Burial and Thermal History of the South Torgay Basin, Kazakhstan

Abstract

Summary The South Torgay Basin is one of the Mesozoic sedimentary basins of central Asia. Its development dates back to the beginning of the Jurassic time and almost all entire Jurassic development was in the rift regime (3–4 km deposits thick). In the Cretaceous post-rift period deposits yet reached up to 1,5km more. Low erosion during Tertiary uplift removed little part of sedimentary cover but has caused structural traps in which hydrocarbon deposits are currently. Results of the analysis indicate that generation of hydrocarbon was mainly in the Lower Jurassic depocenters. The occurrence of these deposits in the synsedimentary grabens lead to rapid burial of sediments and has started generation processes already in the Middle Jurassic time. Geological modelling of the basin thermal history shows that the present heat flow is insufficient to generate a quality of present hydrocarbon deposits. Between the current hot corridor (thermal gradient <4°C/100m) and depocenter from the Jurassic period is a good coincidence. This hot corridor during the Jurassic time probably existed in the same place, but the heat flow value was higher than at present approximately 50–100%.