Supracrustal suite of the Precambrian crystalline crust in the Ghor Province of Central Afghanistan |
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Authors: | Gediminas Motuza Saulius Šliaupa |
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Affiliation: | 1. Department of Geology and Mineralogy, Vilnius University, M.K.?iurlionio 21/27, LT-03101 Vilnius, Lithuania;2. Nature Research Centre, Akademijos 2, LT- 08412 Vilnius, Lithuania |
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Abstract: | The Proterozoic pre-Ediacaran metamorphic basement of the southern Tajik (North Afghanistan) continental block and the adjacent Band-e-Bayan zone is exposed in the Ghor Province of Central Afghanistan. It is predominantly composed of the EW-striking supracrustal succession consisting of interbedded felsic schists and gneisses (metapsammites), amphibolites (metabasalts), calcite and dolomite marbles. The metamorphic facies changes from greenschist in the Band-e-Bayan zone to amphibolite facies in the Tajik block. The supracrustal rocks of the Band-e-Bayan zone and Tajik block possess common features suggesting that the former represents a tectonized part of the latter. The geochemical characteristics of metapsammites indicate derivation of the clastic material from a continental arc and, partly from a passive continental margin, whereas the composition of metabasalts suggests their possible formation in a continental rift basin. The tectonic setting of supracrustal unit could be interpreted as a back-arc type basin. We presume that the Tajik microcontinent split off the Gondwana supercontinent along an ancient rift zone during the late Paleozoic. |
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Keywords: | Afghanistan Tajik block Proterozoic rock units Continental arc Back-arc basin |
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