General investigation into Upper Paleozoic sedimentary environment in southern Central Iran

Abstract

A thick sequence of Paleozoic rocks in Central Iran with special characteristics has been investigated. This corresponds to some other regions in Iran. The aim of this research is to investigate several facies of the Paleozoic in the southern part of Central Iran containing supertidal, intertidal and lagoon facies carbonates that are found in arid climate, similar to the southern Persian Gulf and west Australian coast and sandstone, black and red shale, siltstone and conglomerate of terrigenous facies. Based on widely extended sandstone layers and the existence of dolomitic layers in the top of terrigenous sequence, we suggest the existence of a littoral environment with slow subsidence for formation of these layers. Black shales are found in the end of delta environments and small islands existing between braded channels .With increase of energy, siltstones and sandstones were formed between black shale's layers. Red shales accompanied with siltstones and tiny to grainy sandstones indicate continental tropical weather. The conglomerate layer on the paleorelief represents an off lap stage and an orogenic phase. In the sedimentary environment of the above mentioned sequence, based on the existence of different fauna, special lithologic and sedimentary structures, there can be recognized marine facies, containing littoral, intertidal, lagoon, bioclastic bar, reef and sandy bar, and continental facies, containing braided river channels and point bar. This study demonstrates that Upper Devonian sediments were laid above the sandstone and quartzite layers, like in other regions in Central Iran, and were deposited chronologically at the Pre-Middle Frasnian.