The geology and petrography of Rimin Zayam and environs, Bauchi, North-East Nigeria

Abstract

The geologic investigation of Rimin Zayam migmatites is aimed at determining the morphology, petrogenesis and geochemical behaviors of the rock outcrops. About sixty-seven samples were obtained from the field, thirty of the samples were selected, the thirty samples were divided into three, the first part was used to prepare thin section, the second part was used for geochemical analysis and the third part was preserved. Based on the macroscopic and microscopic studies of the study area, six distinct litho-petrological units were discovered. These includes; Ryolite Dyke, Biotite Granite, Metatexite (Banded Ortho-Gneiss, Stromatic Migmatite), Diatexite (Leucocratic Diatexite, Mesocratic Diatexite, Melanocratic Diatexite), Nebulite and Schist. They were petrographically studied to contain biotite, quartz, plagioclase feldspar, alkali feldspar, hornblende, pyroxene, etc. The presence of orthopyroxenes indicates an intensed prograde metamorphism (granulite facie). The area is affected by NE/SW trending Pan-African structures being cross-cut by NW/SE trending Cretaceous trends as evident from the Rose plot. The ductile stress that affected the terrain brought about the numerous ptygmatic folds which make the area to be declared a Shear Zone.