the eastern bolivia mineral exploration project “proyecto precambrico”
Transcription
the eastern bolivia mineral exploration project “proyecto precambrico”
THE EASTERN BOLI VI A MI NERAL EXPLORATI ON PROJECT “PROYECTO PRECAMBRI C01 1 by Jevan P. Ber r ang6 The Precambr i an a厂east ern Br azi l i s now t he s ubj ect of a maj or p r o gr am o f t ec h ni c al c o ope r at i on ca r r i e d out j oi ntl y by Bri t i sh and Bol i vi an sci enti sts . 加 an area until now un kn own, f our or o ge ni c c ycl es h ave bee n i dent i fi ed r angi ng f rom 2000 Ma to l ate Pr ecambri an i n ape and anew Mesozoi c al kal i ne pr ovi nce has been di s c ov er e d. Thi s ar t i cl e p r e s en t s a ge ol o gi c al ov er v i ew of t he r e gi o n an d a n acc ou nt o f t he mi ne r al dep os i t s a nd pot e nt i al , i ncl u di n g t he f i r s t r egi on al compi l at i o n map. I nt roduct i on Or gani zati on of t he Proj ect Bo l i v i a c an co nv en i en t l y be di v i d ed i nt o t hr ee maj org eo - l og i c - p hy s i o gr a ph i c pr ovi nce s . The And ea n Mobi l e Bel t i t s s edi ment s , vo l ca ni c s and i g ne ou s i nt r u s i o ns o f Ph an er oz o i c a g e, f or ms t he mo un t a i nou s s out hwe s t e r n p ar t of t he cou nt r y 、V ilh and t ower s above t he f l at Quat er nary Al l uvi al Beni -Chaco Lo wl a nd s. The s e gi v e way ea s t wa r d t o t h e mor e r u gge d t er rai n f ormed by rocks of t he Pr ecambri an Shi el d. Tradi - t i onal l y, the Andean Mobi l e Bel t has been the s our ce of Bo l i vi a' s mi n er al wea l t h, i n cl u di ng t i n, s i l v er , l ead, b i s mut h, c o pp er , wol f r am, z i nc, a nt i mony, c admi u m and go l d. How- e v er , a s t h e r es e r v es her e ar e r ap i d l y be i ng dep l et ed i t i s neces sar y to fi nd ot her sources. The Precambr i an across t he b o r d er i n Br a zi l has dep os i t s of t i n , i r o n, man gan es e, gol d and di amonds, and t he Bol i vi an Shi el d was therefore an obvi ous target f or an ore- search program. The Ea s t er n Bol i vi a Mi ner al Ex p l o r at i on Pr o j ec t , us ua l l y r e f er r ed t o a s " Pr oy ect o Pr e cdmb r i c ol l , i s an Ang l o - Bo l i v i a n Tec hn i c al Co op er a t i on Pr o j ec t be i ng ca r r i ed out b y t h e I ns t i t u t e of Ge ol o gi c al Sc i en ce s QGS) on b eh al f of t he Over - s ea s Dev el o pmen t Admi ni s t r at i on ( ODA) i n co l l a b or a t i o n wi t h t he Se r v i ci o Geo l 6gi co d e Bo l i v i a ( GEOBOL) . Th e i mmed i at e ai m of t he Pr oj ect i s to make a r api d but systemati c i nt eg r at ed s u r ve y of t h e ge o l og y a nd mi ne r al p ot en t i al o f t ha t p ar t o f t he Pr ec ambr i an Br az i l i an Sh i el d l yi ng wi t hi n eas t e r n Bo l i v i a. The l o ng t er m o bj ect i v e i s t o a s s i s t i n t h e ove r a l l de ve l op ment o f t he r eg i o n by i d en t i f yi ng a r e as of pot e nt i a l l y v al uab l e mi ner al s a nd r ock s . Mi n i ng s uc h d ep os i t s cou l d i ncr ea s e Bo l i vi a ' s exp or t s a nd f o r e i g n ex cha ng e e ar n - i ng s , b es i d es b oo s t i n g t h e p r es ent r u r al ec ono my by pr ovi di n g empl oy ment an d enc ou r ag i ng t he b ui l d i ng of r oad s and o t he r Fi gur e 1: Cat ar at a Ar c o I r i s di scovere d by Pr oyect o Pre- c c f mbr i c o geol o gi s t s wh i l e ascendi ng the Ri o Paucema, Serrani a 月uanchaca. EPI SODES, Vol . 1982, No. 4. 3 by i nfr as truct ural devel opment, as well as s ti mul ati ng i mmi grat i on t o the "Ori ent e" ofsettl er s f rom the hi ghl ands. 物彝 ;寮法止羡 只 蕊绪 牛;典 nto two zones to be At the outs et t he Proj ect wasdivided i s ur v ey ed i n t wo ph as e s . Dur i n g Ph as e 1 , whi ch r a n f r om 1 97 6 t o 1 979 , r e co nna i s s an ce ( a t 1 : 100 0 00 0 a nd 1 : 25 0 00 0) geo l og i - c al ma pp i n g an d ge och e r ni c al s ur vey s wer e car r i e d out ov er t he S out he r n Zone一 t hat p or t i on of t he Pr eca mb r i an s hi e l d l y i n g s out h of l at i t ude 1 6' . Ph as e I l ( 1 9 80 -1 9 83 ) i nv ol v es d et a i l ed f o l l o w- up wor k o n p r o mi s i n g g eoc he r ni cal an omal i es an d mi n er al i z at i o n di s co ve r ed dur i n g Pha s e 1 , a nd al s o c on t i n ue s t h e r eco nn ai s s a nce ma pp i ng an d g eoc he r ni c al expl or at i on i n t he Nor ther n Zone. The Pr oj e ct ar e a i s a pp r ox i mat el y 220 0 0 0 k M 2, i . e. a f i f t h of t h e t o t a l a r ea o f Bol i vi a a nd ne ar l y t he s a me s i ze as Gh an a or t he Un i t e d Ki n gdo m. I n t e r ms o f b ot h t h e s i z e of t he ar ea 蘸彝 燕 蒸 beinf ! surveved and the num ber of U . K . M ecial ists invol ved 彝攀一 称摹一 窄 ki u-iu, vr oyecTo vr ecaM Dri co i s Tne i argesT