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

(1)We用统计学方法研究了索拉奇群至耶佐群的主量元素和次量元素的地层过渡，以及放射虫丰度和特征成分。位于北海道的手盐中川地区。我们澄清，化学过渡是很大的不同，从清晰的视觉变化之间的继承上Sorachi和较低的Yezo集团。(2)We从生物地层学的角度，利用菊石、菊石、浮游有孔虫、层序地层学和稳定碳同位素地层学，对北海道中屯别地区上白垩统同一剖面进行了联合研究。我们检测到一个显着的尖峰碳同位素波动在同一地层的灭绝inoceramid双壳类。这一结果使我们能够进行高分辨率的国际相关。(3)We从海相双壳类生物地层学、孢粉学、稳定碳同位素地层学和层序地层学等方面，对叶佐前弧盆地物源的中国东北鸡西群进行了联合研究。我们得到了一个高分辨率的相关组与日本太平洋，欧洲部分。

(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.