Cretaceous in Sakhalin and Cretaceous events in North Pacific

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The Cretaceous System in the southern part of Sakhalin, Russian Far East, was studied biostratigraphically, combined with matnetostratigraphic and carbon isotope stratigraphic surveys in 1997 and 1998. to establish a more precise bic- and chronostratigraphy for the Cretaceous System and to interpretate various aspects in biotic and physical evolution during the Cretaceous in the North Pacific regions, At the sections along the Naiba and Makarov rivers, we obtained the most reliable bio- and chronosratigraphic scheme in the North Pacific regions for the Santonian, Campanian and most part of Maastrichtian. The results, together with the middle and upper parts of the Cretaceous along the Ai River section, provide a sound basis for the biostratigraphic correlation based on marine invertebrates such as ammonites and inoceramids, and for our understandings of marine faunal characteristics in time and space. Carbon isotope changes from terrestrial organic carbon were examined to show globally recognized events and o prove its utility as a stratigraphic tool. Mineral composition and monazite ages in the Cretaceous sandstones indicate the same provenance as those in central Hokkaido. Although not conclusive, we collected additional data on the marine K/T boundary at the Naiba River section. The "Danian" part is still needed further investigations, and only its uppermost part is characterized by plant megafossils of Tertiary type.