Evolutionary paleontologic, stratigraphic, and geochemical studies on the Cretaceous environmental changes.

(1)用统计方法研究了从索拉奇群到耶佐群的主次元素地层转换，以及放射虫丰度和特殊成分。在北海道的Teshionakagawa地区。(2)从生物地层学的角度，对北海道Nakatonbetsu地区上白垩统的同一剖面进行了联合研究，利用菊石、线虫、浮游有孔虫、层序地层学和稳定碳同位素地层学等方法对上白垩统的同一剖面进行了联合研究。我们在双壳贝类灭绝的同一地层层位上发现了碳同位素波动的显著峰值。从海相双壳生物地层学、孢粉学、稳定碳同位素地层学和层序地层学的角度对叶佐前弧盆地物源区中国东北部鸡西群进行了联合研究。我们获得了该群与日本太平洋和欧洲剖面的高分辨率对比。

(1)We studied the stratigraphic transition of major and minor elements in terms of some statistical methods from the Sorachi to the Yezo Group as well as of radiolarian abundance and specific compositions. in Teshionakagawa area, Hokkaido. We clarified that the chemical transition is much different from the clear visual change in the succession between the upper Sorachi and the lower Yezo Groups.(2)We made a joint work on the same sections of the upper Cretaceous in Nakatonbetsu area, Hokkaido from the viewpoints of biostratigraphy by using ammonoids, inoceramids, planktonic foraminifers, sequence stratigraphy, and stable carbon isotope stratigraphy. We detected a significant spike of carbon isotope fluctuation at the same stratigraphic horizon of the extinction of inoceramid bivalves. This result enable us to make a high resolution international correlation.(3)We made a joint research on the Jixi Group in NE China of the provenance of the Yezo forearcc basin from the viewpoints of biostratigraphy of marine bivalves, pollen, stable carbon isotope stratigraphy and sequence stratigraphy. We obtained a high resolution correlation of the group with the Japanese Pacific, and European sections.