الفهرس | Only 14 pages are availabe for public view |
Abstract The basement rocks covering the area between Wadi Um-Maghra to Wadi Tweiba rep resent one of the main metamorphic belts in Sinai and refer as ”Taba belt”. The Taba belt comprjses both metamorphic and igneous rocks of Pan-African age (not more than 800 Ma ago) . where the metamorphites represent about 77% of the total Precambrian exposu re. The metamorphic rocks comprise schists. Metagabbro-diorite Complex which are related to the initial tectonic stage (backarc association); migmatites, orthogneisses and associated schistose dykes which are related to the syntectonic association. On the megascale. uprooting of the different rocks unitS due to ascending of the Younger Granites with conjugate normal faults in between are observed. A. Initial tectonic stage (back-arc association) 1. Schists The schists occur in the northern part of the study area, where they rep resent the oldest rock unit. {t is exposed at Wadis Tweiba. Khileifiya and el-Morakh. The preserved bedding strucrure and tbe chemical criteria of the schists suggest their derivitation from a sedimentary source initially dominated by psammitic to semipelitic (gr aywackes and pelitic graywackes) in composition. They were depos ited in a tectonic setting intermediate between island arc and active continental margin regime. At Wadi Tweiba. the schists are fine grained biotite-, garnet-bi otite~, staurolite-bioti te-, and andalus ite biotite schist varities. At Wadi Khil eifiya. the schists are represented by biotite- and garnet-biotite types, underwent retrograde overprint leading to chloritization of biotite and sericitization of plagioclase . At Wadi el-Morakh , medium-grained biotite- and garnet-bi otite schist varities are exposed. The predominant part of the schist belt belongs to the garnet zone. A smal! area south tO Wadi ei-Morakh belongs to the biotite zone seperated from the garnet zone by the WNW-ESE trending garnet isograde. Staurolite and andalusite bearing schists are confined to a local area west to Wadi Tweiba, where the staurolite schists occur as bands in the biOtite and/or garnet schists. |