HR: 1340h
AN: T13B-0473    [Abstracts]
TI: The Role of Rheology and Basal Décollement Properties on Accretionary Wedges
AU: * Mills, C J
EM: cmills@whoi.edu
AF: Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 United States
AU: Montesi, L G
EM: lmontesi@whoi.edu
AF: Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 United States
AB: We present here recent results from finite-element models of accretionary wedges using the commercial code ABAQUS. These models were constructed in order to better understand the role rheology and basal décollement properties play in the surface expression of the wedge and in the formation of the internal fault network of the wedge. To accomplish this, we imposed a priori the basal décollement slope and frictional coefficient, as well as the internal rheology of the wedge. For all of our models we used either an elastic or elastic-plastic rheology with strain dependent weakening and/or hardening. Some models included hardening rheologies in order to simulate the possibility that as a wedge deforms and develops faults, new fluid pathways may be created, thereby increasing the escape rate of fluids and decreasing the pore-fluid pressure in the shear zone. We varied the rheology between wedges of similar geometry and décollement properties, while we varied the décollement properties both within models and among models of similar rheologies. In this way we isolated the effect each has on the behavior of the wedge. The wedge rheology had a large effect on the formation and propagation of internal faults, and only certain rheologies produced fault structures similar to those found empirically in wedges around the world today. These rheologies suggest that pore-fluids play an important role in the formation of faults within the wedge. Additionally, changes in décollement properties produced results that agreed well with critical wedge theory, first developed in Davis et. al. [1983].
DE: 0545 Modeling (4255)
DE: 8104 Continental margins: convergent
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: Fall Meeting 2005