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Repub l ic of Botswana Dep a rtment of Geological Survey

Ministry of Mineral Re sources a nd <later il ffa irs

Interim Report on

\,a ter Supply for J waneng Investi gation on Groundwater Resources

in ii rea tl.

J. Da vies D. Hutchins G. Nelis s e

Distri buti on : !<lin.

by

Perm~ nent Se creta ry, Geologi c"l Survey Archi ves

Ministry of Miner a l Resour ce s & <later Affairs 4 6 2

Mr. J . Da vies 1 Mr. D. Hutchins 1 Mr. G. Nelisse 1 Dr. W. Dechend 1 Well field Consul ting Services 1 De Beers Prospecting Bo t swana 1 ilngl c j,merican Corp or a ti on 1

Re port No :

BCrSHY!/ /?-1 1.pproved for i ssue by the Direc t or

- I -

Page No"

List of enclosures III

Summary IV

L Introduotion I

1.1 Background 1

L 2 Geograpbi oal setting 1

1.3 Pr0vious studies 2

1.4 Metbod of study 3

2 Geology 4

2.1 Previous Dtudies 4

2.2 Str8. ti gr''"'.nhy 4

2.2,1 Descriptiun elf t'1o LiLcstrctigraphic Units Identified 6

2.202 RegioD21 F(]~:.turG8 10

2. 3 Struoture 10

.3 H;vdrcgeology 12

3.1 Pr{3vious Studi2S 12

3.2 Terms used to dcscribo 'quifers ?nd thoir C;hcrc;cteristics 13

3.4 Speci fi C A,qui fGrs

3.4.1 :'}E~torberg sandstonos

3.4.2 TimobalJ. Hill cI"0.ortsi to[.'l

3011.3 TimebDll Hil) 811::188

304 .. 4 Transv8!}.1 Jolomi ti c LimestoneS

3.5 GrOULc1vi2 t2l' flo\·,

3,6 Groundwctar ceracity

3.7 Drillin,':; pr., ',Y.Y'nrN.'1Q

3,8 Hydro chemi s try

3.9 Hccherge

14

14

15

15

16

16

17

18

19 21

23

Contents (cont.)

4.0. Geophysical Investi,;5ations

4.1 General aspects

4.2 Central cutline

4.3 "estern cutline

Eastern outline

5. Future work end Conclusions

5.1 Futuro ;Iork

5.2 Conclusions

References

II

Page No.

24

24

26

28

29

29

29

30

31

III

List of enclosures

Table l,

Table 2 "

Table 2 1)

T2ble 3.

Table 4.

ilppendi x L

jippendi x 2.

Fig. L

Fig. 2.

Fig. 3.

Fig. 4.

c

Formetional and Hydrogeological Features.

Cattlepost And village boreholes loc2tod wi thin area il.

Project Boreholese

Hydrochcmi eel analyseso

Total lhrdness.

Project boreholes, geological logs.

Schlumbergor soundings.

DGtailm8p JVlfl,neng Investigation ~,rea 2424D) Scale 1:50,000.

J v18Y10ng area I I LOCAtion map; I: ':"

". (p2rt shee';

ki

Southern part of aree Scale: 1:125,000"

I . I L Structural geology

Isopiezometric contour map~

IV

Summary

The amo~nt of t-Jater require-,:'!. f r tho J1iJaneng :Diamond mi.~'3 being

5 000 m /d2.y 2S a first demand. During the phase of the water

source

raised

invosti82ti)D pro,:,;Tammo m'

to 15 000 /day.

the nnlOunt of required vlater

It was 8bTuod uron that Go S" :)0 should take part in the 'vlater

source invGs ~igation pr::-'grammo i:~ ,~n arGa south of J"n~nenz

Diamond minc"

Tho geology and stratigrarhic[ll !:';cquenoG 'h10ro investigated

and tho resul ts 81'0 given in this replJrt" Basic data were

obtained from pr~vious stucli,)s, av.-:::ileble rocords ancl from

fieldwork especially carried out for this programme"

The hydrogeolog-ical ;.,ropGrtics of the different geological

formations in the aro!], of inv8stigation is affectod 1);y faul-

1he main aqui fers are :rh', terberg end Transva81 quart zi ti c

sst~ and TrDnsva21 Dolomi ti c limcstoDeso The sst. must bo , "

fau1 tod and Holl jointccl. Dolomitic limostcnes arc af-feoted

by karst t;:.rro ;,veathcring ii ttlo if arcy recharge t? these aqui-

feI's tc.L~_8S place. qcn(::I'Gl ':12tGl' quality is good, But detcrio-

Tho results frctn geophysical invGstigation "leI'8 interpreted

and correlfitod '/Ji th ti,iO <5c:)1:){~ic(-1 Gnd h;ydrogeological data

and lfJl:ore Decess:;.ry r(;iDtcl~"r(d8ticD 1128 beGYJ carrierl out.

From the geologic::l an,;1 g8o~~h3rsicel investigation 'drill sites

were all,:,cated on sj. tcs \·Jh.,':;re n]('r(;) :::lGt,~il.3j knc,:,'J1Gdge on the

stratigraphicBl sequ-:;nC;(3 1j}8G ,~'.(~;::irc~ble, to obtain bettcr ro­

sultso

DUG to 2 breakd('.-wn ef driJ.l oquip!f:;Jnt the 1ril.~ pro_,?nmme was

do1aye d. It oan be unc~or8tood th2t for 2 final and ovor211

intorjirGt2tion the rl.rill progrr:mmc sh,::uld bG oarried out as

eutlined to ,1)rovid2 the roquir.;.;c1 dataa ~,s sem: 3S thesG data

are avail2blc a final int3rpretBtion can bo carried uut and

the final repcrt oomp1etc,d.

.I

- 1 -.

1. Introduction

Sufficient supplies of >later must be located before develo­

pment of the J >laneng Diamond mine can take place. The ini­

tial phase of developing the infrastructure and constructi­

on of the mine comp1e~ should be completed before the mine

starts production in 1981. The amount of >later required

>las ori ginally estimated to be 5 000 m3/daYi but this amou­

nt has since been revised to 15 000 m3/day. An initial st­

udy of all water sourCes within a 200 km. radius of Jwaneng

indicated a total lack of slli.table surface I,ater sites. The­

refore during the short term ground>later supplies will have

to be relied upon. If these prove to be insufficient longer

term plans could be put into operation involving water being

piped into the area from the Limpopo or the Okavango Delta.

At the rec;uest of the Anglo Amerioan Corporation, Uellfield

Consulting Services submitted propoElals fcr the location of

sufficient groundl,ater supplies for the proposed mine, at

the rate of 5000 rr. 3/day for a twenty year period. l'lellfi­

eld Consulting Services proposed the assessment of the >later

potential of three areas, all wi thin a 30 km. radius of

At the request of the Botswana Government the Bots>lana Geo­

log,i cal Survey Departn:en t undertook to examine the water

potential of area A, situated south of J>laneng, and north

of the main Lobatse - Ghanzi road.

1.2 Geoel'aphical Setting

The area of study is located within the >lestern half of quar­

ter degree square 2424D. The southern half of the area en­

compasses several 10," ridges and steep sided hills, e. g.

")p D:ikgomo Di Kae Hills ahout 1 300 m. above sea level.

The northern half of the area is generally a flat feature­

less plain I,hose average al ti tude is about 1 200 m;' ;if

- 2 -

A large depression, Seki'Jele Pan is located in the western

central part of the area.

Surface drainage fea tureE are almost noneri stant, al though

a wide sha11o>l valley, the Naledi Valley, trending north­

we!9,:;l,o~theast runs through the northeastern part of the

area,' 'although its presence is reoognisable only with di­

ffi cul ty

The eoonomy of the area is primarily based upon the rearing

of cattle and small stock. Stock are watered at a sparse

network of boreholes. Most of these boreholes are located

along the main Lobatse - Ghanzi road, the main'route of

communi ca ti~r; throu gh the area.

Rainfall is sporadic in nature usually occuring as heavy

storms of short duration betvleen September and March.

.. -~---- Previous Studies

The boundaries of area A and the Dikgomo Di Kae area as

mappe Cl b;y Cu] J en (19 ~i8) in 1956, are essen ti all y the same,

both being ,Ii thilC the western half of quarter degree square

2424D, Boocock (1961) and Crockett (1972) contributed much

to the kno,/ledge of the geology and teotonic development

of the area.

The Department of Surveys and Lands is presently remapping

the area at a Ecale of 1: 50 000, essentially based upon their

reently flo\m aerophotogTaphic survey of the area. Dye

line copies of their preliminary maps were made available

to this depart.ment.

As part of their prospecting activi ties within the J,;aneng

area De Beers Prospecting (Bots\;ana) has recently completed

on aeromagnei.ic survey of the Jl'laneng and adjacent areas.

No reports exist relating specifically to the j-,ydrogeological

characteristics of the Waterberg and Transvaal formations

"

- .3-

wi tbi)1 area li. The resul ts of studies undertaker. by Jennir.gs

(1971) and Houston (1972) of the hydrogeological characteri­

stics of tbeiiateY-berg and. Transvaal aquifers in the Lobatse

and Kanye areas could be applied 1.0 those in area Ao

1.4 Method of Study

From a stud;y of avaiJn(;]I .. ~ r.1:'·~e (sec above) a 8eries of reeo .....

nnaissance maps viere drafted.. These VJere llpf:',Taded periodioa­

lly as more data became available.

vlhilst drilling equipment was being mobili~:ed a surface geo­

physical survey of the area Has undertaken un, )Ig geo-electric

sounding ancl surface magneti c techniques. The rem)l ts obta­

ired were related to the aeromagnetic survey resul ts. li

seri es of appro,amately 20 dri 111 ng targets were selected

from the interpretation of geoph~·sical and geological data.

DriLling was to be undertaken initially within the area of

exposed and faul ted I'/aterberg and Transvaal strata that

forms part of area li. This wa" to be folloVled by the drilling

of a seri es of holes in the northern part of the area wi th

the aim of supplying sufficient geological data to anow the

detailed interpretation of geoplj'j!13ical logs.

All of the holes d.rilled are to be logged geophysically where

possi ble. Boreholes from "hi. ch ;yields in excess of 100 l/min.

are obtained by airlift methods are to be test pumped, follo­

wing the drillin,,; of observation ",ells adjacent to the test

\;el1. In this way the aquifer parameters of each aquifer can

be obtail,ed in its faulted and undi sturbed condi tions.

- 4 -

2. Geology

Du Toit (1954) first recognised the presence of Precambrian

sedimentary rocks iy, the Dikgomo Di Kae area, but it 1;as

Cullen (1958) who recognised the stratigraphic range of these

sediments and the nature of the igneous basement. Boooock

(1961) oompared the Transvaal sediments of the Dikgomo Di Kae

area wi th those oocurring wi thin other parts of Bots'/3na.

He concluded that three sep8:r:aw basins of deposition e>:isted

in Southern Botswana durirg Transvaal times. Crookett (1972)

remapped the area, paying parti cular attention to the Transvaal

lithostratigraphic units and their structural development.

He recognised features indicative of gravity sliding similar

to those present in the Lobatee basin.

