History and modes of Mesozoic accretion in Southeastern Russia

Abstract

Abstract The history of Mesozoic accretion and growth of the Asia eastern margin, occupied by Southeastern Russia, includes five main events; two main tectonic regimes were responsible for the growth of the continent. In the Triassic‐Jurassic, Early Cretaceous and Late Cretaceous‐Paleogene, the subduction of the oceanic lithosphere resulted in the formation of wide accretionary wedges of the Mongol‐Okhotsk, Khingan‐Okhotsk and Eastern Sikhote‐Alin active continental margins, respectively. These stages of the comparatively slow growth of the continent were broken by stages of rapid growth and drastic changes in the shape of the continent, since at these stages large terranes of various tectonic nature collided with active continental margins. At the end of the Early‐Middle Jurassic, the Bureya terranes collided with the Mongol‐Okhotsk active margin, and at the beginning of the Late Cretaceous there was collision of the Central and Southern Sikhote‐Alin terranes with the Khingan‐Okhotsk active margin.Collision‐related structural styles in all cases are indicative of oblique collision and great strike‐slip motions along the main sutures. The peculiarities of the terrane's geological structure show that prior to collision with the Mongol‐Okhotsk and Khingan‐Okhotsk active margins, they had already accreted to Asia and then migrated along its margins along the strike‐slip faults. The Bureya terranes were squeezed out of the compression zone between Siberia and North China. This compression zone originated after the Paleozoic oceans which divided these cratons had closed. The Khanka terranes and Mesozoic accretionary wedge terranes of the Sikhote‐Alin shifted along the strike‐slip faults subparallel to the Asia Pacific margin. Strike‐slip motions resulted in duplication of the primary tectonic zonation.