CGS Foreign Development Cooperation - Zambia

Regional mapping project – Muyombe and Luwumbu River areas, NE Zambia

The regional mapping at a 1:100,000 scale, with assessment of the geo-potential of Muyombe-Luwumbu terrain, was initiated in 1999 as a joint project involving the Czech Geological Survey and the Geological Survey of Zambia, with the collaboration of the British Geological Survey, as part of the ERIPTA project supported by the World Bank. The major objectives were to carry out regional geological mapping and to assess the mineral resources of an area of about 4,500 km². The acquisition of basic geological field information involved the gathering of geological, structural, metamorphic, geochemical, and geochronological data in this remote and unmapped area. The project covered a multidisciplinary program toward establishing the geological and structural evolution of NE Zambia, with a special emphasis given to the mineralisation and the field evaluation of industrial mineral resources. On-going geochronological and geochemical studies helped to refine the stratigraphic framework of the area and provided the basis for regional correlations.

The Paleoproterozoic basement in the Muyombe and Luwumbu River areas of northeastern Zambia comprises a WNW-ESE (to E-W) trending cordierite-garnet-sillimanite granulite unit with numerous enderbite bodies and an amphibolite-facies migmatite unit. Zircons from a biotite metatonalite that intruded the granulites were dated at 1960.7 ± 0.4 Ma. Mesoproterozoic intrusions into this basement are represented by a nepheline syenite at Mivula Hill (zircon age: 1360.1 ± 0.8 Ma) and the porphyritic Ntendele biotite metagranite (zircon age: 1329.1 ± 0.6 Ma). The Mesoproterozoic greenschist-facies Mafi nga Group occurs in two major belts imbricated in the basement.

Mylonitization affecting the basement complex near the Mafinga Group slices resulted in strongly sheared domains with a corresponding Irumide-age structural and metamorphic overprints (JOURNAL OF AFRICAN EARTH SCIENCES, 2004, 38, 1–21).

New prospective Cu-Cr-Ni-Zn stream sediment geochemistry anomalies were delineated. Interesting dispersion aureoles of pyrite and arsenopyrite, abundant gem quality tourmaline, and Cr-pyrope with associated pyroxene were found in the heavy mineral concentrates.  Pegmatite swarms that may be a source of economic minerals (chrysoberyl, beryl, topaz) are mainly confi ned to certain areas of Makutu Hill and Kalanga Hill ridges. Good quality ceramic raw materials can be obtained from some pegmatites of the Mivula Hill Prospect. The mapping also revealed new localities with possible supplies of dimension stones (nepheline syenite, gabbroic and dark charnockitic rocks) suitable for block quarrying and decorative uses.