Hangibayna, Aspiron (2015) Metamorphism and Deformation History of Precambrian Rocks of Sorobo, Konso Area, Southern Ethiopia. Masters thesis, Addis Ababa University.
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Abstract
Metamorphism and deformation evolution history of Konso Sorobo is described, which is part of the Pan-African Orogeny, Mozambique Belt of southern Ethiopia. It comprises polydeformed and metamorphosed mafic-ultramafic to felsic rocks, high grade complex gneiss rocks. Also synto post-tectonic intrusives that range from ultramafic to granitic in composition and various preto post-rift deposits are geologically described. From field observations and petrological studies four phases of deformation and two metamorphic events are differentiated. D1 predated migmatization and high grade metamorphism of the paragenesis. It has resulted large open recumbent isoclinal folds with nearly horizontal axial surface. D2 phase formed open-reclined folds having NE axial surface. During D3 phases, the rocks were intensively sheared creating tight flexures having NW axial surface and local mineral lineations were developed. Whereas D4 was brittle-ductile deformation resulting faults owning several strike orientations. Mineral assemblage of the area shows high grade metamorphism, which is represented by amphibolite facies to granulite facies. D1 and D2 phases were enhanced the progression of the M1 metamorphism. Conversely, the existence of low temperature minerals in shear zones evidenced that there was retrograde metamorphism M2. This M2 retrograde event was syn-D3 and shows that late Pan-African Orogen-parallel shearing occurred, with the shear zones acting as important fluid conduits. Epidotization, chloritization, serpentinization alterations are common at plcaes. Thin section studies evidenced (1) partial melting as the temperature raised and (2) drop in temperature led high pressure-temperature minerals to alter into low grade minerals.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Metamorphism, Deformation, Progression, Retrogression |
| Subjects: | Q Science > Q Science (General) Q Science > QE Geology T Technology > TN Mining engineering. Metallurgy |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 06 Sep 2018 13:13 |
| Last Modified: | 06 Sep 2018 13:13 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/4926 |
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