Geochemistry and Origin of Talc Mineralization in Kagara Area (Sheet 142 SE and Part of Sheet 142 SW) North Central, Nigeria

Abstract

This paper discusses the geochemistry and origin of talcose rocks in Kagara area, North central Nigeria. The study area is part of the Kushaka schist belt of the Northern Nigeria Basement Complex. It lies within latitudes 10° 00"²N and 10°15"²N and longitudes 6°10"²E and 6°30"²E, sheet 142 SE and part of Sheet 142 SW.

The major rock units in the area are migmatitic gneiss, banded gneiss, granitic gneiss, meta-arkosic rock, amphibolite, talcose rock, phyllite, granodiorite, porphyritic granite, fine-medium grained granite, and pegmatite. Petrographical studies revealed that quartz, microcline, plagioclase and biotite constitute the major minerals present in the migmatitic gneiss, porphyritic granite, fine-medium grained granite, meta- arkosic rocks and pegmatite with epidote as the dominant accessory mineral. The talcose rock contains in addition to talc, appreciable amount of chlorite, magnesite, anthophyillte with magnesite and quartz forming the accessory minerals.

Geochemical characterization of the talcose rock shows SiO₂ (28.63-34.99) wt %, MgO (29.21- 35.13) wt %, Fe₂O₃ (6.36 - 13.20) wt %, and variable proportion of CaO (0.02-0.18) wt % and Al₂O₃ (0.58-13.20) wt % are characteristic of the rock. The talcose rock also shows negative Eu anomaly and therefore paucity of plagioclase. High Ni (210-1850 ppm), Co (82-91 ppm), and Cr (170-1930 ppm) values indicate that the talcose rock was derived from an ultramafic protolith which has undergone moderate degree of metamorphism.