A geobotanical study around the fluorite Mineralization in Kerio valley, Kenya

Abstract

The study area is geologically situated on the Central Kenya Dome, on the western flank of the Great Rift Valley. It is geographically bounded by latitudes 0° 18'N and 0° 22'N, and longitudes 35° 38'E and 35° 40'E, and falls within the jurisdiction of the Kenya Fluorspar Company Limited. The geobotanical study includes analysis of panchromatic multidate aerial photographs, sequential Landsat Multispectral Scanner (MSS) and Thematic Mapper (TM) imageries; as well as field studies which incorporated collection and analysis of biogeochemical samples. The field studies show the existence of some relationship between vegetation communities and pedological, geomorphological and lithological units. It is evident from the study that, the major vegetation communities cg~form to the major lithological units, while the plant species Harrisonia abyssinica, Vangueria acutiloba and Balanite aegyptiaca localize the fluorite mining sites: interms of the anomalously high concentration values of the elements copper, strontium, uranium, zirconium, rubidium, and manganese in plant ash. Soil samples assayed indicate high concentrations of copper, rubidium, calcium and uranium as associated with the fluortie mineralization, while the trace elements are seen in soil, as accumulations in the valley bottom. The parent rock, which is probably hydrothermally metamorphosed limestone, coincides with Geobotanical Unit (GBU) I'. In this unit, the dominant species are Laudetia kagerensis, Acacia tortilis, Combretum molle (with swollen stem), Commiphora africana Indigofera brevicalyx, Harrisonia abyssinica, Rhynchosia spp., Plectranthus spp., Pellaea adiantoides and P. calomelanos. GBU I' is distinctly characterised by an acacia - croton - combretum commifora - Harrisonia vegetation community and a distinct photographic and spectral anaomaly.