Tectonic Settings and Petrogenesis of Pan-African S-Type Granitoids in Anka Schist Belt, NW, Nigeria

Abstract

Research into geotectonic settings of the Anka schist belt was regionally carried out by (Holt, 1982) stating that there is no evidence of significant partial melting or metasomatism. This research uses chemical data of some Pan-African granitoids within the Anka schist belt to explain the tectonic setting and petrogenesis of the S-type granitoids intruding the metasediments within the Anka schist belt. Twenty-five (25) representative samples of granitoids was analyzed for major oxides and trace elements composition. Results obtained from the chemical data was used to plot various classification diagrams. The granitoids in the study area plots within the orogenic class and the use of trace element discrimination diagrams as a means of fingerprinting the tectonic environments revealed that the granitoids ranges from syn-collision to late orogenic field. The granitoids which plotted in the syn-collision field is a characteristic of chemical affinity of syn-collision peraluminous granites with highly fractionated volcanic-arc magmas.  The petrogenesis of the S-type granitoids in the study area are greywacke sourced which is largely metagreywacke and metapelitic sourced during partial melting.

Keywords: Granitoids, Pan-African, S-type, Metasediments, Partial melting

DOI: 10.7176/JNSR/10-2-08

Publication date: January 31^st 2020