Uranium in the Groundwater of the Kalahari Regions South of the Molopo River M
URANIUM IN THE GROUNDWATER OF THE KALAHARI REGIONS SOUTH OF THE MOLOPO RIVER M. LEVIN, B.B. HAMBLETON-JONES AND M.C.B. SMIT (Nuclear Development Corporation of South Africa (Pty) Ltd., Pretoria)
ABSTRACT
During the past eight years more than 2 000 groundwater samples have been collected from boreholes in the Kalahari south of the Molopo River. The areas investigated are bounded by the edge of the sandcover in the south and are situated between 20 0 and 25 0 E longitude. The results were interpreted against geological, geohydrological and hydrogeochemical maps compiled for the areas investigated. In the area north of Vryburg (Piet Plessis Block) uranium anomalies in the groundwater were located in basement granite. In the western area between the Korannaberg (22 0 15' E) and the South West Afri ca/Nami bi a border (20 0 E) (Gordonia block) uranium anomalies in the groundwater were found to occur in basement granite, Dwyka Formation and the Kalahari Group. Radiometric borehole logging of a limited number of boreholes confirmed the presence of uranium anomalies within these rock types. Occurrences of uranium were discovered at Tsongnapan in the Dwyka Formation in the form of phosphatic argillaceous nodules in which uranium is associated with apatite. On the farm Rus-en-Vrede near Vanzylsrus, uraniferous diatomaceous earth was discovered at the junction of the Madala palaeodrainage and the Kuruman River. Although no new uranium deposits have been found as a result of this study, several new occurrences of uranium were indicated. A study of the distribution of uranium provinces and its time-bound characteristics suggest that the Kalahari Desert, both in South Africa and Botswana, still holds potential for uranium deposits. With the present recession in the uranium industry no further investigations are envisaged, but, should the market improve, some of the anomalies located may It/arrant further attention.
INTRODUCTION Discoveries of uranium deposits in the arid parts of Western Australia during the early seventies sparked off an interest in similar regions in South Africa. Government airborne radiometric surveys in the Kenhardt area successfully pinpointed several uraniferous calcrete occurrences (Treasure, 1977). Similar radiometric surveys flown over the sand covered areas of the north-western Cape, however, failed to reveal any anomalies (Day, 1976a, 1976b). To augment these surveys and to stimulate uranium exploration of the vast sand covered area, NUCOR embarked on a groundwater survey of the
234 Gordonia Block. A multidisciplinary approach was adopted and the study 1[ entailed an evaluation of the distribution of uranium in the groundwater against all the relevant geological, geophysical and hydrological data in order to
(i) establish potential uranium source and host rocks, and (ii) evaluate the uranium potential of the area.
As a result of this survey, occurrences of uranium in the Dwyka Formation and younger deposits were found and reported on by Levin (1978,1980, 1981). The area of investigation was extended from 22 0 E longitude eastwards to the Korannaberq. The uranium distribution in the groundwater was studied with the aid of natural isotopes and radiometric borehole logging (Levin, et al., 1983).
Extensive data on the geology, hydrology and hydrogeochemistry of the sand covered areas east of the Korannaberg were published by Smit (1977). In a joint venture, NUCOR and a French company investigated the uranium in the groundwater of areas selected on the basis of Smit's work.
