The hydrocarbon potential of the Miocene siliceous formations in Tsugaru Basin, northern Japan, based on the geochemical analyses

Abstract

Middle-late Miocene siliceous sedimentary formations are considered important targets for petroleum exploration in the North Pacific, including northwestern Honshu Island in Japan. In this study, we present data on the diatomaceous siltstones of the Akaishi Formation and the siliceous mudstones of the Odoji Formation from the DTH27-1 well in the Tsugaru Basin, southwestern Aomori Prefecture. Organic geochemical data from the Rock-Eval pyrolysis were used to evaluate the hydrocarbon potential of siliceous mudstones in western Aomori. S1+S2, TOC, and T_max data indicate that the siliceous mudstones are prospective source rocks in this region. However, the low maturity of these formations indicates that formations of western Aomori Prefecture could not expel hydrocarbons. Although in this area productive source rock horizons are not present, siliceous mudstones with the same age of the Odoji Formation in the Tsugaru Peninsula could represent future targets for the hydrocarbon exploration in the Aomori Prefecture.