Lithology, stratigraphy and sedimentary environment of clastic carbonate rocks in Permian chert of the Northern Chichibu Belt in the Kanto Mountains, central Japan.

Abstract

Clastic carbonate rocks in Permian chert were found in the Sumaizuku Unit of the Northern Chichibu Belt in the Kanto Mountains. Clastic carbonate rocks are composed of clastic limestones and clastic dolostones, both of which are accompanied by volcanic rock fragments, lacking in terrigenous clastic materials. Clastic limestones are composed of limestone breccia, lime-sandstone and lime-mudstone in ascending order. The successions of limestone breccia and lime-sandstone grade upward into fining and limesandstone has laminae. The boundary between limestone breccia and lower chert is erosional surface. Clastic limestones are considered to be deposited by sediment gravity flow. On the other hand, clastic dolostone consisting of fine and well-sorted grains, is supposed to be carried and deposited by bottom current.