The Origin Analysis of “reversal foreset” of Late Carboniferous MKT Formation in Central Block of Pre-caspian Basin

Abstract

Abstract The configuration of “reversal foreset”, which is a common geologic sedimentary phenomenon in seismic exploration, has been fully understood on its mechanism. In central block of pre-caspian Basin, a series of NE “reversal foreset” configurations were found. This kind of reflection is completely opposite to the paleogeomorphology which is high in the west and low in the east. It is difficult to clarify the origin mechanism of the “reversal foreset” configuration without sufficient data and understanding of regional tectonic evolution. Interpretations provided by previous studies did not reach a consensus understanding of the tectonic and sedimentary structures in the area. In this paper, based on well and regional data, the previous interpretations are analyzed, and the idea is put forward that the “reversal foreset” configuration represents superimposed retrogradation bodies developed in the process of rapid water flooding, and its formation is controlled by three factors -- “weak supply of single source”, “rapid transgression (weak source supply)” and “low and gentle depositional slope”. This recognition helps understanding the sedimentary evolution characteristics of the Late Carboniferous MKT formation in central block of Pre-caspian basin and promotes the later exploration of lithologic reservoir.