Cl'ockett and Jones (1975) cor.cluded that the lithostratigTaphy

of the Waterberg IISysteJr. 1I of Botswana ·,/a8 of too complex a

nature to be subdi.vided into typical lithostratigraphic units

of national extent. Therefore no attempt is made in this

report to subdivide the 11atorberg sediments of the Dikgomo

Di Kae areao

The follo1,ri.ng table of litho8tratigraphic units was adopted

by most of the above authors : -

Kalahari Beds

l~a terber g "Sys tem"

Transvaal

"System"

'I

J

1 Igneous

Basement

- 5 -

Pretoria

Series

Dolomi te

Series

Black Reef Series

Kanye Volcanics

Ga borone Grani te

Felsi tos

Ferricrete, silcrete and calcrete

Fine grained wind blown sands

Sandstones, grits and conglomerates

Magaliesberg

Stage

Daspoort

Stage

Timeball Hill

Stage

'.

Shales

Banded Chart

Quart zi te

Upper Shales

Volcani cs

Lower Shales

Quart 0. te

Shales

Chart Brecei a

Banded Ironstone Dolomi ti e

Limestones

Quart zi te

11 ci d Igneous Extrusi VE

Rapalci vi c Grani te

Feldspar Porphyries

c·-';'·· ,"<

1

- 6 -

From aerial photographic interpretation and an analysis of repo­

rts and borehole records a geological map of the southern part

of area A has been drafted. (fig. 1). The Precambrian geology

of the northern two thirds of area A is concealed beneath a se-;,­

quenoe of Kalahari sediments of variable thickness. The various

lithostratigraphic units have been identified in the field where

exposed, to facili tate their recogni tion in borehole samples.

" The formational ano, hydrogeological characteristics of the litho-

stratigraphic units are tabulated in table 1, and hydrogeological

data from boreholes located vJithin area A are tabulated in tables

2 a and 2 b.

2. 2.1 Description of the Lit.hoE<trati graEhi c Un} ts I~nti~

BIFick feldspar porphyries displaying typical rectilinear jointing

crop out in a small pan southeast of Lobapa. Grey felsi tes "Q th

pi nk fel dspar pheno erys ts have been i den ti fi ed in tNO boreholes:

1. Borehole number 24.24D/62, located 4. km south of Kgome Pan

penetrated_ grey felsite after passing through 53m of Kala­

hari se di men ts. (see appendi xl) •

2. A boreloole preser:tly bein" drilled by the Department of "later

Affairs at a cattle post some 1') km west of Kgome Pan pene­

trated felsite after passing through a sequer.ee of Kalahari

sediments, 1>laterberg sanc1stones ancl doleri te.

Bo+,h of the above holes were dri lIed to depths in excess of 150m>

,,_, no Nater being struck in ei ther ease.

Ga borone Grani te

No expO[oure of Gaborone Grani te loas been found~ in area A, al tho­

ugh an outcrop of red rapakivi granite exists at Tshono Pajl,

,,,hieh is si tuated some 15 km east of area A. Red Gahorone type

granite has been reeorded from a bOl'eholo at Mogobe ~Ia DiYlonyane.

"

I

- 7

This borehole yields a small supply of poor quali ty water from

the weathered grani te.

Exposures of dark-green-grey tuffs, silicified agglomerates and

banded rhyolites occur between Senyamadi and the Oki Hill.

These rocks have been assigned to the Kanye Volcanic Series.

No boretoles are known to have been drilled into this unit

for "ater abstraction purpOEres. The water poter:tial of thie

unit is likely to be poor.

The Black Reef quartzi te that forms the basal member of the

Transvaal "System" is typically a fairly thin, 6m - lOm, hori zon

of coarse to medium grained, pale grey, well jointed orthoquart.­

zi te. The uni t is well exposed along the main eastern baseline,

<;<r' (Fir; 1), east of Senyamadi. Although well jointed in nature this

l' unit has a 10H water potential being of limited thickness.

])olomi te Series

This is a thick sequence of grey dolomitic limestones with banded

and brecciated cherts. The banded cherts commonly occur in the

upper part of the sequence, above the grey dolomi tes. In areas

to the east of area 1\ the banded charts pass up;,ards into a

banded ironstone uni t, Hhich has not been recorded from area A.

The banded chert.s ccmmonly contain stromatoli ti c features, and

ma;y occur in large brecciated IT'iasseso

The dolomi tes are commonly compact VIhi te and grey crystalline

dolomi ti c limestones that di splay typi cal 'elephant skin I

'oJeathering on exposed surfaces. Only one exposure of dolo-.

mi te VIas located, in a steep sided gully southeast of Lobapa.

Dolomi to has been recorded from several boreholes Hi thin

area fA e. g.

- 8 -

" ,

.1. Borehole number 2424D/27 located at Senyamadi was

drilled into a sequence of faulted dolomite.

2. Borehole number 2424D/66 located southeast of

Mokumba Nas drilled to a depth of 125m almost

completely ,Ji thin a series of hard compact dolomi tes.

3. A series of exploration holes drilled in an area about

10 km north of Mokumba penetrated dolomi te beneath

a thin Kalabari sedimentary cover. The'Dolomite Series

of area A may be assumed to form a major aquifer a8 it

does in other areas,notably in the Lobatse and Northern

Cape areas.

Pretoria Series

Timeball Hill Stage

This is a thick sequence of shales and quartzitic sandstones.

The shales are commonly black, carbonaceous and pyri ti c. They

grade upNards into a sequence of well jointed, purple-red, fe­

rnJ p;inous , medium grained, current bedded quartzitic sandsones.

The shales are nONhere exposed in area A. Borehole number 2424D/63

was drilled to a depth of 130m. almost Nholly within the lo\;er

shale sequence. (see appendixl).

The quartzitic sandstones crop out along a low gently sloping ridge

(fi g 1). These sandstones are cut by numerous faults and several

boreholes have been drilled through this rock adjacent to these

faul t zones. Both the sands tones and the underlying shales,

when fractured, yield appreciable quantities of water. The quart­

zitic sandstones are very similar in ap]l3O'rance to the overlying

11aterberg sandstones.

Daspoort Stage

This stage of the Pretoria Series is a thick sequence of orange'

and pink shaley mudstones, ,Ji th an interbed.ded series of volcanics.

The top unit of this stage is a distinctive white medium grained

orthoquartzite of limited thickness.

- 9 -

No exposures of the shaleJ' mildstones have been recorded I,d. thin

area A. However shallow pi ts have penetrated red and pink shaley

mudstones at shallow depth beneath a thin superficial sandy cover.

(Cullen, 1958).

The interbedded volcanic extrusives are recorded as being' composed

of andesi tes, banded rhyoli tes and amydaloi dal basal ts. However

no exposures Here located Hithin area A, only blocks of blue-gTey

andesites being found at the surface. Associated Hith these are

blocks of a cherty conglomerate that, in adjacent areas, have been

recorde d as underlyi ng the vol cani cs sequence.

The whi te quartzi te, at the top of the sequence, 'is Hell exposed

along a fairly prominent ridge in the area imnoediately north of

the Dikgomo Di Kae hills. Where fractured this quartzi te uni t

forms a fairly good aqui fer.

Magali esberfj Stage

Only the lo",er part of this stage is present "Jithin area A. It

consists of a sequence of poorly exposed 'shales, underlain by a

thin layer of banded chert.

This system is represented by' red-purple, ferruginous medium grained

curren t be dded sands tone, coarse gri ts and impersi sten t conglomera tes.

These rocks are well exposed in a series of low hills running par­

allel to and, on the northern side of, the main Ghanzi-Lobatse road.

The best exposures are found in the Dikgomo Di !Cae hills. These

?) sandstones, 'gri ts and conglomerates have a regional dip of 10° to

the south and unconformably overlie the older Transvaal and Basal

Igneous Complex rocks.

- 10 -

Kalahari Sediments

"~cc' The northern two thirds of area A ,ip covered by a thin mantle of

wind blown sands and evaporite deposits of variable thickness.

Al though generall y they form a flat, fea tureless, treeless plain,

deep depressions such as Sekwele Pan occur in whi ch there are

appreoiable amounts of calcrete eJ:posed at the surface. Ferri­

cretes occur in the Kgome Pan area and form a series of low ridges

separated by shallow gullies trending in a northeast -southwest

direction. These features may represent the surfaQe expression

of sub-Kalahari faul ts.

Al though the rocks of the Transvaal system have been fairly well

folded their general dip is about 300

to the southwest. The re­

latively undisturbed I'/aterberg System rocks rest unconformably

upon the Transvaal uni ts, wi th a dip of about 100 to the south.

In the southern part of area A the lateral extent of the vlaterberg

and Transvaal lithostratigraphic units is illustrated in figure 1.

However borehole evidence indicates that both 11aterberg and Trans­

vaal uni ts underlie a fairly extensi ve part of the northern t"J(l

thirds of area A. The true extent of these units will only be

kno"m on completion of the present drilling programme and associated

,,' rei n terpreta ti on of gecpbysi cal da ta.

Structure ------The tectonic structure of the area has been studied by Crockett

(1972). Only the Transvaal lithostratigraphic units have been

grossly affected by folding and faulting to a recognisable degree.

Three phases of movement have been recognised and Crockett summa­

ri zes the structures of the area as fo11o,,;s; -

l-'-,L«) '!

"At Dikgomo Di Kae the overall regional dip is to the south-east.

1l number of east-Hest trending folds occur, hOH8ver, ",hich are

oblique to the regional strike. Some overthrusting to the north

is associated with the folding. Following- the folding and the thru­

sting but prior to 1'Iaterberg System times the Transvaal rocks were

- 11 -

affeoted by a number of north-east or east-north-east trending

faults"

Movement along the latter faults appears to have continued into

t1aterberg "System" times. The more prominant of these faul t zones

effectively divide the Transvaal strata irto a series of well

defined, fad t bounded blocks. Eaoh of these blocks is affected

by a dense network of smaller faul ts. (F·ig. 3).

From analyses of aeromagnetio oover and surfaoe geophysioal data

it is apparent that these major north-east and east-north-east

trending faul ts can be traoed into the northern part of area 1\

below the Kalahari sand cover. The water potential of these faul t

zones and their assooiated blooks, in the northern part of area A,

will be assessed during the future programme of drilling and test

pumping.

- 12 -

3.1 Previous Studies

The hydro geology of the Dikgomo Di Kae area has not formerly

been studied. Jennings (1974) and Houston (1972) studied

the wa ter potential of certain \Ia terberg and Transvaal li tho­

stratigraphic units in the Lobatse and Kanye areas. Certain

parallels may be drawn behJoon the hydrogeological condi tions

in these two areas and the Dikgomo Di Kae area.

Jennings studied the aquifer ch3racteristics of the Lobatse

Basins. The aquifers of tl1ese basins are located within Pretoria

Series quart zi tes and the .:lolomi. ti c limes tones of the Dolomi te

Series. The former are usuallJ' in a frectured state whilst

the latter are weathered in " form typical of karst terrains,

io8o solution channels along joint 2.nd fault zones. Pumping

tests conducted at several boreholes adjacent to the B.M.C.

works recorded highly variable a,quifer parameters consistent

with the inhomogeneou2 net.ure of the aquifer. F'ar example the

storage coefficinent values o"')tained varied between 0,23 and

0,0000116. Jennings concluded that the storage capacity of

anyone of the basin aq11ifers could not be calculated from

test pumping data alone.

