GEOLOGY ANDGEOCHEMISTRY OF MALALI-KWARU BASEMENT ROCKS IN KADUNA, NORTH WESTERN NIGERIA: INSIGTHS INTO THEIR ORIGIN AND METAMORPHISM

Abstract

Geological and geochemical studies of Malali-Kwarubasement rocks covering an area of 85 km2
were carried out in order to classify and shed more light on their protolith and nature of
metamorphism. The Geology of the rocks in Malali-Kwaru and environs show that the area is
underlain by migmatite, biotite gneiss, banded gneiss, and porphyritic granite. Porphyritic
granite dominates the NE and NW part of the study area, followed by the biotite gneiss in the
central to SW part of the study area, migmatite were found in the south and NW part of the
study area, while banded gneiss is located at the SW part of the study area. Six representative
samples were subjected to petrography and XRF geochemical analysis. The rocks are
characterized by a wide range of SiO2 having tholeiitic to calc-alkaline affinity, metaluminous
to weakly peralkaline compositions, similar to rocks found in island arcs. Results of this study
indicates that the Malali-Kwaru area, is underlain by a low to medium grade (greenschist facies
to lower amphibolite facies) metamorphic rocks of basic to intermediate protolith. These rocks,
which are thought to be Paleoproterozoic in age was later intruded by the Pan African
porphyritic granite