Melas Dorsa, Solis Planum, Mars (HRSC)
Global Tectonics of Terrestrial Planets Laurent Montesi University of Maryland
CIDER 2014 Marc WieczorekCIDER 2014 Marc WieczorekCIDER 2014 Marc WieczorekCIDER 2014 Global tectonics on Earth Strain rate map (Corné Kremeer) http://gsrm.unavco.org/
CIDER 2014 Recognizing Plate Tectonics
• Rigid interior / • Divergent motion deformable boundaries • Normal faults • Linear belts of activity • Rift morphology with • Earthquakes volcanism • Volcanoes • Convergent motion • Topography • Differentiated volcanism • Faults • Accretionary wedges • Plate interior • Coherent motion • High-grade • Reconstructions metamorphism • Geodesy • Strike-slip motion • Negligible current • Horizontal offsets activity • Limited volcanism
GEOL412/789A – Lecture 07 Planetary Observables Earth Mars Venus Distribution of earthquakes Soon (InSight) Not available Distribution of volcanism Yes Yes Composition Hypsometry Hypsometry Flow morphology Flow morphology Surface composition Surface composition Samples Remote sensing Faulting Visible images Radar images Topography Laser altimetry (global) Radar altimetry (global) Interferometry (local) Interferometry (local) Geodesy Not available Not available Ages Cratering (coarse) Cratering (coarse) Geological units Yes Yes Geoid Yes Yes Heat flux Soon (InSight) Not available Resources • Google Earth • Google Mars http://www.google.com/mars Native to Google Earth (also Google Moon and Google Sky) • Google Venus (under development from Scripps and Google) • ftp://topex.ucsd.edu/pub/sandwell/google_venus/Google_Venus.kmz • Careful with measuring scale: 1 km on the map is 1km on Earth, would be ~0.95km on Venus • Blue or white tint comes from Earth’s landmass vs. distribution; Ocean glimmer effect can be bothersome. • Other resources • http://planetologia.elte.hu/globes/index2.html • http://www.digitalplanets.org/ (Venus is buggy) • Other Planetary GIS • PIGWAD http://webgis.wr.usgs.gov/ • JMARS http://jmars.asu.edu/map-layer • Map-a-planet http://www.mapaplanet.org/
CIDER 2014 Extension on Venus
Normal faults, Zverine Chasma
CIDER 2014 Rift on Venus: Zverine Chasma
CIDER 2014 How much extension?
Balch crater, Devana Chasma (BetaRegio)
CIDER 2014 Large-scale view (Beta Regio)
CIDER 2014 Large-scale view (Beta Regio)
Plume-driven uplift What does it mean for the East African Rift?
CIDER 2014 Dali Chasma
CIDER 2014 Corona-rich rift (Dali Chasma)
CIDER 2014 Coronae
Nei-Teuvez corona
Mantle Plume? Delamination?
CIDER 2014 Artemis
Largest corona? Subduction rollback?
CIDER 2014 Artemis (topography)
“Prism” is a rift!
CIDER 2014 Artemis Chasma
… Although a weird one
CIDER 2014 Ridge belt
Pandrosos Dorsa
CIDER 2014 Ridges and fracture belts
CIDER 2014 Ridge and fracture belts
Some positive, some negative relief
CIDER 2014 Ridge belt vs. fracture belt
Lavinia Planitia
CIDER 2014 Northern highlands
Fortuna Tessera
Akna Montes
Lakshmi planum Maxwell Montes
CIDER 2014 Akna Montes
Fold belt
CIDER 2014 Maxwell Montes and Fortuna Tessera
CIDER 2014 Tessera
At least two (often more) tectonic events
CIDER 2014 Ribbon tessera
1) Narrow, parallel graben 2) Orthogonal folding
CIDER 2014 Ovda deformation sequence
1) Narrow, parallel graben 2) Orthogonal folding 3) Broader graben
CIDER 2014 Global compression
Wrinkle ridges, Guinevere Planitia
CIDER 2014 Tectonic summary
• Minor rifts • Globally consistent tectonic • Influence of mantle upwellings sequences • Parallel sets of ridge belts • Tessera ribbons followed by folds • Low plains followed by wrinkle • No large-scale plates ridges • Global reach of Artemis? • Climate-induced tectonics (Solomon et al., 1999)
Evolution of surface temperature and stress following the eruption of a volume of lava equivalent to a global layer 500 m in thickness (Solomon et al., 1999) CIDER 2014 Mantle convection regime
• 2D Mantle convection coupled with atmosphere, melting, and degassing • 4 stages: • Early stagnant lid (efficient escape) • Mobile lid removes internal heat • Stagnant lid replenishes internal heat • Episodic lid with local (?) resurfacing events • Artemis? Dali? • Timing of transitions? Armann and Tackley, 2012; Gillmann and Tackley, 2014 CIDER 2014 The global reach of Artemis?