LOCATION AND PHYSIOGRAPHY The area investigated covers some 70 000 km 2 within the sand covered :;ordonia, Postmasburg, Kuruman and Vryburg Districts of the northern C:ape (Fig. 1). The topography varies from a monotonous undulating
FIG. 1. LOCALITY OF THE STUDY AREA IN THE KALAHARI SOUTH OF THE MOLOPO RIVER
2.35 REPUBLIC OF BOTSWANA
• ZEERUS,
+ + + + + + + + + .... + .... + + SWAI -. .,t' + + + + + of- + NAMIBIA + + +..,. + + + + + + + + + .;:>tt, pu:~. .~iCHTENSURG ++++'1:+++:+++++++++++++++ ~ + + + ~ + + + + + + + + + + + : + + + + + + + + + + :- + + + + + + + + + + + + + + + +.+ + + + di-DY-t-!-f +::~~~.+ TRANSVAAL + + + -'- .... + + + ...... + + + ••1f::: eQ£LAREYVILLE eARQAS + + + + + + ..".. . , .... + + .... SSIS ,BL,OC,K " CD evRYBURGI 0') N
,,
ARIAMSV.,EI SO 100 km
2. PRE-KALAHARI GEOLOGY
CAPE PROVINCE ~ KAROQ SEQUENCE f12j GRlo.UALAND w~ST SEQUENCE o NAMA GROUP [] VEN1ERSDORP SUPERGROUP D KDRAS GROUP G GRANiTE GNEISS
§ WllGENHQUTSDRlf GROUP ~ KRAAIPAN GROUP o OlifANTSHOf..K SEQUENCE --- AREAS SAMPLED
;"=.=".,, I landscape consisting of grass-covered red Kalahari sand dunes in the Gordoni a Block to the fl at savannah-type pl ai ns north of Vryburg and Kuruman (Piet Plessis Block). The only topographic features are the Kuruman Hills and the Korannaberg, both striking north-south (Fig. 2). The climate is semi-arid with extremes in day and night temperatures, especially in Gordonia. Annual rainfall decreases from east to west from about 300 mm. at Vryburg to about 200 mm. in Gordonia. The greater part of the precipitation occurs as thunderstorms between February and Apri 1 each year.
The area investigated includes the catchment areas of the Kuruman and r~olopo Rivers. Both these rivers are ephemeral, draining to the west, to join in Gordonia.
GENERAL GEOLOGY
As about 80 % of the area is sand covered, earl i er workers such as Rogers (1907) and Du Toit (1916) mapped the outcrops along the edge of the sand cover and the few exposures in drainages. A pre-Kalahari geology map (Fig. 2) was compiled from Smit (1977) and Levin (1980) using publ ished material, borehole records and an interpretation of the aeromagnetic surveys.
Basement Granite Outcrops of basement granite are restricted to a few exposures along drainages north of Vryburg, while outcrops are absent in Gordonia. In general the granite is medium grained, white, greyish to red and consists mainly of microcline, quartz and muscovite. In Gordonia, biotite-rich gneiss grades into granite. The granite in the Piet Plessis Block has been dated at 1 800 Ma (Levin,lg81) and is intrusive into the rocks of the Kraaipan Group.
Pre-Karoo Geology The distribution of the rock types of the pre-Karoo formations east and west of the Korannaberg is reviewed by Smit (1977) and Levin (1980) respectively. The pre-Karoo geology occurring in the area is as foll ows:
Ventersdorp Supergroup - Volcanic rocks and quartzite of the Allenridge Formatlon are the oldest of the pre-Karoo rocks. Griqualand West Sequence - The oldest formation in the sequence is the Vryburg Siltstone Formation consisting mainly of siltstone which is followed by the dolomite and chert of the Campbell Group and jaspil ite and banded ironstone of the Griquatown Group. The Gamagara Shale Formation follows the Griquatown Group and consists mainly of shale with interbedded quartzite. The r~akganyene Diamictite Formation precedes the lavas and banded ironstone of the Cox Group.
237 Olifantshoek Sequence - An unconformity separates the Olifantshoek Sequence from the underlyi ng Cox Group. The Sequence compri ses the Mapedi Shale Formation, the Lucknow Quartzite Formation, the Hartley Andesite Formation, the Volop Quartzite Group, and the Groblershoop Schist Formation. Wilgenhoutsdrif Group - Comprises mainly schist and phyllite of the Zonderhuis Formation and schist and metavolcanic rocks of the Leerkrans Formation. Koras Group - comprises alternating sedimentary, andesitic and quartz porphyry formati ons.
Nama Group - Only quartzite with intercalated purple micaceous shale of the Fish River Formation occurs in the area.
