PROVENANCE OF PALEOPROTEROZOIC BIRIMIAN METASEDIMENTARY ROCKS IN PARTS OF THE WA-LAWRA BELT, NORTHWESTERN GHANA

ABSTRACT Shales from the Paleoproterozoic Birimian Supergroup in parts of the WaLawra Belt, Northwestern Ghana, were analyzed for their major and trace element contents using ICP-MS and ICP-AES with the main aim of establishing the geochemical characteristics of the shales and inferring their provenance. On the whole twenty-two (22) samples of the shale was collected for analysis. The studied shales were compared to Early Proterozoic crust (EPC) and Post Archean Australian Shales (PAAS), and the various models proposed suggest that the studied shales show enrichment in the transition metals (TM) and depletion in the High field strength elements (HFSE) but shows resemblance in REE patterns with characteristics to their Archean equivalence. The geochemical data also suggests that the studied shales may have been derived from a confined source of mixed felsic and mafic compositions, with the mafic dominating. A model of 60% basalts, 20%TTG and 20%UCC explains this derivative. Hence, the source rock composition within the study area is more of andesitic to basaltic volcanic rocks and this may be suggested to have been derived from the mafic volcanic rocks and their associated granitoids in the Birimian greenstone belts. The corrected CIA values of the studied shales ranges from 70 to 85, suggesting intermediate intensity of weathering at the source area under semi-arid to arid conditions and are deposited in a tectonic setting comparable to modern Island arcs, with minor contribution from the older upper crust (i.e., Pre-Birimian sources). Geochemical features of the studied shales in parts of the Wa-Lawra Belt show trace element variations which suggest a significant compositional variation through time. ii DEDICATION This research is dedicated to the Almighty God for His presence through