ano m osT am- b i t i ou s ODA/ I GS geo l o gi c al an d mi ne r a l e xp l o r at i on p r oj ect e ve r mou nt ed. On e of t h e gr eat s t r e n gt h s of t he Pr oj ect i s t hat i t has been abl e to draw on the speci al i st ser vi ces avai l abl e i n the var i ous I GS uni t s, bot h i n the U. K. and by 彝 Fi g ur e 2: He l i c opt er wi t h al umi ni um c an oe t i e d u nde r n eat h, bei ng l oaded up pri or to l i f t- of厂介om t he bas . ecamp near t he Ri o Ver de, Ser r ani a Huanchaca. wor ki ng v i s i t s t o t he f i e l d as r e qu i r e d. As pa r t o f i t s con t r i bu t i o n, ODA h as pr ov i de d es s ent i al l y al l t he eq ui pmen t ne ed ed. Th i s i nc l ud es 1 7 La nd Rov er s and s p ar e par t s , can oe s and out boa r ds , c amp e qui pment , f i e l d s u r ve y i ns t r u men t s, r adi o t r an s ce i v er s , mi c r o s co pe s, s t e r eo - s c op es , dr a wi ng o f f i c e and l ab or at or y e qu i pment . At t he s t a r t o f t he Pr o j ect a comp l et e g eo ch emi ca l l abo r at or y was s e t u p i n t he Sa nt a Cr uz hea dq ua r t er s an d e qu i pp ed wi t h a r o ck cr u s her , an at o mi c ab s or p t i on s p ec t r o ph ot o met er , a p o r t a bl e X- r ay f l uo r e s ce nc e a na l y s er an d var i o us ot her i n- s t r ume nt s f or co l or i met r i c an d c hr o mat ogr aph i c ana l y s i s . By a l s o ma ki ng u s e of t h e GEOBOL op t i c al emmi s s i on s pec t r o- gr aph i n L a Paz, we ca n car r y o ut qu an t i t at i ve a na l ys i s f or Thu s be f o r e ge ol o gi cal wor k cou l d c ommen ce i n t hi s zo ne, b as emap s s h owi ng t he dr ai n ag e, r el i ef and ot her ge og r ap hi c f eatures had t o be prepar ed. These maps are based on i nt e r pr e t a t i o ns of enh an ced L ANDSAT i mag er y i nc l ud i n g col our c omp os i t es of L ANDS AT b an ds 4 / 5 / 7, and bl ac k- a nd - whi te bands 5 and 7, wit h detai l s added fr om conventi onal aer i a l p hot og r ap hy. The p r el i mi nar y map s ar e s ubs eq ue nt l y upg r a de d wi t h ad di t i o nal i nf or mat i o n, i nc l ud i n g ge og r ap hi c n ame s , g at h er e d i n t h e f i e l d. Th es e t op og r ap hi c b as emap s ar e t he ms e l ve s a ver y s i gn i f i c ant c ont r i bu t i o n t o de ve l op - me nt of t he r egi on an d ar e a l r ead y i n d emand by s et t l er s , r an ch er s , p i l ot s , pr o s p ect or s , l u mbe r co mpa ni e s and t he Na - about 25 di ff erent el ement s. As of September 1 982 some ti onal Centre f or Forestry. 2 36 00 s amp l es had be en ana l ys e d, wor k wh i ch i n vol ved mor e The Nort her n Zone i s an ar ea of trackl ess forest and swamp, t han 276000 el ement det ermi nat i ons. A compl ete petro- gr aph i c l a bo r a t or y was a l s o s e t u p i n Sa nt a Cr u z an d eq ui pp ed wi t h r oc k cut t i ng, gr i n di ng and p ol i s h i ng mach i ne s , mi cr o- s c op es , an el ect r oma gn et i c s e pa r a t or a nd ot he r e qu i pme nt f o r r out i n e t h i n - s e ct i oni ng an d mi c r o s co pi c exa mi nat i o n of r ock sampl es, and s eparati on of heavy mi ner al s f or mi cr os cop i c an d ge och emi c al s t u d i es . Th e GEOBOL con t r i bu t i on has i nc l u de d t he p r ov i s i on of co un t e r p ar t s t af f i nc l ud i n g a co- di r ec t o r , g eo l o gi s t s, c hem- i s t s , l a bo r a t or y a s s i s t a nt s , ad mi ni s t r at or s, d r af t s me n, s ecr e- t ari es, dri vers and fi el d l abour er s. GEOBOL al s o provi des of fi ces and l aborat ori es i ncl udi nR use of thei r ful i v eaui nr i ed u r _} } iaDoraTorv in 七a v az. in aaaliion. i : nev SUDDIV ine topogr apni c oas emaps k wnere avai i aDi e) , aeri ai, pnoi ograpns a n d e nha nc ed LANDSAT i mag er y. GEOBOL, al s o c ove r s r u nn i ng e xp en s es b ot h i n Sa nt a Cr u z a nd i n t he f i el d, al l l oc al t r a ns p or t cos t s i nc l ud i n g ch ar t er f l y i ng ( ex cl u di n g hel i co pt e r s wh i c h a r e p ai d f or by ODA) and ce r t a i n s er vi ces f or t he I GS team . Th e r e s ul t s of t h e Pr oj ec t a r e be i n g i n co r p or a t ed i n 21 co mpr eh en s i ve r e po r t s i n b ot h Eng l i s h a nd Sp an i s h. Some de s c r i b e t he ge ol o gy and mi ner al pot e nt i al of t he i n di v i du al ma p a r e as s h own o n Fi gur e 3, and ot h er s a r e de vo t ed t o t he mi ne r a l pr o s p ec t s b ei n g s t u di ed i n d et ai l d ur i ng Phas e 1 1 . The r e a r e a l s o ov er a l l s u mma r y r ep o r t s and one de t ai l i n g t he r e s u l t s o f t he a ge det er mi nat i o n pr o gr am. Al l t he s e r e por t s ar e b ei ng pu t on op en f i l e f or c ons ul t at i on at I GS ( Lo nd on a nd Key wo r t h) and GEOBOL ( La Pa z an