Karoo Sequence Although the Dwyka Formation has a wide distribution under the sand cover (Smit, 1972) it outcrops mainly in the pans of western Gordonia and along the South West African border. In the east, Smit (1977) noted a single exposure in a brickworks quarry south-east of Kuruman. It is horizontally bedded and consists mainly of blue to grey mudstone, siltstone, shale and tillite. The distribution, thickness and suboutcrop of the Karoo Sequence in Gordonia were determined from borehole data (Levin, 1980). In this region it I."as subdivided into an upper sandstone and shale member, the equivalent of the Prince Albert Formation of the Ecca Group and the lower tillite and shale of the Dwyka Formation. In the Vanzylsrus area, the Dwyka Formation occurs in synclines or glacial valleys.
Kal ahari Group With the exception of the mountains and the few isolated outcrops, the entire region is covered by the Tertiary to Recent deposits of the Kalahari Group. About 75 % of the area is covered by aeofian sand which attains thicknesses of up to 30 m. in Gordonia. Underlying the sand is a sandstone layer which is both calcretised and silcretised. Red and yellow clay, which is locally calcareous, overlies basal gravels.
URANIUM DISTRIBUTION IN THE GROUNDWATER Sampling of the qroundwater for uranium was done in three phases; ( il about 300 samples were taken in the wes tern pa rt of the Gordoni a Block by NUCOR, (i i) 200 sampl es in the eastern part of the Gordoni a Block by NUCOR and (iii) 1 700 samples in the Piet Plessis Block by a French company in a joint investigation with NUCOR. Anomalous areas are shown in Fi gure 3 and are consti tuted by urani um values in excess of 25 ppb.
238 .,_.,.. ----,--
--- .
REPUBLIC OF BOTSWANA
eZEERUS1 , ,______~:[A A-I )",Af-EKENG. 5~ ...... -.-.- SWAI , ,~ , , ( MOROKWENG "'" eU(HHNBURG NAMIBIA /'" • ~ -:.~J 1___ _ " ," , -' _ ___ ... ---_f' %1 , TRANSVAAL /' ·DELARE'T'V1L~E eARQAB t ~____" N cv <0 \!~E_T_;LESS~C~/ .VR'I'BURGi
z -- ,' < ' I 5 --'------) , ~ , I ~ :i ...... _.- :0 KUPUMAN FIG. 3. URANIUM DISTRIBUTION IN TH:: GROUNDWA TER CAPE PROVINCE LEGEND URANIUM ANOMALY IN THE GROUND.'"" e0l 15 ppb U 1 ANOMALY NUMBER RS--S= 'C 1<",,-'" AREAS SA/PUll CATION FIELD ANION FIELD FIG. 4 PIPER DIAGRAM In order to divide the areas safl1~led into ground,vater regimes, all the analyses were plotted on the Pi per di agram (Fi g. 4). The method employs plots of relative percentages of cations and anions in the two triangles, with the reacting values being extrapolated to a single point in the intervening diamond-shaped field. In this way, the chemical character of each sample is obtai ned. Based on thi s method three regi mes were recogni sed, correspondi ng to the di stri buti on of the total dissolved solid (TOS) (Fig. 5): Group I (Fig. 6) are waters originating from the recnarge areas of the Kuruman Ri ver and the Korannaberg. The waters are relati vely hi gh in bicarbonate and low in uranium, the latter correlating with ms. There are no urani um anomali es in thi s group. Group 11 (Fig. 7) are waters originating from outcrop areas and where surhclal cover is usually less than 30 m. Uranium correlates with TOS. Group III (Fig. 8) are waters restricted largely to western Gordonia and are generally more saline but with a relatively low bicarbonate content. There is a correlation between uranium and bicarbonate content, possi bly due to the formati on of the urani um-bi carbonate complex. URANIUM POTENTIAL OF THE SAND COVERED AREAS The sol uti on geochemi stry of urani um is well documented (Hostetler and Ga rre 1 s, 1962 and Hamb 1eton-J ones, 1978). Urani um in source rocks oxidises from the (IV) to the (VI) state to form the uranyl cation as foll ows: 240 REPUBLIC OF BOT S WANA o ~O>(A. , I r------, ,1 SWAI O, ' I " , .,""IIIH""", NAMIBIA ,: ~ ~/'";,!' ,~ ___ w,---_r ,'C Q) , " ! 