Petrography, Field Relationship and Morpholgical Classification of Migmatites Around Gada Biyu- Maiturare, Part of Sheet 148 Toro S.E

Abstract

The study area is located within the Pan African Older Granite and is located in Rimin 
Zayam is east of Toro L.G.A. in Bauchi State and is accessible through Bauchi-Jos Road. 
Using Sawyers classification of migrants, the study area has various 
morphological units of migmatites that are mainly metatexite (Banded) 
Orthogneisses and Stromatic), diatexite (Schlieren and Nebulitic diatexite) and 
rhyolites occurring as dyke. Petrographically, the presence of metamorphic mineral 
garnet, sillimanite, hornblende, orthopyroxene and cordierite minerals in the rock’s 
morphologies suggest a high metamorphic grade. The change in morphologies is 
due to change in partial melting rate. Extinction observed on quartz grains in all 
slides suggests an intra-crystalline deformation and the polycrystalline nature of the 
quartz grains suggest a high temperature deformation as a result of grain boundary 
migration. The presence of structures like the ptygmatic folds, crenulation cleavage, 
Gneissic foliation are all evidence that a complex shearing episode has affected the 
study area. The grade of metamorphism increases from metatexites, which is 
indicated by preferred elongation of biotite and abundance of biotite + muscovite + 
hornblende, through to the diatexites, which is indicated by the general coarsening 
of quartz grain size and depletion of the paleo-structure of the schist.