Fusulinoideans from limestone clasts within the Lower Cretaceous Wakino Subgroup (Kanmon Group), Miyawaka City, Fukuoka Prefecture, Japan

Abstract

Fusulinoidean-bearing limestone clasts are exposed in a new road-cut exposure of the Lower Cretaceous Wakino Subgroup at Otaraguchi, Miyawaka City, Fukuoka Prefecture. The clasts are sub-angular and occur only in a debris flow deposit (tuffaceous pebbly sandstone) in the basal part of the Nyoraida Formation. Well-preserved Middle Permian fusulinoideans (i.e., primitive Neoschwagerina spp., and Parafusulina sp., Schwagerinidae gen. and sp. indet.) and fragments of crinoids are observed in the clasts, indicating that the non-crystalline limestone was deposited in the Tethyan faunal realm or the Circum-Pacific region during the Middle Permian, and that in the Early Cretaceous it was exposed in the hinterland of the sedimentary basin in which the Nyoraida Formation was deposited. The subjacent Permian Aida Formation, which includes accreted blocks of limestone, is a potential source of the limestone clasts.