HR: 0800h
AN: T31A-1269    [Abstracts]
TI: Lithospheric heterogeneities and crustal deformation
AU: lemery, c
EM: husson@cdf.u-3mrs.fr
AF: ENS-Lyon, 46, All‚e d'Italie Cedex 07, LYON, 69364 France
AU: * husson, l
EM: husson@cdf.u-3mrs.fr
AF: College de France, Chaire de G‚odynamique Europole de l'Arbois Bat Laennec - Hall D - BP 80 , Aix en Provence, 13545 France
AU: ricard, y
EM: ricard@ens-lyon.fr
AF: ENS-Lyon, 46, All‚e d'Italie Cedex 07, LYON, 69364 France
AU: bellahsen, n
EM: nicolasb@pangea.stanford.edu
AF: Universit… Roma Tre, Dipartimento di Scienze Geologiche Largo S. Leonardo Murialdo, n.1, Rome, 00146 Italy
AB: Crustal deformation depends on the disequilibrium between boundary stresses, either at the base of the deforming lithosphere or at its lateral boundaries, and buoyancy stresses arising form lateral density variations within the lithosphere itself. Based on the thin viscous sheet approximation, we propose a modelling technique, which account for both crustal and lithospheric thickness and density variations. The transport of the crustal moment is given by the continuity equation while the transport of the lithosphere, considered as a thermal boundary layer, is described from the heat equation. Combinations of theoretical and real Earth examples, in both extensional and compressional settings, highlight the fact that lithospheric instabilities and small-scale convection play a prominent role during crustal deformation. In extensional settings, particular attention is paid to the evolution of rifts, using additional insights from analogue modelling. We recognize a three stage evolution, i) boundary stresses dominate, ii) crustal buoyancy stresses dominate, iii) mantle buoyancy stresses counterbalance crustal buoyancy stresses and prevent the collapse of passive margins. In compressional settings, we consider the role of mantle lithosphere heterogeneities in the growth of high plateaus. In the Central Andes, the fast velocity lithospheric keel beneath the Eastern Cordillera may likely explain the kinematics of the Altiplano growth.
DE: 8102 Continental contractional orogenic belts
DE: 8109 Continental tectonics--extensional (0905)
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8150 Plate boundary--general (3040)
DE: 8164 Stresses--crust and lithosphere
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting