The Geology And Geochemical Prospecting Of Part Of The Pangani River Escarpment

Abstract

The text describes the geology and the geochemistry of part of the Pangani River Escarpment lying in north east Masai- land, Tanzania. It is bounded by longitude 370 lSIE to the west, Pangani river and a reservoir to the east and latitudes 30 42 I Sand 40 08 IS to the th d th t . 1 Th' nor an sou respec ~ve y. e area consists of three morphological units, nam-al y , the Pangan r valley to the east, the escarpment and a plateau zone to the west. In this study, an attempt is made to relate the geology to the distribution of copper, nickel, lead, zinc and rare earths. Assessment of possible occurrence of non-metallic minerals is also made. The roc~s in the area include a thick succession of Usagaran rocks of Late Archean age which are comprised of metasediments and metaigneous rocks. The rocks were later subjected to intense folding and regional metamorphism which produced features of great structural complexities. After long periods of denudations and peneplanation, Tertiary downwarping and Neogene faulting took place. It was found that copper and nickel are favourably associated with the metai~naous rocks whereas zinc and lead are found in higher proportion~ in the metasediments. Rare earths t~nd to acc.ompany these rocks·fn trace amounts. Metal relation of Cu/Ni, Cu/Zn, CulPb was found to be unique fo~ each rock type having a tendency to variation at different concentrations. In the text bivariate distributions have been performed in order to derive regression equations that are characteristic for the main rock and soil types. Copper stained rocks were found when this work was in progress and the area has been proposed for further investigation. Hinerals of possible kimberlitic origin were also found but their mode of occurrence is still obscure.