HR: 18:15h
AN: T34A-08    [Abstracts]
TI: Global Geodynamic Constraints on the Structure and Dynamic State of the Continental Lower crust
AU: * Auerbach, P
EM: auerbachpaul@gmail.com
AF: Département des sciences de la Terre et de l'Atmosphère, Centre de recherche en géochimie et en géodynamique, Université du Québec à Montréal, GEOTOP Université du Québec à Montréal C.P. 8888, Succ. Centre-Ville, Montreal, PQ H3C 3P8,
AU: Forte, A
EM: forte60@gmail.com
AF: Département des sciences de la Terre et de l'Atmosphère, Centre de recherche en géochimie et en géodynamique, Université du Québec à Montréal, GEOTOP Université du Québec à Montréal C.P. 8888, Succ. Centre-Ville, Montreal, PQ H3C 3P8,
AU: Moucha, R
EM: rmoucha@gmail.com
AF: Département des sciences de la Terre et de l'Atmosphère, Centre de recherche en géochimie et en géodynamique, Université du Québec à Montréal, GEOTOP Université du Québec à Montréal C.P. 8888, Succ. Centre-Ville, Montreal, PQ H3C 3P8,
AU: Perry, C
EM: claire.perryravard@gmail.com
AF: Département des sciences de la Terre et de l'Atmosphère, Centre de recherche en géochimie et en géodynamique, Université du Québec à Montréal, GEOTOP Université du Québec à Montréal C.P. 8888, Succ. Centre-Ville, Montreal, PQ H3C 3P8,
AB: Owing to the paucity of direct observations or constraints, the structure, composition and rheology of the lower crust of continents is not as well understood as the upper crust. Knowledge of lower crustal rheology is important for understanding how deep-seated lithospheric stresses generated by the convecting mantle are transmitted to the overlying brittle crust and how these stresses maintain surface topographic inequalities. Understanding the lateral variability of lower crustal thickness and density yields important clues on the thermo-chemical processes that have controlled the evolution, growth and mineralogy of the continental crust. Here we present the initial results of a global-scale study concerned with inferring the lateral changes in the lowermost crustal thickness and/or density and the implications for the stresses acting between the lithospheric mantle and the crust. Our approach involves quantifying the relationship between components of the non-isostatic topography, inferred by stripping away the isostatically compensated CRUST2.0 (Bassin et al. 2003) model, and predictions of surface dynamic topography predicted on the basis of a mantle convection model incorporating a recent joint seismic-geodynamic tomography model (Simmons et al. 2009). The specific focus will be on the modifications needed in lower crust structure that yield an optimal match between the CRUST2.0 inferences of non-isostatic topography and convection-driven dynamic undulations. The modified crustal structure will be used to explore the implications for the gravitational potential energy (GPE) of the compensated crust and hence the basal stresses acting at crust-mantle interface. Our overall objective is to constrain the dynamics of crust-mantle coupling and its contribution to surface geophysical observables.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 8103 Continental cratons
DE: 8110 Continental tectonics: general (0905)
DE: 8164 Stresses: crust and lithosphere
SC: Tectonophysics [T]
MN: 2009 Joint Assembly