STRUCTURAL CONTROLS AND GEOCHEMICAL PROPERTIES OF MIGMATITES IN PLATEAU STATE, NIGERIA

This study explores the structural lineaments and geochemical characteristics of migmatites within latitudes 9º10'00"N and 9º10’45"N and longitudes 9º30’00"E and 9º30‘35"E, and covered a portion mapped of WASE sheet 191-SW, on the scale of 1:100,000. A total of 15 samples collected, 12 representative samples were studied macroscopically and petrographically. Therefore, field mapping and morphological features, our findings reveal four (4) different lithologic units, vis: Metatexites, Ditexites and a diverse range of mineral assemblages, including microcline, silimanite, cordierite indicative of varying degrees of metamorphism and partial melting. The structural analysis highlights the fluids movement and significant lineament orientations that suggest history of tectonic stress regimes – two inversions trending NW-SE Liberian Orogeny, and NE-SW Pan-African Orogeny. The major elements composition shows that the rocks are characterized by high SiO2 in the range of 51.04 - 97.34 wt % with an average of 78.74wt%, JJ-8 and FeO3 and Al2O3 enrichment are pronounced in the rock samples showing average of 17.76 wt% (JJ-11), 19.90wt% (JJ-4) and 19.91 wt% (JJ-4), 20.33 wt% (JJ-11) respectively. In addition, Na2O remains consistently less than K2O in most of the samples. The rocks are generally depleted in, MgO, and MnO. The diatexite migmatite rock in this study was found to be originated from sedimentary protoliths of various compositions. Fractional crystallization which encompasses the formation of plagioclase and biotite as indicated by the negative correlation between the values of SiO2 versus CaO, MgO, Na2O, Al2O3 and Fe2O3, are in congruent with the field and petrographic proof of plagioclase and biotite abundance