Geology and Petrography of Basement Rocks around Paki, Northwestern Nigeria

Abstract

The geology and petrography of basement rocks around Paki and environs was studied with the aim of characterizing different rock types present based on their petrographic analysis. The area is part of Ikara Sheet 103NW Federal Survey Topographic Sheet underlain by rocks belonging to northwestern Nigerian basement complex. From the field mapping, three major lithological units belonging to one rock type were observed namely; porphyroblastic gneiss, medium to coarse grain gneiss and fine grain gneiss. These rock types were intruded by pegmatites, quartz veins and aplites belonging to Pan African magmatic suite. Specimen of the rock samples were studied based on their hand specimen mineralogical composition, colour, and texture in the field. The results of the petrographic analysis showed that porphyroblastic gneiss consists of quartz, plagioclase feldspar, orthoclase feldspar and biotite as essential minerals. Visible grains of orthoclase feldspar, biotite, quartz, hornblende and epidote were observed in Medium grain gneiss whereas Fine grain gneiss was also characterized by the same set of mineral assemblage but in varying proportion. The geological structures observed in the field include fracture, foliation, fault and veins which serve as the structural controls to mineralization in the study area.