Composition and Provenances of Mesozoic Sandstones in Sikhote Alin

摘要

The composition of sandstones constituting different structural stages of the Jurassic accretionary wedge in the Samarka (upper and middle? structural levels in the Lyamfana Creek and Katen River basins, respectively) and Nadan'khada-Bikin (lower level in the Ulitka River basin) terranes of the Sikhote Alin region reflects changes in provenances and tectonic settings of the near-continental sedimentation basin in different periods of the wedge formation. In the terminal Middle Jurassic (Lyamfana Creek), the region was dominated by the subduction regime with sedimentary material transported from the eroded part of the continental-margin magmatic arc. During the Kimmeridgian-Tithonian (Katen River), erosion of granitoid batholiths of the arc exposed blocks of the crystalline basement along strike-slip faults. In the Tithonian-Ber-riasian period (Ulitka River), the role of these blocks increased, suggesting intensification of oblique subduction or development of transform faults during the accretion.