Stratigraphy and fossil molluscan fauna of the Upper Cretaceous System in the Bibai area Hokkaido, north Japan.

Abstract

The Bibai area is located in the western limb of the Sorachi Anticline, the Ishikari Coal field, central Hokkaido. The Upper Cretaceous System of this area consists of the main part of the Middle Yezo Group, the Mikasa Formation, the Upper Yezo Group and the Hokobuchi Group in upward sequence. Four traceable key tuff beds are recognized in the Cretaceous System in this area. The Paleogene Ishikari Group unconformably covers the Cretaceous System. -from English summary