TECTONIC SETTING OF THE CRETACEOUS SEDIMENTS IN THE LOWER AMUR REGION, RUSSIAN FAR EAST

Abstract

Data on heavy minerals from the Valanginian-Cenomanian sedimentary rocks of the Lower Amur region are interpreted on the basis of actuallistic approach with the use of previous study results on heavy mineral assemblages from the modern deposits accumulated in the known plate-tectonic conditions. As a result, the following has been found out; Deposits of the Valanginian-Barremian ensimatic island arc and its adjacent marginal sea, Barremian-Albian active continental margin, and Albian-Cenomanian passive (or transform) continental margin were combined in terranes of the Lower Amur region. Major tectonic processes that resulted in these were large-scale strike-slip movements and accretion processes associated with oblique subduction, and some collisions among the arcs mentioned, continental margins, and rigid blocks of oceanic lithosphere.