Fouston studied the ir!2,terberg sandstone and Dolomi te Limes­

tone aquifers of th_e l{anye srea~ He conduoted specific o~pa­

oity tests at a series of boreholes, io8o he related the

yields of " borehole to the dr2;]down, E;xperienced from tl1e

results obtained. he derived v"lues of trsnsmissivity for the

dolomite aquifer of betwee;l 50 m2/d8Y and 4 35('- m2/day, The

karst type weathering of this aquifc,r is responsible for the

high variance in t.~8 value;:: obtained. The values of trDnsmi­

ssivity obtained from the Watarberg sends tone aquifer were

more consistent, io8e between 10 m2/ 2nd 15 m2/daYe The

instrinsic permeabilit;;, of these Bandstanos is adjudged to be

minimal therefore the feirly hi gh transmi Bsi vi ty val ues are

ettributed to fissuring"

The general conclusions obt3ined from these studies of Jennings

and Houston can be sumillarised 8.S follo~'\l8 ~ -

The ':Iaterberg and Transv8<el q""srtzitic sa"dstones and the

Transvaal DoloC'li tea form -good aquifer's onl;y \.'111ere the former

are Nell jointed and strongly fractured 2nd 1,)h8re the latter

have experienced E: P' riod of !-:arst t;V)G l'lGatheringo These

conclusions may have applicetio?l to the stucl.;y of area A.

302 Terms Used to DescribG _~quifers and 'Their Characteristics

l~n aquifer is defined as a 'L'ater beari:],g formE:tion having a

"porous or fissured structure that permi ts vi8ter to move thro­

ugh it under ordinary field condi tions.

11 semi~pormeabl~ boO. or ,aquiclude is defined as a formation

trJhich~ a1 though porous/and capa:)le of absorbing "later slowly?

will not traDsmi tit :fast onough to furnish an appreciable su-

pply for a 'Jell.' /,' , ,-,-,

( . i". " 1,<,,' ,', ,_ '

An impermeable bed or aquifuge is defined as a rook vlbich

oontains no ('later conn'30tcd o:peningc, O:f' intcrstioies and

therefore nei t!:~8r a bso::'bs no::' tr8ll.smi ts Ha ter.

Four principal 't~':})0S of ,src\.Fl_d .... ·wto::-- can be cii.stinguished

Ylamely ~ -

(a) l]r,col1fined

,"") (b)-\'IKarstic

(c)(' 'Co!1finc:d. (artesianr

Cd) Vein or fracture

.• <,

ynoonfined gTOun dVJ8 tel~S a 1'-:; charactsrisGd by a frGG surface

i'Jhich existR in equilibriwl1 v.)ith atmospheric presuure. This

upper surface of t;hQ zone of naturation is referred to ac

the Hater table.

unconfined9 but ~lS t.::oy iilGVC dO,\:.jl1'\,)3rds to d.epth may be asso-

" "

ciated ,J'li th tur't.'uJ.0;",C0e T~18se groundweters occur principally

in limostcnes an,~l. dolomi to"', :)];.6 other strata/ subj8cted to

solution effocts 2nd leachi:1go

/,

'\ - 13 "'

Confined (2r_~~.~8n) ;Tl'oundwatGrs occur when an aquifer (cha­

racterised by unconfined gr(n":J'l\l1t!ater condi tions) passes bene-

GroUl:dNstcr is then 0011-

fined sf ~))Bt if the: aquifer is piercGd by' drilling~ (s'Tound­

>later )~~\~<i: rirc8 to a 10'101 a):,,)vo tile base of the overlying

confining bGcl~ t:',n h-::t·)r bc.:ini"- f.:uhjoct to hydrostatic pressureD

Vei_~~f~_:~(,8 .z:,2~!]ii..!i~,~2L ;-::8), oft·:jrl be found rising from

considGrablc depths rlU0 ·:::i·;;h~r tc hydrostatic or gasoous hcadso

Suoh Nate:rs tG!"'td te occur j_B 2,01'>38 of tectonic fr80t'.11'o o

The various ~'l':':2:.~"E .. .Rm::.amet;t'.Qs oalculated inolude

(a) Permeability

(b) Transmisiivity

(0) Storage Coeffioient.

Permeabili ty Jintrinsio) m2'J' bo defined as a mOElsurs of the

relative ease vJith w~:.ich Cl porous medium cnn transmit 8 liquid

under a poto'ntial gradient"

Transmissi vi t;y rnay be clofincd a~', the, rato

of the provailin,?,' kinematic viscosi t;, is

at whi ch I'J3 ter /,", ' "".,~,/(,('(~.

transmi tte cl. through

a unit Clidth of the aquifer undGr a unit hydraulio gradient.

Though spoken of a8 2. ';";roport;)- of th(,; aquifer9 it embodies /,!., , e (

also the saturatsd thickllGSG of the aquifer cnd tho.properties

of the oontained fluid.

The Storage Coefficiont is tho volume of water 811 c)quifor

rel08S88 from or tal~GG into storago POT' unit surface area of

the aquifer pGI' uni t chDn8;C~ i:1 ~1C;ad. In a confined water

body the 'f')st:;r dorived. fro!'!! storage.: Hith docline in hoad comes

frort. expansicn of tl,;c v.mt2r and compression of tllG aquifer;

similarl;)") 'h1atur addGd to stornge; '\oJith a rise in head is acco­

rfwdated f2.rt12, b~" eX:-v8!1s:~on cf the aquifer" 1::--; an unconfined

1.!Jater bod~r, 'k~r:; B.!:10Ul~-t. of ;i,,i.::~t~~r dcriv0d fron: or added to the

aq'l,iI8t' by tllcse proc8sr-:,,~8 gGDor:::11s iD nc,:;ligable compered

to that involv(;d in grevit; drai,'L:::~t,G or fillin,'~~ or pores:

hODce? in [.11 unc'.:y:fii18d \,I,lCltcr")ody the. storago COGfficioJ!,t

is virtually (;c~ual to th<3 sy.;ocific:. yi8::"de

.- 1·4 -.

Data >lUS available from a to'" " of

wi thin arGa A prior to this studyo Of these fifteen two 1'1ere , '

recorded as being dry; t~% had been abandoned and therefore

could not be located accu'Catelyo The remaining thirteen were

located accurately u)on 1:50 (JOO maps of the are"o All bore­

holes were observed in 2. pumping oondi tiOD and water samples

were taken at eacho 'later levels coulJ not be measured in

any of thes'J borehclos becausG of lack of access at the Hell

head. The 10.' capoci ty pumps already inotalled on these bo-

reholes precludod specific capacity testingo Therofore the

only reliable data derived from thGSG holes is :

10 Dep th of l,,'ljators f::itrucko

2.. Rest lovels~

30 Geological logso

40 Borehol.:.! 'Ha tor ChO:!li s tryo

r:ehe abOVE dsta is pres(J~itGd in tables 2a i 2b and 30

~ ." '

r ;. ," !

From 81121;y-ses of bor;::~1018 }~e(., v,s 1 '\.1.<..1.0 s-Gudies of Houston

(1972) and Jennings (1974), 2~d the aquifer characteristics

of the varjouG lithostrc'tigr21!hin un:ts found vrithin area 111

it is concluded th"t :e Ohe "'"in aquifers exist within the study

81'020

20 Time 1')2J.l Hill qU21'tzitic sandstonesc

3~ Timcb211 tr.ll shalG8~

40 Transvaal do~ nr,1i tic limestones"

Of the above; t.Ile L'st thrGG ""re folded and faul ted i,n times.

Since the l,.~atGrb8rg ~s ~ilj1(3:;':': pra- 1'.'2teriJerg tectonic 9.ctivity

,',' ,

- 15 -

These are a series of \-loll jointed, mediwn grained, sands tones

that crop out along the Lobatc~-Ghanzi road in the southern

part of area A~ They

(see fi g, 1), and dip

are of fairly extensive lateral o

at abuut 10 to the south.

exten t

1r,lhere these reeks erG ex},osed the contained 8ql1ifer arpears

to be semi-confined/leaky in character, Eouston (1972) con­

cluded that similar }1['tGrberL~ SBDdstones in the Kanye area

possess a very 10;.' intrinsic permos.bili ty, but fairly high

values of tr2~smissivit;y and stcrage coefficionto The latter

he attributed to the \-Iell jointed and fissured nature of the

rock o The same conclusions could be applied to the Watetberg

sands tones of ar2a AQ 'The aquifer dips to the soutl1~ beneath

a cover of Kalahari 8Gdiments~ to becomo almost confined in

character,

movemont is

, '·h thin the confined zone the direction of

to the \-lest .. parallel to the direction of

,Ta ter f II .. ',,")

strike.

Water obtS.ir.:od from t.'ds 84uifcr in the exposed zone is typi-

cally a Ca .- ffig - B(;O" type ';Jatdr~ with a 10'1.1 total dissolved , . .) solids (TUS) co;:r'(;ento"""Ac t~J.is 'VJater passes do~ ... m dip into the

/confinod. zone so the ci1omistr,}, of the water ch2nges to an

'" NaGl 1.r.]ater type 8ud i ts quali~': cletGr~c:::"ates? m'uch high:.·T TDS

vc.l ues being rGccTdcd·.

TheSe are c seri·2s of medium gr8ined~ vJell jointed 9 quartzitic

sandstones" Th~so rocks frequentl;y contain appreciable quan­

tities of iron rich and manganiferous mincr,:::lso Bc 1 Ct,'.! the

exposed area tll<) 8quifJI' ar"<~er8 tc be semi-confined/leaky

in ch2Tact·:?r" T.be derth of t/wt-:3l" struck is of th·::; crder of

100 m 'IJhilst rest leveJ,s arG bet"'JG~:Yl 75rn 8nd 2Smo DO\-ln dip

the aquif<~r b,3cor:,:.;s cOllfiECd bc~lo,/~ JJe.sp]')ort shaley ;::udstoneso

The aquifer c]:£.'ract;::;ristj.Cf'i ef this unit are similar to those

of tho youngeY' :'~8t-:;~~'UGrg sandf3tcnes? i 0 80 intrinsic perrnc2bi­

lity i:j vury l01/J but t.he \IH311 joir;.t8C~ Dnd fr~;'ctur(;d rl.:?ture of

the unit :C)l~0motGS rGl~tiv01y high trensmissivity and stor2go

cceffici'8nt ve1ues

.- ~ , '

- 16 -

This unit has been markedly affected by a series of large

east-north-east trending faults and a dense network of smaller

faul ts (',eo fi g. 3).

The quality of water obtained from boreholes drilled into this

unit is fairl;y good, TT;S valuGs of bet,.)een 450 and 550 ppm.

bei ng common. The wa tor type i 8 Ca-Mg-HCO 3' (f'"

This is a sequonce of shales and muds"tones only known from

borehole number 2424D/63. The upper part of t'le unit is a

sequence of brown, yello1d and light grey soft shaley mUdstones.

