NEEP602 Course Notes (Fall 1997)
Resources from Space
Lecture #15: The cool red hills of Mars!
Title: Evolution of Mars
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Comparison of Earth and Mars in space (NASA Photo) Radius 3390 km vs. 1738 km for Moon and ---km for Earth |
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Mars (Note marked differences between northern and southern hemispheres |
Notes:
Apollo
Model: Stages of Lunar Evolution
* Lunar Model, with some additions, probably applies reasonably well to Mars through the Young Large Basin Stage (3.8 b.y. ago).
- * Evolution or Mars as a planet would be modified relative to Earth
and Moon by:
- Intermediate radius of 3490 km (versus 6378-6275 km for Earth and 1735 km for the Moon).
- Intermediate gravitational field (versus 3/8 of Earth's and 1/6 on the Moon).
- Greater distance from the sun with semimajor axis of 1.52 AU (more abundant water in parent portion of the solar nebula and 57% less insolation per unit area than the Earth).
- Lack of interaction with a large Moon or, alternatively, not affected by the formation of a large moon by fission of the parent body as might have been the Earth.
- Highly variable obliquity from near 0o to near 60o (currently about 25o)
- Unknown factors:
* Some implications of above factors on the planetary evolution of Mars.- Greater size, relative to the Moon, resulted in lighter elements being retained during formation, most significantly, water and carbon dioxide, but also elements of less mass number than 22 (Na).
- Prolonged internal heat generation due to greater size.
- No evidence for plate tectonic processes or extensive sedimentation
- Early atmosphere may have been significant, however, this atmosphere largely disappeared due to lower gravity, possible impact removal, possible hydrodynamic (hydrogen) entraining, solar wind sputtering due to the lack of a perpetual and strong magnetic field, and lower insolation contributed both to greater loses to space and "early" removal of water as ice.
- Cratering effects would be modified by the presence of an atmosphere, including effects on ejecta transport and the filtering out of smaller events as a function of atmospheric density (similar to Earth and Venus).
- Highly variable weather and seasonal patterns.
- Water ice observed at the poles, along with seasonal carbon dioxide frost.
- Evidence for past surface water activity strong.
Major Stages of Martian Evolution (Synthesized largely from material presented by Munch, 1976; Carr, 1984 and 1996, and the cratering age estimates of Soderblom, 1988)- NOACHIAN SYSTEM
- BEGINNING-----------------------------------------4.57 b.y.
- MAGMA OCEAN/PLANETARY DIFFERENTIATION-------------4.5-4.4(?) b.y.
- CRATERED UPLANDS/CLAY SOUP -----------------------4.4(?)-4.2(?) b.y.
- MAGMA OCEAN/PLANETARY DIFFERENTIATION-------------4.5-4.4(?) b.y.
- HESPERIAN SYSTEM
- LARGE BASINS--------------------------------------4.2(?)-3.9 b.y.
- PLANETARY VOLCANISM ------------------------------3.9-2.0(?) b.y.
- AMAZONIAN SYSTEM
- MATURE CRUST/ATMOSPHERE---------------------------2.0(?) b.y.-PRES.
1. Beginning 4.57 eons- Accretion from a water rich portion of the Solar Nebula (without possible complications of a large moon)
- Duration of a few hundred thousand years (?)
- Water retained initially by the infant Mars depended on:
- Water content of the coalescing planetismals (carbonaceous chondrites)
Figure: Composition of carbonaceous
chondrites
- Note: Theory indicates that the solar nebula in the vicinity of Mars more water-rich than that from which the Earth/Moon system formed.
- Apportionment between:
- Interior
- Surface and near-surface
- Primitive atmosphere
- Rates of introduction and erosion of water from the atmosphere
- Water content of the coalescing planetismals (carbonaceous chondrites)
- 2.Magma Ocean/Planetary Differentiation Stage [4.57-4.4(?) by ago]
- Center of mass and the center of figure of Mars are offset by ~3 km (Smith and Zuber, 1996) similar to the Moon's ~2 km offset.
- Planet-wide differentiation of a silicon-rich crust and magnesium/iron rich mantle (similar to Earth and upper mantle of the Moon)
- Iron and iron-sulfur core formation would favor an early strong magnetic field (?) (similar to Earth).
- No subsequent differentiation of the mantle or mixing with the crust (see below).
