The studied seep carbonates from Tsushima, Japan, are embedded within marine siliciclastics of the lower Miocene Taishu Group and represent the earliest evidence of hydrocarbon seepage in the Sea of Japan. In contrast to Miocene and Pliocene examples from Honshu, which are often found above anticlines, the seeps from Tsushima formed within a pull-apart basin before major anticlines had formed. The three carbonates from Fukuzaki, Kanoura and Tanohama are composed chiefly of calcite, with significant admixture of ankerite only at Kanoura. The stable carbon isotope composition of calcites (δ13C as low as −40.2 ‰ VPDB for Fukuzaki, −41.8 ‰ VPDB for Kanoura, and −52.8 ‰ VPDB for Tanohama) indicate methanogenic origin of the carbonates. Textures of these deposits, including radiaxial and yellow cements, are indicative of formation at a methane seep. The stable oxygen isotope composition of calcites (δ18O values as low as −14.4 ‰ VPDB for Fukuzaki, −14.5 ‰ VPDB for Kanoura and −13.9 ‰ VPDB for Tanohama) indicate that they were influenced by burial fluids. Burial diagenesis is also indicated by the stable isotopic compositions of ankerite (δ13C ranging from −19.1 ‰ to −7.1 ‰ VPDB, δ18O from −11.1 ‰ to −9.7 ‰ VPDB). Molecular fossils from Tanohama comprise n-alkanes with short-chain predominance, interpreted to have formed due to thermal cracking of organic matter. The carbonates yield a chemosynthesis-based community comprising vesicomyids Pleurophopsis chitanii, P. cf. hamuroi, the bathymodiolin ‘Bathymodiolus’ akanudaensis, the lucinid Lucinoma sp. and the provannid Provanna? sp., which have never been hitherto identified. ‘Bathymodiolus’ akanudaensis, Lucinoma sp. and Provanna? sp. are the oldest records of these taxa in the Sea of Japan.

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日本对马中新世大树群冷渗碳酸盐的形成、成岩作用及动物群

研究的日本对马渗出碳酸盐嵌入下中新世太树群的海相硅质碎屑岩中，代表了日本海油气渗漏的最早证据。与经常在背斜上方发现的本州中新世和上新世的例子相反，对马岛的渗漏在主要背斜形成之前就在拉开盆地内形成。福崎、卡诺拉和田野滨的三种碳酸盐主要由方解石组成，仅在卡诺拉有大量的铁白云石混合物。方解石的稳定碳同位素组成（δ13Fukuzaki 低至 -40.2 ‰ VPDB， Kanoura 低至 -41.8 ‰ VPDB，Tanohama 低至 -52.8 ‰ VPDB）表明碳酸盐的产甲烷成因。这些沉积物的纹理，包括径向和黄色水泥，表明在甲烷渗漏处形成。方解石的稳定氧同位素组成（δ18O 值低至福崎的-14.4 ‰ VPDB， Kanoura 的-14.5 ‰ VPDB 和Tanohama 的-13.9 ‰ VPDB）表明它们受到埋藏流体的影响。Ankerite 的稳定同位素组成也表明埋藏成岩作用（δ13C 范围从 -19.1 ‰ 到 -7.1 ‰ VPDB, δ18O 从 -11.1 ‰ 到 -9.7 ‰ VPDB）。Tanohama的分子化石包括n-具有短链优势的烷烃，解释为由于有机物的热裂解而形成。碳酸盐产生了一个基于化学合成的群落，包括 vesicomyids壳多糖,P。参看。羽室井, 深海芋'深海棠'阿卡努达, 清醒的卢西诺玛sp。和provannid普罗万纳? sp.，迄今为止从未被发现。'深海棠'阿卡努达,卢西诺玛sp。和普罗万纳? sp。是日本海这些分类群最古老的记录。