CRETACEOUS TECTONICS AND GEOLOGICAL ENVIRONMENTS IN EAST RUSSIA

Abstract

By the Late Jurassic, the northern part of the East Asian continental margin was diversified. Principal structural constituents were the Siberian (or North Asian) craton bounded on the east by a miogeosynclinal fold belt, a system of smaller ancient blocks, and a collage of terranes that had been attached to the craton from the east and southeast at different times. Such a diverse structural environment caused variability of Cretaceous landscapes and related sedimentary systems. Global processes of lithospheric plate interaction and related regional tectonic processes played a leading role in Cretaceous environmental changes in the continental margin of East Russia.During the Early Cretaceous, the oblique plate convergence produced a transform continental margin over a long period of time. During the Middle Albian, a collage of terranes were attached to the continental margin of East Russia. Then during the Late Albian period, the angle of convergence increased, subduction resumed, and a giant East Asian volcanic belt formed along the continental margin. This belt was morphologically represented by a chain of mountain ridges (up to 3000 m), thus creating a sublongitudinal tectonic and climatic zonation. The active continental margin with a typical environmental arrangement of marginal seas–island arcs–the open sea, persisted until the end of the Cretaceous. The Late Maastrichtian tectonics was mostly characterized by overall uplift of the region.