Abstract
Corals, nerineid gastropods, bivalves and cidarid echinoids were discovered from limestones in western Yamaguchi Prefecture. The fauna is comparable to the Torinosu Fauna widely distributed in the Chichibu Belt, Outer Zone of SW Japan.These limestones have been regarded as lacustrine facies belonging to the Lower Cretaceous Wakino Subgroup (Kanmon Group). The formation containing limestones is divided into four members in ascending order ; Lower Mudstone Member, Middle Sandstone and Mudstone Member, Upper Limestone Member and Uppermost Sandstone and Mudstone Member. Uppermost Sandstone and Mudstone Member is correlated with the Yoshimo formation (Toyonishi Group) with brackish fauna, accordingly, it is concluded that conformably underlies Upper Limestone Member also belongs to the Toyonishi Group. Coral-limestone indicates that the Tethys Sea expanded to studied area in Early Cretaceous.
