Evidence for Recent Groundwater Seepage and Surface Runoff on Mars

Malin, M. C.; Edgett, K. S.

doi:10.1126/science.288.5475.2330

Cited by 982 publications

(822 citation statements)

References 27 publications

(13 reference statements)

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“…Results from the MOC camera have shown that surface water may have flowed intermittently on Mars in geologically recent times, creating gullies (Malin and Edgett, 2000a;Hartmann, 2001). Concentrated brines are able to exist in a liquid state at temperatures of down to −63 • C (Brass, 1980), and as mean surface temperatures on Mars are typically in the range −33 • C to −68 • C between 60 • N and 60 • S, it seems likely that brines are associated with these features.…”

Section: Evaporation and Evaporites On Marsmentioning

confidence: 99%

Untitled

Bridges

Catling

Saxton

et al. 2001

Space Science Reviews

214

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Abstract. The SNC (Shergotty-Nakhla-Chassigny) meteorites have recorded interactions between martian crustal fluids and the parent igneous rocks. The resultant secondary minerals -which comprise up to ~ 1 vol.% of the meteorites -provide information about the timing and nature of hydrous activity and atmospheric processes on Mars. We suggest that the most plausible models for secondary mineral formation involve the evaporation of low temperature (25-150 o C) brines. This is consistent with the simple mineralogy of these assemblages -Fe-Mg-Ca carbonates, anhydrite, gypsum, halite, clays -and the chemical fractionation of Ca-to Mg-rich carbonate in ALH84001 'rosettes'. Longer-lived, and higher temperature, hydrothermal systems would have caused more silicate alteration than is seen and probably more complex mineral assemblages. Experimental and phase equilibria data on carbonate compositions similar to those present in the SNCs imply low temperatures of formation with cooling taking place over a short period of time (e.g. days). The ALH84001 carbonate also probably shows the effects of partial vapourisation and dehydration related to an impact event postdating the initial precipitation. This shock event may have led to the formation of sulphide and some magnetite in the Fe-rich outer parts of the rosettes.Radiometric dating (K-Ar, Rb-Sr) of the secondary mineral assemblages in one of the nakhlites (Lafayette) suggests that they formed between 0 and 670 Ma, and certainly long after the crystallisation of the host igneous rocks. Crystallisation of ALH84001 carbonate took place 0.5 Ga after the parent rock. These age ranges and the other research on these assemblages suggest that environmental conditions conducive to near-surface liquid water have been present on Mars periodically over the last ~1 Ga. This fluid activity cannot have been continuous over geological time because in that case much more silicate alteration would have taken place in the meteorite parent rocks and the soluble salts would probably not have been preserved.The secondary minerals could have been precipitated from brines with seawater-like composition, high bicarbonate contents and a weakly acidic nature. The co-existence of siderite (Fe-carbonate) and clays in the nakhlites suggests that the pCO 2 level in equilibrium with the parent brine may have been 50 mbar or more. The brines could have originated as flood waters which percolated through the top few hundred metres of the crust, releasing cations from the surrounding parent rocks. There is no spectroscopic or photographic evidence for extensive evaporite deposits on the current martian surface but some salt precipitation through solute concentration must have occurred as floodwaters associated with many of the martian channels ponded in low-lying areas. The high sulphur and chlorine concentrations of the martian soil have most likely resulted from aeolian redistribution of such aqueously-deposited salts and from reaction of the martian surface with volcanic acid volatiles. However, the SNC...

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Section: Evaporation and Evaporites On Marsmentioning

confidence: 99%

Untitled

Bridges

Catling

Saxton

et al. 2001

Space Science Reviews

214

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“…Numerous workers have proposed that these regions were the sites of standing bodies of water or lakes (e.g., Carr, 1996). Recent MOC data show evidence for layered deposits in many impact craters, suggesting that standing bodies of water occurred in these locations (e.g., Malin and Edgett, 2000). Such locations have been cataloged and are abundant and widespread (e.g., Cabrol and Grin, 2001).…”

Section: Lakes and Oceansmentioning

confidence: 99%

Geological Processes and Evolution

Head

Greeley

Golombek

et al. 2001

Space Sciences Series of ISSI

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Abstract. Geological mapping and establishment of stratigraphic relationships provides an overview of geological processes operating on Mars and how they have varied in time and space. Impact craters and basins shaped the crust in earliest history and as their importance declined, evidence of extensive regional volcanism emerged during the Late Noachian. Regional volcanism characterized the Early Hesperian and subsequent to that time, volcanism was largely centered at Tharsis and Elysium, continuing until the recent geological past. The Tharsis region appears to have been largely constructed by the Late Noachian, and represents a series of tectonic and volcanic centers. Globally distributed structural features representing contraction characterize the middle Hesperian. Water-related processes involve the formation of valley networks in the Late Noachian and into the Hesperian, an ice sheet at the south pole in the middle Hesperian, and outflow channels and possible standing bodies of water in the northern lowlands in the Late Hesperian and into the Amazonian. A significant part of the present water budget occurs in the present geologically young polar layered terrains. In order to establish more firmly rates of processes, we stress the need to improve the calibration of the absolute timescale, which today is based on crater count systems with substantial uncertainties, along with a sampling of rocks of unknown provenance. Sample return from carefully chosen stratigraphic units could calibrate the existing timescale and vastly improve our knowledge of Martian evolution.

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“…Gamma-ray spectrometry data from Phobos 2 (McLennan, 2001) and Mars Odyssey (Taylor et al, 2003) indicate higher levels in Martian soils than recorded in the meteorites, but still at lower concentrations than on Earth. Nevertheless, evidence for working of surface detritus by water on Mars (Malin and Edgett, 2000) suggests that concentrations of radioactive mineral grains are a possibility. As bicarbonate was probably the dominant anion in water on early Mars (Catling, 1999), it could have contributed to the formation of organic molecules through irradiation as discussed above.…”

Section: The Potential For Irradiation On Other Rocky Planetsmentioning

confidence: 99%

Mineral Radioactivity in Sands as a Mechanism for Fixation of Organic Carbon on the Early Earth

Parnell

2004

Orig Life Evol Biosph

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Abstract. Irradiation of organic molecules by mineral radioactivity is a feasible alternative to cosmic irradiation to precipitate solid organic carbon-rich matter on the early Earth. Radioactive (uranium-and thorium-rich) minerals have been concentrated at the Earth's surface, and accumulated accretionary coatings of carbon due to irradiation, since early Archean times. The organic accretion process could have occurred at the surface or in the sub-surface, and is independent of a terrestrial or extraterrestrial source for the carbon.

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Evidence for Recent Groundwater Seepage and Surface Runoff on Mars

Cited by 982 publications

References 27 publications

Untitled

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Geological Processes and Evolution

Mineral Radioactivity in Sands as a Mechanism for Fixation of Organic Carbon on the Early Earth

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