BRITISH GEOLOGICAL SURVEY -LIBRARY SERVICES Serial No. l/v, <: t~:'::O 93 &an /' ._ .. Dispia Xemx / Geo~y. Map Lib ~ ;<.. Min . ;tjm=.s..P.- ..~ ..· .....- ...-. -;z:~.-==-- Cat. /' Mill. S~~,!~~F~~= Cmulate In: RelOID to ~ Library REPUBLIC OF BOTSWANA ,> (.:' ,:' .:-) ANNUAL REPORT OFTHE GEOLOGICAL SURVEY DEPARTMENT FOR THE YEAR 1984 PRICE: P3,OO PRI1\"TED BY THE GOYEIlI'\MENT PRll'\TER, GABOROI'\E, BOTSW,\l\'\ 1. GENERAL 1.1 Introduction The Geologicfll Survey Department remained within the Ministry of Mineral Resources and Water Affairs and continued wi·~h its main funct.ions of gathering, assessing, and disseminating all data related to the rocks, mineral deposits and groundwater resources of Botswana. The departmental organisation remained as in previous years and consists of the Directorate, three operational divisions of Field Geology, Hydrogeology and Geophysics, plus an administrative division. Support to these divisions was provided by the Chemistry and Industrial Minerals laboratorLes, Drawing Office, Library and Records and Drilling sections. The staffing position within the professional and technical cadres remained "reasonably satisfactory, though the Geophysics and Hydrogeology Divisions were understaffed, mainly because of the recruitment freeze imposed following the water restrictions introduced in the Gaborone-Lobatse area. The posts of Senior Chemist and Technical Records Officer were both filled in 1984. A long serving local officer, Mr. R.J. Malejane, retired from the Civil Service after working for more than 20 year's at the Survey. Mr. D. Buckley, Hydrogeologist, returned to the UK on completion of his tour, having served in the Survey for three years, while Dr. Chr. Neumann-f((,dlin, Senior Hydrogeologist, returned to BGI!, Hannover, after serving for 5 1/2 years with the Geological Survey Dl?parCrnent. 1 Mr. C. Black, Deputy Director, left the Survey in early 1984, when his post was localised by the appointment of Mr. M. Sek,"ale. Thus 1984 saw the completion of the localisation process initiated in late 1983 with the appointmen: of IVJr. M.P. Modisi as Assistant Director. On the 1st of January, 1984, Mr. T.P. Machacha and IVJr. M. Sekvvale were appointed Director and Deputy Director respectively, while Dr. G.C. Clark, former Director, \Vas appointed adviser to the new incumbents for a period of six months. Dr. Clark finally left the Survey in July, 1984, after serving with the Department for a period of nine years. A satisfactory work programme was completed by the Field Geology division. Final reports of surveys conducted in the previous year were completed. Field ~llapping of the poorly exposed parts of Southern Botswana, (ODS 2421+D and 2525C,D) was completed. Mapping of the Foley quarter degree sheet (ODS 2127C) was completed and the accompanying map and bulletin were to be compiled in 1985. Field mapping of the Letlhakeng Sheet (ODS 2425A), was started this year while preparations for mapping the Kanye Sheet (OD:,) 21+25C) were underway. The division also continued with its strong exploration activity in the field of industrial minerals and a limited amount of work in base metal and coal exploration. The Mineral Resource Report No. 7, on the potential for quick lime production, was published during the year. 2 A close overview of the explorat.Lort work undertaken by the private exploration companies was maintained, where the mal n thrust continued to be directed toward,; the '.leuI'ch for diamondiferous kimberlites and detailed evaluation of the known coalfields. This year also saw a lot of interest being shown in base metals and platinum group metals in the Molopo Farms Complex. Both the Hydrogeology and Geophysics divisions continued to be heavily involved in groundwater exploration and development projects. However their work was slowed down by the recruitment freeze imposed during the year because of the water restrictions. The two divisions continued to do work in response to the country wide drought conditions and to the serious water supply shortage in the Gaborone-Lobatse area. The Department, in conjunction with the Department of Water Affairs, continued the search for water in parts of eastern Botswana. All groundwater explorat.ion and development projects introduced in the work programme in 1984 under the drought and the Gaboroile-Lobatse water supply crisis were completed during the year. Work on the production of the 1:500 000 hydrogeological reconnaissance map sheets was continued during 1985. Map Sheet No. 11 was compiled and completed, while the compilation of map sheet No. 8 was started. This m~pping programme was a joint research project with the 'Department of Geology at the University of Botswana. The Geophysics division conti nued to ,mppo[' t Cl reBearch project by the University of Michigan, USA, whereby heat flow measurements were obtained from deep boreholes drilled at several localities throughout Botswana. The final measure­ ments were made in July, 1984. In the support section the Drawing Office completed the second edition of the geological map of Botswana, which was finally published in early 1984. The Chemistry Laboratory was for the first time fully staffed, with four pro1fessional chemists. In late 1984, however, most the technical staff had left the Survey for overseas courses. The drilling unit continued to be staffed by two expatriate drillers. One bilateral technical aid project funded by the UK as part of the GS-17 project over the Molopo Farms area was completed in 1984 and the project leader, Dr. David Gould, left Botswana in September. The two new aid projects initiated by CIDA in 1983 continued to run smoothly in 1984. ThesE' ... are the driller training project which started in May, 1983 and is due to end .in May, 1986, and the CIDA funded prq,gramme to localise the geophysics unit. DUTing this year three more students were sent to Canada for training as geophysicists and electronic engineers. Two other students were also sent to Canada to train as geological technicians. The German government started another technical aid project as a continuation of the GS-17 programme. The project is for mineral exploration over the Vumba Schist belt, North­ east District. The project started in September, 1984 and is 4 due for completion in August, 1986. The UK government carried out a feasibility study on the possibility of undertaking a mineral exploration/mapping project on the Ghanzi-Chobe foldbelt. Their conclusions were positive, so that if funding is available this project is expected to take off in late 1986/early 1987. 5 5. HYDROGEOLOGY DIVISION 5.1 Introduction The year 1984 saw the completion of all groundwater exploration and development projects which had been introduced in the work programme in 1984, under the drought and water shortage crisis in Gaborone and Lobatse. As the year progressed the division was increasingly affected by the recruitment freeze imposed by government early in 1984, following the introduction of water supply restrictions for Gaborone and Lobatse. Posts falling vac8nt during the year could not be filled in time to maintain continuity in the divisional work. After May, 1984 no new projects were accepted. The shortage of experienced hydrogeologists hampered the training progr~mme for local hydrogeologists and severely reduced the capacity of the division as consultants for Government and public. As hydrogeologists left and projects were completed all remaining resources were concentrated on the training of local hydrogeologists as well as technical assistants. The ground­ water monitoring programme, largely operated by technical assistants, was expanded and further efforts concentrated on the up-grading of the borehole records archives. Mr. Marobela and Mr. Selaolo, both BSc graduates in geology, joined the division in January as Assistant Hydro­ geologists. They received training in hydrogeology. Mr. J. Sethono joined the division in July, 1984 as a trainee 17 Technical Assistant. 5.2 Groundwater Exploration and Development Projects Letlhakeng Groundwater Study The first phase of this study, which had been commenced in June, 1983 was completed in August, 1984. The objective was to investigate the hydrogeolbkyof the Karoo succession in ., . the area between Molepolole and Letlhakeng and to assess its groundwater potential for possible regional water supply. An underlying objective had been to investigate the possible . , existence of a groundwater resource of the magnitude similar to the one developed in the Jwaneng wellfield. The conclusions derived from the first phase of the study can be summarised as follows: The area between Molepolole and Letlhakeng is underlain by geological formations unfavourable for large ground\vater storage. The exceptionally favourable aquifer characteristic~ of Jwaneng probably exist in a delta with sands developed on the margin of the Karoo basin. Geophysical investigation techniques and data interpretation methods applied with this first approach did not produce the information expected. In a follow-up, the search for delta sediments along the Karoo basin margin will be continued. A largely geological approach will be taken. Simultaneously geophysical investigation techniques and data interpretation methods are to be reviewed with the aim of developing techniques suitable for the detectim of lineaments under Kalahari cover and the tracing 18 of basement structure under Kalahari!Karoo over-burden. Experimental geophysical investigations in the Letlhakeng area and the Jwaneng wellfield were