- Note: Differentiation of Mars into a crust, mantle, and core is inferred from the density, known moment of inertia (density distribution), the Viking orbital data, the Viking surface analyses, and the composition of the SNC meteorites (see Carr, 1996). The 12 known SNC meteorites have been established as coming from Mars by analysis of their volatiles which bare the distinct elemental and isotopic signature of the Martian atmosphere.
- The SNC meteorites (after Gooding, 1992, Mckay, et al., 1996, NASA)
history and size of intrinsic magnetic field, if any.
Figure: Composition of carbonaceous
chondritesCrust (100-200 km)
Mantle (1300-2000 km)
Core (1300-2000 km)
| METEORITE | AGE ........ (B.Y.) |
PETROLOGY (DESCRIPTION) |
| Shergotty | 0.165-0.205 0.350 |
Shock-metamorphosed basalt with pyroxene and plagioclase |
| Zagami | 0.116-0.230 | Shock-metamorphosed basalt |
| ALHA77005 | 0.187 | Shock-metamoposed lherzolitic (olivine and pyroxene) basalt with cumulate minerals |
| EETA79001 | 0.150-0.185 | Shock-metamorphosed basalt with light colored xenoliths, melt and cumulate minerals |
| *Nakhla | 1.240-1.370 | Pyroxene-olivine cumulate or coarse basaltic lava |
| *Lafayette | 1.330 0.274-0.655 (iddingsite) |
Pyroxene-olivine cumulate or coarse basaltic lava |
| *Gov. Valadares | 1.320 | Pyroxene-olivine cumulate or coarse basaltic lava |
| *Chassigny | 1.230-1.390 | Olivine cumulate |
| ALH84001 | 4.5 | Igneous orthopyroxenite cumulate with miner maskelynite, olivine, chromite, pyrite, and apatite |
QUE 94201 (Science News 148, 250) |
Not available | basaltic |
| LEW88516 | Not available | lherzolitic basalt |
| Y793605 | Not available | lherzolitic basalt |
- SNCs, largely basalts or cumulates with igneous textures, have a model radioisotopic age of 4.5 b.y. (same as lunar basalt model ages) indicating that there has been little or no mixing of their source (the mantle) or mixing with the crust since this differentiation occurred (radioisotopes and their decay products have not been separated). In contrast, the model ages of rocks from the Earth's mantle are about 2 b.y., indicating significant mixing since it formed 4.57 b.y. ago.
- Further, the 142Nd-146Sm systematic of several of the SNCs (* above) indicate that 142Nd was conserved in Mars at least until 1.33 b.y. ago (Treiman, 1996) unlike the Earth (Bowring and Housh, 1995).
- Pathfinder/Sojourner APXS analysis of boulder "Barnacle Bill" indicates a similarity to the SNCs (EOS, v 78, p293-294)
- The crystallization ages indicate that materials exist in the Martian crust that span the spectrum from 4.5 to 0.170 b.y., that is, volcanism and or magma intrusion continued throughout most of Martian history, paralleling the history of the Earth in that respect.
- The SNC exposure ages and formation ages cluster in three groups that also are distinct rock types, suggesting that they sample three distinct impact craters on Mars, one in the ancient megaregolith of the Uplands and two in the volcanic provinces of the northern hemisphere.
- Core formation by the movement of liquid iron, probably mixed with sulfur, released potential energy and is estimated to have raised the temperature of Mars by 300o K. This heat at least added to the depth of the Magma Ocean, if not causing the entire mantle to melt, slowed its rate of mantle crystallization, and probably enhanced the tendency of the mantle/magma ocean to transfer heat by convection.
- Core formation also may have converted much of the water in the young mantle to hydrogen as Feo reduced H2O to FeO + H2. This hydrogen may then have reduced carbon to methane (CH4) and nitrogen to ammonia (NH4). Methane and ammonia migration to the surface may have played a critical role in the warming of the primitive Martian atmosphere in the presence of a sun 25-30% less luminous than today (Sagan and Chyba, 1997). This in turn may have enhanced the stability of surface water, the production of atmospheric hydrocarbon aerosols to protect greenhouse gas NH4 against the effects of extreme UV, and the production of complex organic molecules from which life might then form.
- Note: The apparent small volume of the lunar core relative to the Martian
core and the evidence of an undifferentiated lower lunar mantle suggests
that the core formation heating was not significant during the lunar Magma
Ocean Stage other than possibly removing H2O from the lunar
interior.
