Analysis and revision of the Miocene boreal faunae of bivalve mollusks of the South Sakhalin. V.D. KHUDIK, Yu.D. ZAKHAROV

Abstract

Analysis and revision of the Miocene boreal faunae of bivalve mollusks of the South Sakhalin. V.D. KHUDIK, Yu.D. ZAKHAROV (Far East Geological Institute, FEB RAS, Vladivostok).

The results on the studying of the faunae of bivalve mollusks remains from Miocene deposits of the South Sakhalin are presented. The analysis of the last ones allowed distinguishing the following three boreal assemblages of mollusks: Nevelskiy, Early Chekhovskiy and Kurasiiskiy, recording the period of climatic cooling in Miocene of the region. Studying of Neogene representatives of Lucinoma and Mya generas allowed identifying some taxa among them which have stratigraphic significance. The detected presence of warm water bivalves in the faunae of the Late Chekhovsky time of the South Sakhalin appears to reflect the initial stage of the tendency of the intensifying climate warming happened during Miocene, with climatic optimum during the Verkhneduysky – Sertunaysky times. An opinion is expressed that the unstable climatic conditions in the northern part of the Japan Sea region during Late Paleogene–Early Neogene could have been the main reason for originating of one of the high-potential centers of evolution of the marine malacofaunae of boreal regions of the North Pacific.