Northern West Siberian–South Kara Composite Tectono-Sedimentary Element, Siberian Arctic

Abstract

Abstract The Northern West Siberian–South Kara Composite Tectono-Sedimentary Element (NWSSK CTSE) occupies over 1 million km 2 of the northern West Siberian Basin and the South Kara Basin. It formed as a result of the latest Permian–earliest Triassic crustal extension following thermal subsidence. The Early Triassic palaeorifts are buried under 10–12 km-thick post-rift Middle Triassic–Quaternary siliciclastic sediments. In the Tithonian–Early Berriasian period, a deep-water anoxic depression formed in the West Siberian Basin and accumulated the organic-rich carbonate-siliceous Bazhenov shales that are the main source of hydrocarbons. The West Siberian Basin, including the NWSSK CTSE, is one of the major petroleum provinces worldwide. Oil and gas deposits have been identified in Paleozoic carbonate basement rocks and Triassic, Jurassic and Cretaceous reservoirs. The main gas reserves are concentrated in the Lower Aptian–Cenomanian play. Significant gas and oil reserves are located in the Berriasian–lowest Aptian and Jurassic plays. The CTSE comprises 18–20% of the world's known gas reserves and provides approximately 90% of all Russian natural gas, which comprises 22% of global gas extraction. In this chapter we provide a summary of the CTSE geology and petroleum geology based on bulk results published mostly in the Russian literature.