Sedimentary settings of marine middle mesozoic allochthonous complexes of northeastern asia and their correlation

Abstract

The correlation of the Jurassic–Lower Cretaceous cherty-volcanic complexes constituting nappe scales of the tectonostratigraphic sections of the Okhotsk-Koryak orogenic belt served as a basis for interpreting the lateral and vertical series of Norian–Barremian marine sedimentary settings in the North Pacific. The correlation was based on radiolarian and geodynamic analyses. The taxonomic compositions of radiolarian assemblage were used as proxies for reconstructing oceanic and marginal marine settings and the seafloor topography (deep and shallow neritic regions, elevated areas (atolls, guyot, and island arcs), facilitating the upwelling). The stage-by-stage reconstruction of the paleoenvironments became possible owing to the stage subdivision of previously almost entirely barren allochthonous formations.