Structure of Salt Diapirs in the Western Siberian Basin and Yenisei‒Khatanga Trough Based on Seismic Data

Interpretation of regional seismic profiles characterizing the structure of the West Siberian basin and the Yenisei-Khatanga Trough to depths of 10‒20 km suggests that salt diapirs played an important role in the structure of this region. Salt diapirs have the following features: (i) large height (up to 5 km or more); (ii) seismic transparency; (iii) presence of growth layers on the flanks of inferred salt rises; (iv) existence of radial fault systems in overlying sediments; (v) isometric shapes of uplifts; (vi) reduced values of the gravity field. Salt deformation explains the origin of widespread ring inversion structures in Jurassic-Cretaceous sediments. Such ring structures probably originated above long-lived salt diapirs. The salts in them are presumably of Early Paleozoic age. The formation of salt strata took place in a large area of salt accumulation at the periphery of the Siberian Platform. The western boundary of the zone of evaporitic sediments distribution is the Trans-Eurasian fault zone, which separated the folded Uralides from the Siberian Platform and tectonic blocks amalgamated with it. The presence of the evaporitic Paleozoic deposits in the northeast of the West Siberian Basin and the Yenisei-Khatanga Trough facilitated the development of large oil and gas pools. Salt cryptodiapirs focused the migration of hydrocarbons from deeply buried, thermally mature Paleozoic sediments into the Jurassic-Cretaceous section, which explains the predominance of gas deposits in these areas, as well as the multilayer nature of the fields.