d S an t a. Cr uz) . A nu mb er of s ci ent i fi c papers have al so been publ i s hed. Wo r ki n g i n Eas t er n Bo l i v i a At t he s tar t of the proj ect, the Proyect o Precdmbr i co ar ea was t er r a i nc o gni t a; i t had n ei t he r be en ma pp ed g eol ogi cal l y no r s ur ve yed s ys t emat i ca l l y f o r mi n e r al dep os i t s , a nd no topogr aphi c maps wer e avai l abl e f or the Nor thern Zone. 4 o nl y s p ar s el y i n hab i t e d a nd l ac ki n g i n r oa d s. Fi el d wo r k he r e i s carri ed out bv maDDi n2 br i 2ades consi sti nQ of one Bri t i sh ano one bonvi an geoi ogi s t, ano si x t o t en peons wno i n a dd i t i on t o t he i r o t her du t i e s c ut l i n es , ba ck- pac k f oo d and e qu i p me nt , h un t an d f i s h and make ca mp. I n or d er t o g ai n a cc es s t o and mo ve abo ut wi t hi n t h ei r ar eas t he b r i g ad es u s e DC3 ' s and s i ngl e en gi ne pl ane s , hel i c opt er s , Lan d Rove r s , ox - c ar t s and ho r s e s , woo den l au nc hes , du go ut s and a l umi nu m c an oe s . Eac h ye ar i nd i vi d ua l br i ga d es ha v e cu t many t e ns o f k i l o met er s of " r oad " t h r ou gh t h e f or e s t t o g i ve acc es s f o r t he Lan d Ro ver s , whi l e ma ny hun dr ed s o f ki l omet er s o f j un gl e t r a i l ar e c ut and s ur vey ed on f oo t . The s t a t i s t i cs t e l l n ot h i ng a bo ut wa di ng t hr o ug h s wamp s , t he s war ms of bi t i ng i ns e ct s , t he s i c k nes s es and i n j ur i es t ha t h av e t o b e co ped wi t h, t he d es er t i o n of pe 面s , t he d i et o f monk ey me at an d r i ce, and t emper atures i n t he shade greater t han 30'C! The mos t di f f i cul t a nd h az ar dou s f i e l d o pe r at i o ns i n vol ved t he map pi ng of t h e S er r an i a Hu a nch ac a d ur i ng 1 980 an d 1 981 . Thi s was t h e ar ea exp l or ed i n 1 90 8 at t he r e que s t of t he Bol ivian i zovernm ent ;bv Eni zl ish survevor. Lt. C ol. Percv r i ar ri son r awcett . i qe i ront i er Det ween bonvi a ano br azi j at t hat ti me was uncer tai n and Fawcett l ed an exDedi ti on UD the Kt o verue to its source in tne , jerrani a m uancr i aca. u n r us r et ur n t o Lo ndo n, hi s gr a ph i c d es cr i pt i on s t o t he Roya l Ge og r a ph i c S oc i et y o f t he f or e s t e d " Gr e en Hel l " al ong t he Ve r de and e s p eci al l y o f t h e my s t er i ou s Hu an ch aca t a bl e l an d bo und ed on a l l s i de s by pr ec i p i t ou s cl i f f s, s t i mu l at ed S i r Ar thur Conan Doyl e to wri te hi s cel ebrat ed book "The Lost Wor l d " whe r e Ju r a s s i c an d Cr et a ce ou s f au na an d fl or a, i nc l u di pg di nos au r s , we r e s u pp os ed t o be p r e s er ved . J Geol ogi cal Rel ati onshi ps The Pr ecambr i an r ocks of east ern Bol i vi a devel oped duri ng f o ur or og en i c cyc l e s ( L i t h er l an d a nd Bl oomf i el d , 1 9 81 ) . The ol des t r o ck s ar e as s i gn ed t o t he Tr a ns - Ama zo ni a n Cycl e EPI SODES, Vol . 1982, No. 4. b el t s f or mi ng s yn cl i nal dep r es s i on s of l oca l f ac i e s var i at i o ns . 土2 600 Ma) and are r epres ent ed by t he Lomas Maneches Gr anul i t e Gr oup and t he bul k of t he Chi qui tani a Gnei ss These schi s t bel ts ar e mai nl y composed of metapel i t i c schi s ts wi th a vari abl e meta- ps ammi ti c f ract i on, and i ncl ude thi n l ayer s of gr aphi ti c schi sts , cal c-si l i cat es, met a- i ronst ones and meta-vol cani cs. There i s al so a basi c/ ul tramafi c si l l - Comp l ex . Th e s e un i t s ar e c ompo s e d e s s ent i a l l y o f h i gh - g r ad e gr anul i t es and paragnei ss es, most ly of met asedi ment arv ori - gi n i Dut mci uai ng Dasi c nypersT nene granuutes ano enc i eroi ti c g r an ul i t e s co ns i d er e d t o b e i gn eou s . 丁he en s i al i c S an I gn aci o Cyc l e( <18 00 -13 00 Ma ) b ega n wi t h f or mi ng p ha s e. The cy c l e cul mi nat ed i n t h e Sa n I g nac i o Schi st Group that i s mai nl y repres ented by di s crete s chi st nerated ext ens i ve mi gmat i tes, synki ner nati c GI and post- Orogeny 一 a regi onal NW-tr endi ng tect ono-metamorphi c ev ent t h at r e wo r k ed t he ol d er gr a nu l i t e b as emen t and g e- t he de po s i t i o n of t h e s ed i men t s now f or mi n g t he Sa n I gn aci o 困口一 翻卿团 一 翼翻一 困困椰因一 困团画皿困一 困国 PHANEROZOI C UNI TS QUATERNARY 充 + + + RED SAN DSTO NES CRETACEOUS 之 一 + 丈_ 十 I 愁 。J _ 准_ 1 _ 1 Q 1 - _ } G + 2 + 9 F 乏。 _ _ 三 入, 十- f }十 十\ %I ,. + + 十 十 M AU WAL . JURASSI C一 ALKALINE I GNEOUS ROCKS CRETACEOUS + S e r r a n i a 。 刨 牵 洁 // SI LURI AN-D EVON(AN TECTONIC SLIDE 生护 , -燕 R T ( 7. ' .十 干、 十 户 , \ + + + 六翻炭 花 ‘ 洛 廿 +G, + 夕 斗 十 广丈 李又 。 