Supracrustal suite of the Precambrian crystalline crust in the Ghor Province of Central Afghanistan

The Proterozoic pre-Ediacaran metamorphic basement of the southern Tajik （North Afghanistan） con- tinental 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 dolo- mite marbles, The metamorphic facies changes from greenschist in the Band-e-Bayan zone to amphib- olite 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.