3. Cratered Uplands/Clay Soup - 4.4(?)-4.2(?) b.y.- Highly cratered crust similar to lunar highlands.
Figure: Cratered Uplands of
Noachis (NASA Life on Mars #2)
- Formation of a megaregolith to about 10 km similar to the 25 km thick megaregolith of the Moon.
- Probable dense, moist, CO2 rich atmosphere with significant
CH4, CH4 derived aerosols, and NH4 (Sagan
and Chyba, 1997, and Kasting, 1997)
- Figure: Megaregolith drawing
- Note: The nature and evolution of the Martian atmosphere through time
consists of many uncertainties, including the following (see Carr, 1996,
Chapters 5-7):
- Initial composition
- Potential of a late infall of water-rich (cometary) material [not likely based on comparison of D/H rations of Earth's water with that measured for comets Hale-Bopp and Hyakutake (Owen,T., and Meier, R., 1997, reported in Science, 277, 318)]
- Variability of obliquity of rotational axis
- Changes in insolation
- Changes in composition due to core formation
- Changes in composition due to weathering of the megaregolith
- Changes in composition due to magmatic and hydrothermal activity
- Amount and stability of greenhouse gases (NH4, CH4, CO2, H2O) through time
- Degree of CH4 derived organic aerosol formation
- Amount and rate of surface regolith carbonate decomposition due to UV radiation (Mukhin, et al, 1996).
- Degree of impact erosion through the Large Basin Stage, below.
- Degree of hydrodynamic entraining by hydrogen escaping.
- Strength of the magnetic field, if any.
- Degree of solar wind erosion (sputtering) (Kass and Yung, 1995, and Johnson, and Liu, 1996)
- Degree of water and carbonate capture and recycling in the megaregolith
- Probable creation and continual stirring of a soupy mixture of water,
clay , carbonate, hydrocarbons and other atmospheric and crustal components
(WCCS).
- Note: This probably is the most likely period for the "evolution" of complex organic molecules as precursors to replication life (possibly self replicating RNA (see Ekland and Bartel, 1996, and Science, 1996, 273, 870-872) (see Lecture 16)
- Large, sprawling, low relief volcanos/calderas, possibly the result of the eruption of residual liquid from the Magma Ocean.
Alba
Patera-volcano in grooved terrain (NASA Photo)
Tyrrenum
Patera-Radial volcano with channels (NASA Photo)
Water cycling contributed to crater and volcano erosion, with the possible interlayering of sedimentary strata along with ejecta blankets and lavas.
Formation of intercrater plains, possibly by water deposition or lavas or both.
Late in this stage, a cryosphere underlain by a hydrosphere may have begun to form as water migrated into Martian crust and the atmosphere cooled as it lost CO2 to impacts and weathering, aerosols to rain, and NH4 to EUV destruction.
Figure: Cryosphere drawing
- 4. Large Basins - 4.2(?) - 3.8 b.y.
Figure: Upland Valley network
(NASA The Red Planet #27)
- Note: valley networks appear to have formed by sapping in the upper megaregolith (Carr, 1996), possibly sustained by increasing hydrothermal activity in response to remelting of the mantle under the Uplands. As noted in Lecture 10, these basaltic liquids would move to the top of the mantle, locally mixing with the Magma Ocean residual liquids (ur Kreep) concentrated there, and then move into the crust and on to the Martian surface, depending on the magma pressures developed by the remelting process.This movement of magmas would potentially recycle meteoric water and CO2 in the megaregolith, producing much hydrothermal activity and recycling of atmospheric volatiles.
5. Planetary Volcanism Stage - 3.8 - 2.0(?)
Figure: History
of Martian Volcanism (after Greeley, 1987)
- Fracturing and uplift of a large region, the Tharsis Uplift #1, of the thin crust in the northern hemisphere, possibly due to phase transitions in the upper mantle as radioisotopic heat accumulated.
- Bulk of the residual liquid left from the Magma Ocean, possibly mixed with basaltic magmas from the remelting mantle (see SNC table above), possibly entered the crust and erupted to form cratered plains in the Large Basins. Within 30-40o of the equator, plains features are crisp, lunar-like. At higher latitudes, plains features are much more complex..
- Fracturing and uplift of a large region, the Tharsis Uplift #1, of the thin crust in the northern hemisphere, possibly due to phase transitions in the upper mantle as radioisotopic heat accumulated.
