千葉県印旛沼周辺に分布する下総層群木下層・上岩橋層の有孔虫化石
2011 年 65 巻 1 号 p. 23-27
詳細
2011 年 65 巻 1 号 p. 23-27
The type sections of the Kioroshi Formation and the Kamiiwahashi Formation are distributed around the Lake Inba-numa, Chiba Prefecture. This study makes clear the distribution of fossil foraminiferal assemblages of these formations in this area. As the result, the foraminiferal assemblage from the upper Kamiiwahashi Formation is characterized by Pseudononion japonicum, and it suggests the central part of bay or the mouth of bay environment. The foraminiferal assemblage from the drowned basal valley fill deposit of the lowest Kioroshi Formation is characterized by Ammonia beccarii forma 1, and it shows the inner bay environment. The foraminiferal assemblage from the lower Kioroshi Formation is represented by Porosorotalia makiyamai and Poroeponides cribrorepandus, and it shows the mouth of bay to the central part of bay environment.
