Ductile shear zones in the northern Red Sea Hills, Sudan and their implication for crustal collision

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Authors:Almond, David C.; Ahmen, Farouk
Author Affiliations:Primary:
Kuwait Univ., Dep. Geol., Kuwait
Other:
Univ. Khartoum, Sudan
Volume Title:African geology reviews
Volume Authors:Bowden, Peter, editor; Kinnaird, Judith
Source:Geological Journal, Vol.22, p.175-184; 13th colloquium of African geology, St. Andrews, United Kingdom, Apr. 1987, edited by Peter Bowden and Judith Kinnaird. Publisher: Wiley & Sons, Chichester-New York, United Kingdom. ISSN: 0072-1050. ISBN: 0-471-91595-5
Publication Date:1987
Note:In English. 21 refs.Winter thematic issue; geol. sketch maps
Summary:In the northern Red Sea Hills of Sudan, deformation is largely concentrated into a network of shear zones. Several of these zones strike N-S, but the important Nakasib and Sol Hamid zones are NE-trending, and there are also minor shear zones which strike E-W. A distinction is made between massive shear zones, such as that of Nakasib, and more diffuse braided shear zones, typified by the Oko zone. The massive type owes its character to an origin as a reactivated oceanic suture, whereas the braided type was characterized by strike-slip shearing from its inception. Most of the shear zone rocks are mylonites formed under greenschist facies conditions, but early shearing along the Oko zone took place at higher T and resulted in gneissose mylonites with amphibolite-facies mineralogy. The NE-trending, Nakasib shearing appears to have preceded a phase of batholithic intrusion, whereas N-S shearing in the Oko and Abirktib zones is younger than the batholithic intrusions, and was in turn post-dated by emplacement of bimodal granite-gabbro complexes. These events cannot be dated precisely as yet, but took place between 99 and 700 m.y., and probably towards the end of that interval. [J.M.H.]
Subjects:Crust; Deformation; Field studies; Lineaments; Plate collision; Plate tectonics; Precambrian; Proterozoic; Shear zones; Structural geology; Tectonophysics; Upper Precambrian; Africa; East Africa; Red Sea Hills; Sudan; Northern Red Sea Hills
Abstract Numbers:89M/0999
Record ID:1989053148
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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