Mars: a review and synthesis of general environments and geological settings of magma–H2O interactions
Published:January 01, 2002
James W. Head, III, Lionel Wilson, 2002. "Mars: a review and synthesis of general environments and geological settings of magma–H2O interactions", Volcano–Ice Interaction on Earth and Mars, J. L. Smellie, M. G. Chapman
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The advent of a global cryosphere likely occurred very early in the history of Mars, and much of the available water and related volatiles (CO2, clathrates, etc.) were sequestered within and below the cryosphere. This means that magmatism (plutonism and volcanism) as a geological process throughout the history of Mars cannot be fully understood without accounting for the interaction of magma and water (and related species) in both solid and liquid form. We review and outline the probable configuration of water and ice deposits in the history of Mars, describe environments and modes of magma–H2O interaction, and provide specific examples from the geological record of Mars. Magma and water–ice interactions have been interpreted to have formed: (1) massive pyroclastic deposits; (2) large-scale ground collapse and chaotic terrain; (3) major outflow channels; (4) mega-lahars dwarfing terrestrial examples; (5) sub-ice-sheet eruptions and edifices; (6) pseudocraters; (7) landslides on volcanic edifice flanks; and (8) hydrothermal sites. The global nature of the cryosphere, its longevity, and the diversity of environments means that Mars is an excellent laboratory for the study of magma–H2O interactdions and the role of related volatile species.
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Volcano–Ice Interaction on Earth and Mars
This volume focuses on magmas and cryospheres on Earth and Mars and is the first publication of its kind to combine a thematic set of contributions addressing the diverse range of volcano-ice interactions known or thought to occur on both planets. Understanding those interactions is a comparatively young scientific endeavour, yet it is vitally important for a fuller comprehension of how planets work as integrated systems. It is also topical since future volcanic eruptions on Earth may contribute to melting ice sheets and thus to global sea level rise.
Papers included here are likely to influence the choice of sites for future Mars missions in exobiologically important areas. On Earth, snow and ice are widespread, not only in extensive icecaps but also as alpine glaciers at high elevations in tropical regions. By contrast, Mars today is an arid volcanic planet with only small polar ice-caps although an abundance of water is believed to be trapped in the cryolithosphere. It is also thought that the planet may have sustained extensive frozen oceans early in its history. The presence of a former hydrosphere, a cryosphere and coincident volcanism thus make Mars the likeliest prospect for the first discoveries of life away from Earth. Much research has assumed that terrestrial volcano-ice systems are plausible analogues for putative Martian examples, but until mankind finally sets foot on Mars, there is no simple test for that assumption.
Our hope is that the knowledge presented here will stimulate research among planetary geologists in this exciting, rapidly expanding field for many years to come.