The Geology of Migmatite Rocks of Miya and Environs, Ganjuwa L. G. A., Bauchi State, Northeastern, Nigeria

Abstract

The geology of migmatite rocks of Miya and environs, Ganjuwa L.G.A., Bauchi state Northeastern Nigeria was found to be one of the Northern Nigerian basement complex that was affected by Pan African Orogeny and series of metamorphic circles. The study area was underlain by granulite metamorphic facie rocks with schlieren, diatexite and nebulite migmatite as the major rock types. The main aim of this research work was to identified rock types underlying the study area through systematic field mapping and sampling. The field work carried out revealed that the rocks were migmatite that were affected by Pan African shear stress which causes deformations and structural dispositions where some rocks were affected and tilted to almost 89o and the rocks were found to be prograding from schlieren-diatexite-cum nebulite migmatites. The nebulite reaches the peak of prograde metamorphism forming charnockite (bauchite), in some places quartz diorite and granulitic granulite were found as extract or pockets (i.e. when the magma contain excess silica it has to be exsolved/remove from the system before a charnockite (bauchite) will be form). Petrographic studies reveal that the migmatites contained quartz, biotite, plagioclase, orthoclase feldspars, orthopyroxene, olivine, sillimanite, cordierite, garnet and opaque minerals under cross polarized light. Myrmikite intergrowth and sericitization process and evidence of grain scale fluid migrations were also seen in some slides. The research come up with the conclusions that the area was underlain by schlieren, diatexite, nebulite migmatites and tin, lithium, monazite mineralization was inferred.

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