点十2 + A 1 + 7 t - r + G1 + 2A 斗 } 飞 嗽奥 21 3 豁 牛 CHI QUI TANI A GNEI SS COMPLEX 11800 ma一 一 一 _ CHI QUI TANI A GNEI SS COMPLEX TRANS 一AM AZO NI C 16'S 弃2 A 二 丁I Ta 台1 2R 2〕G } 3二万 28 一 件 熟 一欲 玲 2R G3 SANJOSE 、 Ri nc6n del T i gr e 盯 I gneous Compl ex 犷, ( S } J 7 . 0 01 30RE G3 C. 氰 , A v ( a / 篡麟 耸 刃 「| 一 L| 」 K " 扩 :入 绘 台心7 ,棍节 k 飞 J曰 150km }火 枯 ,,,: 户日 、, : G1 100 。, 26 5一 k 切 2R 七分・ 、 厂尔 So 50 口 效】 a1 4G 穷了伙、 1 6* S \ 、2日 负 C A a f k , a d t e i n l e a r i C a o m p i o x 气 :. .… …盆 哥解 夕 签 ) ‘ 一 介 SAN MATI AS 一囚d咤n心团 招酥 叭04 毅 臀滚 2 A - N - 勘 丈一-A 子 _ 2日 - 卜之0‘」 _ 1 _龚 奎- T " - - -丝 } l 篡 SAN IGNACIO. 攀S -1 . , C r . . S , JP8/D8 LOMAS MANECHES GRANU LITE GROU P G3 BO LIVIA BASI C AND ULTRABASI C ROCKS SAN I GNACI O SCHI ST GROUP 、{G, Ta SYNTECTONIC GRANI TOI DS t 撰 01, 心3 POST-TECTONI C GRANITOI DS 巧0 品尹 万 I O N( F拼 G1又 G, Au v旧 O SIG ROUPS -130OMa一 一 ~ 一 + C + I P A I 6 ! E N T + 0 I v V v 、 , . 八 探生班 任 袭 召心 HUANCHACA, SUNSAS AND 〔 3 UL TRABASI C AND ASSOCI ATED ROCKS SA N IGNAC I O + } A ' 扮 Sn 锡月 熟 NJ 飞 j 冬刊训门 诀理卜 日呀 仆 . 自 士卜叹夕 、 川 合 _ 、 任尸 - SYNTECTONI C GRANI TOI DS 协 i f 蕊 A S C E N 5 S . I O e N l x } 1 - G4 POST-TECTONI C GRANITOI DS SU NSAS + i ' l l 一 3 欲" M O NTE VERDE 士950m ._ 一 _ _ 十 + ( unconf or mi t y} BO G UIG RO UP W + 丫 锁 }呀帝 彭 1 } 戈 才、十、+ 资范: 重丰 BRASI LI ANO V - A i } v + ' + % I A + G I 淤斗共 澎 ; 氰 牛 十 G2 , ( 〕三) 十 创{, + - 2} } 心匕 . 一 TU CAVACA GROU P \ 广 + 斗 夕 犷泥 + + + O ROG ENIC CYC LE 龙车 洲- 4- 十 + + 、十 G1 半 币 3 弋 + 十 ,牛一 3拜 CARMEN M URCIELAG O GRO UP PROTEROZOI C ROCKS 泞 + 蕉俄加 0。,刽叫‘} 到 砚 丫 'BAURES SANDSTONES,SHALES ?CAM BRI AN ,( LLAZON EL MAJOR FAULT L ALLUVIUM 汉 - 卜} } ) 1 } " )、 1: 1 00, 000 geol ogi cal map and repor t 1: 250, 000 geol ogi cal map and r epor t 0一却 The most important mineral prospects &/Or deposits Fi gure 3: Geol ogi cal Compi l ati on Map a厂Easter n Bol i vi a. EPI S ODES, Vol . 1 982, No. 4. 5 ki nema t i c G2 g r a ni t e s . I n t h e No r t h er n Zo ne t hes e f or m t he ver y extensi ve Pensami ento Gr ani toi d Compl ex. Th e Sun s a s Or oge ni c二艺SL e( <13 00 - 95 0 Ma) b ega n wi t h t he er os i on of pr e- e xi s t i ng r oc ks a nd dep os i t i on of t he mol as s e- l i k e s e di me nt s as s i g ned t o t he Su ns a s , Vi bos i and Hu an ch aca Gr oup s . S ubs eq ue nt def or ma t i o n o f t he s e and ol der r oc ks was es s ent i a l l y c on f i ne d t o t he NW- t r en di ng cur vi l i ne ar S uns as Or oge ni c Be l t now f o r mi ng t he s ou t hwe s t e r n p or t i on o f t he s hi el d ou t cr op. Def or mat i on wa s acc ompan i e d b y a ma j or ph as e of gr an i t oi d ( G2 , G3 ) d ev el op ment . The ou t cr op pat t er n o f t h e S an I gna ci o Gr oup s c hi s t be l t s i n t h i s S uns as Or oge ni c Bel t i s d ue t o ov er p r i nt i ng by t h e Su ns as Or o gen y. The nor t h eas t er n mar g i n o f t he Su ns a s Or o gen i c Bel t i s f or me d by t h e t ec t o ni c Conc epc i 6n a nd Sa n Di a bl o Fr on t s or " s t r ai ght en i ng z one s " be t ween i t a nd a qu as i - c r at on i c Mar gi - nol Zo ne t hat o nl y un de r went mod er a t e an d l oca l i z ed d ef o r - mat i on. Furt her toward the NE thi s semi - stabl e zone pass es i n t o t h e Par a gu a Cr at on, a r i g i d st a bl e b l oc k on wh i c h t he S un s as s ed i men t s a r e es s ent i al l y u nde f o r med. The cl os e of t he Sunsas Cycl e marked the cratoni zati on of the shi el d. The Ri nc 6n del Ti g r e La ver ed I gne ou s Co mpl e x(1 9 92 Ma ) i s de s cr i be d b y Fl et c he r e t al . ( 1 9 81 ) . Mor e r e cen t d et a i l ed mapp i ng s hows t ha t Cer r o Man om6 i s f or med of a hi g hl y br ecc i at ed and i nt ens e l y s i l i c i f i ed p ar agn ei s s co r e s u r r o un ded by a l e s s h i ghl y a l t er ed au r eo l e. Thes e ar e al l c ut by a n i r r eg ul a r net wor k o f car bon at i t i c dy k es and s h eet s t hat h ave al s o und er gon e p er vas i ve mul t i ph as e hy dr ot her ma l al t e r at i on ca us i ng d es t r uc t i on of al l t h e car bo nat e mi ner al s , i nt e ns e s i l i ci f i ca t i o n, a nd acc ompa nyi ng l i ber at i on and de po s i t i on o f a range of mi neral s descr i bed bel ow. Mi nor amount s of apa t i t e r oc k, agg l omer at es and l a vas al s o occ ur . Nume r o us ups t an di n g qu ar t z b r ec ci a r ee f s cut t he b as ement comp l ex and t h e r o ck s o f t he Ve l a s co Al kal i ne Co mp l ex around whi ch t hey are part i cul ar l y common. They are pr o ba bl y of Te r t i ar y ag e and co ns a ngu i ne ou s wi t h t he s i l i c i f i - cat i on of Cer r o Ma nom6. The Ter t i ar y h i s t or y i s al s o mar k ed b y t hr e e t o f o ur s uc ces s i v e cyc l es of l at er i l i z at i on Mi neral i zati on Nu mer ou s mi n er a l s howi n gs and geo che mi cal an omal i es ha ve b ee n f ou nd d ur i ng t he cou r s e o f Pr oy