Geology, Geochemistry and Structural Analysis of the Basement Rocks of Gora Area, Part of Keffi Sheet 208 NE, Northcentral Nigeria

Abstract

The basement complex rock that underlies Gora and its surroundings consists
primarily of banded and porphyroblastic gneisses, biotite schist, and the minor rocks
being pegmatites and quartzo-feldspatic veins. This study aims to characterize, at a
1:25,000 scale, the geology, structure, and geochemistry of the rock units in the
Gora region. To attain this aim, field research, petrographic, and geochemical
studies were conducted. Quartz, feldspars, biotite, and hornblende were identified
as major minerals in petrographic analyses of the gneiss, with muscovite and apatite
present in trace amounts. X-ray fluorescence (XRF) analytical methods were used
to determine the rocks' geochemical compositions. Fold, fault, pinch, and swell, and
vein sizes were all quantified. Major fractures, joints, and veins all run NW-SE,
while smaller ones run NE-SW. The structural NW-SE and NE-SW trends are also
reflected in the data that has been linearly analysed (SRTM DEM). The geochemical
results obtained revealed that the gneisses and biotite schist are high-K calc-alkaline
and orthogneiss derived from igneous protoliths. The gneisses and biotite schist
were further classified on the SiO2 vs. FeOt /MgO binary diagram in calc-alkaline
series. The gneisses and biotite schist are peraluminous in nature. The gneisses and
biotite schist were formed in a passive continental margin tectonic setting.