ESCI 214: Mars: What and Where. Survey of Major Geologic Features

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ESCI 214Mars What and Where.(Survey of Major
Geologic Features)

• Patrick J. McGovern
• Lunar and Planetary Institute
• Thursdays presentation will be
• Mars How it all got there.

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Crustal Dichotomy

• Martian Southern Hemisphere
• Heavily Cratered, topographically rough
• High elevation, thick crust.
• Contains several Large Impact Basins (Hellas,
  Argyre, Isidis).
• Networks of apparently water-cut valleys.
• Highland Paterae low eroded volcanoes.
• High-intensity magnetic bands.

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Crustal Dichotomy

• Northern Hemisphere
• Low elevations, thin crust.
• Topographically smooth surface.
• Apparent crater density much lower than Southern
  Highlands surface units much younger.
• HOWEVER Stealth Craters and buried basins are
  evident in topography.
• Densities comparable to those in Southern
  Highlands.
• Northern basement comparable in age to Southern
  Highlands

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Tharsis

• Huge volcano-tectonic province.
• Roughly centered on Equator (240 E).
• Broad rise up to 10 km in elevation.
• Tall, young shield volcanoes.
• Rise and volcanoes covered by basaltic flows.
• Somewhat older Plains with wrinkle ridges
  (thrust faults).
• Numerous graben radial orientations.
• Some swarms exposed in very old terrain.

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Tharsis Components Volcanoes

• Olympus Mons Tallest (NOT NECESSARILY
  LARGEST!!!) volcano in the solar system.
• 600 km in diameter, 23 km height above base.
• Covered by young basaltic lava flows.
• Central caldera system..
• Basal escarpment up to 10 km high.
• Aureole deposits surrounding flanks to North and
  West likely landslides from flank failure
  (Hawaii analogue see Prof. Morgan).

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Intro to Olympus (MOLA-style)

• Edifice
• Basal Scarp (variable)
• Aureole Lobes (Deposits)

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Comparison Hawaii
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Tharsis Components Volcanoes

• Tharsis Montes Ascraeus, Pavonis and Arsia
  Montes.
• 400 km in diameter, 15 km height above base.
• Edifices aligned NE-SW along crest of Tharsis
  Rise.
• Covered by basaltic lava flows, circumferential
  normal faults (Pav. and Ars.)
• Rifts oriented NE-SW through each edifice.

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Tharsis Components Volcanoes

• Alba Patera.
• 6 km height above base, flat-topped dome.
• Lava flows extend well into northern plains.
• Annulus of normal faults surrounds summit, linear
  bands of radial faults on lower flanks.
• Topography, faults probably due to intrusion of
  magma into edifice.
• Similarities to some Venusian coronae.

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Tharsis Components Faults

• Valles Marineris.
• Canyon system 4000 km long, 700 km wide, up to 10
  km deep.
• ESE-WSW trend, roughly radial to Tharsis.
• Eroded fault scarps evident at base of walls.
• Suggests rift origin.
• Abundant layering seen in walls.
• Noctis Labyrinthus chasms at head of VM (eastern
  Tharsis).

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The Other Volcanic Rise

• Elysium Rise
• 6000 km E, 1000 km N of Tharsis.
• Broad rise with 3 superimposed shield volcanoes
  (similar to Tharsis).
• 6 km height above base, flat-topped dome (similar
  to Alba Patera).
• Radial lower flank faults, annular near-summit
  faults (similar to Alba Patera).

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Catastrophic Floods

• Chaotic Terrain source regions for catastrophic
  floods issuing from Southern Highlands.
• Prominent near Chryse Basin, mouth of Valles
  Marineris, and elsewhere near dichotomy boundary.
• Downdropped blocks from removal of ground ice.
• Outflow channels carry flood materials into
  Northern Lowlands.

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Polar Caps

• North cap
• Mostly water ice.
• Main cap surrounded by ice/dust mixture.
• South cap
• Mostly carbon dioxide on surface.
• However, CO2 too weak to support observed
  topography (interior must be water ice).

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Eolian Features

• Dunes.
• Slope Streaks.
• Dust Storms.
• Dust covers large fraction of Mars Surface.
• Gullies.
• Usually considered fluid-activated.
• Alternative dry debris avalanches.

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