UNDERSTANDING THE TECTONOSTRATIGRAPHIC DEVELOPMENT OF THE UPPER PERMIAN–MIDDLE JURASSIC CLASTIC SUCCESSION ON THE BARENTS SEA SHELF

The Barents Sea Shelf (BSS) is an epicontinental platform area of ~1.4 million km² covered by a hydrocarbon-rich, Upper Permian–Middle Jurassic, clastic succession, included in the Exclusive Economic Zones of Russia and Norway. Like the sedimentary succession in the Appalachian Basin, the BSS succession can be interpreted as the product of a series of orogenies and included tectophases generated during the closure of an ocean. In particular, the BSS succession reflects closure of the Uralian Ocean as Siberia collided with the northeastern margin of Baltica from Carboniferous to Jurassic time. Across the BSS, this collision generated at least three, unconformity-bound clastic wedges, similar to the tectophase cycles of the Appalachian Basin. The first wedge was deposited from Late Permian to Late Triassic time during the docking of Siberia with Baltica (Uralian orogeny) and is reflected in westward migration of basinal black shales and an overlying deltaic complex called the Triassic Boreal Ocean Delta, depositing sands as far west as the Svalbard archipelago in the northwestern-most BSS area. Moreover, the sequence was interrupted by a regional Permo-Triassic unconformity related to emplacement of the Siberian superplume. The second wedge was deposited in Late Triassic time (early Norian to late Rhaetian); it is represented by another sequence of westwardly migrating black shales and clastics deposited during the Pai-Khoi-Novaya Zemlya orogeny that reflects the transpressional indentation of the Baltican margin and elevation of the Novaya Zemlya archipelago as a source area. The third wedge was deposited during Early to Middle Jurassic time and represents marginal-marine to fluvial deposition. This event might be correlated to the final continent-continent collision and accompanying thrusting of the Novaya Zemlya archipelago. Unconformably overlying, deeper-marine clastics represent the opening of the North Atlantic Ocean and have a different tectonostratigraphic development than those of the underlying successions. Clearly, the Upper Permian–Middle Jurassic clastic succession on the BSS reflects a complex tectonostratigraphic evolution, but applying the Appalachian Basin as an analogue may help in refining exploratory assessments for the BSS area.