0 \ PIET PLESSIS .., i , l~O km TOT AL DISSOLVED SOLIDS DISTRIBUTION IN THE CAPE PROVINCE o <2S00ppm AREAS SAMPLED o 2500-5000 ppm 0,.. 5000 PPI'1I REPuBLIC OF BOTSWANA SWAI NAMIBIA GOPOONi{, GlO(K "~~-""::;:: li FIG 6 GROUP I GROUNOWATER REGIME CAPE PROVINCE GROUP I OIS TRIBUTlON CORRESPONDING 10 THE CHEMICAL CHARACTER AS INDICAHD ON THE PIPER DIAGRAM 50 100 km SeAL( 0 , (I - .- .. -.-"~-.--_ 241 REPUBLiC Of' BOTSWANA SWAI NAMIBiA '- - TRANSVAAL PIPER DIAGRAM FIG. 7 GROUP IT REGIME LEGEND CAPE PROVINCE GROUP IT DISTRIBUTION CORRtSPON[)j~G TO THE CHEMICAL CHARACTER AS INOICATEO ON THE PIPER DIAGRAM 50 SCALE 9 REPu5UC Of BOTSWANA .,". , " / • ,------, / , / ,H... "lt... , ...... " ., / JI TflANSVA/<1 .''\il·<:[<\",:,1 PIPER DIAGRAM .. • FIG 8 GROUP mGROUNOWA HR REGIME LEGEND (AP[ PROVINCE GROUP mOISTR,BUTION {DRRESPOIlDI~G 10 THE CHEMI(AL CHARACTER AS INOI(A1ED ON THE PIPER DIAGRAM 50, 100 km -- [, (I ---- 242 REPUBLIC OF BOTSWANA SWAI NAMIBIA TRANSVAAL A,~KAM SCAlE. PRE-KALAHARI DRAINAGES CAPE PROVINCE .... -.,. PRE-KALAHARI ORAINAGE ..... ITH FLOW OIRECTION -L... PRESENT OA'( DRAINAGE ,.,.' "\- ..... GRANITE SUBOUTCROP AREAS SAMPLED o 10 20 30 40 50 RECENT CALCRETE vZIII?III/I/lldl??I??III??????????I?IIII?I??I] SAND t?( /I???I KALAHARI CALCRETE E: I ?ZZ22ZZZ7772ZZZZZZZZZZ/7 777ZZZ2ZiiZZiiZZI GROUP CLAY + SS [(/ 7?ZZ??;J GRAVEL DWYKA TlLUTE p////? /?????????I FMN. MUDSTONE GRANITE-GNEISS 1':77777. '/////, '//////// AVERAGE VALUES FIG.10 GAMMA RESPONSES IN BOREHOLES (ppm eU 3 Os) 243 In the presence of carbonate ions two stable uranyl carbonate complexes form at 25°C and 100 kPa. 2+ 2- ,,- U02 +2 co] +2112 ° ~ U02 (CO] )2 .2l!" ° Uranyl dicarbonate 2+ 2- 4- U0 +3C0 --';;U0 (C0 )3 2 3 2 3 Uranyl tricarbonate Studies by Levin (1980) of the pre-Karoo and pre-Kalahari geology of the Gordonia Block have depicted depositional areas (basins, channels or troughs) in which possible uranium mineralisation may have taken place. A map of the pre-Kalahari drai nages (Fi g. 9) was compi led from the work of Smit (1977), Willemink (1983) and Levin (1980). The presence of a granite-gneiss ridge in the Gordonia Block could have acted as a source area for uranium deposition to the west of it. The general east-to-west drai nage of the groundwater may have ai ded the process of mi neral i sati on. In the Piet Plessis Block, target areas for groundwater sampling were specifically selected on evidence of pre-Kalahari drainage. The area sampled covered converging drainages, which have a higher potential as depositi ona 1 envi ronments for u ra ni urn mi nera 1i sa ti on. Radiometric borehole logging was performed in certain boreholes within the anomalous areas and gamma-log responses for the various rock types are given in Figure 10. Unfortunately some of the key boreholes were not available and should be included in any future program. Some