These overlie a series of black carbonaceous pyri tic splint8ry

shales. 'rh8 upper series of mudstcnes possess high primary

porosities but very low intrinsic permeabilities. They thore­

fore form an upper confining layer to the 101Ner black shales

which because of t;,cir splintery n&ture possess an appreciable

intrinsic permeability. :!Ihen affected by faulting these shales

may also possess'high tr2nsmissivity and stor3ge coefficient

proPerties~

Ir18 ters fe und wi thin shale forma-!'- ions usually h2ve hi gh 8a1ini ty

contents~ hOl,rJever th·s quaIi ty of vJ2tcr obte.inod from ,this shale

aqui fer is qui te gae d1 th::; ltJe tor t,lpe being Ca-Mg'-HCO 3' This

good quali t;;, of water may be due t,-, Cl fairly high degree of

't. groundwa ter movem,O n t thro"l).g.h thi s shale squifer along faul ts

and joints"

Transvaal Dolomi tic Limestc'nes -----,--~- .. -, - ... ------,

This is " sequence or' herd compact \<Ihi te grey crystalline dolo­

mitic limestones w:i.t.h. ch8rt~l horizonso The intrinsic permeabi­

lity ef this formation is negligableQ Howevsr it has beeD ex­

tensively faulted 2nd would appear to be well jointed,

Dolomi tes end limestonos. are T0edily attacked by the weak form

of carbonic acid formed by tho solution of atmospheric carbon

- 17 -

This acidic solution actively ccrrodes limestone along joints

and fissures to produce a karst type or "eathering. By this

action extensivG pettorns ef solution channGls eTe corroded et

the water table hori zon, over long periods of time ..

Considerir..g the 8g'C: of this dolomitio limestone unit it must

have experienced numGrous 'wet' p~riods of active karst type

weathering.. Therefcrc it is ccncoivable that sevoral palaeo­

karstic weAthered hcrizons ma31 Gxist within this uniti

Borehole number 24241)/66 was drillod to a depth of 125m through

compact grey dolomi to, at a "i te located 4 km. southeast of

Mokumha. This holo intersected a lm VJide solution channel at

a depth of 112m. This oh2nn81 is filled "ith fine grained wind

blO'/11 sand, similar to the suporficial Kalahari sands.

sand is complerelYf;aturatcd ",ith "atar.

This

Values of transmissivity Gn:::~. stOTegC coefficients calculated

from test pumping exercises upon this aquifer wCould be very

variable. T'ho storegc cr;rncit;y of such 8n aquifer is impossi-

bIe to define wi tl: any degTo0 of aocuraoyo,'

Tho genorAl dirocti on 0f groundwa terflow throug1; the arGa is , " ,1.-, \ -, < '

from east to v.]est~ ;')er!111el to the regional strike. Three se-

parate grounciwatGr regimes are recognised ",Ji tbin area 11, each

haVing its own flOto) ps ttorn. Those are :

1. Tho WstGrberg sandstone aquifer.

2. The faultc1 TraDsva· 1 aquifers of the southern part of arc A.

3. The northern pArt ef ereB A in t: j vicini ty of JioJsneng.

~Jithin the Waterberg sandstone aquifer, the f~neral direction !<' .

of ground'.rV8tCI'fl.?~J is frem 82St to \I\,lest at 3 gradi3nt of 2PP­

roximately 1 in 500. In Llo vicini ty of Dikgcmo Di Kao the

direction of flc,'J veors tc- th,z, nort~lWGst. The main flow dire-

ction a)'p()2rS t" be structurally controlled, being 'Oblique to

the direction ef dil' hut prrallol to the axis of the primary

deposi tional besin of the Waterberg sandstonos. ,(

1

- 18 -

ThG direction of gr,-'und",]atorflot~ in the Transvaal aquifors

of th0 southern part of the area is generally from northeast

t, south",est at a gradient of BPrroximatcly 1 in 300. This

gradient of flow appears to stoepen along the meJor fault -([) ;', /\"'()

zones? the faul ts 89Poaring t(:· 80t es conduits permi tting

floH between struotural blocks. h:i thi 11 the i nili vi dUB 1 s truc-

tural blocks groundHatorflo," is restricted by mudstone aqui-

eludes confining the lower aquif~~rs. Struoture therefore do-

minates the flow pattern in these aquiferso

lr!hat lit'clG infcrm8tion oxists about nquifer parameters of the

water bearing fe,rmaticns in th'3 vicinity of Jwaneng suggests

groundHatorfloH to the northeast.

A groundwatcr divide is therefore rocognised trending north­

,JOst-southoast betHoen Kgome Pan and L')bapa. This is possi bly

associated 'Ni th a p'cstuleted ll','rth,;est-southeast trending SUD­

Kalahari ridge of }s.borcnc Gr2ni te? the presence of which is

indicated from areomagnetic dota of tho area.

306 Grcundllmter Capaci ty

No estimate of the ,,¥,_..:undvJator cHpaci ty of the main aquifers

present in 8rea A is pGssible at present9 on1;y scant aquifer

parameter dote being available.

,; ,~ /' I i

- 19 -

3.7 Drilling Programme

A total of 21 boreho18 sites \""re proposed, based primarily

upon the preliminary interpretation of surface geophysical

ane1 goologicel data. This prO€;Tamme of drilling was designed

to :

(8) Jlssess the nature ·;;f t:to form2tions unclerlying the

Kalahari CCV(jY.' in tho n~'rthQrn two thirds of the

(b) Assess the aquifer characteristios of th\: Seditn0n­

tary units present, in their faulted End nonfaulted

(c) Assess the degree of karst \;Gathering wi thin the

'Transvaal dolomi ti c limestones.

Four holes have boen drilled by the Geological Survey Depart­

ment to date (600 Table 2)3). The first hob was drilled to

a depth ~f 165m near Kgcme P8n. Only a small yield of about

20J/rnin lrJaS recorded by air lift frem fractured hiaterberg Sand­

stone? \vhich overlics dark red s;yeuiteo

The second hole, locat,)cl 4 :cm scu.th of Kgome fan, ,,8S drilled

almc.'st entirely in grGJ' felsitc to 8 de;,th uf 183m an<'t was

to tally dry.

The third holo ';Jas drilled in t.'lG ar09 between Lobapa and Lehoko.

The interpretation of gQGJltY8ict~~1 results Dbt91ned from this

area indicated th::., )1'08(:n08 of "l'J.s<tcr b02ring shaloso The bo-

roh01e was drilled in-to D s:::q"J.C:1CO ef 81121':.:8 t,", a depth of 130m

V\Tatcr bein!! struck at 98rno DurinG' an air lift test more than

120 l/min '.'lore pumped. ThE: bc.,reholc cDulCl. not be deepGned

furt!'lcr, the amount c-,f 1:JDtor ~·.yGsGnt in the hole hindered

drilling tc t,..·· gTCi"t an 2xt<3~-·.to 1'11i8 helo 1'128 therefore tem-

porarily abOnHdonGd~

11 fourt,' hole '!las drilled, at,.asLI;G/ 3km. north",ost of Lehoko, !

into faul ted '1'imoball Hill ~uartzi ks. This holo "as drilled

to a darth of 104,5m. water being struck at a depth of 98m.

- 20 -

A !iercussion rig loaned to the Geologioal Survey Department

by De Beers Prospeoting has completed two holes. The first

was drille_s(into!hard blue-grey dolomite to a depth of 125m,

1~4i~:_._~O":~I1 __ ~".I3!_~~_~~_~~~~~~ "ater was struok at a depth

of 112 m., the water being located within a 101. wide solution

cavi ty infilled with what appears to be a fine grained wind

blo>m sand. This cavi ty may be a palaeokarst feature.

None of the above mentioned holes has yet been test pumped.

I

- 21 -

3.8 Hydro chemi s try

,!ater samples v]ere obtained from operating boreholes and sur­

face, water occurrenoes located within area 2424D.' This survey

was later extended into the adjacent areas of 2424G and 2524B,

in order to obtain regional disthbutions of the various che-

micalparameters assessed. Tho

ate discussed ~n.-dot"'i-'±r-'bel'0wl

, I ; cheml cal tesul ts !f.J>0m'--a,pea-,A j

, ,

in thG context of the chemical

parameters definod on a res,-iol1e.l scale,f.~';",.,: The chemi cal ana­

lyses of twelve water samples oolleoted frcm opE)rating boreho-

10 s (,ri:-t-hi-R----S'f'e",,,11 are p re sen te din ta bl G 3.

Total Di 8s01 ved Soli ds ('pS)

The maxiinum concentretion of TDS permissi ale wi thin waters used

Onl:; one sample

from the 2rca, that frem i)cre:101a,"number 12~ recorded a TDS

conoentration gTe,~ter than 1 000 ppm". Samples cbtain2d from

the ether borehc.les wit-hin .'?.""f'.?:C! ... A rG.P9):~A~d TDS concentrations

of between 100 and 60( rpm,

Regiona,lly 101" 1'00 'ooniCent,ratiims havl3 been noted. along the'

:·{a,t--er ber'(5 Sand.s VH18 C U't"Cr0p, I'[;)."ti,oul arl~>"

the Dikgom'O Di K~;e 1Ii n s; In the so'uthern

in the;~i cinity 6f,

,-,art ~r"':~';~c":a\ 1;' ,/ "

Zones: with' large', imJ'reHBes in Tnc3 oonoentrations coincide with

pH values vary frcm 6 1 5 tc 7, 9 l,;:i. thin/aree ik·j

. l'." 1,)-

\/ (-~

T'otal ha:rdness conCGntrations cxrr,'ssod in terms of mg/l o.f /{(,. '

! . .l." .-~>"-.-"--.-,, A ~_'~;_003f' in 'samp,108 collocted N1:-v}l:!.oJ.~,-·-·ar.e.a,-~~? arQ r,resented in

>~:Tebl~~AII hiater samrlcs obtai~1ed' fr'fm th·? 1'ransvc.c-l B'quifeI's~

in tl;~ southern part of a'r'Ge /1, ,."4sua),ly reoor'd high 'Ilt)tal Har­

dness oonce;-,tr .. ,tions, i. e, "f the order between 290 and 560

mg/l of CaC03, These waters would not appear to be suitable

for use' as boill3r feo:d -watci'rs''o, .

- 22 -

Softer waters wi th total hardness c;)TIcentrations of between

28 and 189 mg/l of CaC03

Nere obtained from ,;aterberg Sand­

s tone and Transva::~l quart zi ti 0 san dstono aqui fers.

Ni trates

A concentrEtiun of greater than 50 mg/l of 1:°3

in domestic

wator may cause Mota.haome.globinomia, when such wat~r is ad-

ministered to very young babies. Only one sample, that from

borehole number 12, recorded a (nitrcte) concentration greater

than that indicated above. Nitrate, in the, form ··f nitroge­

nous organic wastG from c8t'slc Gtc., enters the aquifer via

the sides of the borohcle.

1'ia ter Typ e Di s tri bu ti on

1. general gradation from calcium bicarbonate to sodium ohloride

waters is usually nc.ted ,Jhen groundVJaters pass d.oNn the hydra­

ulic gradient from an unconfined t() a confined situation~

This transformution is dUG to ionic exchange.

The concentr;~tion of certain cations and anions within particu­

lar ground",aters is also depencient upon the chemioal composi­

tion of the host rock type, Le. ,"aters rich in calcium occur

in limestone aquifers v;lhilst those rich in r{l(}gnesium occur

in dolomi tes. Sodium rich ~'J2ters may be found in gTDnitic

rocks ri ch in orthoclase. Chlori des may be derived from anci-

ent seawaters tr~:"ped in pOTespaccs at the time of deposi tion.

