HR: 1330h
AN: T52B-0270    [PDF]
TI: Transient Stages of Suppression for Total Strike-Slip Partitioning Induced by Pre-existing Variable Topography and Overload.
AU: * Del Castello, M
EM: mdelcastello@tiscali.it
AF: CNR-ISMAR, Institute of Marine Geology, Via Gobetti, 101, Bologna, Bo 40129 Italy
AU: McClay, K
EM: ken@gl.rhul.ac.uk
AF: Fault Dynamics Research Group, Geology Department, Royal Holloway University of London, Egham, Surrey, TW20 0EX United Kingdom
AU: Pini, G
EM: pini@geomin.unibo.it
AF: Department of Geology, University of Bologna, Via Zamboni, 67, Bologna, 40126 Italy
AB: 3D sandbox modelling is used in this paper to investigate the mechanics of doubly vergent Coulomb wedges, deforming along highly oblique convergent margins that are affected by unbalanced topography and variable overload. During the experimental procedure, a pre-existing topography was generated by a first phase of subduction in one direction. A second phase of subduction was then initiated in the opposite direction (simulating a subduction flip). Animations of experiments will be displayed trying to show how a distinct feedback mechanism between mechanical conditions existing at the outboard region basal d‚collement and retrothrust activity control how deformation is partitioned within the wedge. Both timing and mode of retrothrust activation are crucial factors in influencing critical wedge mechanics as a whole. These may control localisation of compressive stress surpluses in the divide region, thus temporarily suppressing margin-parallel wrench faulting. In addition, experimental results suggest that differential disequilibrium characterising the topographic profile with respect to a given basal/internal coefficients of friction ratio will have a strong impact on the wedge growth history.
DE: 8010 Fractures and faults
DE: 8020 Mechanics
DE: 8099 General or miscellaneous
DE: 8102 Continental contractional orogenic belts
DE: 8168 Stresses--general
SC: Tectonophysics [T]
MN: 2003 Fall Meeting