NORTHWESTERN MARGIN OF THE EAST SIBERIAN SEA, RUSSIAN ARCTIC: SEISMIC STRATIGRAPHY, STRUCTURE OF THE SEDIMENTARY COVER AND SOME REMARKS ON THE TECTONIC HISTORY

Abstract

Multichannel seismic reflection data, acquired by MAGE in 1990, provide the first view of the geological structure of the East Siberian Sea between 76.5–80N and 152–164E. This northwestern part of the East Siberian Margin may be considered within the context of a passive-transform model bordering a Late Mesozoic–Early Cenozoic Makarov Basin of the Arctic Ocean. The continental basement is formed by Paleozoic and Mesozoic rocks, which were folded in the Late Mesozoic. The sedimentary cover includes Cretaceous (Aptian) to Cenozoic terrigeneous deposits. The total thickness of the sedimentary cover varies from a few tens of metres to 8–9 km, generally increasing northward. At least 10 sedimentary units are correlated and stratigraphically identified from the seismic data. Three structural sequences, Cretaceous (Aptian to Santonian), Campanian to Lower Paleocene, and Cenozoic, are distinguished in the sedimentary cover. They may correspond to three main stages of deep margin evolution: continental breakup (125–80 Ma), drift (80–60 Ma) and post-drift (60 Ma to present). The present morphology of the northern shelf and deep margin is the result of continental-terrace progradation and gravity-driven slope processes.