East Siberian Sea Composite Tectono-Sedimentary Element, Siberian Arctic

The East Siberian Sea Composite Tectono-Sedimentary Element (ESS CTSE) occupies most of the central and southern parts of the East Siberian Sea (ESS) and extends onshore into the Chukchi Peninsula. The first multichannel seismic reflection data, acquired in this region in 1989 and 1991, revealed its structural complexity and the presence of a deep sedimentary depocentre in its central part. In the 2010s, the first long-offset seismic data provided a much better understanding of the geology of this remote segment of the Arctic Shelf. It includes a large extensional basin that started to form in the Albian(?)–Cenomanian, post-dating the Barremian–Aptian Chukotkan Orogeny and the formation of the New Siberian–Chukchi Fold-and-Thrust Belt (FTB). The latter experienced extensional collapse and developed into the tectonic basement that underlies the CTSE over its entire extent. The ESS CTSE is mainly composed of Upper Cretaceous–Holocene siliciclastic sedimentary strata, with a total thickness up to 14 km. This succession has not been drilled deep enough to test its hydrocarbon potential since the beginning of exploration around 2013. However, the strata contain abundant terrestrial organic matter and are considered as potential source rocks that are sufficient for generating gas accumulations.