Petro-Chemical Characterization of Basement Plutonic Rocks and Associated Volcanic Outcrops in Homosha-Kurmuk Area, Western Ethiopia
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Date
2023-05
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Addis Ababa University
Abstract
The primary objective of this study was to characterize the petrography and geochemistry of the rocks in the study area with the goal to determine the classification of the lithological units that were discovered there. Field investigation, petrographic study, and a complete silicate geochemical analysis were done for this aim. According to the petrographic findings, the primary components of the rock units in the research region are quartz, plagioclase, k-feldspar, olivine, pyroxenes, biotite, hornblende, and opaque minerals. According to the TAS classification, the geochemical findings identified the rock units in the research region as granite, basalt, rhyolite, and diorite. Additionally, it placed the mafic/basaltic samples in the tholeiitic series on AFM and the felsic samples in the calc-alkaline series. The rock units in the studied area are thought to have formed as a result of fractional crystallization combined with crustal contamination, according to the Harker variation diagram of the major oxides versus SiO2. This fact is demonstrated by the fact that while the concentration of the major oxides like Na2O and K2O displays an increasing pattern with the increasing SiO2 concentration, the concentration of the major oxides like TiO2, Al2O3, MgO, CaO, P2O5 and FeOt decreases with the increasing concentration of SiO2. The granites are determined to be of post-tectonic origion at continental arcs while the basalts are determined to be of subduction zones.
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Dul-Undu, Gule, Homosha-Kurmuk, Volcanic Outcrops