Development of geological structure modeling technology based on regional tectonic process (Joint research)

Tagami, Masahiko*; Yamada, Yasuhiro*; Yamashita, Yoshihiko*; Miyakawa, Ayumu*; Matsuoka, Toshifumi*; Xue, Z.*; Tsuji, Takeshi*; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Amano, Kenji; et al.

JAEA-Research 2012-036, 110 Pages, 2013/02

JAEA-Research-2012-036.pdf:44.93MB

Northeast strike faults developed in and around the Mizunami Underground Research Laboratory (MIU) control groundwater flow. These faults were possibly formed as a part of pull-apart structure by the right lateral movement of the Tsukiyoshi fault distributed in the north of MIU site. But the formational mechanism of these faults is still uncertain. In this joint research, the analog experiment and the numerical simulation were used to restore the geological structures around MIU site. The paleo-stress analysis were exposed an ancient deformation mechanism, and the formation timing was presumed in the regional tectonics. The results are adopted for the design of the analog experiment and the numerical simulation. The results of obtained analog experiment and numerical simulation are verified three-dimensionally, and then compared to the current geological structure model. Then the geological structure in the uninvestigated area is estimated.

Analysis of the tectonic history of Mizunami area, 2; Kinematics of the Tsukiyoshi Fault

Yamada, Yasuhiro*; Yamashita, Yoshihiko*; Miyakawa, Ayumu*; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Tagami, Masahiko

no journal, , 

Tsukiyoshi fault displaces Toki granite and middle Miocene Mizunami group, and it was regarded as the reverse fault from apparent displacement. However, the arrangement of the Tsukiyoshi channel and several NNW-SSE trend faults between the right step region of ENE-WSW strike Tsukiyoshi Fault. This implies that right-lateral displacement created a pull-apart basin. In order to support this working hypothesis, we have designed analogue experiment and 3-D numerical simulation, to restore a similar structure around the southern side of Tsukiyoshi fault. It succeeded in reproducing similar structures of the present geological model in analogue experiment by dextral moving the reduced 3-D block model of the present Tsukiyoshi fault plane.