Biostratigraphy of the Ulleung Basin, East Sea (Japan Sea)

Abstract An interpretation of both micropaleontological and palynological analyses was carried out for eleven wells from the Ulleung Basin, East Sea (Japan Sea). Based on bioevents of microfossil groups (calcareous nannofossils, foraminifera, diatoms, dinocysts, spores and pollen) twenty-three datums are established. The biostratigraphic and paleoenvironmental data indicate significant tectonic events such as subsidence (17 Ma), closing of the Korea Strait (15 Ma), and uplift in Dolgorae deformed region (12.5–10.2 Ma) of the basin. The high resolution sequence biostratigraphy, correlated with wireline log and seismic data, provided to be effective for constraining the interpretation of depositional systems tracts of the basin. The Paleogene reworked taxa in Neogene section suggest that the provenance of sediments of the basin was southern offshore basins of Korea, and/or southwestern Japan (Kyushu area) and the Fukue Basin.