Upper Jurassic Sediments in the Western Side of the Frolovskoye Basin in West Siberia: Diverse Patterns and Environments of Deposition

Abstract

Abstract —The paper presents data on different types of Late Jurassic carbonaceous–siliceous–shale sequences of marine deposits in the western side of the Frolovskoye basin. The diverse sedimentation patterns in the area were presumably controlled by tectonics, sea bottom topography, and currents, with voluminous gas venting through large faults. Recent exploration drilling in the Elizarovo trough and the Vygnlor basin revealed Upper Jurassic sections of a previously unknown type with low-radioactivity lower strata markedly thicker at the account of biogenic radiolarite intercalations affected by postdepositional carbonatization. The lithology of these rocks is described with implications for deposition environments and extent of such sections.