The Petrology of Granitoid Rocks around Kariya area, Ganjuwa, Bauchi, Northeast, Nigeria

Abstract

The study area received less attention from earlier workers which they consider the rocks as older granites that were barren, but according to this research work the rocks were found to be among the metamorphic terrain specifically migmatite rocks formed as part of Northeastern Nigerian Basement Complex rocks which were affected by series of orogenic cycles that undergoes regional metamorphism and intrusion of younger granite rocks occurred sporadically in the study area. Detailed field mapping and sampling was done in order to identify and record the physical features of the rocks. Petrographic studies were conducted in both plane polarised
light and cross polarised light in which microscopic structures were identified and noted. Field investigations and petrographic studies reveal that the rocks in the study area are metamorphic rocks based on certain structures observed, some of the structures include ptygmatic folding, crenulation cleavage, pinch and swell, undulus extinction and pleochroic halo which are characteristics of metamorphic rocks. Therefore, the area was found to be underlained by migmatite rocks which were classified as banded orthogneiss, straumatic, and nebulitic migmatites and some intrusion of younger granites. Tin, tantalite, tourmaline, Lithium and
corundum mineralization were inferred