Ge/Si Ratios Reconstructed from the Miocene Diatomaceous Sediments in the Japan Sea

Abstract

During the middle to late Miocene global cooling, diatomaceous sediments were widely deposited in the North Pacific region including the Japan Sea. It is proposed that the organic carbon burial associated with the diatomaceous sediments might have a great influence on the global cooling through the carbon cycle. In this study, we reconstructed the Ge/Si ratios of diatom frustules extracted from the Miocene diatomaceous sediments on Sado Island in Niigata Prefecture and in Suzu City in Ishikawa Prefecture in Japan to obtain information about the silica cycle during the Miocene. The obtained Ge/Si ratios in the Japan Sea during the Miocene show higher values than those in the open ocean, which might result from the depletion of the dissolved silica in the sea surface water or the contribution of the hydrothermal input characterized by the extremely high Ge/Si ratios. Our new data will lead to progress in understanding the mechanism of the formation of the diatomaceous sediments in the Japan Sea during the Miocene.