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.New Frontiers in Integrated Solid Earth Sciences Phần 4

Phần lớp đá của Trái Đất (hay thạch quyển) bao gồm phần nhân, lớp phủ trung gian (độ sâu 35-2900 km) và lớp vỏ (độ sâu 0-35 km, dao động tùy theo từng chỗ, có thể từ 5-70 km). | 116 E. Burov Fig. 6 Model setups. Top Setup of a simplified semi-nalytical collision model with erosion-tectonic coupling Avouac and Burov 1996 . In-eastic flexural model is used to for competent parts of crust and mantle channel flow model is used for ductile domains. Both models are coupled via boundary conditions. The boundaries between competent and ductile domains are not predefined but are computed as function of bending stress that con-rols brittle-ductile yielding in the lithosphere. Diffusion erosion and flat deposition are imposed at surface. In these experiments initial topography and isostatic crustal root geometry correspond to that of a 3 km high and 200 km wide Gaussian mount. Bottom. Setup of fully coupled thermo-mechanical collision-subduction model Burov et al. 2001 Toussaint et al. 2004b . In this model topography is not predefined and deformation is solved from full set of equilibrium equations. The assumed rheology is brittleelastic-ductile with quartz-rich crust and olivine-rich mantle Table to change in the stress applied at their boundaries are treated as instantaneous deflections of flexible layers Appendix 1 . Deformation of the ductile lower crust is driven by deflection of the bounding competent layers. This deformation is modelled as a viscous nonNewtonian flow in a channel of variable thickness. No horizontal flow at the axis of symmetry of the range x 0 is allowed. Away from the mountain range where the channel has a nearly constant thickness the flow is computed from thin channel approximation Appendix 2 . Since the conditions for this approximation are not satisfied in the thickened region we use a semi-analytical solution for the ascending flow fed by remote channel source Appendix 3 . The distance ai at which the channel flow approximation is replaced by the formulation for ascending flow equals 1 to 2 thicknesses of the channel. The latter depends on the integrated strength of the upper crust Appendixes 2 and 3 . Since the common