房総半島沖堆積盆の形成機構  [in Japanese] Development process of the sedimentary basin at offshore Boso Peninsula in the south Kanto district, central Japan  [in Japanese]

The Plio-Pleistocene Kazusa Group occupies the large area of the Boso Peninsula. Seismic procepecting reveals that the group is widely distributed off the east coast of the peninsula and contains its lower part which is not distribute in the peninsula. In the northeast part of this area the group dips generally northwest, abutting the basement with low angle and its depocenter migrates the northwestward. We studied the evolutional process of such a geological structures and mecanism causing migration of depocenter by means of simulation system using finite element method, called Virtual Basement Displacement Method (KODAMA et al., 1985). The result of this simulation shows that the principal fractures occured in the simular in the basementat some stages during sedimentation of the Kazusa Group, and then, the various geologic structures begun to be formed. It is also represented that the vertical block movement of the basement caused the migration of depocenter. This movement appears to relate to the distributive pattern of Pre-Tertiary basement rocks.