ec t o Pr ec z i mb r i co, a nd a l t h ou gh on l y a s mal l f r a ct i on o f t h es e c an be ex pe ct e d t o a l ayered si l l -l i ke pl uton esti mated to be between 3000 and eventual l y devel op i nto economi c mi neral deposi ts, a number 4 60 0 m t h i c k, me as ur i ng s ome 62 x 2 7 km and ex po s ed ove r of t h em l ook v er y p r o mi s i ng a nd war r ant f u r t h er wo r k. I n a ddi t i o n t o t h e mi ner al p r o s p ect s act ua l l y di s cov er ed b y Pr o yec i o Pr ecAmb r i co t h er e ar e ot her i mpor t ant mi n er a l an ar ea of about 720 kM2. I t compr i ses a basal Ul tr amafi c Uni t ( max. 30 00 m) of al t er nat i ng cy cl i c uni t s i nc l ud i n g s erpenti ni zed duni tes, bronzi ti t es, pi cri te, mel anor i te and fi el ds that have been known for some ti me and whi ch i n the h ar z bu r g i t e; a med i an Ma f i c Un i t ( max. 155 0 m) of nor i t e, mag ne t i t e g ab br o a nd t hol ei i t i c gab br o; a nd a t opmos t Fel s i c Uni t ( 7 50 m) of g r a nop hy r e. Th e pl u t on was i n t r u de d i nt o t he Mar gi nal Zon e, d i f f er e nt i at ed a nd t hen ope n- f ol de d wi t h l i mb d i ps of up t o 450 . Thi s r e n ewed i nt er es t i s l a r g el y a di r e ct r es ul t o f t h e i nt e r es t i n t he mi n er al p ot e nt i al of t h e Pr ecamb r i a n s hi e l d ge ner at e d by t he Pr oj e ct . The mos t i mpor t an t mi ne r al i z ed ar eas i n t h e r e gi on a r e s ho wn on t he map and ar e d es cr i b ed i n t h e The Br a zi l i an Or og eni c Cy cl e ( <95 0 - 500 Ma ) i s r e pr e s e nt e d i n Bol i vi a b y un met amor p h os ed s e que nc es on t he e as t er n and s out her n mar g i ns of t he s hi el d. I n t he ea s t , geo s y ncl i na l s edi ment s of t he Boq ui Gr ou p t h at i s an ex t en s i o n o f t h e Par agu ay - Ar a gua i a bel t i n Br a zi l ( Al mei da et a l . , 1 97 6) , c ompr i s e con gl omer at e s ar k os e s, s hal es , l i mes t on es , g r ey - past few years have begun to be worked on a smal l scal e. f ol l owi ng. Cer r o Ma nomo wa s f i r s t i de nt i f i e d on s at el l i t e i mag er y b y I GS geo l o gi s t s i n 1 976 pr i or t o t he s t ar t of t he Pr oj ect and was a t ar get f o r i nve s t i ga t i o ns ear l y i n Ph as e 1 . Ano ma l ou s concentrati ons of ni obi um, vanadi um, rare earth el ements, s c and i u m, t ho r i um, ur ani um, bar i um and pho s ph at e wer e wackes, banded i ronst ones and cherts. These were l ocal l y found i n i ts soi l s and rocks. Thi s s ti mul ated detai l ed f ol l ow- f ol d ed abo ut N- t r en di ng ax es , an d a r e unc on f or mabl y o ver l ai n b y t h e Mu r ci jl a go Gr o up o f r ee f and non - r ee f l i me s t o ne s of p r ob ab l e Ca mb r i an ag e. On t he s o ut h er n f l ank of t he s h i e l d t he mi oge os ync l i nal dol omi t i c l i mes t on e s, s and s t one s and s h al es of Tuc av aca Gr o up ar e c on f i n ed t o a WNW一 t r end i n g f a ul t - con t r o l l e d b a si n ( au l a co gen) . Th e u n conf or ma bl y ov er - up wo r k i n Pha s e 1 1 t hat i ncl ud ed t he con s t r uct i on o f a c ont ou r ed 1 : 1 000 0 s ca l e t op ogr aph i c b as e map of t he moun - t a i n, det ai l ed geo l o gi ca l map pi ng, ge oc hemi c al s amp l i ng of s o i l s and r oc ks , p i t t i ng, r a t emet er and s p ec t r o me t er s u r v eys , an d t hou s and s o f c hemi c al ana l y s es of t he s a mp l es co l l e ct e d. l i e rocks of t he Sunsas Cycl e i n t he west and the Boqui Gr oup Mes o zo i c i gn eo us ac t i v i t y i n ea s t e r n Bol i vi a i s r ep r e s e nt e d t hr ee s e par at e al ka l i n e co mpl e xes . Th es e l i n e up al on g me ga l i nea me nt t ha t i s a co nt i nu at i on of t h e Par ag uay Bel t r e gar ded as a f a i l e d ar m o f a t r i p l e p oi n t r e l a t ed t o t he b r eak - up of t h e S out h Ame r i c a- Af r i ca pl at e ( Fl et c her a nd Li t he r l a nd, 1 981 ) . Thi s wor k has proved the exi st ence, on the Eas ter n Spur, of a m easures some 20 x body of r adi oacti ve apati terock. This 115 m at the sur face wi th a mi ni mum measured r es erve, based p i t t i n g , o f 5 8 0 0 0 me t r i c t o n s . I t h a s a n a v e r a g e on 9 门〕 吻a i n the east . rade 01 3. 5% P2 05 ( r a ng e1 . 5 - 22 %) ; 0. 1 % U ( r an ge 0. 01 - The three- . 57%) and 0. 2% Th ( r an ge 0. 05-0. 