Upward shallowing sequence and gravely sediments in the Miocene Ogawa Formation, Northern Fossa Magna, central Japan

Abstract

The Middle Miocene Ogawa Formation in Northern Fossa Magna Region is composed mainly of sandstone and conglomerate deposited under nearshore condition. This Formation has ten cycles of sedimentary sequences in the study area. One sequence was formed by the transgression and following regression.
The conglomeratic sediments in these sequences are classfied into the six types. Three types of them were deposited in shoreface under storm condition. Two types of them were deposited in the upper-shoreface to foreshore. Another conglomerates was deposited on the transgressive surface.