HR: 08:30h
AN: T41F-03    [Abstracts]
TI: Testing Kinematic and Mechanical Solutions for Coulomb Wedges
AU: * Brandon, M T
EM: mark.brandon@yale.edu
AF: Yale University, PO Box 208109, New Haven, CT 06520-8109, United States
AU: Wilson, N J
EM: nat.wilson@yale.edu
AF: Yale University, PO Box 208109, New Haven, CT 06520-8109, United States
AB: We have devised a "two plate" model for studying kinematics and mechanics of a Coulomb wedge. Our apparatus consists of a 2 meter-long box, bound by two vertical glass walls and a flat internal base. Two stepper motors are used to drive mylar sheets along the base of the box, such that both sheets pass through a central slot. The mylar sheets are covered with a flat layer of dry sand, which is the deformable material that will make up the wedge. This design extends the "doubly vergent" model of Malavieille (1984) to include two "tectonic plates". One mylar sheet is pulled downward through the central slot to simulate subduction. The other mylar sheet is pulled out of the slot and rearward through the back of the box to simulate back-arc divergence. The sand above these mylar sheets deforms into a doubly-vergent wedge, with a contractional pro-wedge above the subducting mylar and an extending retro-wedge above the divergent mylar. In this way, we can produce a steady-state wedge where accretion on the proside is matched my decretion on the retroside. We use a digital camera and particle image velocimetry (PIV) to measure the velocity field within the wedge. Other studies of sand wedges have focused on the unsteady behavior of the wedge, associate with fault imbrication and accretion. The fact that our wedge maintains a steady size means that we can study the time-averaged velocity field to see how it compares with the theoretical solutions of Dahlen (1984) for flow in a homogenous wedge.
DE: 8194 Instruments and techniques
DE: 8199 General or miscellaneous
SC: Tectonophysics [T]
MN: 2007 Fall Meeting