Hansen, 2010 CIDER 2014 Wrinkle ridges
without interbed slip
with interbed slip
Wrinkle Topographic offset
Backthrust Ridge
Thrust Layered plain
CIDER 2014 Basement Hesperia Planum
Influence of buried structures
CIDER 2014 Topography-derived sets
Arcadia Planum
CIDER 2014 Larger thrusts
Amenthes Rupes
CIDER 2014 Normal faults
Ceraunius Fossae
CIDER 2014 Rifts of Tempe Terra
CIDER 2014 Tempe Terra
CIDER 2014 Tharsis tectonics
CIDER 2014 Tectonic centers
• Missing wrinkle ridges to NW • “CF” reinterpreted as strike-slip fault (Yin, 2012)
" !"
! !
Anderson et al., 2001 CIDER 2014 Elastic flexure
• Extension predicted by the topography and gravity of Tharsis with an 100 km thick elastic spherical shell (Banerdt and Golombek, 2000; Golombek and Phillips, 2010)
CIDER 2014 Elastic flexure
• Compression predicted by the topography and gravity of Tharsis with an 100 km thick elastic spherical shell (Banerdt and Golombek, 2000; Golombek and Phillips, 2010)
CIDER 2014 Valles Marineris
CIDER 2014 Origin of rifts
Graben widened by erosion
CIDER 2014 Strike-slip faulting…
CIDER 2014 Montgomery et al., 2009
GEOL412/789A – Lecture 07 Plate or landslide?
• Solis Planum as a mega-landslide over a salt layer • Mechanics are problematic • Wedge mechanics imply the décollement should dip 2° to 20° over 2000 km!
Montgomery et al., 2009 CIDER 2014 Basin-centered tectonics
Utopia Planitia
CIDER 2014 Mars summary
• Limited horizontal motion • 40 km maximum extension/compression • Possibly 250 km left-lateral strike-slip at Valles Marineris • Centers of activity, mostly Tharsis • Success of flexure models implies an intact plate, limited strain • Global contraction • Modulated by regional and local stress sources • No confirmed evidence for plate tectonics • Magnetic lineations (Connerney et al., 1999): not linear, not symmetric, not along long circle • Oceanic plate to the north (Sleep 1994): preserved ancient structures inconsistent with volcanic “arc” of Tharsis; inconsistent tectonics on edge • Rollback tectonics (Yin 2012) has major timing and mechanical issues
CIDER 2014 What’s up with the Earth?
Estimats of Martian heat flux from flexure • Interior process? (McGovern et al., 2002) and wrinkle ridge spacing (Montési and Zuber, 2003) • Intensity of convection? • Interior layering? Laul et al., 1986 • Lithosphere process? Treiman et al., 1986 • Presence of water? • Presence of continents? • Rheology of the Half-space cooling lithosphere? • Surface process? • Erosion allows large fault offsets
CIDER 2014 Localization
• Structural changes (grain size, fabric) can weaken rocks. • Under what conditions are these changes efficient? Continent Oceanic Mars Venus Unresolved questions
• Origin of the crust • Thick basaltic crusts: • Is there enough partial melting in the mantle? • Generation of a thick depleted lithosphere? • Heat producing elements partitioning and thermal evolution • Localization in the lithosphere? • Can the lithosphere fail as a whole? • Role of water, crustal thickness? • Metamorphic assemblages?