84%) . known and di mens i onal f orm of the apa ti t er ock body i snot d r i l l i ng i s now r eq u i r ed t o det er mi ne t hi s and the total t o nn ag e an d gr a de of t he or e. Al t hou gh t oo hi gh i n i r on t o b e The vol can o - pl ut o ni c Ca ndel ar i a Al kal i ne Co mpl e x ( 11 6- 9 0 Ma) occ ur s al o ng s i d e t h e E- t r en di n g Mer c ed es Ri f t . i t comp r i s es a ne ph el i n e s y en i t e pl ut o n a nd a s ep ar at e bo dy f ormed mai nl y of nordmar ki t e and trachyte wi t h mi nor f oy ai t e a nd p ho no l i t e p has e s . Ou t l i er s o f re d co nt i nen t a l - t yp e Cr et ace o us s a nd s t o ne s ou t cr op near by. The El Ti g re A卜 kal i ne Compl e x i s a coa r s e- g r ai ned nor dmar ki t e pl ut on , s ome 42 km i n di a me t er , s ho wi n g pr o mi ne nt cumul at e l a ye r - i ng and cur r en t bed di ng. The Vel a sc o Al k al i ne Compl e x ( 1 46 -1 3 4 Ma) i s by f ar t h e l ar ge st of t h e t hr e e c ompl e xe s . I t co ns i s t s of an e ar l y v ol c an i c s ui t e o f ag gl o me r at es , wel de d a nd b r ec ci at ed t uf f s a nd p or p hy r i t i c t r a chy t e f l ows , and a s er i es of 1 4 i nt er f e r i n g ci rcul ar, ri ng and el l i pt i cal pl utons i ncl udi ng f oyai te, pul as - te, ri ebecki t e gr ani te and k i t e, no r dmar k i t e, q uar t z syeni Fl etcher and b i ot i t e gr a ni t e a s t he m ain rock types ( km 2 and Li ther l and, 1981) . These pl utonsc o ve r som e 440 oc cu r li es a 6 on a NE- t r en di n g l i nea ment , atthe N E end of w hich carbonati ti c compl ex 一 Cerr o Man omd 一 or i gi n al l y Fi qure 4: Ri o Ver de basecamp on t he Serr ani a Huanchaca. EPI SODES, Vol . 1982, No. 4. s ui t abl e f or t he manu f ac t u r e of s uper ph os p ha t e, t he r o ck c oul d b e us e d as a s mal l - s cal e s our ce o f f u s ed s o da pho s p hat e f ert i l i zer. El sewhere on Cerr o Manom6 enri chment i n ni obi um and rare eart h el ement s has been confi rmed but at l evel s too l ow to be of economi c i nter est. The Ri nc6 n del Ti gr e I gn eou s Compl e x was r e co gn i z e d e ar l y o n as a p ot e nt i al l y f a vou r ab l e t ar g et f or as be s t os , ni c ke l , copper, and pl at i num mi neral i zat i on and was therefor e s t udi ed i n s o me det a i l du r i n g一 Pha s e I . The r es ul t s of t he g eoc he mi cal s ur v ey s wer e s u f f i c i ent l y enc ou r ag i ng t o war - r ant f o l l o w- up wor k du r i n g Pha s e I I , an d det ai l e d ma ppi ng, t r en ch i ng a nd pi t t i n g, geo che mi cal a nd ge oph ys i ca l s ur v ey s wer e ca r r i e d ou t o n s ur vey ed gr i ds cut a cr o s s t he a nomal ous areas. Al t ho ug h c hr omi t e an d as b es t os h av e bee n f ou nd i n t h e Ri nc6n r o ck s, r es u l t s t o d at e s u gg es t t h at t he s e mi ner al s d o not occur i n suffi ci ent concentr ati ons t o be of economi c i n t er es t . Howev er , pi t t i n g a nd s a mp l i n g i n t he Cer r o Pel o n s ec t or of t he c ompl e x has l ed t o t he f i r s t do cu me nt e d di s co ver y of g ar n i er i t i c ni cke l i n Bol i v i a. The ni ck el d ep os i t s ave r a ge 1 . 0 % over a met e r t hi c kne s s , t o t al l i n g ap pr ox i ma t e l y 50 000 tonnes of metal l i c ni ckel . Thi s i s i ns uf f i ci ent to mi ne, b ut as on l y 7 kM2 of app r o xi mat el y 550 kM2 u nd er l ai n by ul t r ama fi c r oc ks i n t he Ri n c6n comp l ex hav e b een s y s t emat i - cal l y pr o s p ect e d, t h e p ot e nt i al f or t h e di s cov er y o f f ur t her ni ckel i s consi der ed to be rel ati vel y hi gh. Det ai l ed s t u di e s of t he r econ na i s s anc e g eoc he r ni c al anoma - l i es hav e r es ul t ed i n t he d i s c ov er y of wi de s p r ead di s s e mi - n at e d co pp er mi ne r a l i z at i o n i n t he magn et i t e ga bbr os f or m- i ng pa r t of t h e ma f i c u ni t of t h e c omp l ex, wi t h l o cal concentrati ons of between 1. 5% and 2. 0% copper. Loose Fi g ur e 5: Ma nha ndl i ng h ea vi l y l a de n al umi ni um c an oe up rapi ds on t he Ri o Negro. t o 53. 5 g. A l ot o f go l d r emai n s t o be won f r om t he a r ea wh i ch i s s ui t abl e f or s ma l l pl ace r op er at i on s. Gi ve n go od val ues these coul d hel p fi nance a search for economi c con- cen t r a t i ons of b edr ock gol d i n t h e ar e a, whi c h al s o h as b as e metal possi bi l i ti es. bl ock s of ma s s i ve ch al c oc i t e - cup r i t e- ma l a chi t e- nat i ve c op per ha ve a l s o bee n f ou nd. The r e s ul t s ar e ve r y enco ur a gi ng, and dr i l l i ng ma y b e car r i ed o ut i n 1 983 . Th e As cen s i 6r i de Gu ar a Vo s Ti n厂 i el d was f oun d b g y eo- Ser r a ni a Sa n Si mc } n q ol df i el d: Go l d i s r umou r e d t o ha ve bee n mi n ed i n S er r ani a Sa n S i m6n by t he I n cas , bu t t he f i r s t aut hen t i c at e d mi ni n g was by t he J es u i t s ove r a p er i od of 30 - ques duri ng Phase 1 1 and is the chemi cal pros pecti ng techni and fr om the ' mother l ode' . Then f rom 1905-1920 Sat ur ni no ner al i zat i on i n Pr ecambri an r ocks of fi rst di s cover