Within DrGD jl four viUter ty::,,)s aTe recognisedo Ca-Mg-HCO 3 , ,

,qaters .{thai;i arc aS8~~ciated with 1'.!aterbcr,~ sandstone and TreDS-

vael quartzi tic sal'l\Jstone aquifeTso

Ng-G8-PCO, wa tors ~

aquifeTs o

~' _ f ;tIle t- Eire typi call;)1 found. in 'Tr[,nsvaal dolomi te

1,1 8-~-'T;O 3 WE: tcrs ~t,:, t! arc f'.'und in tl:e cenfi no d :Jands tone aqui fers

in the Jwa110H8; area.

Na-Cl waters ti}ct prciominc.t.e in the groni tic and felsi to aquifers , - i

of the t'12tor divide area, ane:. are indicrtive of minfma~ r0charg~1'

i> .

- 23-

3.9 Recharge

The ground",ater to/pos recognised as occuring beneath the Kala­

hari sand COVGr typi cEllly havG fsi rl;y hi gh TDS conCen tra tions

Infiltration of reinwat,Jr through

the sand eavor end recharge 1:;' thn undGrl;ying aquif0rs is

therefore unlikely.,'!;

the southern f.8rt of tll'::: area' ir..fil trotion of rain'l-lRter into

the various equifsrs ap,\.lcars to bo £) distinct b-;s~j\~i(ilt0y".':' t(·)V;"':\'([

The hi lly tope :;r2phy of t'lG ar()A, "spe ci ally th" Dikgomo lJi

Kee hills, ap0Gars tc bo of sufficient aspect tc promote the

occurrence of ere grnr !1i c rainf,Clll.

Rapid runoff of rDin ',I2tOT f::2;Y be GX}locted? much of this run-

off accumulating UP(,.';1 the rel<3tivel;y impc!rvious shaley mudetoDes that

form the low lying areas" Therefore re aheY go by rainl,!8 tor coul d

only take placG along the sDndstone ri dges, over the fairly

extensive areas of neer surfece dolcmite, and along fault zones.

That recharge elves take ,;" " >- ./~;" ,(, "-"/"' ."'.'. " ,'. '.:

plecc,i,,!/ir.dicat8d'bY the distinct

east-vlost axis of lOVJ TIC cc.1cO:1tr;;ticns coincident with the

waterberg sandstono soerpo

From data produced by UNESCOjF;,O (Pike 1971) there is a 50)1-

probabili to' that 400mm c'f rsin fells upon area ;, annually.

The total areEl of,I'area ~i is 1 400 sqokmo .i\' surning thet the

nor thorn 60~ ef the 8rG3 is c·~_·vcro,.~ b;)T r80her 6e inhi bi ting

Kalahari sands only tha sout~~rn prrt of thu area may be in

reoeipt of S(,m8 rechorgo o

Considerin~!, th8t the en:".uel rate of (~v2por2tion is 8;)r'ro:ximately

114me the onl;)T 1.\18Y that r,:~inf811 .cen rech2rge the underlying .. I' ...

aquifers is via rDpid runcff 2nd infiltrati~~. ~ssuming that

activG infiltrati.,n can ta~G ~l8c8 via jointed sandstcnes and

limestonos an~ foult 201105 ur: to 4; ,-::f the annual rainfall

may bo rGci~,::::tgiJd tc t~;s aquif .... ~rs, in the:: SOllthorn 1-·3rt of area 1:'0

Thereforo t··~tc.l 2nnuel rOChDriG t.:' t~11,) ::,.'.;).t0rberG,' ?Dd Transv221

aquifers in tn.o sOI:'cthGrn p<:rt cf er28.~. may b\; of the Grder of

250 000 m3jannum.

- 24 -

4.0 GEOPHYSrCL INVESTIG;,TIOllS

4.1 General ~srBcts

j~nalysis of the ae:rc~:Je{~ne'~ic coverAge of the J\oJaneng area (De

Boors Prospocting (Botswena) Fty Ltd,,) rev88ls sever21 s(..'cJ.th ....

\"J8st-n(;rtheast lineaments. These linGernonts roflect bedrock

faul ting 1r.Jhi ch is c-:;xpGsed in th~ D0Uth but cr,ncG81ed by Kalaha­

ri sediments in the north arour:~J. the JVJ2neng arC8 0 In order

to loc2tc those frul t zones and to determine the bedrock geo-

109'Jf gTound geophysic21 lTICtL10cLS (geoelectrics and magnotias)

were conducted elong three cut-lir:es (Fig .. l)o The three cut ....

lines extend southwards from tho Jwancng area to the main Ghanzi­

Lobatse road vJhere bedrock exposure provides geological control,

(Cullen, 1958).

j, IiicPhar G~re 70 Prcton MagnetometaT was used to measure the

absolute magni t"l.-,;-le of t!.18 t:::·tal mag:'1etic fielde Readings were

taken at 100 metre intervals along the cut-lines.

Gooelectrical (resistivity) soundings using the Schlwnberger

arra;y' "'Jere conducted at 1 ]-.,".m intervc-}ls; their centre pcints are

located on the map. Station LwnbGrs 132-140 were conducted by

lcIellfiold Consulting ServicGs (Pto") Ltd. The maximum current

electrode sep8retion varied from 360 n;(~tres to le 4 km depending

on th0 gcolo:?:1.ca1 ccnclitionso The majorit;y \.:f the: suundings

attained aD elJctrode se::arati0rl in exCess ef 700 metres.

The geoolcctric21 sounding ourves lrJorG interpreted. in the:; field

by curve-matching of t',l'.j 2nd thrc;e-la;ycr masters in conjunotion

Hith auxilliar;,/" oharts (Crellane. snd Moonel;y~ 1966~ Rijk1-later-

staat, The r:,:;the:Y'lands? 1969)0 Tho geo81ectrio sections in the

form of hori zonta11y str8tifiei leyors of difforent resistivit;y

is difficult tc int"rpret "it)(Qut adequate geological control.

L certsin degrc:c of cc:ntrol i[~ provided by ths surfaoG exposure

in tho south, but -the look of sufficient boroholo data in the

area makes the i~ter~ret2ti0n of tl:c soundings extremely tenta-

ti ve.

- 25 -

The incli vi duel Boundings oombine to provi de [: geoeloctri cal

seotion along the cut-lines? and geoelectrical layers were

tentatively ascribed to geological units N\orevcr possibleo

~'jpparel1t zcnos of faulting arG indicated by a clistinct change

in geoelcotrical ID;/Gring1 in semI) casos associated wi th a

change in magnetic char2ctero 'TJ-w original field interprGta­

tion of tho soundings coupled ~\d. th the magnetic traverses

formed the basis for tllG early selection of borehole sites.

The boreholes h1ill "rovido addi ticnal geological oontrol and

~vill assist in tLc S'Gological intGrrr8taticn of the geoelectri­

cal sections? 8;1C':. inr:licot0 pOf.::siblo stre.tiform and faultod

aqui fers.

Reintorpretation f the {;eoolectrical sections has been mad.e

on the oompletion ,f drilling and this "ill oontinue as drilling

progresseso Unfortunately (Only 3 boroholes havo been oompleted

out of the fiftoen si tes selcotedo In addi tion to re-interpre­

tation of the gecoloctrical soundings based on drill inf()rmation~

the interpretation of a seleotion of so~u,dings, the majority

of l!Jnich are loc3toct at boreholc si t(:.s~ h:::'ve boon oheokod using

oomputer metho~~80 ~,geoelectrical curVe If.!&S computed from the

postulated geoelGctri.cal mod.el and cor."lparod with the field

curV8 0 The model 1Jlas 8ubsJquc;ntl;y modified in order to improve

agreomcnt o The interprotaticn cannot be reg2rded GS a unique

solution, however, until the rosults of drilling beoome availableo

30""ehole si tes

The gooclectrical secti ,~lns~ (:1ognetcmctc1' traverses, and the

oomputed and fiold ourves "i th ass~oiatod geoelcotrionl models

hlill aooompany the final rerort 2n-:! formed tl'G basis for bore­

halo si to sclection o The g'Gcrl1ysical interpretation is dis­

cussed for 8Pch boroJ.101o site and e tent2tiv8 geological section

has been e.ssi2,'TIod hlherever possi 1)100 '2hc o2mputed an,) field

curves are given in .. _ppendiy 20 .. ,t the-sc; sites \\1h01'o drilling

he.s boer. completed tho 8:coelcctrical mc;Qol bas beon com;)21'ed

tc· the geology obt2:i:1Cd i.n the bo:,oholc o

i;ll ori[,-'inal fiGld :i<:-:tn is 2vailablG for ins··cction at the Gec­

logical Surv0~'~ Lobats00

- 26 -

4,2 Central Cut-line

This was the first cut-line survo;yod and consequently some

drilling results are availablo t(, assist in the interpretation.

site C.26

To the south c·f CQ 26? \'~atorberg sanc1stonos Clnd conglomerates

are exposed (Cullen op.oit), _,t 026 a thin oOVer of sand_ and

conglomerato (8 motros) oVQrlies a lay~:,r with a resistivity of

210 ohm-metros. _, thin oonoxcoti VG larr 12 ohm-metres at a

depth of 55 metres rests abovu a resi sti ve layer of 130 ohm-

metres. This IDJ'cT m8.J' ropresGnt e saturDted sandsfDne faulted

against s11ales (\r.]hich occur i:~lm8di8tely t-'.' the north) 0

siteC.23

}Torfuh of C.26 and extollding fcr 4 l:ms, the soullding8 are o11a­

racterisod by extrOr:lol;y low resistivity values f bct.ri heer sur ....

free and at de:cth. Tho borel~ol~ log shows 2 metres of soil

ovorlying brl:,l,·m s~laley mUdstone chcnging to black shales at

68 metres. Ua.ter strl)ck 8t 103 metrGS coincides fairly well

wi th the gooelcctrical layers vlhich change from 30 ohm-metres

to 6 chm-metros et an indic?tG'~1. de~- tn of 110 metre!3.. Thus the

extremely low resistivity values of the lower unit in this

reg""ioD passi bl;y reJ.)resents sptuJ.'atod black shales ..

si te C.9

The sounding at this site oxhibits similar chClractoristics to

C0 23 althc.ugh tha resistivi·ty values 81"2 no·t as low at depth?

possibly indic2ting [; le :;; s8t1...1rc-jtc~~1. fJl:fll e fcrmation"

The intcrveni:'"l{S' sounc~ing[i at Co 20 and Co 21 exhibit high resis­

ti vi ty values n·2.,:r surfacQ~ r,I'O 1.:'2 bl;y reflecting snbeurface do-

lomiteo Tho magnetic :-)ho~;;c::-',·0clo,~.0/ ond gcoelectrical soundings

inf.J.cat() tlle existenco of f31...·,lting !Jetw·;ci. (~021 anfl ~22 in the

south and between Cc 19 an::: (,020 tCi the ncrth ..

