Geochemistry Characterization of Migmatites Around Nabardo- Toro Environs, North Eastern Nigeria

Abstract

The geology of the Nabardo area comprises of migmatites that appears to have undergone varying degree of metamorphism and multiple phases of deformation. The geochemistry of these rock suites is analyzed using X-ray Fluorescent. A total of thirty (30) samples were analysed for major and trace elements. The geochemical data are plotted on major tectonic discrimination diagrams to distinguish the nature of original magma content. This paper aims at characterizing the three migmatites types of the Narbardo area. The metatexites are mostly calc-alkaline with some slightly theoleiitic. The plot of alumina saturation versus alkalinity (A/NK vs A/CNK) diagram (ASI) of Maniar and Piccoli classifies the diatexites as predominantly peraluminous which tends to indicate that they are sedimentary type (S-type) protolith, while those that shows metaluminous are indicating source from Igneous sources (I-type). The molecular plot of Al2O3/ (CaO + Na2O + K2O) versus SiO2 after White and Chappel, 1977 showing nebulite plotting in the I-type field implies that the original magma from which they were formed contained great amount of granitic or crustal material. Based on the geochemical plots and REE signatures, fractional crystallization alone cannot account for these migmatites but rather partial melting and metamorphic differentiation are the major source of these migmatites. They are formed by partial melting of mafic rich protolith that were formed during the Pan-African orogeny.

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