HR: 1330h
AN: T52C-0292    [PDF]
TI: The heterogeneity of the seismogenic fault rock fault along the strike in Shimanto accretionary complex.
AU: * Sakaguchi, A
EM: arito@jamstec.go.jp
AF: Institute for frontier reserch for Earth evolution, Japan Marine Tecnology and Science Center, 3173-25 Showa Kanazawa ward,, Yokohama, 236-0001 Japan
AB: The typical evidence for the rapid slip of the pseudotachylyte is found in the Shimanto accretionary complex where is inshore extension of the Nankai seismogenic zone. The Latest Cretaceous Okitsu Melange, 0.8 km in thickness, is composed of at least fifth sheets of the imbricate oceanic stratigraphy with the duplex structure. The seismogenic fault where is replaced at the roof thrust of the duplex structure, is characterized by the concentration of the vein mineral layers. The fault rock suffered deformation of the pressure solution creep with S-C fabric and the rapid slip with pseudotachylyte formations repeatedly. The thermal analysis indicates that the Okitsu Melange suffered much higher temperature than the surrounding strata, and the seismogenic fault was affected extra higher temperature among the melange zone. Such a higher temperature of the melange than the hanging wall must be caused by the hydro-thermal fluid flow along the horizontal decollemant zone of the roof thrust of the duplex structure in the Okitsu Melange. The two types of deformations of the creep and rapid slips may related with the flux of the fluid flow. This characteristic feature, however, is discontinuous along the strike. The western extension of this outcrop approximately 1 km in distance, the faultrock has cataclacite with random fabric without vein mineral. The precipitation of the vein minerals with fluid flow would cause the cementation of the fault breccia and reduce of the pressure solution creep to release the elastic strains. Thus cementation is able to make the faultrock strength with time. In the friction theory, time depend strengthen is required for velocity weakening behavior of the seismogenic fault, and strain is concentrated at the local contact area of the asperity. The vein mineral concentration area with S-C fabric of pressure solution deformation is probably comparable with the asperity. The another outcrop along the strike of the fault looks the cementation of the fault and interseismic strain localizations were ineffective, because of lack of vein mineral and deformation fabrics within the fault zone. The vein mineral concentration and pressure solution deformation are probable feature of the fault rock of asperity in accretionary prism.
DE: 1744 Tectonophysics
DE: 5475 Tectonics (8149)
DE: 8000 STRUCTURAL GEOLOGY (New field, replaces single entry 8165)
DE: 8010 Fractures and faults
SC: Tectonophysics [T]
MN: 2003 Fall Meeting