HR: 16:30h
AN: V14A-03    [Abstracts]
TI: Energy feedback in the Jelly Sandwich
AU: * Regenauer-Lieb, K
EM: klaus.regenauer-lieb@csiro.au
AF: CSIRO Exploration and Mining, PO Box 1130, Bentley, WA 6102 Australia
AU: * Regenauer-Lieb, K
EM: klaus.regenauer-lieb@csiro.au
AF: Johannes Gutenberg University, Chemistry, Pharmacy and Geosciences, Mainz, 55099 Germany
AU: Rosenbaum, G
EM: rosenbaum@uni-mainz.de
AF: Johannes Gutenberg University, Chemistry, Pharmacy and Geosciences, Mainz, 55099 Germany
AU: Weinberg, R
EM: Roberto.Weinberg@sci.monash.edu.au
AF: Monash University, School of Geosciences, Clayton, VIC 3800 Australia
AB: The classic strength profile of continents is a quasi-static view of their rheological response which does not consider the dynamic interaction between brittle and viscous responses of rocks. It does not consider the complexities of failure in the brittle-ductile transition and the need to couple energy to understand strain localization. We solve the fully-coupled energy, momentum and continuum equations to study deforming continents. Here we show that this approach produces unexpected feedback processes focused on the brittle-ductile transition, the stress-bearing part of the crust, leading to fundamental changes in the response of jelly sandwich.

The Brace-Goetze strength profile predicts, for instance, that the stress-bearing part of continents lie at the same brittle-ductile transition where detachments develop, making the brittle-ductile transition the least likely depth for detachment faults. Whilst weak layers could plausibly initiate detachment faults our calculations demonstrate that they are unnecessary as mid-crustal detachments arise spontaneously from the thermo-mechanical feedback between the viscous and brittle layers even in a homogeneous crustal medium. If rheological stratification such as a simple quartz-olivine composite lithosphere is considered, natural features observed in nature, such as: the thickness of the crustal seismogenic zone, mid-crustal detachments at the otherwise strongest crustal layer, lower crustal channel flow above crust-mantle decoupling zone, and lack of flexural strength or seismicity in the continental upper mantle are robust features of dynamic energy interactions.
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8121 Dynamics: convection currents, and mantle plumes
DE: 8123 Dynamics: seismotectonics
DE: 8159 Rheology: crust and lithosphere (8031)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005