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Birr~R GEOLOGICAL SURVEY -,Llli!RYSERVICES
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REPUBLIC OF BOTSWANA
ANNUAL REPORT
OFTHE
GEOLOGICAL SURVEY
DEPARTMENT
FOR THE YEAR
1981
PRli'\TED BY THE GOVERl\'MEI'T PRl!'\TER, G,\BOROl'\E, BOTSWM":,\
)
_/--
1. GENERAL
1.1 Introduction
The organisation of the department was amended
slightly by the amalgamation of the Regional Mapping
and Economic Geology divisions into a single Field
Geology division. In recent years it was apparent that
strict separation of the functions between field
mapping and certain aspects of economic geology was at
times more artificial than real and the amalgamation
improved the allocation of duties between staff. The
Geophysics unit was upgraded to an operational division,
largely in response to the increasing amount of geo
physical work being undertaken throughout Botswana,
particularly in the Kgalagadi. The three main divisions
of Field Geology, Hydrogeology and Geophysics continued
to be supported by the technical service branches of
the Chemistry Laboratory, Mineral Dressing Laboratory,
Drawing Office, Library and Records, and Drilling; plus
Administration. A departmental organisation chart is
included in this report.
The serious shortage of professional staff
experienced in 1980 was to SOITe extent overcome during
1981 and by the year's end only three professional
posts, that of geophysicist, chemist and coal geologist,
remained vacant. Mr. C.D.G. Black arrived in June to
1
fill the vacant Deputy Director post and Dr. C. Mortimer
joined the department in April as Assistant Director.
Both officers are on secondment from the Institute of
Geological Sciences, U.K. Other posts were filled by
Dr. D.T. Aldiss (geologist), Mr. S. Bruno (hydrogeologist
on secondment from Holland) and Mr. D. Buckley (hydro
geologist). Mr. Sekwale returned after successfully
completing his post graduate studies in U.K. and took up
his duties as hydrogeologist. The duties of principal
administrative officer were taken over by Mr. M.D. Tau
on transfer of Mr. L. Botlhole to the Department of Water
Affairs on January 1st 1981.
In the Field Geology division staff shortages
continued to hinder progress in the geological field
mapping programme. With the completion of work on the
Mmathethe sheet early in the year field surveys came to
a halt and only recommenced in August with the initiation
of a full re-survey of the Tsetsebjwe area (2228A), in
preparation for the production of the first full colour
edition of this sheet. Other field work undertaken was
directed towards the evaluation of industrial minerals,
with particular emphasis being placed on brickclays and
carbonate deposits. The division continued to be
responsible for monitoring the exploration activities of
the private sector, as well as advising the Minister on
the issue of new prospecting licences. Private sector
interest in mineral exploration continued at a
2
very satisfactory level throughout the year. Seventy
three prospecting licences were on issue in January and
seventy-eight were active by the year's end. Expenditure
on prospecting by the private sector in licence areas
outSide the existing mine leases exceeded eight million
pula.
The Hydrogeology division was fully staffed by
the year's end, a staffing situation that was a welcome
relief from the acute shortage of personnel that has
existed in this division for several years. The
complement of five hydrogeologists devoted most of their
efforts towards major groundwater studies in the
eastern part of the country and the production of the
1: 500 000 hydrogeological reconnaissance maps,
temporarily halted during the year, will hopefully
re-commence in 1982. The U.K. funded bi-lateral aid
project, "Evaluation of Undergrcund water Resources" was
completed in March and a final report prepared.
The activities of the Geophysics division were
largely devoted to the on-going groundwater search
studies and providing input into various donor funded
mineral exploration projects. These technical aid
projects were largely undertaken in the Kalahari area
and have a strong geophysical input in their work
programmes. The technical service branches functioned
satisfactorily throughout the year. The Chemistry
Laboratory, as well as providing routine analyticsl
3
support work, conducted a field oriented hydrogeo
chemical project in the Molopo Farms area, whereby
analyses of groundwater were examined for concentration
of elements which may be related to sub-Kalahari bedorck.
The new Mineral Dressing Laboratory is proving to be a
well used addition to the department's facilities and
the work load in the laboratory was largely derived
from the on-going programme of evaluation of brickclay
deposits. An X-ray diffraction unit has been donated
by the Japanese government and after installation will
form a very useful item to the laboratory's equipment.
The equipment of the drilling unit was improved by
the replacement of old compressors with three new units.
The Ingersoll Rand rig was re-conditioned by the
manufacturers but it is apparent that it is reaching the
end of its useful life and will need replacing in the
very near future. The Hydreq Gryphon rig was used
successfully in drilling groundwater exploration holes
and for ftost of the year this rig was used almost
exclusively for this purpose.
The departmental activities received strong support
from several donor funded bi-lateral aid projects.
These projects were related to groundwater search (GS10,
funded by the U.K.) to mineral exploration (GS17, funded
by Japan, West Germany and the U.K.) and to further
elucidation of the sub-Kalahari geology (GS12, the final
phase of the airborne magnetic survey, funded by Canada).
4
All these projects require departmental support in either
expertise, personnel, transport or equipment and they
are all providing much new information on the geology
of Botswana. The department's facilities have been
supplemented and, in some directions, greatly expanded
by equipment purchased from donor funding, such as GS18,
Geological Survey Equipment, funded by West Germany, as
well as other items supplied from the Canadian and
Japanese projects.
With the improved equipment, a return to almost
full staffing, departmental activity, through its own
resources and those of bi-lateral aid projects, will
continue to make satisfactory input into the broad
development and growth of Botswana.
In May the department was honoured by a visit of
H.E. the President and Mrs. Masire, who were accompanied
by Dr. Chiepe, Minister for Mineral Resources and Water
Affairs, Mr. C. Blackbeard, Minister for Works and
Communications, Mr. Tibone, Permanent Secretary, Mineral
Resources & Water Affairs, Mr. Steenkamp, Permanent
Secretory, Office of the President.
5
FIELD GEOLOGY Assistam Director ,-_Or
"IN EX:~~I:~TiON~"APPING Geologist
Ge~~~ist Ger9isi . Technic<ll ASs!.
""m' Geologist Officer
I Publication OffICer
I
'T STA/TA STAjTA STAjT,A
"- --
HYOROGEOlOGy Principal Geoklgisl
I Seninr
Geologist
I Geoklgist
131
STA/TA 16)
GEOPHYSICS Principal GeologISt
I Senior
Geoklgis\
Geologist I Electronics (2) Engmeer
, :TA/TA TA 13) 110)
I RECORDS MANAGEMENT REGIONAL GEOLOGICAL SALE Of PUBUCATIONS MAPPING
SAMPLE STORAGE GfOTECHNICAL SURVEYS
GEQCHRONOtOGY MINERALOGY/PETROLOGY
El r tQPHVSICAl SURVEYS ECTRONIC EQUIPMENT
DESIGN AND MAINTENANCE
ADMINISTRATION OF REGIONAL HYOROGEOLOGlCAl PRIVATE SECTOR MAPPING WATER BOREHOlE
EXPlORATION RECORDS O{~ARTME~! EXPLO~TlON _ GRO~~QWAI~B STUp~
MINISTRY OF MINERAL RESOURCES AND WATER AFFAIRS DEPARTMENT OF GEOLOGICAL SURVEY
DIRECTOR J 1---- ?el${lnal
SllCfetalY
DEPUTY 0'iRECTiiR I
ADMINISTRATION
I Principal
Adminisll11tion officer
Personal Secretary
Admin. O!hcel Admin. Officer Admin.Officfr
~ro_) A"1.ffi ~"'"I""I °t"ll SAA/A S"hand TYPISt $AA/AA SAJi/AA
Typist
STAFF ACCOUNTS STORES TRANSPORT
REGISTRY TYPING
CHEMISTRY LABORATORY
Principal Chemist
,-l, Chemist
I Senior
TeChnical OffICer
Chemist Chemist
Tethni:al 0"",
slAllA 12)
i Chemist
OR~WING OFFICE
Chie! Tedmical 0"""
lCaf1ography) I
Senior Senior Technical Technical OffICer Officer
I Technital
OffICer
sllllA SIA~IA 12) { )
PRODUCTION OF MAPS DRAWINGS AND
PHOTOGRAPHS fOR PUBliCATIONS AND INTERNAL REPORTS
DRILLING SECTION
1 Senior Senior
Technical Technical OffICer OffICer
lA lA
ORILlING FOR
MINERAL LABORATORY
Technital Officer
I STAlTA
12)
MINERAL EXPLORATION GROUNOWAHR
STRATIGRAPHIC SURVEYS GEOTECHNlrAL SURVEyS
ROCK AND MINERAL SAMPLE PREPARATION
INDUSTRIAL MINERALS TtSTING
. __ .. __ .
