Palaeontological and geochemical study of Late Cretaceous oceanic anoxic event

通过岩相、巨生物相、遗迹相、含硫量和硫/有机碳比值的研究，明确了除西北太平洋以外世界公认的所谓塞诺马尼亚/图罗尼亚海洋缺氧事件在北海道奥尤巴里和奥比拉的中野三群的塞诺马尼亚/图罗尼亚界线层中的存在。我们在法国格勒诺布尔和英国伦敦举行的一些国内年会和国际会议上报道了这一结果。首席调查员在非洲北突尼斯和法国普罗旺斯进行了访问和采样，并比较了北海道、北突尼斯和普罗旺斯之间C/T边界上的化学地层模式，证实了西北太平洋存在塞诺马尼亚/图罗尼亚海洋缺氧事件。这位首席调查员在第29届国际地质大会期间，在北海道奥尤巴里和米卡萨的C/T边界暴露处进行了实地考察，讨论了所研究层的OAE的可靠性，从而成功地获得了事件的时间和全球范围，我们正在研究的进一步课题是澄清与地球结构及其节奏有关的原因。

We clarified the existence of the so-called Cenomanian/Turonian oceanic anoxic event, which is world-widely recognized except Northwestern Pacific, in the Cenomanian/Turonian boundary bed of the Middle Yezo Group distributed in Oyubari and Obira, Hokkaido by the study of lithofacies, megabiofacies, ichnofacies, sulphur contents and sulphur/organic carbon ratio. We reported this result in some domestic annual meetings and international conferences which were held in Grenoble, France and London, UK. The head investigator visited and sampled in North Tunisia, Africa and Provance, France and compared chemostratigraphical patterns across the C/T boundary between Hokkaido, North Tunisia and Provance, confirming the existence of the Cenomanian/Turonian oceanic anoxic event in the Northwestern Pacific. The head investigator carried out the field trip in the occasion of the 29th International Geological Congress at the C/T boundary exposures in Oyubari and Mikasa, Hokkaido, discussing the reliability of OAE at the studied beds.Thus we succeeded in getting the timing and world-wide scale of the event, and further subject which we are now studying is to clarify the causal factor in relation to the earth structure and its rhythm.