Classification, geotectonic setting, and mineralization potential of the minor intrusion in the eastern margin of Igarra Schist Belt, southwestern Nigeria

Abstract

Petrographic and geochemical studies of the minor intrusion that occurs as sill in the eastern boundary of the Igarra Schist Belt with the  granite-gneiss of the migmatite-gneiss complex were undertaken to classify it and determine its tectonic setting and mineralization  potential. Petrographic study and geochemical classification revealed that the sill is microgranitic in composition, comprising an  aggregate of medium grained microcline and quartz, and accessory actinolite, possibly formed by the alteration of hornblende. The  geotectonic setting showed that the sill is orogenic, probably derived from the same upper mantle magma that got contaminated by crustal materials as Igarra batholith. A study of its mineralization potential revealed the microgranite to be intensely sheared being  heavily brecciated, and contains quarts, quartzo-feldspathic and pegmatite veinsfeatures that predisposed it for mineralization. The  average contents of Ag, As, Au, Bi, Cu and Fe are much higher than their average abundances in standard granites and could host iron  oxide-copper -gold (IOCG) deposit with Ag, Au, Bi, Cu and Fe ore minerals.