HR: 09:45h
AN: T41A-08    [PDF]
TI: Low Friction Subduction Erosion, a Model to Test With Ocean Drilling
AU: * von Huene, R
EM: rhuene@mindspring.com
AF: University of California, Davis, 2910 North Canyon Road, Camino, CA 95709 United States
AU: Ranero, C R
EM: cranero@geomar.de
AF: Geomar,Kiel & SFB 574, Wishhofstr 1-3, Kiel, 24148 Germany
AU: Vannucchi, P
EM: paolav@geo.unifi.it
AF: Universita' di Firenze, NN, Firenze, 0000 Italy
AB: Subduction erosion models commonly invoke concepts of high friction abrasion. We present a low friction model involving reduced strength from a disintegrating hydrofractured upper plate. Our model is constructed from features in high-resolution seafloor morphology, refraction and reflection seismic sections, and magnetic anomalies. It consists of a frontal prism and margin wedge upper plate underlain by a bend-faulted lower plate. The frontal prism maintains its modest width and taper in equilibrium with local conditions through feedback from subduction zone dip, friction along the decollement, and material strength. The prism elevates fluid pressure in the subducting plate forcing pore fluid into fractures above the plate interface thrust that hydrofract the underside of the upper plate margin wedge. Beneath the base of the slope, upper plate fracturing is aided by the up-and-down riffling over subducting topography. Progressive fracture and upward fluid migration shift the zone of least strength upward. The interplate thrust seeks the zone of least strength and shifts with the upward migrating fluid thereby detaching underlying upper plate material and transferring it to the lower plate. This process may begin at the seismogenic zone and progress updip to the landward part of the frontal prism. Beneath the lower slope fluid pressure and fracturing weaken the upper plate so that its strength decreases to the level of the subducting sediment. The model we propose can be tested with deep scientific ocean drilling.
DE: 3025 Marine seismics (0935)
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 8150 Plate boundary--general (3040)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting