tectonic landforms - upmcganymede.ipgp.jussieu.fr/.../hauber/martian_tectonic_landforms.pdf · long...
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Tectonic landformsTectonic landforms
• Global distribution• Extension
Long and narrow graben (“simple grabens“)Complex graben systems (“rifts“)
• CompressionWrinkle ridgesLobate scarps
• Strike-slip faults• Outlook: Implications for geophysics
• Global distribution• Extension
Long and narrow graben (“simple grabens“)Complex graben systems (“rifts“)
• CompressionWrinkle ridgesLobate scarps
• Strike-slip faults• Outlook: Implications for geophysics
Review papers:
• Tanaka et al. (1991) • Banerdt et al. (1992)
Review papers:
• Tanaka et al. (1991) • Banerdt et al. (1992)
com
pres
sion
exte
nsio
n
western hemisphere eastern hemisphere
from Banerdt et al. (1992)
Global distribution
Extensional features (graben)Cross-cutting relationshipsExtensional features (graben)Cross-cutting relationships
Surface expression forgiant radial dike swarms?Terrestrial analog:Mackenzie Dike Swarm (Canada)
from Wilson and Head (2002)
Alternative view:local volcanism and smaller dike swarms [Mège et al., J. Geophys. Res., 2002)
Description: Multiple 'grabens' in Canyonlands. The Grabens are a system of linear collapsed valleys caused by the movement of underlying salt layers towardCopyright © Martin Miller, University of Oregon
Canyonlands National ParkCanyonlands National Park
• often considered to be a terrestrial analog forlong and narrow Martian grabens
• but: deformation due to (relatively shallow)ductile salt layers
• often considered to be a terrestrial analog forlong and narrow Martian grabens
• but: deformation due to (relatively shallow)ductile salt layers
fromSchultz et al. (2000), after Tanaka et al., J. Geophys. Res. 96 (1991)
a) Faulting at bimaterialinterface (e.g., mega-regolith overbasalt)
b) Faulted upperlayer separated bysills fromdetachment zonefrom undeformedsubstrate
c) Graben wedgefalling into space-accomodatingtensile crack
d) Graben faultsnucleated be dikedilatation at depth
Schultz: Modelle langer und schmaler Gräben
Simple grabens on Marsthin-skin vs. thick-skin tectonics
Previous view: symmetric, strainconcentrated above the
décollement
Current view: asymmetric, faultscontinue to depth as network
from:Schultz, LPSC XXXI (2000)
after Watterson et al., J. Struct. Geol. 20 (1998)
"Hourglass" model forplanetary grabens
fromSchultz et al. (2000)
1000 m1000 m
13.0°N, 103.2°W13.0°N, 103.2°W
Collapse pitsnortheast flank of volcano, Ascraeus MonsCollapse pitsnortheast flank of volcano, Ascraeus Mons
no raised rims, no ejectano raised rims, no ejecta
Tantalus Fossae –Pit craters associated with faultingTantalus Fossae –Pit craters associated with faulting
38.2°N, 103.8°W38.2°N, 103.8°W
p i t c r a t e r c h a i n („c a t e n a“)
p i t c r a t e r c h a i n („c a t e n a“)
~3 km~3 km
diameters up to > 4 kmvolumes up to > 7 km3
Wyrick et al., J. Geophys. Res. 109 (2004)
diameters up to > 4 kmvolumes up to > 7 km3
Wyrick et al., J. Geophys. Res. 109 (2004)
Ferrill et al., GSA Today 14 (2004):dilatational normal faulting and collapse
Ferrill et al., GSA Today 14 (2004):dilatational normal faulting and collapse
• Crosscutting relationships
• pristine morphology
• Lack of sediment accumulation
• on the bottom
• Crosscutting relationships
• pristine morphology
• Lack of sediment accumulation
• on the bottom
activeformation
today?
activeformation
today?
Tempe Fossae:Are they comparable
to a terrestrialcontinental rift?
fromHauber & Kronberg (2001)
Complex grabensystems (“rifts“)
com
pres
sion
exte
nsio
n
western hemisphere eastern hemisphere
from Banerdt et al. (1992)
Global distribution
Image examples from:Montesi and Zuber,J. Geophys. Res. 108 (2003)
Viking
MOC
wrinkle
ridge
common landforms on Mars, the Moon (maresurfaces), and Venus
Terrestrial analogs:Regularly spaced
anticlinal ridges assurface expression of
folding and thrust faulting(Yakima Fold Belt,
Columbia River Basalts)
Wrinkle ridge topographyDifferent spacing reflecting different lithospheric properties?
from: Watters, Icarus 171 (2004
Structural modelsproposed forplanetary wrinkleridgesa) Buckle folds with nucleations
of thrust faults [Watters, 1988]
b) Simple thrust fault c) Conjugate thrust fault
[Allemand & Thomas, 1992; Mangold et al., 1998]
d) Fault-bend fold [Suppe, 1983; Suppe & Connors, 1992]
e) Fault-propagation fold[Mercier et al., 1997]
fromSchultz, J. Geophys. Res. 105 (2000)
Questions• Depth of faulting: Thin- or thick-skinned
tectonics?
• Geometry and number of faults?
• Importance of folding?
• Mechanical model of Watters (2004): thin-skinneddeformation of upper crustal material, singlethrust fault with listric geometry
• Outlook: MARSIS radar on Mars Express will investigate shallow crustal structure
Wrinkle ridges
• Typical for plate tectonics on Earth (e.g., San Andreas fault, North Anatolian fault)
• Evidence on Mars is very rare (Schultz, Nature, 1989)
Lateral movements(strike-slip faults)
Outlook (1)
• Improved understanding of potentially seismic regions on Mars
• Mapping of faults
• Assessment of fault ages
DLR