PETROGENESIS AND GEOTECTONIC SETTING OF THE PAN-AFRICAN BASEMENT ROCKS IN BAMENDA MASSIF, OBUDU PLATEAU, SOUTHEASTERN NIGERIA: EVIDENCE FROM TRACE ELEMENT GEOCHEMISTRY

Abstract

The rocks of the Obudu Plateau range from high-grade metagreywacke-pelite sequence to metaigneous (granitic to tholeiitic) and polymagmatic (calc-alkaline granitic to olivine tholeiitic) igneous rocks. Several co-variance diagrams and other parameters indicate that the trace elements of rocks in southern Obudu Plateau exhibit systematic variations and suggest highly heterogeneous protoliths. The tectonic setting of the rocks indicates rifting and collisional to non-orogenic emplacements in oceanic to ensialic environments. The calc-alkaline and tholeiitic nature of the magmatism as well as the greywackepelite sequence is suggestive of an Andean-type continental environment.