Fossil shell assemblages and 14C-ages on the Holocene shell bed discovered at Takahama-cho, western Fukui Prefecture, central Japan

Abstract

Holocene shell beds were discovered in Takahama-cho, Oi-gun, Fukui Prefecture. The sequence of the Holocene strata occurs between 2 and 6 m in depth, and was divided into six stratigraphic horizons on the basis of the characteristics of lithology and fossil molluscan assemblages, foraminiferas and ostracodas. According to the shell-assemblage results from synecological analysis, the following paleoenvironmental transitions were clarified: the Takahama area was a mud-depositing intertidal zone 5000 years ago, a sand and mud-depositing shallow-water bottom during a minor transgression 4000 years ago, an intertidal zone due to gradual lowering of the sea level 2000 years ago, a brackish water area 1000 years ago, and a swamp-like land influenced by rivers since that time. -from English summary