SOUTH SAKHALIN TECTONICS AND GEODYNAMICS: A MODEL FOR THE CRETACEOUS-PALEOGENE ACCRETION OF THE EAST ASIAN CONTINENTAL MARGIN

Abstract

This paper presents new data for the geological structure of South Sakhalin which is a connecting link between the structural features of the Sakhalin and Hokkaido islands which form the Late Mesozoic-Early Cenozoic Hokkaido-Sakhalin fold system. These data were used as a basis for deriving a new model of the tectonic evolution of the region, derived on the basis of terrain analysis. They illustrate the evolution of the East Asia continental margin during the larger part of the Cretaceous and during the Paleogene. The tectonic data available for this region recorded five epochs of structural readjustments, which separated the periods of the accretional growth of the continental margin. It is shown that the geodynamic evolution of the East Asian continental margin was controlled by the combination of convergence and transformation environments at the continent-ocean boundary and was complicated by the accretion of large intraoceanic volcanic rises and by the collision of ensimatic island arcs.