of the results were published by Levin (1978) for Gordonia and Smit (1981) for the Piet Plessis Block. In both areas anomalous responses were given by the granites and values up to 50 ppm eU308 were recorded. The Dwyka Formation was radiometrically logged in Gordonia and several boreholes gave anomalolls values of up to 252 ppm eU308 Over 310 mm at a depth of 225 m. Four boreholes covering 100 km 2 consistently gave anomalous values at the base of the Dwyka Formati on. Work in thi s area led to the discovery of an anomalous zone outcropping at Tsongnapan in the west where phosphati c nodules contai ni ng up to 1 000 ppm urani urn occur. The uranium is associated with apatite occurring in a calcitic matrix (De Waal, 1979 and Brynard, 1981). The Kalahari Group gave no anomalies in the Piet Plessis Block, but in Gordonia, boreholes logged within anomaly 1 (Fig. 3) in~cated concen trations up to 95 ppm eU308 between 54 to 101 m in the basal gravels, and anoma li es of up to 38 ppm eU308 were intersected in the ca 1- cretes. In the Vanzyl srus area urani urn was intersected above the water table in anomalies 2 and 3. Severe disequilibrium is known to occur in the area and therefore no accurate grades coul d be determi ned. On the farm, Rus-en-Vrede, uraniferous organic-rich diatomaceous earth was discovered, which is very similar in appearance to the ore from Henkries (Fi g. 1) in the north-western Cape. Grades were low and further explorati on was di sappoi nti ng. The natural isotopes, 14C, 180, and the 234U;238U rati 0 in the groundwater along the Madala 244 Ma AGE TONS U x o 0 r A FR I C A 'ii:iiErBiiiiillmm!iilli .... '''Ly SANDSTONE OF WYO'""NG I f/ ~~~ IIIUI " , 200 1--- ~[R""AN SANDSTONE UIO GRAHITlC O(POSflS Of EUROPE A>lD COI/O"'A>!A '00 () 2 '00 o W -' 500 '"<1 ROSSING HID DINER G~AHITIC O[POS!T! CL O2 '00 INCREASING LIFE FORMS INCREASE 200 GLACIATION 000 900 I 000 () I 100 8 50 '''''USSAO Al.AUNE IGIHOUS DEPOSIT (GREENLANOI CL a: I 200· CL w "f-o I 300 a: CL I 400 I 500· VE IN 1'"0<.) '00 }-----I I 700, o WN" .. ,," UHcOllrOR .. ,TY -'0 RELATED DEPOSlTS OF Oa: O I 600 ow }CANAOJ\ AND AUSTRALIA 2 "6 INCREASING 900 a: CL 1-----12:2::::::::8. DkL0 ~(OI"(IITARY DEPOSIT 10480NI I PIIALAOORWA 2 000 i CO'UL[_ ISOIIII< MRICAI/T£ltO "[TASEOI,,,[N1S (f"HA'")1 TRANSITIONAL ATMOSPHERE 2 100 U 2 200 -0 N ANOXICISING a: 0 W a: ." laR·~'LI ATMOSPHERE '00 ;< w 0 f- -' 0 400 a: CL OUARTZ 500 ""lWAT[RSRAIID SUPE~QIIOUP (SOvHl PEBBLE AfR'CA) CONGLOMERATES 2 600· 200 () OO""NIOI< GRQUr ISOV111 URIC"") 0 N 800 0 W :z: U 900 a: <1 000 o 10 !! 12 IJ 14 15 16 METRIC TONS U x 10 5 FIG.II. DIAGRAM ILLUSTRATING THE TIME BOUND CHARACTER OF THE WORLD'S MAJOR URANIUM DEPOSITS (AFTER TOENS , 1981 245 Ma METRIC TONS 0 SURf>CIAl O(PQs,rs 100· 200 ~ARO" HQWlNC! (SANOSTOH AHO COAl O£POSlTS) ,o0 o '"N 40~ o W --' POST ·lECTONIC ALASKIHS 500 " 0, ~ IN O"W .. R.. HQUENC! 600 700 800 CAP, SUP(1I6ROUP 000 ! 