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Geological Constraints Lecture 6: Geodynamics Carolina Lithgow-Bertelloni.

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Presentation on theme: "Geological Constraints Lecture 6: Geodynamics Carolina Lithgow-Bertelloni."— Presentation transcript:

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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 Density Contrast (Mg m -3 ) [Forte and Mitrovica, 2001]

5 Changes in Mass Distribution: True Polar Wander 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] [ ]

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 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

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]


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