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A Planetary Example of Tectonic Inversion: Folding and Thrusting in Valles Marineris, Mars

INSU. A Planetary Example of Tectonic Inversion: Folding and Thrusting in Valles Marineris, Mars. Daniel MEGE Jean-Pierre PEULVAST Philippe MASSON. Planetology and Geodynamics Lab, University of Nantes Geography Institute, University of Paris-Sorbonne IDES, University of Paris-Sud, Orsay.

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A Planetary Example of Tectonic Inversion: Folding and Thrusting in Valles Marineris, Mars

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  1. INSU A Planetary Example of Tectonic Inversion: Folding and Thrusting in Valles Marineris, Mars Daniel MEGE Jean-Pierre PEULVAST Philippe MASSON Planetology and Geodynamics Lab, University of Nantes Geography Institute, University of Paris-Sorbonne IDES, University of Paris-Sud, Orsay

  2. 10 km Blasius, Cutts, Guest, and Masursky, 1977 Geology of the Valles Marineris: First Analysis of Imaging from the Viking 1 Orbiter Primary Mission, Journal of Geophysical Research N

  3. 10 km Interpretation • Fractured anticline/syncline axes oblique to graben trend Suggests transpression MEGE, Ph.D. thesis, 1994 PEULVAST et al., Geomorphology, 2001 strain partitioning sHmin s1 s1 sHmin

  4. GERYON MONTES IUS CHASMA NASA/JPL/Arizona State University 200 km Study area Themis image mosaic of Valles Marineris Data used • Themis imagery • MOC imagery • MOLA DEM

  5. Imagery 1 Themis IR image 2 Themis VIS images 2 MOC images Viking image

  6. S N PLATEAU IUS CHASMA GERYON MONTES

  7. truncated layers spurs thrust plane truncated layers spurs 1 km N S MOLA profile South-dipping layer horizontal layer horizontal floor

  8. top layer inner layer thick central layer erosional scarp d e g r a d e d i n c l i n e d l a y e r s Northern slope N NE

  9. 1 km top layer 1 km inner layer Fold layers W 11° 11° thrust fault

  10. S N Southern slope SW NE moat e r o s i o n a l s c a r p m o n o c l i n e floor deposits

  11. unloading of water-saturated walls? Origin of shortening Sackung gravitational unloading ridge top splitting landsliding

  12. Reconstruction: from stretching to shortening 1 Rifting initiation GERYON MONTES IUS CHASMA SOLIS PLANUM N S

  13. (1 - previous stage) N S 2 Rifting N S

  14. (2 - previous stage) N S 3 Spur and gully development Onset of detrital sedimentation (monocline layers?) N S

  15. upper fold layer oldest, exhumed deposits (monocline layers, innermost fold layer?) (3 - previous stage) N S 4 Wall sapping Water level lowering Channel development on graben floor MOC E1801111 N S

  16. (4 - previous stage) N S 5 Late-stage stretching N S

  17. (5 - previous stage) N S 6 Dry erosional processes (mass wasting, aeolian activity) Sabkha deposits N S

  18. (6 - previous stage) N S 7 Geomorphological processes dominated by sackung N S

  19. 8 Sackung and associated debris slope Structural inversion Aeolian reworking (sand dunes, deflation patterns) N S

  20. 20 km Perspectives Look for similar features in other places in Valles Marineris landslide ridge top splitting Other sackung features in Coprates Chasma NASA/JPL/Arizona State University

  21. Perspectives • Try to quantify stretching in order to estimate shortening • Use shortening quantification and observed fold structure to determine • thrust plane geometry and displacement • Constrain rheology at depth from this and from composition of rock units • as from OMEGA • Model slope stability and failure through sackung

  22. Intepretation of geologic units 6 5 4 3 2 1 Dune fields (reworking of Fms 3-5) Sabkhas (on Fms 3 and 4) Dark, resistant floor material Weak, thinly layered deposits Exhumed resistant layers Wallrock material

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