"
5. HYDROGEOLOGY DIVISION
5.1 Introduction
A large part of the year's programme was taken up
with field work for the Serowe groundwater study.
Towards the end of the year, when three more hydro
geologists were appointed, long outstanding commitments
were re-generated and new projects were initiated.
The consultative work always rendered to various
bodies inside and outside Government was continued
throughout the year at almost the same level as in the
past.
Dr. Goldberg remained as Principal Hydrogeologist
and was assisted throughout the year by the Senior
Hydrogeologist Dr. Neurnann-Redlin, both officers
seconded from West German Government Service.
Towards the end of the year there was a great
improvement in the staffing situation. Through the
appointment of Messrs S.A. Bruno from the Netherlands
(6.10.81) and D. Buckley from the U.K. (23.12.81) the
number of professional staff increased to five after
Mr. M. Sekwale successfully passed his higher degree
(MSc) course at the University College in London and
re-joined the Division in October.
Mr. C. Cheney (GS10 project staff member) remained
20
with the Survey for a further three months after
completion of the project on the 31st March. His
contract was extended specifically for setting up
equipment for the determination on core samples of
aquifer parameters such as porosity and permeability.
5.2 Staff Deployment
For most of the year Dr. Goldberg and Dr. Neumann
Redlin were mainly engaged in three major groundwater
studies. Early in the year the consultative work to
the Gaborone Additional Water Supply Exploratory
Programme by Messrs. Wellfield Consulting Services (pty)
Ltd. in the Ramotswa area was brought to an end. The
Letshana Groundwater Resources Study was completed by
Dr. Neumann-Redlin. His conclusions regarding the
potential for groundwater development are included in
his report CNR/2/81 (53 p., 50 fig., 5 tab., 3 encl.).
In February the work on the Serowe Water Supply
Augmentation Study commenced which kept the then two
hydrogeologists alternately occupied until the end of
year, finally assisted by Mr. Sekwale after his return
from his overseas study tour. For the study 20 holes
were drilled by the Hydreq-Gryphon rig of Geological
Survey, the metreage totalling 1759 metres. In addition
three observation holes were cored with the Boyles 17A
rig, with a total metreage of 342 metres. Altogether
21
135 km of lines were cut for geophysical surveys along 6
traverses. 2340 hours of test pumping were carried out
and 52 water samples taken.
Since the activities of the two professional staff
were completely absorbed by this study the hydrogeological
mapping programme had to be postponed until the time when
additional staff arrived late in the year. Consequently
no other map sheet was compiled. However Dr. Neumann
Redlin was able to carry out final checks on the proof
prints of sheets Nos. 1 and 2 and so complete the
editorial work. Due to technical conversions of the
printing machinery at Government Printers these two maps
were subjected to format changes and, therefore, could
not be published before the end of the year. With the
arrival of Mr. Bruno the compilation work on sheet No. 7
was recommenced.
Dr. Goldberg apart from attending to all divisional
activities, was also engaged in various types of
consultative work to Central Government, other Government
institutions, parastatal organisations and the private
sector. Special prominence was rendered to the Central
Eastern Botswana Water Resources Study, Orapa Mine 'Water
Supply Review and Extension Study, Domestic Water Law
Consultancy and meetings of the Water Apportionment
Board.
Within the last week of the year Mr. D. Buckley upon
22
request from the Department of Water Affairs started
working on two groundwater assessment studies for Mochudi
Bnd Kanye villages water supplies. The work involved
desk top studies comprising the evaluation of all
available data on groundwater occurrences and quality
that is stored in the Geological Survey archives or
contained in reports, coupled with field investigations.
