2. Geological Constraints Lecture 6: Geodynamics Carolina Lithgow-Bertelloni

3. Constraints  Mass distribution and change  Geoid and free air gravity  TPW  Plate motions past and present  Magnetic anomalies  Topography  Flooding record  Stresses  Sources  Measure strain  Record of volcanism

4. Mass Distribution -0.18 -0.08 +0.02 +0.12 +0.22 Density Contrast (Mg m -3 ) [Forte and Mitrovica, 2001]

5. Changes in Mass Distribution: True Polar Wander -0.18 -0.08 +0.02 +0.12 +0.22 Density Contrast (Mg m -3 ) Inertial interchanges

6. Hotspots [Steinberger et al., 2004] Hotspot Tracks -Taking into account mantle wind -Letting hotspots move relative to each other -Taking into account plate deformation

7. Present-day plate motions [Forsyth and Uyeda,1975]

8. Magnetic Anomalies [Müller et al., 1994]

9. Plate Reconstructions:Cenozoic [10-25] [25-43] [43-48] [48-56] [56-64]

10. Plate Reconstructions: Mesozoic [Lithgow-Bertelloni and Richards, 1998] [64-74] [74-84] [84-94] [94-100] [100-119]

11. Topography

12. Continental flooding Ocean-volume variations ice cap melting Changes in volume of ocean basins spreading rates Isostatic balance of crust Orogenesis (short uncompensated ) Epeirogeny long dynamic topography; tectonic uplift; post-glacial rebound

13. Sea-level -0.18 -0.08 +0.02 +0.12 +0.22 Density Contrast (Mg m -3 )

14. Ages: 64 Ma [Xu and Lithgow-Bertelloni, 2004]

15. Bathymetry and sea-level [Conrad, Lithgow-Bertelloni and Xu, 2004] Following Pitman (1978) [Haq et al.] [Using G&J, 1986] [Using Hall (2000) for Philippine plate]

16. Contributions to Topography rr Mantle Flow Factors:  Isostatic balance of crust  Orogenesis  short uncompensated  Epeirogeny  Long  Tectonic uplift; post-glacial rebound; dynamic topography (Mitrovica et al., 1989; Gurnis, 1993)

17. Dynamic Topography 11 22 rr h   r /  g h Mantle Flow

18. Surface Topography Crustal Structure [ Laske et al., 2001] [Laske et al., 2002]

19. Residual Topography Continents-Crust 2.0; Oceans-Bathymetry from Isostasy No Depleted Mantle Continents-Crust 2.0; Oceans-Bathymetry from Age No Depleted Mantle Depleted Mantle [De Koker and Lithgow-Bertelloni, 2004]

20. Lithospheric Stress Field Contributions: Mantle Stresses; Crustal Heterogeneity [Reinecker, J., Heidbach, O. and Mueller, B., 2003] (available online at www.world-stress-map.org)

21. g Inhomogeneity Topography Edge Tractions Basal Tractions Sources of Stress

22. Surface Topography Crustal Structure [ Laske et al., 2001] [Laske et al., 2002]

23. [Lithgow-Bertelloni & Guynn, 2004] Mantle Tractions

24. Modeling the stress field [Lithgow-Bertelloni and Guynn, 2004] Combined effect of crustal contribution and mantle flow LVC+TD0 Fit to observations (Variance Reduction) Azimuth-59% Regime-61%

25. Episodic Crustal Production? [Condie, 1998]

26. Plume Frequency 3 Different Experiments [Lithgow-Bertelloni et al., 2001]