Palaeontologic and isotopic study on the environmental changes during the Late Mesozoic

1. 订正了北大张地区下、中野三群的菊石和菊石生物地层学，稳定碳同位素地层学基本建立。该区域极有可能重建OAE 1的四个子事件。2 .中川地区下、中野三群的氨虫、针虫和放射虫生物地层基本建立，生物地层控制得到了很大的加强。演化过程基本建立了稳定的碳同位素地层，生物地球化学特征也发生了变化。因此，很明显OAE 1是在这个领域产生的。建立了日本白垩纪菊石的种级时间分辨率数据库。结果表明，日本白垩纪菊石的多样性变化在很大程度上受oae的控制。结果表明，在晚白垩世，氨类生物多样性逐渐减少，从700种减少到690种，且K/T影响极小。

1. Ammonoid and inoceramid biostratigraphy for the Lower and the Middle Yezo Group in the North Oyubari area was revised, and the stable carbon isotope stratigraphy was nearly estblished. It is highly possible to reconstruct four subevents of OAE 1 for this area.2. Ammonoid, inoceramid and radiolarian biostratigraphy for the Lower and the Middle Yezo Group in Nakagawa area was nearly established, and the biostratigraphic control was much improved by this work.3. The stable carbon isotope stratigraphy was nearly established for the succession, together with the change of biogeochemical features. Thus, it became clear that OAE 1 arose in this area.4. Database of Cretaceous ammonoids in Japan at the level of species was completed in the time resolution of subage.5. It was elucidated that the diversity change of the Japanese Cretaceous ammonoids was strongly controlled by the arise of OAEs.6. It became clear that ammonoid diversity gradually decreased during the Late Cretaceous from about 700 species to 690 species, and the influence the K/T impact is extremely small.