Petrographic and Geochemical Characteristics of Medium to Highgrade Metamorphic and Associated Intrusive Rocks in the Konso Zone (Kholme Cluster Tebelana & Quchele Kebele)

Mulatu, Hana

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dc.contributor.author	Mulatu, Hana
dc.date.accessioned	2026-09-01T08:57:02Z
dc.date.available	2026-09-01T08:57:02Z
dc.date.issued	2024-07
dc.identifier.uri	http://ir.bdu.edu.et/handle/123456789/17204
dc.description.abstract	This study investigated the petrographic and geochemical characteristics of metamorphic and intrusive rocks in the Kholme Cluster, Konso Zone, Southwestern Ethiopia. Fieldwork, petrographic analysis, and geochemical evaluations were employed to achieve this objective. The dominant geological units in the study area are high- to medium-grade metamorphic rocks, including granitic gneiss, amphibole gneiss, and biotite gneiss. Additionally, intrusive granite rocks are present. Petrographic analysis revealed compositional banding within the gneiss units. Hornblende, plagioclase, biotite, and quartz were identified as the primary mineral assemblage, with minor amounts of opaque minerals. Field observations and structural measurements indicated various geological structures, such as foliation, folds, joints, dikes, boudinage, veins, and veinlets. These structures are attributed to multi-phase deformation events and play a significant role in the metamorphic processes. Geochemical analysis revealed that most granitic gneiss units fall within the calc-alkaline series on the AFM ternary diagram, except for amphibole gneiss, which plots within the tholeiitic series. All studied rocks, except one sample, displayed geochemical signatures indicative of igneous origins. And exhibited geochemical characteristics suggestive of a sedimentary source. The enrichment of large-ion lithophile elements (LILE) relative to high-field-strength elements (HFSE) in both gneisses and granitoids points towards subduction zone enrichment and crustal contamination of the source region. Harker diagrams for the granite units did not reveal a clear geochemical trend, although they suggested the influence of crystal fractionation processes. The scattered trends are likely due to the pervasive metamorphic alteration within the area. Geochemically, the granites are characterized as high-potassium, calc-alkaline, and peraluminous, indicating magma activity derived from mixed sources. The rare earth element (REE) patterns displayed a slight enrichment in heavy rare earth elements (HREEs), reflecting the acidic nature of the rocks. The negative europium anomaly observed in the granites suggests plagioclase fractionation. Discrimination diagrams utilizing Rb-(Y+Nb), Ta-Yb, Rb-(Y+Nb), and Nb-Y ratios suggest that the granites formed in a volcanic arc or syn-collisional granite (syn-COLG) tectonic setting. However, one sample was plotted within the within-plate granite (WPG) field.	en_US
dc.language.iso	en	en_US
dc.subject	Petrology	en_US
dc.title	Petrographic and Geochemical Characteristics of Medium to Highgrade Metamorphic and Associated Intrusive Rocks in the Konso Zone (Kholme Cluster Tebelana & Quchele Kebele)	en_US
dc.type	Thesis	en_US