Evolution and hydrocarbon habitat of the South Turgay Basin, Kazakhstan

The South Turgay Basin is a Mesozoic intracontinental rift with a Lower Jurassic to Lower Cretaceous fill. It is underlain by a basement complex comprising Precambrian metamorphics and Palaeozoic carbonates and clastics, and was formed as a result of right lateral movement on the Karatau–Talasso–Fergana Fault. Four principal graben systems are found in the basin. These are the Ariskum, Akshabulak, Sarylan and Bozingen grabens. The graben fill is represented by up to 5 km of dominantly continental sediments, with lacustrine, alluvial and fluvial units, with a series of gross fining-upwards sequences in the Lower to Middle Jurassic (syn-rift) and Upper Jurassic to Lower Cretaceous (post-rift). Marginal marine conditions began to become established during the Apto-Albian with a marine transgression from the west. Tertiary regional uplift resulting from the India–Eurasia collision stripped off later deposits. Recoverable hydrocarbons in the order of 1 billion barrels of oil equivalent have been proven to date in the large Kumkol Field and a number of smaller pools.