Paleogeodynamic Reconstruction of Cenozoic Sedimentation Settings in the West Sakhalin Terrane Based on the Material Composition of Terrigenous Rocks

Abstract

The results of studying the material composition of sandy rocks from Cenozoic deposits in the West Sakhalin Terrane are considered. It has been established that sandstones in the terrane correspond to graywackes and petrogenic (“first cycle”) rocks. They are characterized by a low maturity degree of the detrital material formed mainly due to the mechanical destruction of source rocks. Paleogeodynamic interpretation of the obtained data suggests that the Paleocene–Pliocene sedimentation occurred directly along the Asian continent margin in a basin associated with large-scale shear dislocations along transform faults. The feeding zone was mainly composed of the following sources: (i) sialic land composed of the granitic-metamorphic and sedimentary rocks; (ii) mature deeply dissected continental-margin arc, where granitoid batholiths at the base were exposed by erosion. The secondary source was represented by fragments of the Sikhote-Alin accretionary prisms involving ophiolites. The U‒Pb isotopic dating of detrital zircons made it possible to establish the main complexes of granitoids that delivered the clastic material to Cenozoic sedimentation basins in the terrane.