Geochemical evidence for magmatic water within Mars from pyroxenes in the Shergotty meteorite

McSween, H. Y.; Grove, T. L.; Lentz, R. C. F.; Dann, Jesse C.; Holzheid, Astrid; Riciputi, Lee R.; Ryan, Jeffrey G.

doi:10.1038/35054011

Cited by 174 publications

(120 citation statements)

References 24 publications

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“…Interestingly, pre-eruptive water content estimates from light lithophile elements for the more oxidized martian basalts, such as Shergotty and Zagami, appear to be consistent with water being involved in their petrogeneses McSween et al 2001;Dann et al 2001;Herd et al 2003). However, the reduced basalts have yet to be examined in this way, and as such, no constraints are on whether or not the oxidized source is necessarily hydrous.…”

Section: Water In the Trapped Liquid Componentmentioning

confidence: 81%

The oxygen fugacity of olivine‐phyric martian basalts and the components within the mantle and crust of Mars

Herd

2003

Meteorit & Planetary Scien

145

206

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Abstract-The oxygen fugacity of olivine-phyric martian basalts is estimated using olivine-pyroxenespinel equilibria, supported by detailed petrography. Results are plotted, along with previous oxygen fugacity estimates, against La/Yb, which is used as a proxy for long-term incompatible-element depletion or enrichment in martian basalt reservoirs. In general, the correlation between oxygen fugacity and La/Yb observed by Herd et al. (2002a) holds for the olivine-phyric basalts. The implications of the correlation are re-evaluated in light of work by Borg et al. (Forthcoming), which indicates that the variations in radiogenic isotopic composition can be modeled by mixing of mantle sources established by 4.5 Ga through crystallization of a magma ocean in lieu of assimilation of crustal material. The results demonstrate that the crust-like component, interpreted as trapped liquid in a magma ocean cumulate pile, must be oxidized to explain the oxygen fugacity of the martian basalts. Consequently, the pre-eruptive water contents of the more oxidized basalts are expected to be higher, although water is not called upon as the cause of the oxidation. Unmixing of mantle components provides an important context for the interpretation of oxygen isotopes, demonstrated here, and of samples returned from the martian surface.

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Section: Water In the Trapped Liquid Componentmentioning

confidence: 81%

The oxygen fugacity of olivine‐phyric martian basalts and the components within the mantle and crust of Mars

Herd

2003

Meteorit & Planetary Scien

145

206

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“…The amount of water present in the Martian mantle is poorly constrained and estimates range from relatively low water contents of 36 ppm (Wänke and Dreibus, 1994) to extremely large water contents in excess of 1000 ppm (Johnson et al, 1991). Geochemical analysis of the SNC meteorites suggest that the SNC parent magmas contained considerable amounts of water (McSween et al, 2001;Médard and Grove, 2006), but given their relatively shallow crystallization depths a crustal origin of this water cannot be ruled out. On the other hand, even the lowest estimated water concentrations of 36 ppm would be about 20…”

Section: Parametersmentioning

confidence: 99%

Crustal recycling, mantle dehydration, and the thermal evolution of Mars

Morschhauser

Grott

Breuer

2011

Icarus

127

167

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Please cite this article as: Morschhauser, A., Grott, M., Breuer, D., Crustal recycling, mantle dehydration, and the thermal evolution of Mars, Icarus (2010), doi: 10.1016/j.icarus.2010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Crustal recycling, mantle dehydration, and the thermal evolution of Mars Mars would then be driven by the extraction of a primordial crust after core formation, cooling the mantle to temperatures close to the peridotite solidus. According to this scenario, the second stage of global crust formation took place over a more extended period of time, waning at around 3500 Myr b.p., and was driven by heat produced by the decay of radioactive elements. Present-day volcanism would then be driven by mantle plumes originating at the core-mantle boundary under regions of locally thickened, thermally insulating crust. Water extraction from the mantle was found to be 1 relatively efficient and close to 40 percent of the total inventory was lost from the mantle in most models. Assuming an initial mantle water content of 100 ppm and that 10% of the extracted water is supplied to the surface, this amount is equivalent to a 15 m thick global surface layer, suggesting that volcanic outgassing of H 2 O could have significantly influenced the early Martian climate and increased the planet's habitability.

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“…The solubility behavior of N 2 is similar to that of CO 2 (Fricker & Reynolds 1968) and we assume P N2 ∼ 0.1 bar. The mass fraction of water dissolved in the magma, x H2O , is related to the partial pressure of water vapor in the atmosphere, P H2O , by the relation x H2O = 6 × 10 −7 P H2O 1 dyn cm −2 0.54 (13) (Fricker & Reynolds 1968 (Craddock & Greeley 2009) to ≈1.4-1.8wt% (McSween & Harvey 1993;McSween et al 2001;Dann et al 2001). We take a median value, x H2O = 0.2wt%, as a representative value (a mass fraction equivalent to the Earth having eight oceans, in line with current estimates by Mottl et al 2007), so that the total mass of H 2 O in the planetary embryo is 6.6 × 10 23 g, and P H2O = 3.3 bar.…”

Section: Chemical Environment Of Planetary Embryo Bow Shocksmentioning

confidence: 99%

Chondrule Formation in Bow Shocks Around Eccentric Planetary Embryos

Morris

Boley

Desch

et al. 2012

ApJ

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Recent isotopic studies of Martian meteorites by Dauphas & Pourmand have established that large (∼3000 km radius) planetary embryos existed in the solar nebula at the same time that chondrules-millimeter-sized igneous inclusions found in meteorites-were forming. We model the formation of chondrules by passage through bow shocks around such a planetary embryo on an eccentric orbit. We numerically model the hydrodynamics of the flow and find that such large bodies retain an atmosphere with Kelvin-Helmholtz instabilities allowing mixing of this atmosphere with the gas and particles flowing past the embryo. We calculate the trajectories of chondrules flowing past the body and find that they are not accreted by the protoplanet, but may instead flow through volatiles outgassed from the planet's magma ocean. In contrast, chondrules are accreted onto smaller planetesimals. We calculate the thermal histories of chondrules passing through the bow shock. We find that peak temperatures and cooling rates are consistent with the formation of the dominant, porphyritic texture of most chondrules, assuming a modest enhancement above the likely solar nebula average value of chondrule densities (by a factor of 10), attributable to settling of chondrule precursors to the midplane of the disk or turbulent concentration. We calculate the rate at which a planetary embryo's eccentricity is damped and conclude that a single planetary embryo scattered into an eccentric orbit can, over ∼10 5 years, produce ∼10 24 g of chondrules. In principle, a small number (1-10) of eccentric planetary embryos can melt the observed mass of chondrules in a manner consistent with all known constraints.

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Geochemical evidence for magmatic water within Mars from pyroxenes in the Shergotty meteorite

Cited by 174 publications

References 24 publications

The oxygen fugacity of olivine‐phyric martian basalts and the components within the mantle and crust of Mars

The oxygen fugacity of olivine‐phyric martian basalts and the components within the mantle and crust of Mars

Crustal recycling, mantle dehydration, and the thermal evolution of Mars

Chondrule Formation in Bow Shocks Around Eccentric Planetary Embryos

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