HR: 0800h
AN: T11A-0344    [Abstracts]
TI: Fragmentation, Gouge Production and Surface Roughness Evolution on Experimentally Simulated Faults
AU: * Renard, F
EM: francois.renard@ujf-grenoble.fr
AF: LGCA-CNRS-OSUG, Universite Joseph Fourier, Maison des Geosciences BP 53, Grenoble, 38041, France
AU: * Renard, F
EM: francois.renard@ujf-grenoble.fr
AF: Physics of Geological Processes, University of Oslo, PO Box 1048 Blindern, Oslo, 0316, Norway
AU: Mair, K
EM: karen.mair@fys.uio.no
AF: Physics of Geological Processes, University of Oslo, PO Box 1048 Blindern, Oslo, 0316, Norway
AB: To investigate the physical processes operating in active fault zones, we conduct analogue laboratory experiments where we track the morphological, mechanical and thermal evolution of an interface during slip. Our laboratory friction experiments consist of a halite (NaCl) slider held under constant normal load that is dragged across a coarse sandpaper substrate. This set-up is a surrogate for a fault surface, where brittle and plastic deformation mechanisms operate simultaneously during sliding. Surface morphology evolution, frictional resistance and heat emission are recorded with accumulated slip. After each experiment, we characterize the roughness developed on slid surfaces, to nanometer resolution, using white light interferometry. We directly observe the formation of deformation features, such as slip parallel linear striations, as well as deformation products or gouge. The striations are often associated with marginal ridges of positive relief suggesting sideways transport of gouge products in a snow-plough-like fashion. Deeper striations are commonly bounded by triangular brittle fractures that fragment the salt surface and efficiently generate a breccia or gouge. An abundance of gouge at the sliding interface reduces the shear resistance, demonstrating that accumulated slip may reduce the friction coefficient. The relative importance of these deformation mechanisms may influence gouge production rate, fault surface roughness evolution and mechanical behavior. Finally, our experimental results are scaled to nature by comparing the experimental surfaces to an actual fault surface, whose striated morphology has been characterized (to cm resolution) using a laser scanner. For both natural and experimental faults, it is demonstrated that the stress field is heterogeneous at all scales during the maturation of the interface with accumulated slip.
DE: 5104 Fracture and flow
DE: 7209 Earthquake dynamics (1242)
DE: 8010 Fractures and faults
DE: 8034 Rheology and friction of fault zones (8163)
DE: 8118 Dynamics and mechanics of faulting (8004)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting