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Geography on Mars: Third Order of Relief

Los Angeles Geographical Society 6 March 2015 Dr. Christine M. Rodrigue Geography California State University, Long Beach. Geography on Mars: Third Order of Relief. Geography on Mars. Third order of relief and deep time on Mars Geological periods (actually eons in Earth terms)

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Geography on Mars: Third Order of Relief

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  1. Los Angeles Geographical Society 6 March 2015 Dr. Christine M. Rodrigue Geography California State University, Long Beach Geography on Mars:Third Order of Relief C.M. Rodrigue, 2015 Geography, CSULB

  2. C.M. Rodrigue, 2015 Geography, CSULB Geography on Mars • Third order of relief and deep time on Mars • Geological periods (actually eons in Earth terms) • Noachian period: formation of planet 4.6 Ga to tapering off of the Late Heavy Bombardment of the solar system ~3.75 Ga • dense cratering of a wide variety of sizes • planetary magnetic field starts and collapses • denser atmosphere, possibly warmer • above water's triple point • ground and surface water: • ocean, seas, and lakes • valley networks • neutral or alkaline hydrochemistry (phyllosilicate clays) • volcanic activity starts and then concentrates spatially • only period potentially friendly to life "as we know it, Jim"

  3. C.M. Rodrigue, 2015 Geography, CSULB Geography on Mars • Third order of relief and deep time on Mars • Geological periods (actually eons in Earth terms) • Hesperian period: until ~3.5 to 1.8 Ga; most commonly thought to fade out around 3.0 Ga • impacts fewer and smaller • loss of atmosphere with loss of magnetic field • surface waters lost to space, permafrost, ice caps • volcanism (and sulfur dioxide) • volcanic activity focusses on Tharsis and Elysium • sulfate hydrochemistry (very acid, hostile to life) • different mineralogy: sulfates, evaporites • outwash floods as magma interacts with permafrost

  4. C.M. Rodrigue, 2015 Geography, CSULB Geography on Mars • Third order of relief and deep time on Mars • Geological periods (actually eons in Earth terms) • Amazonian period: "young" Mars, from ~3.0 Ga to today • Cratering low level, low size • May be dampening of slopes by groundwater seeps • There is evidence of recent volcanic eruptions but not at Noachian or Hesperian levels • Giant outflows may occasionally occur • Ice ages may occur due to axial and orbital changes • Wind is the dominant agent, however • Dust devils are very common • Occasionally, planet-covering dust storms • Geochemistry is dominated by oxidation of iron into anhydrous oxides, creating reddish dust

  5. C.M. Rodrigue, 2015 Geography, CSULB Geography on Mars • Third order of relief and deep time on Mars • Geochemical periods (just to stir the pot) • Phyllosian period: time of the phyllosilicate clays • Up to late Noachian, when volcanism took off and pumped out so much sulfuric acid into the atmosphere • These clays form in neutral or alkaline surface or subsurface waters • Theiikian period: time of the sulfates • Late Noachian/much of the Hesperian • Sulfate minerals and evaporites form from a lot of water • Acidic conditions (related to volcanism) • Hydrated sulfates (gypsum, magnesium sulfate) • Siderikian: time of iron oxidation • Late Hesperian and the Amazonian • Oxidation of iron-rich rocks

  6. C.M. Rodrigue, 2015 Geography, CSULB Third Order: Deep Time on Mars

  7. C.M. Rodrigue, 2015 Geography, CSULB Third Order: Varying Crater Densities • Noachian Hesperian Amazonian

  8. C.M. Rodrigue, 2015 Geography, CSULB Third Order: Noachian Regions

  9. C.M. Rodrigue, 2015 Geography, CSULB Third Order: Hesperian Regions

  10. C.M. Rodrigue, 2015 Geography, CSULB Third Order: Amazonian Regions

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