Thermal and tectonic evolution of the Kashmir basin vis-à-vis petroleum prospects

Abstract

Investigation of the formation of peri-Atlantic basins and evaluation of the mechanism of lithospheric break-up provide a guide for understanding the pre-collision history of the Himalayan region. As an example the Kashmir basin is discussed. The present form of the Kashmir basin is that of a graben bounded by two horsts. The stratigraphic succession shows a complete record of shallow marine sedimentation from the Cambrian to Middle Carboniferous. In the Upper Carboniferous the depositional environment changed to continental type, accompanied by large-scale erosion (especially on the western side) and the deposition of Agglomeratic Slate and then, in the Lower Permian, by the Panjal Trap volcanism. Whilst the eastern side, after this continental phase, again subsided and received marine sediments until the end of the Triassic, the western side experienced repeated uplift and volcanism. Gravity and seismic data indicate the presence of high-density material and a shallow depth of the Moho beneath the basin, and also the eruption of the Panjal Trap lava along two deep-seated faults ( F 1 and F 2) on the flanking horsts with dips towards the present Indus-Tsangpo suture. After the upper Carboniferous a continental phase is noted all over the Himalaya. This is thought to mark the initiation of the break-up of the Indian plate from the Siberian-Cathysian block which finally occurred at the end of the Triassic. Based on the stratigraphie and tectonic set-up of Kashmir in particular and the whole Himalaya in general, a model is presented to explain the formation of the Kashmir basin. Good compatibility of the model with observed tectonic and stratigraphie aspects of Kashmir and the whole Himalaya is found. The geothermal history of different strata in this basin indicates promising conditions for hydrocarbon generation; a few of the more promising strata are identified for intensive investigations.