HR: 0800h
AN: T11D-0410    [Abstracts]
TI: Analogue Modeling of the Neogene North Fossa Magna Basin, Central Japan
AU: * Elouai, D
EM: driss@earth.kumst.kyoto-u.ac.jp
AF: Department of Civil and Earth Resources Engineering, Faculty of Engineering, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto, 606-8501 Japan
AU: Yamada, Y
EM: yama@electra.kumst.kyoto-u.ac.jp
AF: Department of Civil and Earth Resources Engineering, Faculty of Engineering, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto, 606-8501 Japan
AU: Zhang, M
EM: m.zhang@aist.go.jp
AF: Research Center for Deep Geological Environments, National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, Tsukuba, Ibaraki, 305-8567 Japan
AU: Nakajima, H
EM: hidenaka@gmail.com
AF: Research Center for Deep Geological Environments, National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, Tsukuba, Ibaraki, 305-8567 Japan
AU: Matsuoka, T
EM: matsuoka@earth.kumst.kyoto-u.ac.jp
AF: Department of Civil and Earth Resources Engineering, Faculty of Engineering, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto, 606-8501 Japan
AB: The North Fossa Magna (NFM) is a Miocene basin developed during the final stage of the Sea of Japan. This basin is bounded in the west by the Itoigawa-Shizuoka Tectonic Line (ISTL) from the Pre-Neogene basement rocks. Previous seismic reflection analysis of the claimed active faults transecting this area, revealed that (1) the ISTL is a thrusting fault system dipping eastward. (2) The West Nagano Basin fault (WNBF) is a reverse active fault dipping westward. The idea to simulate the extension phase of the NFM (since 14 Ma.) is based on to visualize the real-time developing structures on a scale model similar to the natural prototype (NFM) and to better understand the tectonic processes created this basin. These geological processes are still manipulating the active tectonic in this area. Similarity condition between the scale model and natural prototype has been considered. The pre-Neogene basement rocks were represented in the sandbox experiments by sand of relatively high internal-friction angle (about 42 degree). The Miocene and Pliocene sedimentary rocks were modeled using less internal-friction angle sand (<35 degree). Preliminary results from these experiments have given more insights on the mechanism of the development of the NFM basin. New findings of growth normal faults state their role on affecting thickness of the strata and even the morphology of the basin itself during the extension. These faults are associated with the master detachment fault and developed in western part of sandbox basin. And could be the prototype of faults actually exposed in Nagano and Omachi areas; where a thickening of the strata is evident from east to west. From these results, the NFM basin appears to be strongly controlled by the tectonic rather than other factors during the Miocene to Early Pliocene period. Extension tectonic influences started to weaken from Late Pliocene, announcing the beginning of the inversion. This tectonic inversion made the whole system of the NFM under compression during the Quaternary and still active nowadays.
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8020 Mechanics, theory, and modeling
DE: 8123 Dynamics: seismotectonics
DE: 9320 Asia
SC: Tectonophysics [T]
MN: Fall Meeting 2005