y of t i nm i one of them a m ean of 600Jg of 3 ha- beenfound, Sn02 perm wi th up to al most 4000 gof ese a met ers of sandy gravel . Th( re very i nteresti ng val ues Sn0 2 pe r m 3 i n t he ba s al t wo comparabl e wit h grades of al l uvi al cass i teri te mi ned i n Brazi l i n the di scovery of copper -l ead-zi nc anomal i es i n soi l s and s t r ea m s edi ment s . The g eol ogi cal e nv i r on me nt i n whi ch t h es e an omal i es occ ur i s ver y f a vour ab l e and i s a na l o gou s t o bu yi ng ext r a mi n i ng equ i p me nt a nd abs co nde d wi t h a l i t e r b ot t l e o f g ol d . Two s epa r at e s ma l l ope r at i on s wer e con du ct ed 1 94 4 t o 1 945 and 1962 t o 1964, and as al ways t her e are numerous tal es of the di scovery and l oss of great ri ches. A det ai l ed fi el d 谗嗜薰 g eoc her ni ca l p r os p ect i ng i n t h i s a r ea d ur i n g Pha s e I r es u l t ed to a hal t when Boyd j ourneyed to the USA on t he pret ext of as ses sment i n 1974 concl uded that the auri f er ous quartz vei ns 粼 训一 S on Jo s j de Chi qui t os : Reg i ona l ge ol o gi c al mapp i n g a nd al l uv i a l and har dr o ck mi ni n g op er a t i o ns . The op er a t i o n ca me 翻 翻引 只资 厂1 肠』 冲 招拢淤 ; 、 热欲 a nd Mal ay s i a. Ac co r di n gl y, a d r i l l i ng pr og r am d es i g ned t o e val u at e t he t i n f i e l d h as b een dr a wn u p and may b e ca r r i ed ou t dur i ng 1 983 . Saucedo, t he l ocal baron of t he area who commanded about 80 sl aves, and his associ ate Juan Boyd s upervi sed bot h 敷 derived from t he weather- eastern Bolivia. The cassiterite is i ng of pe gmat i t e dy ke s a nd i sconcentrated i n the gravel fraction of t he al l uvi um wi thi n nearby canyons. Three in shall ow drillho l es have been put down i nthe canyonsand 40 years i n t he 18t h Centur y. Rel i cs of thei r worki ngs s ugg es t t ha t t h ey won a gr eat d ea l of g ol d, bot h f r om pl a ce r s 龚 呱 t h e Kat an gi d e- Damar i de Be l t of c ent r al a nd s ou t h wes t er n Af r i c a. Fo l l o w- u p s ur vey s i n t he San J os 6 ar ea d ur i ng Phas e 1 1 ver i f i ed t he s e i nt er e s t i n g bas e- met a l anoma l i e s an d l oc at e d 豁 吕 黔萝 巍 薯 哪黎 ot her Pr ecambri an s edi ment ary and vol cano-sedi mentar y st rat i for m ores such as t he copper and l ead-zi nc deposi ts of 玺 ‘1 , 尹 沂面盛 诀 哭叹 zones of al terat i on and sul phi de mi ner al i zati on. Fur ther detai l ed work has been recommended. S an J avi er / San Ram6 n g ol d f i el d: Al l u vi al gol d, di s c ov er e d i n the Sant a Ros a de ] a Mi na area to t he s out h of San Javi er, was mi ned sporadi cal l y fr om 1888 to the mi d-1950s. At one ti me over 7000 peopl e were empl oyed. I nter est has agai n been ki ndl ed by Pr oyect o Precdmbri co and the rel ati vel y hi gh 滋 缝 簿 蒸鬓黔蒸汀一 pr i ce of gol d. A s ma l l g ol d r us h s t a r t e d ear l y i n 1 9 82 wi t h t he r edi s co ver y o f g ood p l ac er gol d val ue s i n a c r ee k ea s t o f San Ramdn. Dur i ng t he f i r s t t hr ee we eks o f t he r us h ab out 1 3 ou nce s of gol d wer e won by l oc al coo pe r at i ve s us i ng ver y pr i mi t i v e t echn i q ues . The gol d or i gi n at e s i n q uar t z ve i ns and Fi gur e 6: Bol i vi an ge ol ogi s t co l l e ct i nq a qeo c hemi c al st r e am occurs i n al l si zes from mi nute fl akes t o nuggets wei ghi ng up sedi ment sampl e f rom t he Ri o Tarvo. EPI SODES, Vol . 1982, No. 4. 粉 获奖燮掩 7 i n one s ec t or co ns t i t u t e a n ex p l oi t ab l e zo ne over 3 x 1500 m car r y i n g an av er age of t wo t o t hr ee gr ams per t o nne, wh i c h as s umi n g a mi n i mum d ep t h o f 1 00 m was es t i mat e d t o r ep r es e nt a r e s er ve o f 578 70 t r oy ou nc es o f go l d. The Sa n S i m6n g ol d f i e l d i s b ei n g s t u di e d i n de t ai l b y Pr o yec t o Pr e - c6mbr i co geol o gi s t s a nd t he r e s eems l i t t l e do ubt t h at muc h gol d sti l l remai ns to be won. Th e Sa n I g naci o and Co nc e pci 血 pe gmat i t e f i e l d s: The comp - l e x pe gma t i t es s out h o f Sa n I gn aci o and Con cep ci dn wer e o r i gi nal l y mi n ed f or mus c ov i t e and b er yl bu t pr o du ct i on ha d cea s ed by 1 968. Howeve r , i n 1 9 80 i n t e r e s t i n t he s e p egma - t i t e fi el ds was renewed and sever al of the m i nes wer e r eopened by l ocal smal l mi ners i n order t o ext ract tantal i t e ( pr i ce i n 1 981 ar ou nd ¥85 / l b) an d co l u mb i t e. Pr oj e ct geo l o - g i s t s ha ve h el p ed t he l o cal mi n er s b y pr ov i d i ng e nco ur age - ment and advi ce and have themsel ves carri ed out det ai l ed s u r v ey s a i med at f i nd i ng t a nt al i t e - co l u m b i t e p eg mat i t es i n t he ar ea. Four d i s c r et e g eo che mi ca l t an t a l i t e