Mr. Bruno, besides compiling map sheet No. 7,
carried out preliminary studies for the assessment of
the groundwater potential around Hukuntsi for the
Ministry of Agriculture's Research Station and the
Matsheng Land Use Plan Project, i.e. work which has to
be continued in 1982.
23
HYDROGEOLOGICAL RECONNAISSANCE MAP OF THE REPUBLIC OF BOTSWANA AT SCALE 1 : 500 000 PROGRESS IN MAPPING AS AT 1. 1.1882
Published [ill]] Under production in Drawing Office
a AI press Under preparation ........
El] Awaiting production D ...... Prepar"ion 1981/83 in Drawing Office
mJ Under revision ----
26°
6. GEOPHYSICS DIVISION
6.1 Introduction
A considerable proportion of the division's activities
were related to assisting the various development projects
funded and staffed from overseas donor countries. As a
result of this commitment to the development projects
additional geophysical investigations were largely confined
to hydrogeophysical studies.
Several new items of geophysi=l equipment were
received during the year and are listed below. The
equipment was purchased as part of the GS18 development
project which was funded by the Federal Republic of
Germany.
6.2 Development Projects
GS10 Evaluation of Underground Water
This project was completed during the year and the
final report included a contribution from the geophysics
division (R.J. Peart) outlining the use of hydrogeophysical
techniques in Karoo lithologies and the use of geophysics
in the delineation and extrapolation of Karoo aquifers
into those areas covered by recent Kalahari sediments.
In addition Technical Note No. 10 and Report No. 3 were
25
completed early in the year (see 8.3.1).
GS12 Aeromagnetic Survey Phase III - Ground Follow-up
Assistance to this CIDA-funded project continued
throughout the year. The interpretation of ground
magnetic anomalies to locate drill targets and estimate
depths and magnetic susceptibilities was conducted for
all sites prior to drilling~ In some cases additional
field surveys were conducted to locate accurately the
drill site on the ground.
One additional site, located some 10 kms. east of
Maun along the old Francistown Road, was surveyed
magnetically to provide an alternative drill site. A
total of 40 kms. of magnetic traversing located a magnetic
high presumed to be associated with the northeasterly
extension of the Toteng diabase.
Early in the project it was realised that the lack of
water would hinder drilling operations in some localities,
particularly in the north west. To overcome this problem
water well drill sites were located near sites 12 and 12A
using electrical and magnetic techniques.
GS17 Mineral Exporation of the Kalahari
Assistance was given to the three bilateral aid teams
engaged in this project. In addition to logistical
26
support of the field parties and the loan of geophysical
equipment, a field survey was conducted for the Molopo
farms project to ascertain the thickness of Kalahari cover.
Eleven vertical electrical soundings conducted in the
northern sector of the project area indicated a close
correlation between depth to bedrock and total longitudinal
conductance. Further soundings will be conducted throughout
the project area, prior to drilling, to eliminate those
areas of thick Kalahari cover.
6.3 Departmental activities
Serowe Underground Water Study
An area to the west and southwest of Serowe was
surveyed geophysically to assist in the location of test
well-sites for the provision of a village water supply.
73 kms. of line were cut and surveyed magnetically and
a total of 36 electrical soundings were conducted at
selected localities to determine the thickness of the
basalt and Cave sandstone. Areas of shallow and thin
basalt were identified and several borehole sites
recommended. In the southern part of the survey area,
where basalt is absent, the resistivity values indicated
that the Cave sandstone was relatIvely thin, with
transition beds and red beds predominating.
27
Hukuntsi Underground Water Study
Cut lines were prepared and surveyed magnetically in
an area around Hukuntsi to locate possible areas suitable
for hand-dug wells. This preliminary phase was conducted
in December and further work, to include electrical
soundings and traversing, will be conducted in the new
year.