- Note: The alignment of three major volcanoes in the Tharsis Uplift strongly suggests the migration of a convective hot spot relative to the crust, similar to that which has formed the Hawaiian island and seamount chain.
Large basin formation largely in present northern hemisphere.
Present rotational dynamics and variability established.
Much of megaregolith concentrated in southern hemisphere.
Remelting of the warming mantle beneath the large basins may have been triggered by the release of lithostatic pressure.
Upland valley networks (see Carr, 1996, Chapter 4) formed late in this stage.
Organization of complex organic molecules into replicating life forms, if it occurred on Mars, probably happened at or near the end of this stage (see Lecture 16)
Figure: History
of Martian Volcanism (after Greeley, 1987) 
Figure: Lava Flows in Elysium region (NASA
The Red Planet # 13)
Continuing or new fracturing and uplift of a large region of the thin crust in the northern hemisphere, Tharsis Uplift #2, probably due to convection at a hot spot in the mantle.
Figure: Viking Orbiter View of Northern Hemisphere and Tharsis region (NASA Volcanoes #4)
- Note:Pathfinder/Sojourner APXS analysis of boulder "Barnacle Bill," which seems to have a chemical relationship to the SNCs (EOS, v 78, p293-294), possibly also has as much as 54% SiO2 (EOS, v78, p 389-390). This suggests that igneous differentiation or fractional melting of sediments produced lavas approachingthe compositions of those seen in andesite provences on Earth, such as the Andes.
- Valles Marineris, a major extensional fracture, 5000 km long, probably
formed in response to the same forces that produced the Tharsis Uplift
#2 but then became an outflow channel.
Valles
Marineris (NASA Photo)
Full Image
Figure: Size of Valles Marineris
(NASA The Red Planet #5)
Figure: Valles Marineris closeup
(NASA The Red Planet #6)
Erosion channel (NASA Photo)
Figure: Outflow Channel into Chryse Planitia (NASA The Red Planet #25 disappeared)
Tharsis Uplift #2
Repeated sedimentation, possibly mixed with lavas and impact debris, in the Large Basins due to repeated discharges along some major outflow channels.
Figure: Streamlined Island (NASA The Red
Planet #26)
Fretted (mesa, knob, and plains) terrain formed across the contact between cratered uplands and cratered plains.
Figure: Outflow channel Ravi Vallis (NASA The
Red Planet #24)
- 6. Mature Surface/Atmosphere Stage - 2.0(?) - Present
- Continued impact cratering at a declining rate
- Note: all craters have features, such as ramparts at the outer edge of ejecta, that suggest the presence of a cryosphere and/or hydrosphere in the megaregolith
Figures: Impact Crater Distribution
(NASA Stones, Wind and Ice #l)
Figure: Fresh Impact Crater
(NASA Stones, Wind and Ice #13)
Figure: Rampart Impact Crater
(NASA Stones, Wind and Ice #28)
Figure: Landside in Valles
Marineris (NASA The Red Planet #7)
- Volcanic eruptions continued but at less volume and frequency (See SNC discussion above). Eruption of now unfractured lavas.
- Atmosphere probably cycled between conditions resembling today's thin, cold, and windy climates and those of more dense, moist conditions, including possible transient greenhouse conditions that permited liguid water at the surface (see Lecture 16).
- Continued formation of crustal ice and polar ice caps as atmospheric temperatures dropped due to reduced cratering rates and continued radiative cooling.
- Continued impact cratering at a declining rate
Ridged and faulted plains apparently formed in response to stresses produced by the Tharsis dome.
Additions of primordial and recycled water, CO2, and other volatiles to atmosphere.
Note: If volatiles were added in sufficient quantities, a period of greenhouse warmth may have accompainied the peak of volcanism and permited standing lakes/oceans in the basins of this time. Strandlines, overflow channels, and exposed sedimentary layers strongly suggest this happened.
Figure: Mars Lake Sediments (NASA
Life on Mars #4)Formation of outflow channels (see Carr, 1996, Chapter 3) by rapid discharges of water from a hydrosphere or rapid melting of portions of the cryosphere of both, generally originating in chaotic terrain in the Uplands, near the edges of large basins.
Full Image
Erosion channel (NASA Photo)Formation of valley networks on volcano flanks by sapping ash flow tuffs or erosion from water precipitation during eruptions.