000 > Z W , '00 POST TECTONIC GR" .. ,I[S 11< NAOoMQUALAHO iol£TAWOAPH1C COMPLEX 0: co , 200 , 'DO , <00 , 500 , 000 '-' , 700 o WN --,0 O 00: 2 , 800 OW ,,:; INCREASING 0:_ , 101' Of THE SUSIlVELO CO"'PLEX ~ - -- - -~ -- - 90O n. PH/lLAOOR"'" CO"'PLt~ OEP()Sll 000 TRANSHIONAL ATMOSPHERE '00 200 BLACI< R~(f OUARTI,T( (ORWAlION ANOXIOISING ATMOSPH(RE '00 2 ,o0 500 , 600 QU"R1Z HSS'( COHGLOWERAT(S /' 700 '-' OO"""'Ok GROUP o N o , 800 W :I: '-' 0: 900 " .. OIA .... G~O"P ? ~ ,0 20 " 4 METRIC TONS U x 10 " FIG.12. DIAGRAM ILLUSTRATING THE- TIME BOUND CHARACTER OF SOUTHERN AFRICA'S URANIUM DEPOSITS AND OCCURRENCES lAFTER TOENS, 1981 ) 246 pa1aeodrainage were used to study the original anomaly (Levin, et ~,1983). It was found that rai nfall and local i nfi ltrati on slowly enriched the underlying groundwater with urani um from local sources: the highest concentrations of uranium in the surficia1 material and the groundwater are at the lower end of the drai nage near the confluence wi th the Kuruman Ri ver. A1 though the resu1 ts of thi s study are at present not encouragi ng, one should keep in mind that 48 % of the free world's uranium resources are tied up in rocks younger than 300 Ma (Fig. 11) (Toens, 1981). For southern Afri ca the resources amount to 12 % (Fi g. 12) whi ch may be an i ndi cati on that these rocks sti 11 remai n potenti a1 hosts for undi scovered urani um deposi ts in thi s age group. CONCLUSIONS The presence of source rocks and uranium anomalies in the groundwater of the sand covered areas are positive indications of the uranium potential of the area. 14ith the uranium discoveries at Tsongnapan in the Dwyka Formation, the presence of uranium-bearing rocks has now been shown to occur throughout the sedimentary formati ons of the Karoo Sequence in South Africa. This fact may be relevant to Botswana, as Karoo formations occur under sand cover. The urani ferous di atomaceous earth occurrence on Rus-en-Vrede is possibly just one of several similar occurrences hidden below surficia1 cover. Smit (1977) menti ons severa 1 di atomaceous ea rth occurrences north of Vryburg but none have as yet been sampled for uranium. Uranium in Recent and Kalahari ca1cretes should be investigated further. Disequilibrium above the water table may lead to anomalies being missed during radiometric logging. Shallow drilling and sampling may be costly but worthwhile, especially in the southern portion of anomaly 2 (Fig. 3). This anomaly is continuous across a very prominent watershed, a fact which seems peculiar and requires further investigation. Looking at the distribution of uranium provinces and their time-bound characteristics, the contribution of the Karoo and surficia1 deposits to South Africa's uranium resources seems low compared to the rest of the free world. The Kalahari region with vast sedimentary deposits may contribute in future towards a more balanced picture. Although no major new urani um deposit \1as located as a result of thi s study, several new occurrences of uranium were indicated in the basement granite, the Dwyka Formation and the Kalahari Group. 14ith the present recessi on in the urani um industry no further i nvesti gati ons are envi saged, but should the rnar~et improve, some of the anoma1i es located may warrant further attention. ACKNOWLEDGEMENTS The authors wish to record their thanks and appreciation to NUCOR for the opportuni ty to present thi s paper at the Kalahari semi nar. We wou1 d further 1i ke to thank everyone i nvo1 ved at some stage wi th thi s project for their efforts. 247 ,---- REFERENCES BRYNARD, H.J. 1981 A mineralogical investigation of a uranium-bearing phosphatic silt- stone from Tsongnapan, north- western Cape Province. Atomic Energy Board, Pelindaba, PER-60. DAY, R.W. 1976a An interpretation of the radio metric anomalies of the Noenieput area northwestern Cape. Geol. Surv~ S. Afr., Rept.