Geochemical and Sr-Nd isotopic records of Paleoproterozoic metavolcanics and mafic intrusive rocks from the West African Craton: Evidence for petrogenesis and tectonic setting

Metavolcanics and mafic intrusive rocks of the Paleoproterozoic Birimian terrane in the southeastern part of the West African Craton, Ghana, were analyzed for major and trace elements and Nd and Sr isotopic data to constrain the geodynamic evolution of the Birimian Supergroup. The metavolcanic rocks consist of metabasalts, meta-andesites, and amphibolites, whereas the mafic intrusions are mainly gabbros, hornblendites, and dolerites. The rocks are tholeiitic in composition and show the classic features of arc magmatism. The metavolcanics display significant enrichments in large ion lithophile elements (LILE) and light rare earth elements, relative to high field strength elements (HFSE) and heavy rare earth elements. The multielement patterns of the rocks also show positive Pb, Ba, Th, and Sr and negative Nb, Ta, and Ce anomalies that are typical characteristics of subduction-related magmas. They also have La/Nb ratios