- 27 ~

Sito e.l3 "Jas sited in an area exhibiting a distinct magnetic

charactor bct;,voen sc'<}nd.ings Co 15 and Co 12 .. In t.~is region a

resisti vc la,:vor I'on,?,ing from 360 to 490 ohm-mGtres 9 coverod

by Kalahari seclil:,cmts (20 ;netros) overlies a less resistive

hori ZCE (130 ohm-mGtres) .. This lOv)oI'-r2sip,tivity leyer may

reprGsont the 'l-12tCJ' t,·',tJl(:; or pcssi bl;,y' a different rock uni to

The undulating basement (infinit<:: rcsistivit;y) is possibly

grani tG~ tho der-th to which varies from 65 metros at C~ 12 to

a maximum of 3S() metros at C.1S.

The geoelootric21 la.yering et C.,)l and Co 10 differs from those

to the soutto ~'" thin suporficiel C,',VOT overlies a 4g metre

layer ~~th a resistivity of 175 ahm-motreso This, in turn?

rests on an oxtromGly rosistivo unit 1'.dlich possibly represents

noar surfaco gTC"nitic basernentf probably faul t cGntrol10do

site C.4

The: 1)orehola at CQ 4 encour:.torOt_1 fc:lsi te gt [' depth (~f 57 motres

and l'Jas terminated at lC33 ni8tr}S in tho Sa1:'i'::; uni to The borehole

was dry. Th'2 upper threo 0'GG31Gctri ca.l l:-:<;.Ters corro8;::ond to

the Kalahari cover com'1risin,; c21crot8s, silcrotes and sendo

The fc:urth layer (150 ohm-m8·t"'G~:3) r'~nrGscnts ·;~.;·)G fc1site with

The geo-

electrical mod31 i;:; similer tc· t!108C G21C01.1nt·3r8d betwoen Co 12

and C,,15, and th~ preeE m2~i be gecJ.o'.~:ically ccmpetiblc9

siteC.O.4

This boreLole Via.'.:; si ted 011 D ~"'r,.>l}(.:unced lino2!:~:8Dt separBting

tv·)O contr?sting sG':~GL,;ctrical s~:undin2so To locc.te: the posi tien

ef t.he f8ul t9 the gl"':;dient arrc"~: Gloctricel met!,cd ~:)3S used

and tho beT'eholo 1/Jt;8 si tocl 4C< motrG5 S"t;,t~·.l of vOo ~'l fault zono

Nas encountered ?l11'l 2. limi too_ sW.j; .. :l~r of w2tor It.l2S struck at 3

depth of 90 metr:)s.

- 28 -

si to C. 3

TIGtl,'Jeen CO and (,.,8 the gooelectrical soun:lings are similar in

character and indicate a thick unit~ ranging in resistivity from

90 t·e 150 ohm-metres, covered by " laY8r of Kalahari sediments.

The uni t overlies an undulating basement (grani te f) at depths

ranginG fr(~m 70 to 400 metres" 'llhe borehole wE~S si t(~d at C.3

"1:tVhere baS8m,--~nt is roL:::tj.vel,),- Dsar surface ..

si to C.9

.. 'It Co 9 the geoelectrical model indicates a low-resistive layer

(shales?) overlying a 360 ohm-meter la;yer (lr,:e.tcrberg ?). This

abrubt ohange; frcm the areD tc the south is rrobebly due to fa-

ul ting.

Three si tes have be·;;n solect(d to rr;)vi de ,geological control

'rho geoelcctri c91 n~·'" del a t si"':.8 ::" 6 inn co tes 2 low-r2si sii ve

layor (80 clrJ-iTI:~trcs) et A depth of ~)O metre;:;" This layer is

ovorlain by 2. 350 ohm-metros le;~ '2r (25 metras) and e. sUl=,erficial

cover of Kalahari scdimentc (16 f:1otres)o 'To t.:'0 SG'.:th and north

(:'·:5 end Ill?) tho .geoolectric curves illClicfJte pOf3sible suppression

of the: Iow-resisti vi ty uni t9 vJi th :i.;OESi bIe.: fsul ting noar lr!o 5

and 11/07.,

La v·) resisti vi t~~- vel ues at Co 13 end Co 14 arc ag2in possi bly asso­

ci8ted \.'Jith 8.1.181080 The lO\!J resistivity unit (40 ohm-metres)

is thickost at ~o14 and thG ~lOl0 unit is a possible aquifer.,

Si to "1.19

8hale are t!lOug:h tc occur at CO 1G 1 CO 19 and Co 201 but exposure

in the sroe is vo~~:/ )Oe-T (CulleD 1958)0 LO\\1-rosistivit;y values r

t;ypical of sh81es in Gtlvr areas 1 h2ve been encountered and the

I

- 29 -

site has been selected in order to pr0vide goclo;j..cal controlo

4,4 Eastern £u2::1.i!!!!..

-Tho gooelectric.':;l sOlmdingf) 81()11,~~ the eastern line are similar

in charaotor and indicate a. roletiv31;y thick Kalahari cover.

There is 1i ttle geological control in the erea and it is not

possi bIe tc. 211ocBic 1 even tonteti vel:)T? geological uni ts at

this stage. Bcrehclc sites ElF :!I:119 E16 and I~20 have been

selected in ordi.'3r to :'lrovido geolc -;ic21 ccntrolo

'1' i

J~ series of tNenty test borshc:J.e8 h2VG still to be drilled?

subject to the aV2~il(:bility of the drilling rig and ancilliar;r

oqui\,ment, .. 11 hol,,,,: drilL,.-, -"ill be logged usins g'Gophysical

down the hole loggin.:;,; tochniq1.1GS" The gGolof,;iocl and geophy-

si021 borehole logs ,:.btainect. ,'lill be used to reintGI'pratc the

assooiatod geo-electric soUn(~i~1gso

~-.ll holes ~~enetrptir;g I.J2t .. 'r bGari~g str2.t~{ will be test pumped

using the airlift t~ohniqueo Cbservation holos will "e drilled

airli ft tes to Such l-~igh ;)Tiol~lins hclof: will bo subject to a

series of tests thet includo; -

(a)

( b)

Ster drPl'Jdo1;,m i;est~ '(;.ll th at le::,r~t four steps,?, t.r" (';{'/

Short tCTlf reCGVJr~1 t8St~ ,.,,'M· <

( c) ,,/'f~ng term const:.:-.... nt yic1 cl tGS to 1"/: ' (i,

( d) Long term 1'0 cc V8r;,/ teG to

tlJater samples ~liJ.l be taker:: frcn~ v-,Intor yielding boreholes at

depths dGt.;::,rt:1ino~l b;l the res"L:lts of geophysical dO,\fm thG hole

loggingo Furt;·~ r surf2co i;:;Gorhy~·:;icc.l SU1~VCyS v.Jill be conducted

as and hlhen requircdo

Rrief asSeSSm0)~ts of the ~atcr ~otentiel of two adjacent areas

1!Jill be made if tit~'lG pcrmit3 0 Th::" 8reD s are :

1, The Rr08 ef rrominont pan development in the south east~rn

part of qucrter c,-egrS!3 square 2424D and the adjacent Selo­

kolela Valley.

20 The approxilTIa t:.:. 21i gnemen t 0 f th~; propose d Kanye-J waneng

r02do

5.2 Conclusions

The geol 0 gi eel e110. to otC:!'li c ne ture of t1!.c southern part of the

area j~ is n01'! f['irl;), 1,'811 unc:1: rstoo·:l.o rrhat of the northern

pert of arC3 ii VIiI}, bG :)(jtt2r un<~erstooc1 upon ccmpletion of

the proposG cl dri 11inC rro bTUmiJe 8n(~ rein t:)rpre to ti on of the

geophysical sOlU1cling c1i1tso

Four main aquif~;rG have been identifier} in the southern :part

of arc a ~:.o 'llhC'~I' s~-:,ecific aq>ifeI' paI'a!i18ters in faulted and

undistur\)ed forms lplill '.1.,-; .388'3';S8d from the results obt2ined

from the future tc',t pum:,,'in!~. >·;. ... ol;r::-'mJ!~eo

The h;ydrochemical dnta that oxlstr.,> at l)r8sC:'lt suggests that

ground'l',at0Y'[; in the northnri1 purt of ti'L:' 8r::;e are Generally

poor in quali t;< cHl:J mf,'!,} be s,-lin.oo

scutlL,rn ·"?..1't of t.h0 21'0: gon(:;::''''E:1I~l totel h8rdnesS

concont1'GticDS meJ(inG tbcm unsuita')le for use as boiler feed

N8ters~ but thc2,' er,-; still 2d.OqU:<t8 for domestic useo

TherG ie; S'.)i11e evic1.::;",ce to S\~gg08t tLlc't re.inl,.12tGI' rli8;:' infiltrate

into an;'], rGch~,r:::e .::,;(, v2ri:::iEL 2cplifcrs i:"1 the r:.-i";1.'.-'t! .'rn pprt of

area "'~ but thct the rate of r'scharge is '::leIlGndont upon t~le

extromely sporar:.ic storm event tY:)8 ~",f rainf91] ~

ThorefGre until ccmr,leticn :Jf t:-'.8 rJrilling <::~n(;. t,}ct pumping­

programme no 2stil~':2,t8 ef the ~_ .. 12.t"r pc·tential c·f clrCe. L can be

arri ve d. a to

I 1

BOOCOCK, C. 1961.

CROCKETr, R. N. 197 2.

CROCKETT, R.N. & JONES, M. T. 197 5.

CU11:iN, D. J. 1958.

DU TOIT, ".L. 1954.

HOUSTON, J.F.T. 1972.

JENNIN OS, C. M. E. 197 4.

ORELLLr.', ~ E~ & MOONCDY, H. M. 1966.

RIJK~~rLT:;RST.:~iiT1 T:TS NGth3r1ands, 1969.

- 31 -

R E FER E N C :i S

Notes on tL3 distribution of rocks of

Transvaal age in the Bachuana1and Prote­

ctOl'at3 4th meeting 5th reg. congo geol.

Pretoria, Pub1. C.C.T.;" 80, 73 - 86.

The Trnnsvaal system in Botswana. Its

geotectonic and deposi tional environment

and special problems. Trans o Geol. Soc.

S. "fr., vol 75 pert 3.

Some aspects of the geology of the Water-

berg system in Eastern Botswana. Trans o

Geol. 2'0. S •. :fr., vol 78, 1 pp 1 - 10.

Gcology of th·3 Dikgomo Di Kae area" Re-

cords ef the Geological Surve~' of Beoh­

uanaland, 1956, pp 5 - 11.

Geolog;,Y of South ~jfrica, 3rdo edition,

Oh ver 2nd Boyd, Edingburgh, 611 pp.

Intc.:>im report on the groundwator reso­

urces available for the supply of Kanya

village. Report of tho Bots"ana Oeologi-

021 GurvGY Department .. (unpublished)"

The hydro geology of Botswana .. Unpublis­

hed. PhDc thosis~ University of Natal,

2 volso

Maste::'" tables and curves for vertical

electrical scunding Over 13.YC::Ted strue-

tur::so l1adrid Int'2rcionza.

