The Geology and Petrographic Characterization of Rocks in parts of Tegina Sheet 142SE and Alawa Sheet 143SW North-Central Nigeria

Abstract

The geology of Kawo, Maigiro and environs was study with the aim of characterizing rock types based on their petrography. The area is part of Tegina Sheet 142 SE and Alawa Sheet 143 SW underlain by rocks belonging to Zungeru- Birmin Gwari Schist Belt of Nigeria and mapped on a scale of 1:50,000. From the geological mapping, four lithological units were observed namely; granite, gneiss, schist and amphibolite. These rocks were intruded with quartz veins at the eastern part which host gold mineralization. Each outcrop location was determined with handheld GPS. Specimen of the rock samples were studied based on their colour, mineralogy and texture on the field. Fifteen (15) out of thirty (30) collected rock samples were selected and sent to petrological laboratory for thin section analysis to determine mineral composition under binocular polarizing microscope with X10 magnification. The result of petrographic analysis showed that gneiss consists of quartz, plagioclase, biotite, homblende, and epidote. Visible grains of biotite, plagioclase, homblende, quartz and opaque minerals were observed in schist. Plagioclase occurs in amphibolite as clongated prismatic crystal, greenish and pleochroic. Granite consists of quartz, plagioclase biotite and homblende. Fracture, foliation, folds, faults, lineation and veins were the observed structures which serve as a zone of mineralization in the eastern comer of the study area.