prbably shallw. t shuld therefre be pssble by trenchng t determne the cause~ The largest zne f self-ptental dsturbance s n the eastern prtn f the area surveyed. Ths zne shws frst n traverse F and cntnues nrthward ver a dstance f mre than feet t traverse Q whch s the nrthern lmt f the present survey. The zne shws several separate small mnma mst f whch h(-j.ve steep ptental gradents (see Plate 2). Here agan t wuld appear that the mneralzatn gvng rse t the anmales s at shallw depth. Hwever t s nt pssble t gve a clear l1.dcatn f the na ture f the mneralzatn. The anmalus zne des nt appear t have any relatn t the knwn cpper-nckel mneralzatn. The ld wrkngs nclude sme trenchng between H.800 and N.800 but ths des nt thrw any lght n the structure. t seems pssble that there s anther basc dyke nt prevusly detected that traverses the eastern prtn f the area and that mneralzatn s asscated wth t. Hwever as prevusly mentned the knwn cpper-nckel mneralzatn shws up nly very weakly n the self-ptental results. Therefre t seems unlkely that the dstnct anmales f ths extended zne are caused by cppernckel depsts but rather that they may be due t sme ther mneralzatn such as a pyrtzed shear zne. The fact that the anmaly cnssts f several separate small mnma f dfferent strke makes t mre lkely that these are due t a pyrtzed shear zne n the cuntry rck. Sme trenchng s recmmended t determne the cause f the anmales and ths shuld be dne n traverses E K r Q. (b) MsKllll9-B~ll.ll.. A satsfactry nterpretatn f the magnetlc results s nt pssble. A few sample magnetc prfles are shwn n Plate 4. Frm these t can be seen that there are n.1m. gnctc anmales f any sgnfcance. t s ften pssble t lcate basc dykes by a magnetc survey because many dykes shw magnetc effects~ Hwever the results ndcate that n the cpper-nckel dstrct ths s nt the case. Measurements carred ut by the.g.e.s. n 1929 (Edge and Laby 1931) n the nrthern part f ths area als shwed that the basc dykes there shwed n magnetc effect. The bre results gven n the S~~ary Reprt (1952) shw that at least fur easterly-dppng dykes traverse the area beng surveyed. These run mre r less parallel wth a nrtherly strke. Small magnetc anmales at least mght have been expected where the dykes crp ut. Snce n magnetc anmales have been bserved t fllws that the dykes are f a nn-magnetc character r else that they have lst ther magnetzatn thrugh -~-.

9 the decmpstn that s bserved t have taken place t sme cnsderable denth. n ne f the ld wrkngs t was nted that the dyke had been cmpletely decmpsed t a depth f 70 feet. ::~ A start has been made n a. gephyscal nvestgatn f the cpper-nckel dstrct f Nrth Dundas stuated 5 mles nrth-east f Zeehan Tasmana. Only part f the self-ptental and magnetc measurements had been cmpleted when the survey had t be dscntnued because f unsutable weather. The self-ptental measurements ndcate several anmales. These anmales dffer n extent and strke but all shw steep ptental gradents ndcatng that the cause f the dsturbance les clse t the surface. t s nt pssble n the bass f the self-ptental results alne t say whether r nt the anmales are due t the presence f cpper-nckel depsts. Snce thse prtns f the area n whch cpper-nckel re s knwn t ccur n asscatn wth a basc dyke shw ~p nly as very weak anmales t s prbable that the defnte anmales btaned are due t sme ther cause than cpper-nckel mneralzatn. The exact nature f the bdes causng the bserved anmales may pssbly be determned by trenchng. The questn f whether r nt there are further unknwn depsts f cpper-nckel re n the area can mst prbably be settled by electr-magnetc measurements. Magnetc measurements made ver prtn f the area dd nt yeld any resu~ts that culd be used t determne the pstn f basc dykes. 6 REC OMJ>.'E ND AT ONS ~ Addtnal gephyscal wrk n the area partcularly t the nrth f the present survey shuld be carred ut. Ths shuld cnsst prncpally f electr-magnetc measurements whch ffer the best chance f lcatng cpper-nckel mneralzatn. Ths vvrk culd nt prftably be attempted untl after the end f the rany seasn. n the meantme trenchng culd be carred ut t determne the type f mneralzatn causng the man anmales revealed by the self-ptental survey_ Ths type f wrk s nt expensve and t wuld be partcularly helpful t have t dne befre the electr-magnetc wrk s begun. The prncpal anmales culd be tested by trenchng carred ut alng the fllwng traverse lnes :- Traverse HCA between pegs 100 and 250 n G t t t tt E' t t 700 " 800 n n K 0 " " 850 " 950 n Q t tt ~

10 k D.M.T.. (1952) Edge A. B. and Laby T. H. (1931) Summary Reprt n the Cpper-Nckel. Depsts f the Fve-Mle Dstrct Zeehan. Unpublshed Reprt Department f Mnes Tasmana. - The Prncples and Practce f Gephyscal Prspectng mperal Gephyscal Expermental Survey Camb. Unv. Press Lndn pp. ~4"'90. (. Keumecke) Qenhz l..:g..tm ~ n : Orgnal - Lbrary (Fle 50T4B). 1st cpy - Chef Gelgst. 2nd n Drectr f Mnes Tasmana. 3rd f; Eagle Metal & ndustral Prducts 4th t - Gephyscal Lbrary. 5th "-" " 6th ". " Pty Ltd. (Thrugh Drectr f Mnes Tas.)