St2n~e.rd grarhs for Y'8sisti vi t;.v prospec­

tinge The ~:ague9 European Lssno of Ex­

plor~~ion Gsophysisistsc

" I I I I I I I I I I I

Stratigrophy

KALAHARI

BEDS

WATERBERG

MAGALlESBERG

STAGE

DASPOORT

STAGE

"

TI MEBALL HILL

QUARTZITE

DOLOMITE

STAGE

BLACK REEF

STAGE

KANYE

VOLCANICS

FELSITES

FORMATIONAL AND

Lithology Thickness (meters)

Calcrete Si Icrete Ferricrete

o - 50

Fine sands

Sandstones >200 ".Iv, m

Shales

Banded

6 - 10 chert

Quartzite 250

upper shale

Ongeluk 500

Volcanics

Lower'sh'ale" 200

Quartzite 150 _ 180

Shale 500-650

Chert

brecc ia

Bonded

ironstone

Banded I ~800 chert

Dolomitic

limestone

Quartzite 6 -10

TufL,;uu,~=

. rh~:,iI t e 5:

Feldspar porphyries

HYDROGEOLOGICAL FEATURES

Lateral !

oJbilih, Joints

Degree of Exposure Poros'lty 0'

Extent Size 'Vo

0 Patchy

0 00 00 Occurence

Main cover of the 000 northern part of , 000 000 -

area A

000 Forms hills in south

0 00 00 (

sand cover south of road

, 0 Poorly I 00 - 0

0 Well - - 0

Well forms ridge 00 - 0 00 I

features

00 poorly 00 - 0

Poorly, odd blocks 00 - - 0

on surface

00 Poorly ,'" 00 - 0

Well, forms persistent 00 0 00 00

ridge featUres

00 Poorly 00 0 0

Well/forms typical 0 - - 0

rounded hills

0 Moderate - - 0

Well, forms low 0 - - 0

ridges

00 Poor except along

- 0-00 00 deep gullies

I

0 Intermittent - 0 00 ,)

,

0 Fairly well - - 0 .....

".

00 In pans - - 00

TABLE 1

, Permeability Joints storage

Water Type Comments Size Volume Capacity

00 00 0 0 Ca-HC03 Perched aquifer of small volume

000 - - 0 Ca -HC03

Usually dry

00 000 00 Ca-Mg-HC03

Transmi5sivity and storage capacity are 00 increased by faulting

- 0 0 0

- 0 0 0 Fe 3 + rich

Tran5missivity and storage capacity are 0 00 00 0 Ca-Mg-HC0

3 increased by faulting

- 0 0 0

- 0 0 0 502-4

- 0 0 0 .. ' . " ,

Transmissivity and storage capacity are 00 00 00 0 Ca-Mg-HCO

3 increased by faulting

Transmissivity and storage capacity are 0 0 00 00 Ca -Mg-HC0

3 increased by faulting

- 0 0 00

- 0 0 0 Ca-Mg-HC0

3 Fe 3 + rich

- 0 0 0

0-00 00 00 00-0 Mg- Ca- HC03

Karstic weathering

0 00 0 0

- 0 0 0

~ ~ n Cl Rirh in f(

!! • "I i;1

I I I I I I I I I I I I I I I I I I

WATERBERG

••• ' .. CCs~< . .......< cC

« ...... STAGE

1< ........ ......

••••••••

SPOORT

/c

STAGE

TiMEBALL HILL

QUARTZITE

OOLOMITE

STAGE"

BLACK REEF

STAGE

KANYE

VOLCANICS

FELSITES

GABORONE

GRANITE

'u" "'""tKBERG

OOLERITE DYKES

- -,"_.- . )"duu UUU I, Ir", .. ~1

Shales 0

Banded

6 - 10 0 chert

Quartzite 250 00

Upper shale 00

Ongeluk 500 00

Volcanics

Lower shale 200 00

Quartzite 150 - 180 00

Shale 500-650 00

Chert 0

breccia

Banded 0

ironstone

Banded ~800 0

c.hert

DoJomitic 00

limestone

Quartzite 6 -10 0

Tuff";vu,~=

_r_h~?_I!tes, 0 " .. ' Feldspar

00 porphyries

Granite 0

Dolerite 0

U vv vv , sand cover south of rOae

Poorly

I 00 - 0

Well - - 0

Welt forms ridge - 0 00 {

features

Poorly 00 - 0

Poorly, odd blocks - - 0

on surface ,

Poorly I 00 - 0

Well, forms persistent 0 00 00

ridge features

Poorly 00 0 0

Well, forms typical - - 0 rounded hills

Moderate - - 0

Well, forms low - - 0 ridges

Poor except along 0-00 00 -

deep gullies ,

Intermittent -- 0 00

Fairly well - - 0

In pans - - 00

Poor - - 0

None - - -

"''-' "".. ........... "J .~ .... - ••• ;:J

- 0 0 0

- 0 0 0 Foe 3+ rich

Transmissivity and storage capacity are 0 00 00 0 Ca-Mg-HC0

3 i ncreosed by faulting -

- 0 0 0

- 0 0 0 502-4

- 0 0 0 ,-

Transmissivity and storage capacity are 00 00 00 0 Ca-Mg-HCO

3 increased by faulting

Transmis5ivity and storage capacity are 0 0 00 00 Ca -Mg-HC0

3 increased by faulting

- 0 0 00

- 0 0 0 Ca-Mg-HC0

3 Fe 3+ rich

- 0 0 0

0-00 00 00 00-0 Mg- Ca- HC03

Karstic weathering

0 00 0 0

- 0 0 0

- 00 0 0 Rich in K

- 0 0 0 Na- HC0

3 Na- Cl High K

- - 0 0 0

KEY

None -Smoll 0

Medium 00

Large 000

G.S. Official. Locality

Number Borehole Number

1 Z2946 Jwaneng

8 2281 Kgome pan

9 3109 Kgome pan

12 891 Mogobe wa Dinonyane

14 1598 Honye

15 1890 Dikokwane

16 1813 Dikokwane

18 1590 Dikgomo D1 Kae

24 1591 Lekwadibana

25 909 1!okumba

26 1470 Lobapa

27 Z 2058 Senyamadi

31 911 Lehoko

57 2374 J",ana Hill

",~~"".,",,<d

TABLE 2A

CAITlE POST AND VILlAGE BOHEHOLES LOCATED WITHIN AP.EA A

Depth Water water

Yield Water

struck Rest QUality Geological Formation (M) <I/min) (M) Level (M) (ppm)

184 144 130 75.8 - 0-47 m Kalahari Beds. 47-184 m PrecambrianShales and Kimberlite.

64.01 0-9 m Kalahari Beds 196.0 125.0 51.82 45 148 9-100 m \Vaterberg sandstone

146 Q 9 100-196 Syentte

0-9 m Kalahari Beds 182.9 84.0 53.84 lS.a - 9-100 m V/aterberg sandstones

100-183 m Syentte

91.4 74.7 71.3 18.9 2072 0-37 m Kalahari Beds 37-91 m Gaborone Grant re

108.2 89.9 78.6 56.8 556 0-108 m Timeball Hill QUartzite (Transvaal Series)

89.6 182.9 118.9 82.0 34.1 556 0-183 m Timeball Hill QUartzites

11504

110.3 104.2 ? 6.1 - 0-110 m Timeball Hill QUartzites

6.1 - - Dry - 0-6 m waterberg sandstone Boulders

91.4 84.7 "53 0 3 22703 128 0-82 m waterberg sandstone 82-91 ID Faulted Magaliesberg Banded Chert

105.5 94.5 82.3 75 0 8 484 0-105.5 m Timeball Hill QUartzitG

113 0 7 97.5 85.3 54.6 424 Lower Daspoort Shale - Timeball Hill QU

61.6 54.9 54.9 90.9 544 0-61.6 m Transvaal Dolomites

73.2 39.6 40 02 51.1 224 0-73m Red Waterberg QUartzite & sandstone

169.2 97.5 76.5 26.6 468 0-169 m Timsball Hill QUartzite

-""-{ F c",

cC

\'""'01

"'">0-,-

TABLE 2B

PROJECT BOREllOLES

I ' , i I

I G.l>. i Offici~ I Depth Hater Water Yield ¥later

N b Boreho.1i.e I LQ;cali:ity (N) Struck ~t (l!rih) Quclii7J Geologice.1 Fo:rnation un er -- i (ll) Level en) (ppn) ilUDber

61 - I KgO:::l e l' ~'1 165 90 53.45 7.5 (.1U.r 364 0-15n Kalahari Bads

i Lift) 15-102I1 Hater-berg Shcles 8: SarcdatQnos 102-156n Syeni to

./ 62 4 lfu South o:f

183 I Dr,r C-57n Kclahari Bods - KgO:::lC Pan - - I - 57-183:1 Fclsitc

63 - 6 lfu North IDI 133

103 76 16[f(Air 356 O-j 33:', Ti.,c1Cbcll Hill Shclcs 1,,,,'101<:0 132 se Lift) J ,

64 - I 3 1fu North of" 104,5 75 To be (--104.5[1 Ti"obcll Rill 'h.'lrlzi to

i LohoJro - 'rusted -65 I 2 Kn North Wrot.

125 98 82.72 To be. 0-125n Tinobell Hill Qun.rtzite - -i 1 of N:akunba Tesited , I 4~5~_lfu Sout,'1. East i 66 . . 1t5 112

To be , C-l25[1 Transvacl Doloni tea - - Tested -

I . of Hokurrba I !

Sanpla G ... S. Boroholo Locnli i;T C0

3 HG0

3 Ho. lIunbcr

77466 8 Kgo::w Pnrr O. 80

776341

12 Naganc ,m 0 395 j llinonyQ.;.Lc

77628 14 Honye 0 176

77633 15 lliJ::okl'If:.-lJ.O 0 464

77639 24- Lckwadibana 0 61

776:N j 25 IIoIrunba 24 346

77627 26 Lobnpn. 0 386

77632 27 Sc.."1.y'no.edi 0 417

77624- 31 1.chQko 0 166

777:N 57 Jwona Hill 0 281

77449 61. Kgono Pan 0 149

77480 63( lQ4n) 4S1m lfort:t of' 0 356 Lohoko

77481 63(12}:l) 4.5ku North of' 0 383 Lohoko

77482 63(St~ 4.5ku North of' 0 381 Lohoko

17483 6;(Mnisb) 4.5ku Horth <11' 0 4{O

Lohoko .

I

Cl.

14

777

183

46

11

73

54

96

23

35

38

50

48

50

48

TABLE 3

IIYDROCHEHIC:AL ANALYSES

ngjl 1

Sun S04 F NO Si0

3 ·3 iJ.nions

13 0.0 8.0 32 147.0 -

183 1.0 67 44 i 1467.2

21 0.6 11 16 407.0

5.t 0.7 31 17 1 591.9

5 0.2 14 40 I -j32.1 .-

18 0.5 I 5 1

20 et! 4-86.8

13 0.5 15 26 i 493Q 8

4 0.1 1 25 I 543.4

7 0.2 10 34 240.5 j

35 0.5 16 30 i 397.3

31 0.0 1.0 21 239.0

35 0.5 1.0 7 448.3

31 0.3 1.0 13 476~7

32 0.2 1.0 15 477~2 I

:N C,2 1.0 1.1 490.6 -- - --_._---

Unhs

Sun K I'T 0;. Ca . Ng TDS Cond pR Cations

3.4 35 6 4 48.0 148 206 6.9

10.3 468 110 70 6fT/.3 m2 3496 7.65

13.8 50 84- 29 176.4 556 932 7.25

3.5 86 63 .38 189.8 556 975 7.41

1.2 5 14 10 30.0 128 158 6.5 -

1.7 23 94 35 153.9 4St, 871 7.3 - -

10 8 47 67 30 14509 424 770 7031

4.6 22 75 62 162.9 544 929 7.4

2.0 11 34 18 66.2 224- 328 6.78

7.2 48 [f3 20 118.8 468 560 7.2

12.8 74 - 7 6 99 .. 8 364 440 7.6

9.4 23 64 39 Dt.9 400 740 7.85

5.7 23 76 40 145.1 440 750 7.85

2.3 23 76 41 141.7 416 750 7.9

c4 --: 21 81 42 146,9 356 . 780 . 7 .. fJj

.-,......~<~----.

