Middle–late Miocene paleoenvironment of the Japan sea inferred by sedimentological and geochemical characterization of coeval sedimentary rocks

The middle–late Miocene siliceous mudstones and siltstones of the Akita Aomori regions in Northern Honshu, Japan, provide an excellent geological record paleoenvironment Japan Sea. In this paper, we present results sedimentological geochemical analyses Akaishi Odoji Formations from Tsugaru Basin region Onnagawa Formation Sugisawa area region. Lithofacies descriptions, compositions (including major elements, total organic carbon [TOC], nitrogen [TN], sulfur [TS]), petrographic observations framboidal pyrite were used to investigate origin detrital fraction, paleoproductivity, paleoredox conditions bottom waters Moreover, through interpretation these data, relationship between preservation paleoenvironmental evolution was clarified. data indicate that paleoweathering moderate high fraction source terrain; originated a felsic probably transported Asia Sea by monsoons Japanese islands riverine input; concentrations biogenic SiO2 primary productivity surface water, induced intense upwelling nutrients; characterized oxygenated whereas low-oxygenated water based on lithofacies variation size pyrite; accumulation mainly controlled paleoproductivity dilution rather than conditions. Alternatively, likely