11 RENSON n.-~) 0 ROSE BERRY LEGEND PLATE MNE.. _- -- "- : -- '" ) MT. LYELL QUEENSTOWN -' pv-- " 177~ ' rw<l 5 fly fed Pr ll'_.l.~ SCALES L SCALE (MLE:;') _ E_ -.. ~-~' ~ CUN NORTH ; j f CUN SOUTH ~ : ~ '- GEOPHYSCAL SURVEY NEAR ZEEHAN. TASMANA. LOCALTY MAPS OF THE NORTH DUNDAS FELD COPPER NCKEL AREA GEOPHYSCST L- t G 32-25;._- -~

12 PLATE 2 SHEET t z J.. z A. _.--._."'-. '-'-'.--;.'" '..~' _ '-' OlnU~8ANC S ON ~~CE -.-c. --.~ -. --' : 7.. : OLD SHAFT ETC.._.-. '-'- B '-' ""-..- "j'"...-' '-.. ~ - ' :-0-=-;--;..-;.. '''''''"" '-. " Z'.: '.. c _ ~.-. ~' '-.. '---._."._. _.-.".'" ".".. '--. -' -_._ ~.-=""'-. -..: '--' c D -. GEOPHYSCAL SURVEY NEAR. ZEEHAN. TASMANA. THE NORTH DUNDAS FELD COPPER - NCKEL AREA E.- _.._ _ jj _.-'-' SELF POTENTAL PROFLES F ~-~---.' _'. --- _~ ---- : ". G ~ _'~''''-."' '-' " '-' '-'" ' ~ "'-"-1':""":::::-=-'-' -jt-'~-- z H " f'-. -_._-_.. -_ ~-..-- '.'. -..'j. l -. " GEOPHYSCST HA w HB > SCALE S a: - VERTCAL 50 HO ZONTAL 100 SO 100 SO MLLVOLTS.J SOO FEE T HC TRAVERSE SEPARATON SCALE 50 TO NCH. ' ad HD ;:.. Of.r--.- '.. L ~~..._._ ; ~ 0 ~ ~.. '"" 0. '-'--"' j---= y.-."..' ' _ 1._._._. '-.." '-. "..-. ' z SHEET 2 HE --' l}'-".4"j '-'-'-'..-.. ~ ~'- :--~::-'."._.-:.=.~ <..~.--:.:~.--= :"'.~.=. NDEX TO SHEETS '" ( ' -'1-". -".. : ". _. ': '--. > HF ' t ' SHEET G

13 a qoo 1000 PLATE 2 SH EET 2. z f 0 " >-. GEOPHYSCAL SURVEY NEAR ZE8HAN TASMANA THE NORTH DUNDAS FELD COPPER-NCKEL AREA SELF - POTENTAL PROFLES u :z "' > q -'--y~. VERTCAl. HOR10NTAl 5 foo 100 sea LE OO~~""~1~50~~200~""""""""~HO ::- ==s 200 )()O feet MllVOLTS TRAVERSE SEPARATON SCALE 50 TO NCH :z " s 1- "" M c '-- ". ~ '-'- ". (. '-. '-- ) ~ "OSQUTO-- - -' SHAFT. :J N DEX TO SHEETS 71 " J J ' < ~ 1 SHEET 2 " '' '. ~ ' ' j ~.' '~' ' -~- PLAn 2 j. SHEET t : &J > K : ) l a ' '- qoo SHEET 2 G 32 26

14 1"--' "---' ~ '" ~ ' PLATE 3 Q Q p GEOPHYSCAL SURVEY NEAR. l than TASMANA THE NORTH DUNDAS FELD COPPER NCKEL AREA SELF POTENTAL N Mll..VOLTS CONTOURS A z. - B c c D D E F ~.... G G H "" "" "" '"." t----t f-t_ --+-~ ~_#_-T--- j t '~~ J[ ~ " HB ~--+-_+_-+-t _+_ '1-----t t--.. -*"'-.-f ~ ~ f P J HA t HB LEGEND BASC DYKE.(A8ANOONE.O) MNE SHAFT.RALWAY H '" '" '" ~9' ~ TRACK. CONTOURS HDA BASELNE BEARNG (MAGNETC) HEA SCALE 100 r.' G 32-27

15 1 PLATE ' 1001 V TRAVERSE r l TRAVERSE F J.---' ~ J ~ ~ '" V) :L "" 100 :L {) "" ~ r T~ T T T-- boo T t qoo < '--'-' T r J qoo 1000 bo l "'- r '.._'" ' TRAVERSE G ~ 100 ~ X t~.. 80 f &0 l :1 Z : J ~ r-----t ' -._--- " :----- _.. -".-~ r boo r -- ~ r FEE T GEOPHYSCAL SURVEY NEAR ZEEHAN TASMANA THE NORTH DUNDAS FELD COPPER-NCKEL AREA SC ALE S MAGNETC VERTCAL FORCE PROFLES HORZONTAL 20 VERTCAL loo ~ 500 GAMMAS ~~--~ GEOPHYSCST '} }; -- " ' G 32-28'

Chapter 3, Solution 1C.

Chapter 3, Solution 1C. COSMOS: Cmplete Onlne Slutns Manual Organzatn System Chapter 3, Slutn C. (a If the lateral surfaces f the rd are nsulated, the heat transfer surface area f the cylndrcal rd s the bttm r the tp surface