ABSTRACT
The Osaka Sedimentary Basin is surrounded by mountains and active faults. The tectonic movement causes the surrounding area to rise and the basin to subside. The basin is submerged in the sea due to sea-level changes, and the marine clay deposits. Using the boring database accumulated by KG-NET, we learn the layer thickness, bottom elevation distribution, and distribution limit of the Holocene marine clay layer. Consider the environment at the time of deposition. In particular, the Kawachi Plain on the east side of the Uemachi fault showed the environment of an inner lake, and it was clarified that a sandbank was formed around the strait when it flowed in and out due to the ebb and flow of the tide. In this area of poorly drained seawater and freshwater, sensitive clays rich in organic matter are thought to have accumulated extensively.
