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Martian Volcanic Gases: Are They Terrestrial-like?
| Content Provider | Semantic Scholar |
|---|---|
| Author | Zolotov, Mikhail Yu. |
| Copyright Year | 2003 |
| Abstract | Introduction: Volcanism was a major geological process in the geologic history of Mars [1-3]. Associated volcanic degassing [4,5] should have affected the composition of the atmosphere, contributed to the greenhouse effect [6,7], and influenced the chemistry and mineralogy of crustal materials through condensation of volcanic aerosols and chemical weathering [8]. Despite the importance of volcanic degassing, the chemical composition of martian volcanic emanations is weakly constrained. The presence of H 2 O, CO 2 , oxidized sulfur, and Cl compounds in the atmosphere and surface materials implies that typical martian volcanic gases contain water, carbon oxides, and S-, Cl-bearing species. Even with tentative detection of magmatic H 2 O and CO 2 in tiny fluid-gas inclusions in pyroxene in the ALH84001 meteorite [9] and the presence of a magmatic amphibole in several martian rocks, martian meteorites generally reveal volatile-depleted magmatic environments [e.g., 10]. Although terrestrial volcanic gases are often used as analogs in martian climatic and geochemical models [4-7], several factors could affect bulk composition, speciation, and the amount of martian volcanic gases compared to their terrestrial counterparts. Here I briefly review those factors and then evaluate the effects of pressure, temperature, oxidation state, and the Cl/S ratio on speciation of modeled martian volcanic gases. Why is Mars' volcanic degassing different from the Earth's? The lack of plate tectonics, low gravity, and low atmospheric pressure on Mars, as well as discrepancies in bulk planetary compositions could account for differences in the composition and abundance of terrestrial and martian volcanic gases. The lack of subduction of lithospheric plates may cause a sharp contrast in the oxidation states [11,12] and volatile contents between the mantle and crust. It could also account for higher liquidus temperatures of H 2 O-depleted mantle magmas. Deep mantle plumes, which could have been responsible for the formation of major volcanic structures (Alba Patera, Syrtis Major, and major Tharsis volcanoes), could have supplied reduced high-temperature and volatile-depleted magmas, consistent with mostly effusive eruptions in those areas. A high percentage of ultramafic rocks among the martian meteorites [10] and the detection of abundant olivine in surface materials [13] imply a broad occurrence of high-temperature magmas that could be characterized by specific degassing products. Nevertheless, mor-phologic evidence of explosive activity, especially in earlier periods of martian history, indicate degassing of volatile-rich magmas [3]. The majority of the volatiles degassed from those and many other martian volca |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.lpi.usra.edu/meetings/lpsc2003/pdf/1795.pdf |
| Alternate Webpage(s) | http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1795.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