Figure: Valley network on Tyrrhena
Patera (NASA volcanos #l7)
- Eolian erosion
- Wind erosion and movement of fine particles has modified many aspects of the Martian surface and has homogenized at least the near-surface portion of the "soil" (see Lecture 16).
Figure: Dust storm at Viking-l
(NASA The Winds of Mars #29)
Figure: Dust devils (NASA The
Winds of Mars#4 )
Figure: Local dust storms (NASA
The Winds of Mars #2)
Figure: Dune types -transverse
and barchan (NASA The Winds of Mars #ll)
Figure: Wind streaks (NASA
Stones, Wind, and Ice #19)
- Figure: Eroded layers (NASA
The Winds of Mars #l9)
Figure: White bedrock ((NASA
The Winds of Mars #24)
Figure: Big Joe Boulder (NASA
The Winds of Mars #28)
Figure: Drifts at Viking-l
(NASA The Winds of Mars #27)
Figure: Wind scour at Viking-l
(NASA The Winds of Mars #25)
View
from Viking lander (NASA Photo)
Questions:
1. Analyze and discuss the implications of the variations in solar energy received on the surface of Mars as a function of the planets orbital parameters and weather.
Text:
Mars environment material
Carr, M.H., 1996, Chapters 1-7.
References:
Ahrens, et al, 1989 Formation of atmospheres during accretion of the terrestrial planets, in Origin and Evolution of Planetary and Satellite Atmospheres, S.K. Atreya, et al, editors, University of Arizona press, Tucson.
Bowring, S.A., and Housh, T., 1995, The Earth's Early Evolution, Science, 269, 1535-1540.
Carr, M.H., 1984, Mars, in M.H. Carr, et al, The Geology of the Terrestrial Planets, p207-263.
Carr, M.H., 1996, Water on Mars, Oxford University Press, New York, 229p.
Crabtree, F.H., 1997, Where smokers rule, Science, 276, 222.
Ekland, E.H.and Bartel, D.P., 1996, Nature July 25 as reported in Science News, 150, 93.
Ferris, J.P., 1996, Nature, May 2, reported in Science News, 149, 278.
Gooding,, J.L., 1992 Soil mineralogy and chemistry on Mars: Possible clues from salts and clays in SNC meteorites, Icarus, 99, 28-41.
Gould, S.J., 1994, A Plea and a Hope for Martian Paleontology, in Neal, Valerie, editor, Where Next Columbus? The Future of Space Exploration, Oxford University Press, Oxford, 107-128p.
Horowitz, N.H., 1998, The Biological Question of Mars, in D.B. Reiber, editor, The NASA Mars Conference, AAS Science and Technology Series, v 71, 177185.
Huber, C., and Wachetershauser, G., 1997, Activated acetic acid by carbon fixation on (Fe,Ni)S under primoridal conditions, Science, 276, 245-247.
Johnson, R.E., and Liu, M, 1996, The loss of atmosphere from Mars, Science, 274, 1932.
Kass, D.M., and Yung, Y.L., 1995, Loss of Atmosphere from Mars Due to Solar Wind-Induced Sputtering, Science, v 268, 697-699.
Kasting, J.F., 1997, Warming early Earth and Mars, Science, 276, 1213-1215.
Levin, G.V., 1988, A Reappraisal of Life on Mars, in D.B. Reiber, editor, The NASA Mars Conference, AAS Science and Technology Series, v 71, 187-208.
McKay, C.P., and Borucki, S.J., 1997, Organic synthesis in experimental impact shocks, Science, 276, 390-392.
Mojzsis, S.J., et al, 1996, Nature 384, 55.
Mukhin, et al, 1996, Nature January 11 reported in Science News, 149, 21
Munch, T.A., et al, 1976, The Geology of Mars, Princeton University Press, Princeton, 400p.
Sagan, C., and Chyba, C., 1997, The early faint sun paradox: organic shielding of ultraviolet-labile greenhouse gases, Science, 276, 1217-1220.
Smith, D.E., and Zuber, M. T, 1996, The shape of Mars and the Topographic Signature of the Nemispheric Diochotomy, Science, v 271, 184-188.
Swindel, T.D., 1997, Jounrnal of Geophysical Research-Planets as reported in Science News, 151, 210.
Soderblom, L.A. 1988, The Geology of Mars, in D.B. Reiber, editor, The NASA Mars Conference, AAS Science and Technology Series, v 71, 43-53.
Treiman, A., 1996, To see a world in 80 kilograms of rock, Science, 272, 1447-1448.
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