HR: 1340h
AN: T53B-1425    [Abstracts]
TI: Experimental investigation of pore fluid assisted detachment in the fold and thrust zone using a new analog modeling system
AU: * Nakajima, H
EM: nakajima.hideo@aist.go.jp
AF: Research Center for Deep Geological Environments, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8567 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 (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8567 Japan
AU: Takeda, M
EM: mikio-takeda@aist.go.jp
AF: Research Center for Deep Geological Environments, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8567 Japan
AU: Aung, T T
EM: aung-than@aist.go.jp
AF: Research Center for Deep Geological Environments, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8567 Japan
AB: Pore fluids play a vital role in hydrogeological and tectonic processes. Movements of chemical constituents and heat are essentially governed by pore fluid flow. In a large scale natural system, pore water flow and pressure are intricately associated with tectonic processes including mineral and/or mass transformation, detachment formation, sediment accretion, fault evolution, mantle alteration, intraslab seismic rupturing, and magmatism. Rigorous conceptual models describing principal processes including pore fluid flow, chemical and heat transports, and/or geomechanical deformation have been proposed. Although mathematical models that integrate such conceptual models and simulate complex natural system have been available, their validity is not fully assessed due to the lack of physical observation data. The natural system is often too complex to be idealized in mathematical models, and initial and boundary conditions of the natural system can never be clearly defined. For this reason, developing laboratory techniques to observe hydrogeologic and tectonic processes coupled with pore fluid movement on a reasonably small geometric and a short time scales is valuable. Using a recently developed analog modeling system, this study focuses on identifying the influence of pore fluid pressure on basal detachment in a fold and thrust zone. The analog models consisted of two layers of different granular materials having large contrasting hydraulic conductivities. The models were subject to monotonic shortening while an upward seepage force was constantly applied; spatial and temporal evolutions of the fold and thrust zone was observed. In the series of experiments, seepage forces were selected between zero and a critical value. In the series of experiments, seepage forces were selected between zero and a critical value. Observations obtained from the ongoing research, especially the formation patterns as a function of pore fluid pressure are presented and discussed.
UR: http://unit.aist.go.jp/deepgeo/english/index.html
DE: 1829 Groundwater hydrology
DE: 1894 Instruments and techniques: modeling
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8194 Instruments and techniques
SC: Tectonophysics [T]
MN: Fall Meeting 2005