Sedimentary environment of dinosaur fossil bearing successions of the Lower Cretaceous Kitadani Formation, Tetori group, Katsuyama city, Fukui, Japan

The Lower Cretaceous Kitadani Formation, Tetori Group in the Kitadani Quarry yields a large quantity of non-marine fossils including dinosaurs. The quarry has large exposure with westward and northward facing surfaces, which allow to analyze three-dimensional variations in composition and geometry. The successions at the quarry consist of clastic rocks of the Point Bar Facies, the Abandoned Channel-fill Facies and the Over Bank Facies. The sandy Point Bar Facies is characterized by sheet like geometry and sedimentary structures caused by lateral accretion. The Abandoned Channel-fill Facies is mainly composed of fine-grained sediments, which were considered to be deposited by suspension fall-out. The depth of abandoned channel is as same as the thickness of the unit of the Point Bar Facies. The Over Bank Facies is characterized by poorly sorted nature of deposits. Crevasse splay sandstones are frequent in the Over Bank Facies. Sedimentary environment of an alluvial plain formed by meandering river is reconstructed.