(t,.S. mgj:r. (Co.C03)

BORlil!IDLE ,

llmMll!JllR T~ Os Mg HCO~ 8°4 ItAJl:l)lfl]lSS

'-S 12: 16 66 14 2S

12 Z74 288 324 191 560

14 2:10 119 g4 22 329

15 1517' 156 , 380 35! 313

2:4 3'5 41 50 5 76

25 235 144 284 19 '579

26 167 123 3,16 14 290

'2!'E 1871 2:55 342 4 442

31 S5 74 136 7 159

5:l 1CYl 82 230 36 189

61 17 25 122 32 4;2

63 ( 104m) 160 '160 292 36, 320

63 (123:1) 190 164 314 32 354

63 (St=ii) 190 '!169 j<j2 33 367

63 (F:imsh) 202 173 328 31 '575

APT'"PNDIX 1

Project boreholes, geological logs.

0-2

3 - 11

12

13

14

15

16 - 24

25 .. ·~1

42 - 102

103 - 156

o - 15

16 - 24

25 - 41

42 - 102

103 - 156

LITHOLOGY

]0.)]1::: brown 8 nncly ooil

Fine grlli'1od mllOOl1oolidCltod s<'1l.1d - sono cCllcro'Co at 3.

Forricro-co cOIlonted bolders - sono il:ilcrote

Unconsolidr,tod light brol'n.1 fine grgined sand

Ferricroto cononted boulders - soue silcreto

Un.conoolidnted fino gr<~inocl light bro,m s[!'Od

Fault broccia of rod qunrtzi tic sands.tono [!'Od clny

Pink clayey 8ho.1o

Uodiun to cOarso grnined darl, rod/groon quc.rtzi tic aandstollG

Dorl, rod with pntchos of black ond dark eroon ignoou-s., rock

STRt..TIGRAPHY

Knla:ho.ri S Gdinon ta.

Fnul toe! 'Il,atorborg Scndstol1D

811n108 U-:.'..torbcre

Snnu.stono

Syonito

· !

4 - 5

5 - 43

43 - 57

57 - 183

LITHOLOGY -~.---.-.-

IJ:i.ght br'own fine ;;rained unconsolidated sand

Silcrete

White calcrete

Light ochre brown uncol!lsolidated fine grained sand

Grey fe~spar porphyr~ (Felsite)

I I

.J;l.ORF!HOLE NO. 2424 D(6J;

DEPTH 133.5 liETER.S,

This hole has still to bo conpletod to 165 netolfflt

DEPTH (nETEIlS) LITHOLOGY

1 2

3- 16

16 18

19 21 22

23 - 31 32

33. - 36 37

38 ~ 40

41 43 44 - !f6

47 58 58 - 62

63

64 - 67 68

69 80

81 87

88 92

93 95 96

97 98 104

105 109

110 112

113 114 115 1 i 8

119 120 - 121

122

123

Brm''ll1 soil.

Br01:m-green shaley nudstones

Pink-brown shaley Iludstones

Brm,m"creen she.ley r.1udstones;

Pink-brmm shale;; nUdstonos

Rrovlll-green sh[\loy l1udstones

Pink-br01ID sh8J:oy nudstorres.

LiCh t-br01ID shaley ;cmds tonos

Pink-brovm· sho.ley l]uds-tOllGS­

Briclr rod shc.loy ;]udstol1os.

LiGht pink sh210y D.udstonos

Brovlll··rod sh"ley Duds tonos

Rod-brOlJl1 shl1.1oy r~udstonos

Licht pink shaloy audstonGs

Off v/hito shaloy cmdstonos

LiCh t br01ID sh[\loy nuds tonos

Br01"n/blac-lc f;h~.,-loy :'-luds tonos

Dlaclc sl1alGs

Bl~.cl' sh"los, Crey fine gr2inod sondstones Md sono- rod 811['.108

BlD.ok 811[2108;

Black shQlos vd th s ubordinQto rod shdos

Black shD.los

Black shclos 1·ri th subordin"te red shales

Blr,ck 8h,,108

Black 8h,1108, finG crDil1Gd GreY-Groon. sMdstol1es, subordinQte rod shales

Black s1111los, SOLlO interbedded pyrito, Cloy-creen fine grainod sandstol1es,. red shales. Black sU''.les Blrcck 8h,,108, imterbodded pyri to

B.lack 8hales

Blrcck Sh[elos, interbedded pyri to

Black sl1[1les

Bl.::.ck shnles, interbedded pyr.ito, fOI'! fro.gnents of ro.dJblack shc.les

124

125 - 129

1,30

132 - 133

Bl"cclc sho.los, li tUe interbedded pyri to, sane fine grcined grey green so.nds tone o.nd red splin tory sho.le

Blo.ck shaleo, interbedded pyrite

Bl[',ck sh['.108 1 80::.18 reel spli try shales and fU1'm-grey she~e

Black shales, little interbedded pyrite sane yellolf and uhi to faul t clo.~~r

Black shaJe

STRAT IG RtJ..?HY

./l.ll of the above arc in the Tine bal1 H:iill s;tage. of

the Transvaal Series

DEPTH (l"lETERB)

1 - 3 4 - 5 6 11

12 - 14

15 - 21

22 - 25 26

27 - 30

31

32

33

YJ. - 39

40 - 41

42 - 46

47 - 50

51 - 52

53 - 54

55 - 58

59

60 - 61

62

63 - 64

65 - 69

70

71 - 74

75 - 80

BOREIlOLE NO. 2424 D!64

LITHOLOGY

Brown sand Red/purple fine quartzitic sandstone boulders

Purple quartzite - much qu,'lrtz veining Purple quartzite fine grained sandstone Purple quartzitic fine grained sandstone 75% as a fine purple unconsolidated sand Purple quartzitic fine grained sandstone White and pink mudstone with 4~1o purple quartzitic sandstone White/Pink/Hed mudstone with 40"/0 purple quartzite fragments occurring rolled in mud­stone Pink/red/brown cl'wey muds tone, 2"/0 black shale and 10% purple quartzitic fine grained sandstone Purple quartzite fragments in IDite and 1 i gh t ±red O':l~l)Ie;W'DUdstone '

Purple qunrizi tic sll.'1dstone and white olElYey nucls:t0nC

Purple fine gr';,inoel qurcrtzi tic sDndstone

Purple fine gr:cined quartzi tic amelstonel$ Ni th sone red sil ts,tones anel shnles

Soft red shv.ley nudD tones - little purple fine g.rainoel qunrtzi tic s1l.1ldstones

Purple reel fine grained quartzi tic s1l.1ldstones 'ili th nicnceous rod sil tstones'

Purple ~)1d red fine grc.ined quartzi tic s1l.1ldstones Green 1l.1ld reel/brown nicnceous siltstones, sone rod/ purple 1l.1ld yellow ochre shale

Red-brown soft nudstone, green rod reel-brown nicaceous silts tones, little purple quartzi tic sandstone

Purple fine grained quartzi tic s1l.1ldstone, green and reel brown Dic~ceous siltstone

Pink silty Duelstone, purple/red qunrtzitio fine grained sl)!ldstone, Md fissile DicRceous siltstone

Purple reel silts tone Md dl'.rk reel Dice.aeous· fine grnined senclstone

Purple reel fine grained qu.o.rtzi tic sandstone

SOft light grey pink silts tone

Purple red nicaceeus fine grained s(>)1dstone, sone red and yellow siltstone

Purple, brown" red to light bro'im!yellew nicaceous, shl':ley silts ton, s

Purple brown to light brown shaley siltstones

BCLaek, purple [CUd de.rk brown fine grnined s1l.1ldstones; sone nicaceous sil tstones

81 - 86

87

88 - 91

92 - 93

'I 9J, I

95 - 99 , I 100 - 102

103 104

105 106

107 108

109 - 110

Light brovm ',0 chocolate brown Dud, purple-red brown sil tS-Gunes, rod brown fine grdned s,,-ndstones COl1Donly vii th rounded edges

Black ,md purple shccley sil tstones, dnrk red to light brown ni caceous fine grc.inod s andSltones

Bro,m-rod and purple fine grtun0d :'licaceous sandstones

Purple ilnd derk grey siltstones. purple fine grmned s.nndstones

Soft dark grey t1nd purple nicnceous silts tones , sone pinlc/groy soft she.lcy [ludstones

Dark grey and purple/brol1n soft slvl1ey sil tstone&

Soft brick r0d cle.y0y nUdstones nnd bleck shele",

Soft brick red cl,o.yey nudstonos bl[lck shnles and purple siltstones

Black [lnd purplo sil ty sh,,10s [lnd nic,::coous silts tones

Black shtw.0Y siltstonos c.nd purple niceceous, silt­stones

Black ,,"'1d dnrk purple she,les, SO:le purple silts tones

BOREHOLE NO •. ?~2~ D/6?

Second hole drilled by De Beers in the Mokumba area

DEPTH UlETERB)

0 - 3

4 - 19

20 - 22

23 - 25

26

27 - 33

34

35 - 39

40 - ~2

43 - 45

46

47 - 62

63 68

69 - 71

72 - 73

74 - 80

81 82

83

8~ - 85

86

87 88

89 - 90

91 96

97 - 111

LI'rHOLOGY

Yellow sand and red qW1rtzite

Red quartzite boulders and gravels

Red quartzite and shale

Shaley mudstone

Shaley mudstone (rIn rich?)

Q,uartzitic sandstone-red

Coarse sandstone

Purple quartzite

Q,U:lrtzi te .'lnd shRle

Red qun.rtzite

Grey quartzite

Micaceous red mudstone, siltstones Rnd some grey quartzite

Chocolate brown TJicaceous shales

Dark grey shale

Chocolate brown sh'l.le

Dark grey shale

Black shale

Brown red shale

Black siltstones

Grey and red shale

Black shale

Brown shale

Black shale - micaceous

Dark grey micaceous shales

First hole drilled by De Beers in the l'Iokumba area

DEPTH (r-lETEHB)

o - 15

15 - 24

24 - 26

26 - 34

35 - 57

58 - 66

67 - 88

89 - 111

112 - 113

114 - 115

116 - 125

LIT;WLOGY

UncciDsolidIC.ted c;rewel of jasper, quartz and qu~rtzitic jasper chert, all Fe strained

Grey fine c;r8.ined Dolomite + chert

50% fine grained dolomite + chert

Grey fine Grained dolomite

Grey, black cherty dolomite + sulphide

Undifferenti8.ted grey, black cherty dwlomite

Grey black cherty dolomite

Grey + grey black fine c;rained dolomite

Y'% dolomite, 5OS/, snnd : solution cavity abundant water, very fine clean sand

Dolomite + weathered sandstone

D~lomite + ~inor hematite

,.If

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