~~:2133. 1976b An interpretation of the radio metric anomalies detected by the Kuruman-Tellerypan-Terra Firma airborne survey (18/74). Geol. Surv. S. Afr., Rept. GH-2228.-- DE WAAL, S • A• 1979 Mineralogical examination of a samp 1 e of the Dwyka argi 11 aceous limestone. Nat. Inst. for Metallurgy, Rept~IN-lbb-.----- DU TOlf, A.L. 1916 Notes on the Karoo System in the southern Kal ahari. Trans. Geol. So~_~~_~fr., 19, 1-1z;------ DU TOIT, M.C. 1965 A geological investigation and correTaTlonof-rock-s be 1ongi ng to rue-I\oras-To-rmaflon' in the GOrdonlilanct-R e nh a rcJtOlstrrcts~ "northern-ra-pe-Provi nce~ MSc. ffisrs;-lriilV:-Ora-n ge-rree S ta te, Bloemfontein, 106p. HAMBLETON-JONES, B.B. 1978 Theory and practice of geochemical prospecti ng for urani urn. Mi n~~ ~ci._~~~, 10, 182-197. HOSTETLER, P. B. and 1962 Transportation and precipitation GARRELS, R.M. of uranium and vanadium at low te,nperature, wi th speci a 1 refer ence to sands tone-type urani um deposits. tcon. Geol. 57, 137-167. ------ 248 LEVIN, M. 1978 Uranium occurrences in the Gordonia and Kuruman Districts - a report on fi e 1dwork conducted during June 1978. Atomic Energy Board, Pelindaba, £fR-31. 1980 A geological and hydrogeochemical investigation of the uranium potential of an area between the Orange and Kuruman Rivers, north western Cape Province. (2 vols.) Atomic Energy Board, Pelindaba, PEL-27T. 1981 The geology, hydrology and hydro chemi stry of an area between the Kuruman and Orange Rivers, north western Cape •. Trans. Geol. Soc. ~fr., 84,(2) 171-190. LEVIN, M. 1983 Geohydrological investigation of TALMA, A.S. and an uranium anomaly near Vanzylsrus VOGEL, ,) .C. in the northern Cape Province. Groundwater 82, Pretoria, 5 - 7 July 1982 (In press). ROGERS, A.W. 1907 Geological survey of parts of Vry burg, Kuruman, Hay and Gordonia. Geol. Commission, Cape of Good Hope, Ann . .B.ep~.: 11-1"22:----- SMIT, C.J.B. 1981 Report on a limited radiometric borehol e-l oggi ng survey conducted in South Africa and Bophuthatswana in the area of Morokweng. Atomic Energy Board, Pel indaba, PIN-S87 mu:- SMlT, P.J. 1972 The Karoo System in the Kalahari of the northern Cape Province. Ann. Geol. Surv. S. Afr., .':' 79-81. 1977 Die geohidrologie in die opvang qebied van die Molopo-rivier in die noordel il 249 TOENS, P.D. 1981 Uranium provinces and their time bound characteristics. Trans. Geo 1 . Soc. S. Afr., 84, (3) 291=JTZ. TREASURE, P.A. 1977 A ground i nvesti gati on of some uran ium anomalies in the Kenhardt area (20/74) Geol. Surv. S. Afr., Unpub. Rept. G-267. --- WILLEMINK, J. 1983 Evaluasie van die groundwaterbronne tussen die Korannaberg, die noordelike gedeelte van die Langeberg en die 22ste lengte graad (Kuiepan- heuwels). Dept. Environmental Affairs, Geohydro logical Division, Pretoria, Rept. YGH- 3258. 250 REPUBLIC OF BOTSWANA (Director: T.P. Machacha) Bulletin Series BULLETIN 29 THE PROCEEDINGS OF A SEMINAR ON THE MINERAL EXPLORATION OF THE KALAHARI OCTOBER, 1983 Edited by D.G. HUTCHINS A.P. LYNAM 1.96&' l Cj '6' S Published by the Director, Geological Survey Department Private Bag 14, Lobatse, Botswana with the authority of the Ministry of Mineral Resources and Water Affairs Republic of Botswana Price: PIO,DO PRINTED BY THE GOVERNMENT PRINTER, GABORONE.