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" Structure, metamorphism and tectonic setting of a gneissic terrane, the Sagan Afelata area, southern Ethiopia "
S. Gichile
W. K. Fyson
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Latin Dissertation
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English
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| Record Number
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1112390
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| Doc. No
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TLpq303968567
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| Main Entry
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S. Gichile
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W. K. Fyson
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| Title & Author
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Structure, metamorphism and tectonic setting of a gneissic terrane, the Sagan Afelata area, southern Ethiopia\ S. GichileW. K. Fyson
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| College
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University of Ottawa (Canada)
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| Date
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1991
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| student score
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1991
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| Degree
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M.Sc.
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| Page No
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265
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| Abstract
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The Sagan-Afelata area, which extends east approximately 100 km from the Main Ethiopian Rift towards the Adola gold fields, is underlain by high-grade rocks, dominantly biotite and quartzofeldspathic gneiss. The gneissic rocks are characteristically of K-rich mineralogy and appear to form a Proterozoic supracrustal sequence rather than Archean basement as thought earlier. The gneissic rocks were subjected to at least three distinct phases of deformation. The first, D, to which probably several generations of structures are attributed, formed migmatitic layering then isoclinal folds that transposed the layers parallel to flat-lying regional foliation (S), during amphibolite to granulite facies metamorphism. The second, D2, formed upright folds in S and parallel layers with subhorizontal NNW to NNE trending axes, accompanied by amphibolite facies metamorphism that overprinted most rocks. D3, resulted in local E-W trending, open, upright folds that are confined to the eastern part of the area. (Abstract shortened by UMI.)
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Earth sciences
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Geology
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