SEDIMENTARY FORMATIONS OF THE CRETACEOUS SAKHALIN BASIN (FAR-EAST ASIA)

The marine sedimentary formations of the Middle Albian to Maastrichtia n in the Cretaceous Sakhalin Basin (CSB) were investigated. These succ essions of strata consist of interbedded sandy, clayey and calcareous rocks which are underlain by heterogeneous metamorphosed (up to greens chist facies) Paleozoic to Mesozoic (pre-Aptian) rocks. The studied se ctions display several different facies reflecting geological settings ranging from an inner shelf to a continental slope. Three depositiona l complexes bound by regional subaerial unconformities are recognized within the marine successions. Since the Albian, the CSB has been a ra pidly subsiding marginal part of the Okhotsk Sea plate. The Naiba Vall ey succession, corresponding to a sublittoral zone, shows extremely hi gh sedimentation rates up to 190 m/Ma. The stratigraphic distribution of lithofacies indicates that the CSB became shallower from the Middle Albian to the Maastrichtian.