Geology and Compositional Variation of Migmatitic Rock Association around Kadage, Bauchi, Nigeria: Implication for Migmatite Provenance.

Abstract

This research work focused on the petrological and geochemical characteristics of 
the migmatite morphology in part of Bauchi. Migmatitic rocks association 
constitute the major rock components of the Earth’s continental crust, which 
suggested to be formed in different geologic environments. The different types of 
morphologies their compositional characteristics, tectonic settings and magma 
sources are outlined. Detailed field geology and mapping (field observation, 
structural and metamorphic structures) and petrographic description have been 
used to investigate the geology and petrology of genetically related migmatitic 
rocks association in the study area. structural features such as stromatic bands, 
ptygmatic folds, crenulation cleavage, mineral alignment and foliation, which is used 
to describe the different rock units in the study area and to ascertain their genetic 
relationship. The study area is dominated by metatexites, diatexites, and charcoalites. 
(Bauchite) and granodiorite. The rocks consist of Biotite, Quartz, Plagioclase, 
Garnet, cordierite, Orthopyroxene, silimanite, and muscovite are all displaying 
metamorphic imprint (both texturally and structurally) with minor accessory 
minerals, which include zircon, ilmenite, apatite, hematite, rutile, and corundum. 
Geochemically, the migmatites suites are ferroan, alkalic to calc-alkaline, slightly 
metaluminous to peraluminous, post-collision S-type granites and were derived 
through partial melting of crustal rocks. The different correlations of most major 
element with increasing acidity (SiO2) on the Harker diagram suggest that fraction 
crystallization has played a significant role in the evolutionary history of the rocks. 
even though erratic indicates partial melting and fractionation nature of these rocks 
during metamorphic and magmatic differentiation. The provenance reconstruction 
indicate that the source of these partially melted rocks is from a metapelitic to grey
metawacke source. The enrichment of LILE and depletion in HFSE indicate partial 
melting and crustal contamination of magma above Volcanic Arc and Syn- 
collisional granitoids. The rocks are S-type, strongly peraluminous in nature. The 
rocks thus provide a genetic relationship between metamorphism and 
compositional variation and similarities.