HR: 11:50h
AN: T52B-07    [Abstracts]
TI: Global analysis of intraplate basins
AU: * Heine, C
EM: christian@geosci.usyd.edu.au
AF: School of Geosciences and University of Sydney Institute of Marine Science, Edgeworth David Buildg. F05 Eastern Ave., Main Campus, University of Sydney, NSW 2006 Australia
AU: Mueller, D R
EM: dietmar@geosci.usyd.edu.au
AF: School of Geosciences and University of Sydney Institute of Marine Science, Edgeworth David Buildg. F05 Eastern Ave., Main Campus, University of Sydney, NSW 2006 Australia
AU: Dyksterhuis, S
EM: scottd@geosci.usyd.edu.au
AF: School of Geosciences and University of Sydney Institute of Marine Science, Edgeworth David Buildg. F05 Eastern Ave., Main Campus, University of Sydney, NSW 2006 Australia
AB: Broad intraplate sedimentary basins often show a mismatch of lithospheric extension factors compared to those inferred from sediment thickness and subsidence modelling, not conforming to the current understanding of rift basin evolution. Mostly, these basins are underlain by a very heterogeneous and structurally complex basement which has been formed as a product of Phanerozoic continent-continent or terrane/arc-continent collision and is usually referred to as being accretionary. Most likely, the basin-underlying substrate is one of the key factors controlling the style of extension. In order to investigate and model the geodynamic framework and mechanics controlling formation and evolution of these long-term depositional regions, we have been analysing a global set of more than 200 basins using various remotely sensed geophysical data sets and relational geospatial databases. We have compared elevation, crustal and sediment thickness, heatflow, crustal structure, basin ages and -geometries with computed differential beta, anomalous tectonic subsidence, and differential extension factor grids for these basins. The crust/mantle interactions in the basin regions are investigated using plate tectonic reconstructions in a mantle convection framework for the last 160 Ma. Characteristic parameters and patterns derived from this global analysis are then used to generate a classification scheme, to estimate the misfit between models derived from either crustal thinning or sediment thickness, and as input for extension models using particle-in-cell finite element codes. Basins with high differential extension values include the ``classical'' intraplate-basins, like the Michigan Basin in North America, the Zaire Basin in Africa, basins of the Arabian Penisula, and the West Siberian Basin. According to our global analysis so far, these basins show, that with increasing basin age, the amount of crustal extension vs. the extension values estimated from sediment thickness decreases decreased. This could be used as a indicator for ``basin maturity''. Furthermore, basins with higher differential beta values show generally slightly lower heatflux values. We have attempted to integrate the results from the observations with numerical modelling of different crustal extension scenarios involving a varying heterogeneous basement architecture and attempting to connect the ``pure'' numerical models with real world data as tightly as possible. In the scope of the project we have tried to build a numerical model library linked to the large scale observations, which offers a new powerful way to investigate the complex lithosphere dynamics and geological processes that account for the evolution of intraplate basins, and the influence of the basement architecture on successful or failed rifts.
UR: http://www.geosci.usyd.edu.au/users/christian
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 8109 Continental tectonics: extensional (0905)
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8169 Sedimentary basin processes
SC: Tectonophysics [T]
MN: Fall Meeting 2005