A Brief Geologic History of Mars Dr. Nicholas J. DiFrancesco Visiting Assistant Professor Department of Atmospheric and Geological Sciences
Abrevaya , X. C., Anderson, R., Arney , G., Atri , D., AzÃºa Bustos, A., Bowman, J. S., ... & Wong, T. (2016). The Astrobiology Primer v2. 0. Astrobiology, 16(8), 561 653. Geologic History On Earth, we can reconstruct geologic time based on observation of rocks, and actually dating rock and minerals to determine their age Martian rocks have only be analyzed in situ by robots and satellites We do not have (reliable) samples from the Martian surface, so age must be inferred
Crater Counting Areas with high crater density , and size diversity are old Noachian M oderate crater density and low size are medium age Hesperian Low crater density are the youngest surfaces on Mars Amazonian Each of these epochs is known to host specific geologic and environmental conditions at the Martian surface Digital Elevation Model (DEM) of Martian Surface
Geological activity as a function of time on Mars. Shown are the relative importance of different processes (impact cratering, volcanism), the time and relative rates of formation of various features and units (valley networks, Dorsa Argentea Formation), and types and rates of weathering, as a function of time. Carr , M. H., & Head III, J. W. (2010). Geologic history of Mars. Earth and Planetary Science Letters, 294(3 4), 185 203. High resolution photography fine detail in landscape and morphology Radar altimetry identification of subtle changes in topography Infrared Spectroscopy mineralogy and hydration Gamma Ray Spectroscopy composition of rock and sediment Magnetic/Gravitational field strength crustal thickness and compositional info Combining this information with the estimated age of the crust allows for the construction of a sequence of evolution of the planet
Noachian Mars ~4.1 3.7 Ga Impact rates were high Origin of the Crustal Dichotomy? Volcanic eruptions common Buildup of Tharsis Development of a planet wide hydrological system Formation of valleys , and hydrated clay minerals
Impacts on Mars Crustal Dichotomy Largest positively identified crater is Hellas deepest basin on Mars Northern lowlands could be a huge impact crater! An impact like that could have partially melted the interior, jumpstarting long lived volcanoes A. Color coded (blue=low, red=high) global shaded relief. 5 km spacing topographic contours are indicated. The so called crustal dichotomy boundary is roughly at the border between yellowish and greenish areas, where the zero datum contour is located (NASA Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) data, Smith et al. (1999)). B. Simplified Gyr ), Gyr ) and Amazonian ( 3.0 Gyr Rossi, A. P., & Van Gasselt , S. (2010). Geology of Mars after the first 40 years of exploration. Research in Astronomy and Astrophysics, 10(7), 621.
Early Mars Volcanism: Tharsis Bulge Area of uplifted crust and high volcanic activity (up to the present ?) Likely fed by a plume of magma pushing against the thick crust More basalt Supplied water to the Martian atmosphere a. A single mantle plume rises beneath lithosphere underlain by a melt residue and causes the initiation of Tharsis volcanism. Zhong proposes that stresses induced by the plume trigger rotation of the lithosphere, which moves the thickened crust away from the plume through time . b. Younger, more voluminous volcanism occurs when lithospheric rotation stops with the plume at the edge of the melt residue layer. On Mars, this occurs at the hemispheric dichotomy boundary Nimmo , F. Mars's rotating shell. Nature Geosci 2, 7 8 (2009 )
Evidence of Water Samples of exogenic landforms and sedimentary deposits. A. Outflow channels: Kasei Vallis (shaded relief derived form MGS MOLA data) B. Valley network, possible sapping: Nanedi Vallis (MEX HRSC nadir from orbit 905) C. Deltas: Eberswalde fan delta (MRO CTX mosaic) D. Interior Layered Deposits (ILD) in Juventae Chasma (MEX HRSC nadir from orbit 243). E. Recent gullies on Mars (MGS MOC R1002078). Widespread valleys and deltas suggest a large amount of water Water from volcanism and impact driven outgassing of steam It is unclear what conditions prevailed during valley formation: Cold, glaciers, with transient melt water flow Warm and wet, with continued runoff Temperate and dry, with groundwater sapping Rossi, A. P., & Van Gasselt , S. (2010). Geology of Mars after the first 40 years of exploration. Research in Astronomy and Astrophysics, 10(7), 621.
Location and Timing of the Martian Valley Networks Most valley networks appear to have formed in the mid late Noachian, into the Hesparian The density of valley networks at low (tropical) latitudes suggests that they are the result of precipitation runoff, though groundwater is suggested for some younger ones Hynek , B. M., Beach, M., & Hoke, M. R. (2010). Updated global map of Martian valley networks and implications for climate and hydrologic processes. Journal of Geophysical Research: Planets, 115(E9).
Clay Minerals Phyllosilicates , and more specifically, clay minerals typically only form in environments with relatively neutral pH water Evidence of phyllosilicates in Noachian aged rock at the Martian surface suggest that this rock was exposed to water shortly after it formed Ladon Â° Â° N, base image CTX B21_017739_1771_XN_02S021W). (c) HiRISE ESP_017739_1770 shows this deposit to be densely fractured. (d) Indistinct, Â° Â° N Ladon Valles (HiRISE PSP_008931_1590) (Figure 4e); and a Thomas, R. J., Hynek , B. M., Osterloo , M. M., & Kierein Margaritifer region of Mars: Implications for paleohydrology and astrobiological detection. Journal of Geophysical Research: Planets
Hesperian Mars ~3.7 3.0 Ga Outflow Channels Appear to have formed rapidly, from catastrophic flooding Surface water likely became scarcer and more acidic from volcanic outgassing Sulfates begin to form in large quantities Valles Marineres forms and begins to erode
Outflow Channels Many appear to form from huge amounts of groundwater erupting onto the surface (probably not lava) Very different from valley networks most contain few large channels Many channels seem to originate around volcanic centers and empty into basins Kasei Vallis (25 Â° Â° north south canyon to the west of the scene shown here. To the east, the channel extends deep into the northern plains. Ravi Vallis (1 Â° Â° Chryse region, emerges from a rubble thought to have formed by an eruption of groundwater. Carr , M. H. (2012). The fluvial history of Mars. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Sulfate Formation Sulfates ( jarosite , gypsum) are identified stratigraphically on top of (younger) than Noachian weathered basalts Highly oxidizing, acidic conditions playa? Global transition to more acidic environment Syrtis Major Geophysical Research Letters, Volume: 39, Issue: 11, First published: 06 June 2012, DOI: (10.1029/2012GL051594) Sulfates exposed near the NE Syrtis northern extent of the Syrtis Major lava flows (purple in Figure 2a) are overlain on CTX images. (b) Sulfates (bright white in Figure 2a), including jarosite and a polyhydrated phase, are identified in B8C2 by comparison to laboratory and serpentine [ Ehlmann smectites and structure upon erosion, interpreted to represent exhumed, mineralized conduits of subsurface fluids (subset of Syrtis Major lava unit that sheds boulders overlies the
Valles Marineris Largest Canyon in the Solar System Opened up as the crust was stretched, as Tharsis rose up Likely formed along the crustal dichotomy because this was an area of weakness Tectonism continued into the Amazonian with ongoing volcanism Marineris : 1,2. Tectonic architecture and the relative roles of extension and subsidence. Journal of Geophysical Research: Planets, 117(E3).
Amazonian Mars ~3.0 Ga present Planet has become increasingly dry, arid and cold Water escaped to space or soaked into the ground? Volcanism continues, but decreases over time Tharsis and Olympus Mons continue to grow Gullies could be formed from small amounts of flowing water/brine Glaciers and ice are the dominant drivers of resurfacing
Martian Glaciers A lot of surface ice interaction occurred on Mars in the last few hundred Ma Sediment morphology and debris flows appear to support recent glacial activity and mass movement at the surface Erosion of crater walls and bedrock is associated with sediment deposits resembling glacial till and other landforms Niquero Crater on Mars, an example with a crater interior ice deposit, arcuate ridges, pasted on terrain and gullies. Conway, S. J., Butcher, F. E., de Haas, T., Deijns , A. A., Grindrod , P. M., & Davis, J. M. (2018). Glacial and gully erosion on Mars: A terrestrial perspective. Geomorphology, 318, 26 57.
Young Volcanics Samples of volcanic landforms, deposits and terrains on Mars. A. Volcanic shields: Olympus Mons (MEX HRSC nadir mosaic, courtesy A. Dumke ) B. Highland Pateras : Tyrrhena Patera , nearby Hellas Basin (MEX HRSC nadir from orbit 1920) C. Examples of Tholus on Mars (MEX HRSC nadir from orbit 2983) D. Lava flow on the flanks of Arsia Mons (MRO CTX P17 007484 1657 XN 14S117W) E. Pit chains over extensional grabens (MRO CTX P17 007813 2132 XN 33N106W). Rossi, A. P., & Van Gasselt , S. (2010). Geology of Mars after the first 40 years of exploration. Research in Astronomy and Astrophysics, 10(7), 621. The last evidence of volcanism on Mars is inconclusive, but it is likely that volcanoes have erupted very late in the Amazonian Fumaroles (volcanic gas and steam vents) may still be operating on the surface perhaps the best chance for life!
Olympus Mons Largest volcano in the Solar System likely still active (somewhat) Started forming earlier, but continued to build and erupt into the Amazonian
Mars Water Today Liquid water is not stable at the surface Water evaporates, and is concentrated at the poles Some water is lost to space sputtering Data suggest that large stores of H 2 O may be in the shallow subsurface Top: Floods that cut the large outflow channels enter the northern basin and form temporary lakes that of the last large flood. Bottom: After the flooding era the ice slowly sublimates, some being lost to space and some being redistributed to form the polar layered deposits and other near surface ice deposits. Carr , M., & Head, J. (2019). Mars: Formation and fate of a frozen Hesperian ocean. Icarus, 319, 433 443.
Gullies and Recurring Slope Lineae (RSL) Recurring slope lineae (RSL) narrow, (0.5 5 m) dark features that appear on steep slopes, fade in colder seasons, and recur annually Can be formed by liquid flows occurring in warm seasons Saltwater brine not pure water Could be dry debris flows , not related to water Typical spur and gully VM RSL. These RSL (purple in false color; white arrows point to two RSL) start just below bedrock, then tributaries merge and the flow continue into the distal sand fan. Stillman , D. E., Michaels, T. I., & Grimm, R. E. (2017). Characteristics of the numerous and widespread recurring slope lineae (RSL) in Valles Marineris , Mars. Icarus, 285
Martian Moons Phobos Phobos and Deimos are the two tiny (27/15 km) moons in orbit of Mars Discovered in 1877, originally thought to be asteroids captured during the Amazonian However very close, near circular equatorial orbits favor an impact genesis theory, similar to Deimos
Mars vs. Earth Why so Different? Earth and Mars formed around the same time, from the same stuff, but evolved very differently Mars is much smaller than the Earth is therefore it took less time for it to cool off internally has a stronger gravitational field and more able to retain its atmosphere and hydrosphere Earth is like a big turkey, to it will stay hotter longer after you take it out of the oven.