Middle Permian Terrigenous Deposits of the Laoeling–Grodekovo Terrane (Southwestern Primorye): Lithology and Paleogeodynamic Nature

The results of the study and paleogeodynamic interpretation of the composition of sandy rocks of the Middle Permian Barabash Formation of the Laoeling–Grodekovo terrane located in the southwestern Primorye are presented. The sandstones studied belong to graywackes and, partly, to lithic arenites. They are petrogenic, “first cycle” rocks that have undergone a single cycle of redeposition. The deposits were formed through the destruction of moderately weathered rocks in denudation areas. Analysis and paleogeodynamic interpretation of the obtained mineral and geochemical data indicate that deposits accumulated in a basin within an active continental margin, most likely complicated by strike-slip movements along transform faults. The main source of the clastic material was the continental landmass – cratons and uplifted basement blocks composed of granite-metamorphic and, partly, sedimentary rocks containing ancient clastic components. Subordinate sources were fragments of an ancient, deeply dissected continental-margin magmatic arc composed of mafic and ultramafic rocks.