a nomal i es ( r ang e 1 3 0 - 560 pp m Ta ) no t a s s o c i at ed wi t h kno wn p eg- mat i t e s ha ve b een f oun d i n t h e S a n I g nac i o a r ea. Fur t her de t a i l e d p r o s pe ct i ng f o r t an t al i t e- b ea r i n g pe gmat i t e s i s i nd i ca t ed by t he s e en cou r a gi n g r es ul t s . La Gai b a- Anai r oc k c r v s f a l an d amet hv s t厂 i e l d: I n t he ea s t er n e x t r e mi t y of t h e Pr oj e ct ar ea, n ear t he bo r d er wi t h Br azi l , ext ensi ve depos i ts of quar tz, amethys t and ci tr i ne oc cu r i n s i l i c i f i ed n or t h- t r end i n g f aul t z o nes c ut t i ng Camb r i an l i me s t o ne s . Thi s s emi p r e c i ou s gemf i el d i s s ai d t o h ave b ee n f i r s t d i s c ov er ed i n a bou t 1 960 and h as yi el d ed un kn own qu ant i t i es o f g em ma t er i a l o ver t h e p as t 20 yea r s , t h ou gh i t i s on l y s i nce 1 980 t h at t he d ep os i t s ha ve b een ex pl oi t ed on a l ar ge s c al e. Amet h ys t s a mp l e s ar e of v er y h i gh q ua l i t y , and gi ven t he r i g ht co nd i t i ons i t s ho ul d be p os s i b l e t o de ve l o p t hi s ge r n f i e l d an d s t a r t a l oc al cu t t i n g and po l i s h i ng i n du s t r y. Trai ni ng En g l i s h l an gu age t r a i ni n g ha s al s o be en p r ov i ded i n S ant a Cr uz , and f ou r GEOBOL g eol og i s t s wi t h s uf f i ci ent co mma nd of En gl i s h ha ve be en s en t t o t he UK t o t a ke s p eci al i s t courses. Perhaps most val uabl e of al l i s the i n-ser vi ce t r ai ni n g al l GEOBOL s t af f h av e r e ce i ve d whi l e wor ki ng al on gs i de t hei r ODA col l e agu es , b ot h i n t he f i e l d and i n t he l a bo r a t o r i e s and dr awi ng of f i ce. I n ODA, wher e t r ai ni n g i s c on s i d er ed t o be a ver y i mp or t a nt pa r t o f t ec hn i ca l coo per a- t i on pr oj e ct s , t he p hi l os o ph y i s : " Gi v e a man a f i s h and y ou f eed h i m f or a da y. Tea ch hi m t o f i s h a nd y ou f ee d h i m f or a l i f eti me". References Al mei da, F. F. M. de, Hasui , Y. and Bri to Neves, B. B. , 1976. The Upper Pr ecambri an of South Amer i ca. Bol. I nst. Geoci enc. Uni v. Sdo Paul o, vol . 7, p. 45-80. Fl et c her , C. J. N. a nd L i t he r l a nd, M. , 1 981 . The g eol ogy and t ec t o ni c s et t i ng of t h e Ve l a s c o Al ka l i ne Pr ov i n ce, ea s t e r n Bo l i v i a. J. g eo l . S oc. L on do n, vo l . 13 8, p . 5 41 - 54 8. Fl e t ch er , C. J. N. , Ap p l et o n, J . D. , We bb, B. C. and Ba s ha m, I . R. , 1 981 . Mi ne r a l i z at i on i n t h e Ce r r o Ma nom6 car bon a - t i t e c ompl e x, ea s t e r n Bo l i v i a. Tr an s . I ns t . Mi n i ng an d Met a l l u r gy , v. 9 0, p. B3 7- B50 . Li t her l and, M. and Bl oomf i el d, K. , 1981. The Proter ozoi c Hi s t o r y o f Eas t er n Bo l i vi a. Pr ecamb r i an Re s e ar c h, v. 1 5, p. 157-1 79. A BOU T THE AUTHO R: Dr . Jev an P. Be r r an g6 wor k ed i n Ca na da, Gr e en l an d a nd Ni ge - r i a bef o r e j oi n i ng t he Ove r s e as i筹夔 攘 Di vi s i on of t he I nsti tut e of Geo- l og i ca l Sc i e nce s ( U. K. ) i n J an u- ary 1966. Si nce then he has Not a l l ou r ef f or t ha s b een put i nt o b us h- b as hi ng a nd l oo ki n g f o r mi n er al de po s i t s : t he t r ai ni ng o f Bol i vi an cou nt er p ar t s t a f f ha s be en ano t he r i mp or t an t as pe ct of o ur wor k. At t he s t ar t of t h e Pr oj e ct f or mal c ou r s e s wer e g i v en by t h e I GS e xp er t s on a wi de r an ge of geo l o gi cal s u bj e ct s . As par t o f o ur t r ai ni n g pr og r am t wo i l l u s t r at ed b oo kl e t s on s t r u ct ur a l g eol o gy an d met amor p hi c pe t r ol o gy we r e pr e p ar e d i n S pan i s h f o r pu bl i c at i on and i s s u e t o GEOBOL g eo l o gi s t s . t a ken p a r t i n v ar i ed t ech ni cal c oo pe r a t i o n p r o j ec t s i n Gu yan a, Brazi l , Costa Ri ca, Vi et nam, Cam bodi a and I ndonesi a. He i s 、 cu r r e nt l y l ea di n g t he ODA/ I GS 鹜 Proyect o Pr ecdmbri co Team based at Casi l l a 3045, Santa Cr uz, Bol i vi a. KAI L AUTOFOCUS PROJECTOR MODEL K- A5 Tr ansf er i nf or mat i on f r om Aer i al Phot os t o Map. Dr af t maps, dr awi ngs, i nf or mat i on t o t he desi r ed scal e. The i mage of any- t hi ng pl aced on t he l ef t gl as s pl at e may be pr oj ect ed ont o t he r i ght gl ass pl at e t o t he si ze desi r ed Scal e r ange: 5X Enl ar gement t o 1/ 5X Reduct i on A mot or - dr i ven l i nkage keeps t he i mage i n cont i nual f ocus t hr cugh t he ent i r e scal e range For mor e det ai l ed i nf ormat i on and pr i ces, cal l or wr i t e Phi l i p B. Kai l Associ at es, I nc 1010 W est Is t Avenue- Denvef , Col ofado, 80223 Ph- 8 ( 303)6 23-5987 EPI SODES, Vol . 1982, No. 4.