HR: 17:00h
AN: T34A-05    [Abstracts]
TI: Mantle detachment faults and the break-up of cold continental lithosphere
AU: Rosenbaum, G
EM: g.rosenbaum@uq.edu.au
AF: The University of Queensland, School of Physical Sciences - Earth Sciences, Brisbane, QLD 4072, Australia
AU: * Weinberg, R F
EM: Roberto.Weinberg@sci.monash.edu.au
AF: Monash University, School of Geosciences, Melbourne, VIC 3800, Australia
AU: Regenauer-Lieb, K
EM: klaus@cyllene.uwa.edu.au
AF: The University of Western Australia, School of Earth and Geographical Sciences (Faculty of Natural and Agricultural Sciences), Perth, WA 6009, Australia
AB: We use a novel numerical approach, which fully couples the energy, momentum and continuum equations, to investigate the physics of extension and break-up of cold continental lithosphere to form new ocean basins. Unlike hot continental systems, where flat-lying detachment faults are nucleated in the strong part of the upper crust, cold continental systems have flat-lying detachment faults nucleating in the strong upper mantle at a relatively early stage. These detachment faults subsequently control the development of a mantle core complex and associated crustal structures. The observed structures are analogous to those developed in mid-crustal core complexes during extension of relatively thick and hot continental crust. In the cold environment, however, a strong elastic core is developed within the mantle, shifting the stress-bearing part of the system to below the Moho. Our modelling results reproduce key tectonic elements of a natural system (the Iberia Margin) by stretching a randomly perturbed, unpatterned lithosphere. Results also explain the "upper plate paradox" by doming of continental mantle separated from the crust by two diffuse detachment zones dipping towards the two future continental margins. Doming is facilitated by channel flow of the lower crust.
DE: 8109 Continental tectonics: extensional (0905)
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8159 Rheology: crust and lithosphere (8031)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting