Geological Survey Department
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( s MINISTRY OF COMMERCE, INDUSTRY AND WATER AFFAIRS ANNUAL REPORT OF THE GEOLOGICAL SURVEY DEPARTMENT FOR THE YEAR ENDED 31 ST DECEMBER 1968 • I GENERAL (a) Introduction The Geological Survey Department in the Republic of Botswana is a "non-integrated" element of the Ministry of Commerce, Industry and Water Affairs. Its headquarters are at Lobatse in southeastern Botswana, 4-7 miles south of the Botswana Government administrative headquarters at Gaborone. The fundamental aim of the Geological Survey is the assessment of the mineral resources and underground water supply resources of Botswana with the intention of stimulating the realisation of their economic poten~al. A necessary preliminary to the attainment of these objectives is a study of the rocks and the geological structure over the whole of the country. Regional geological mapping and the publication of maps and reports describing the geology of Botswana is thus the main, prime function of the Geological Survey Department. Mineral survey work is carried out and this includes field geological and geophysical survey of mineral occurrences supplemented by laboratory work; prospecting for new mineral deposits; render ing assistance to prospecting organisations and operating mines; and wherever possible fur thering interest in Botswana's mineral potential. A third major task of the Geological Survey is the development of underground water supplies and general hydrogeological survey. In underground water development work the Geological Survey carries out the siting of water boreholes after geological and geophysical investigations and then controls drilling of the selected sites to the stage where productive boreholes can be passed to another Department within the Ministry, which is responsible for equipping boreholes and for the maintenance of Government pumping units. Hydrogeological research work is also carried out and the Geo logical Survey is gradually building up a considerable body of information about the nature and occurrence of underground water resources in Botswana. In underground water develop ment work, borehole drilling is carried out by the Drilling Branch section of the Geological Survey, which has its headquarters at Gaborone and is under the control of a Drill Superin tendent who is directly responsible to the Director of Geological Survey. Besides these main activities, the Geological Survey undertakes special investigations where geological advice is required, such as in certain engineering problems, and also renders assist ance to other Government Departments whenever required to do so. Special geological and geophysical investigations and research work are also undertaken where they are needed for a better understanding of the basic geology and geological structure of Botswana. The Director of Geological Survey is Mining Commissioner for Botswana and the Depart ment includes a Government Mining Engineer's division. Apart from specific functions the Geological Survey performs in relation to prospecting and mining this division is responsible for safe mining practices, the inspection of mines and machinery, and the implementation of explosives regulations. In the exercise of its dual functions as a Geological Survey and Mining Commissioner's office, the Department is responsible to Government for ensuring that mining company prospecting operations in Botswana are carried out energetically and efficiently with due regard to the provisions of the Mines and Minerals Act in force in the country. The main costs of running the Geological Survey and the full costs of the development of underground water supplies in Botswana by drilling during 1968 were again borne on normal budget estimates. Funds were also provided from a special Development Project scheme to allow an expansion of the.Geological Survey by the formation of the Government Mining Engineer's division. (b) SUDlInary of the Year's Work Recruiting difficulties continued to be met with during 1968, and as a result of a number of resignations amongst both professional and technical staff the Geological Survey remained short-staffed throughout the year. The position in this regard was particularly serious during the second half of the year and even steps taken to provide an enh:nced entry point for Geolo gists did not assist recruitment. The staff shortage affected work in all spheres of Geological Survey activity. Regional reconnaissance geological mapping was continued and a total of about 1,750 square miles of previously unmapped country was geologically surveyed on a scale of 1: 125,000. Mapping was completed on three quarter degree sheet areas. Revision geological mapping was continued in southeastern Botswana. Owing to the staff position only a limited amount of work could be carried out on direct mineral survey projects. A regional survey of the mineral potential of an area in northern Botswana was initiated. Iron-ore and manganese-ore occurrences were investigated. Special investigations work in the sphere of mineral survey included case history geophysical studies on nickel deposits in northeastern Botswana using up to eight different ground geophysical techniques. In addition to the case history studies over known ore bodies, which are the subject of detailed investigations by mining companies at the present time, ground geophysical work was also carried out on behalf of one company to evaluate certain geophysical anomalies resulting from airborne electromagnetic and magnetic surveys. During the year 17 State Grants were issued conferring special prospecting licences over various areas of Botswana for a variety of minerals. At the end of 1968,21 grants of prospecting rights were in force. Brief summaries of the work carried out by mining and prospecting com panies in terms of these Grants of prospecting rights are given under the section on mineral survey in Part II, ECONOMIC GEOLOGY, of this report. Six applications for the grant of special prospecting licences were under consideration at the end of the year. In underground water development work, geological and geophysical surveys were again carried out in nearly all District Council areas. Considerable assistance was also rendered to World Bank consultants investigating water supply problems in connection with developing mines. This was carried out as a Government counterpart contribution. Ground-water research programmes were intensified in certain areas. During 1968, a total of86 completed boreholes (both Government and for the private sector) were drilled on sites selected by officers of the Geological Survey. Of these boreholes, 70 were successful representing an overall success value of 81.5%' The Government Drilling Branch worked on 101 boreholes (including 16 cleaned and retested). The total footage drilled was 23,627 feet of which 16,844 feet were drilled in successful boreholes. (c) Organization and staJl" Certain minor changes were made in the schemes of service for professional officers. The two posts of Senior Geologist were retitled Principal Geologist. The post of Geologist was retitled Geologist/Senior Geologist with the title changing to Senior Geologist on entering the 2 (f) Q.uarter Degree Sheet 2022», Lake Ngaud C.M. Thomas carried out a geological reconnaissance of this area during September prior to systematic mapping planned for 1969. Representative samples of the main lithological types found in the Ghanzi Formation, the Kgwebe Porphyry Formation, the Bodibeng sandstone (Karro System) and other sedimentary rocks of uncertain age and correlation were collected for study. IV UNDERGROUND WATER DEVELOPMENT (a) Geological Survey Activities The Geological Survey continued to be responsible for the control of all underground water development work in Botswana, including both the siting of boreholes following, geological and geophysical work, and the subsequent drilling of selected water borehole sites. In the course of this work geological and geophysical surveys were carried out in the Centra]" District; the North East District; Kgatleng District; Kweneng District; Ngwaketse District; South East District; Kgalagadi District; and Francistown and Lobatse township areas. During 1968, a total of 86 completed water boreholes (both Government and private) were drilled on sites selected after geological and geophysical surveys carried out by officers of the Department. Of these 86 boreholes, 70 were successful representing an overall success value of 81.50/0 which compares well with that achieved during 1967 (81 %) The total number of completed boreholes, however, is about 180/0 lower than the number completed on Geological Survey drilling sites in 1967. This was due not only to the severe shortage of professional and technical staff experienced by the Geological Survey itself during 1968, but also because of a shortage of supervisory drilling personnel, due both to absences on enforced leave periods on completion of contracts and to resignations. A contributory factor as regards the number of completed boreholes was that m many areas the average depth drilled was well above that for previous years. A tabulated list of boreholes drilled on sites selected by officers of the Geological Survey is given in Appendix IV. (b) Drilling Branch Activities During 196B, a total of23,627 feet was drilled by the Drilling Branch section of the Geological Survey in boreholes drilled for the development of underground water supplies. This footage is 8,236 feet less than the footage drilled in similar work during 1967, when a record