Selebi-North geophysical study
A geophysical survey was conducted over the Selebi
North prospect in north-east Botswana. The surveys were
conducted with the full cooperation of B.C.L. and the
objectives were twofold; firstly to test the newly
acquired Pulse E.M. and I.P. equipment over known massive
sulphide deposits and secondly to locate a possible
extension of the Selebi-North ore body.
The equipment trials proved successful in locating
the known ore body, and supported the geological inter
pretation. Unfortunately no obvious extensions to the ore
body were located although a faint anomaly on later
channels of the Pulse E.M. warrants further investigation
using the Crone Deep-EM system.
Pan Study
Further geophysical traverses (gravity) were conducted
28
it!' Illl Wl 11'11
" It! ,Ill
design consultancy. In early December a local firm of
structural engineers was appointed to consult on the new
design. A review of core held on site at Lobatse 'head-
quarters was undertaken to assist in producing realistic
design options. It transpired that the Survey had at
that time approximately 5,300 boxes of core, with an
aggregate length of about 49 kilometres and weighing
about 260 tons.
7.2 Evaluation of Underground Water Resources (GS10)
(U.K. funded technical co-operation)
The early part of the year was devoted to completing
the computer storage of hydrogeological data from the
study area and to writing up the final report. The
project was formally completed on 31st March.
The project leader Mr. J.L. Farr, returned to U.K.
leaving Mr. C.S. Cheney, who had been granted a 3-month
extension, to set up a rock permeability and porosity
testing facility.
This aim was only partially realised due to delays
in delivering of equipment. However, the final report
was completed and sent for printing and binding.
32
Two portable pH meters
Scintrex HGG-3 mercury analyzer
Scintrex UA-3 uranium analyzer
Stainless steel fume cupboard
Dionex - 10 ion chromatograph
Perkin-Elmer 2280 atomic absorption spectrophotometer
8.1.2 Analytical Development
A scheme of rapid instrumental silicate analysis
was introduced which allowed determination of all
traditional parameters with a slightly reduced precision
in less than a quarter of the time of previous methods.
The old methoffiwere retained for cases where higher
precision is required.
A method was developed using differential pulse
polarography for the determination of chromium in natural
waters down to 50 parts per billion.
A pyrolysis apparatus was constructed which, together
with background corrected atomic absorption, enabled the
direct determination of mercury in soils to be made at
the parts per billion level.
8.1.3 Assistance with Development Projects
GS10 - Underground Water Evaluation
Until the completion of this project on 31st March
41
P. Francks continued to assist with programing the Hewlett
Packard 9845 for hydrogeological data storage and
manipulation.
GS12 - Aeromagnetic Survey
A limited amount of assay work was carried out.
GS17 (UK) - Mineral Exploration of the Kalahari
Some 8600 samples were analyzed for Cu, Ni, Zn and Cr.
GS17 (W. Germany)
Owing to delays in the sampling programme only a few
samples were analyzed for Hg.
8.1.4 Internal investigations
Molopo Farms Hydrogeochemistry
Field work on this project was undertaken from 8th
May until the end of July. Analysis was carried out as
far as possible in the field using the mobile laboratory.
Forty one samples were analyzed for 10 trace elements in
addition to the usual range of major ions. Contamination
from borehole equipment was shown to be negligible and
chromium and nickel anomalies indicated the existence of
the ultrabasic body suggested by geophysics. Several
42
Sheet No. 2425D Gaborone (2nd Colour Edition)
Sheet No. 2525B Lobatse (2nd Colour Edition)
8.2.2 Hydrogeological Mapping
The following maps at a scale of 1: 500 000 were
under production for printing in full colour.
Sheets Nos. 1 and 2
8.2.3 Kalatraverse Maps
The four colour maps in this series were produced
and lithographed. These maps at a scale of 1: 250 000
are included in the Kalatraverse 1 Bulletin and depict
the surface geology and sub-surface geology of Rysana Pan
and Deception Pan.
8.2.4 Map of the Karoo in Botswana
The map at a scale of 1: 2 000 000 was produced and
printed in full colour.
8.2.5 Special purpose Maps
Two maps showing areas held under prospecting licences
and mining leases as at 1st January, 1981 and 1st July,
1981 respectively were produced and printed. Two maps
47