Application of the MELTS algorithm to Martian compositions and implications for magma crystallization

Balta, J. B.; McSween, H. Y.

doi:10.1002/2013je004461

Cited by 34 publications

(45 citation statements)

References 103 publications

(209 reference statements)

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“…Et_Then does not fit with the other known compositions by having much higher Fe contents and having a high amount of olivine addition (>20%). This is presumably due to the weathered nature of Et_Then increasing the Fe content [ Schmidt et al , ] or due to orthopyroxene fractionation at depth increasing the Fe content and decreasing the Si content of Et_Then [ Balta and McSween , ]. Therefore, our calculated results below for Et_Then are not indicative of the primary magma composition nor of its formation conditions, and we will exclude them from the final evaluation.…”

Section: Calculated Resultsmentioning

confidence: 93%

Constraints on the depth and thermal vigor of melting in the Martian mantle

Filiberto

Dasgupta

2015

JGR Planets

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Studies of rocks in Gale Crater and clasts within the Martian meteorite breccia Northwest Africa (NWA) 7034 (and paired stones) have expanded our knowledge of the diversity of igneous rocks that make up the Martian crust beyond those compositions exhibited in the meteorite collection or analyzed at any other landing site. Therefore, the magmas that gave rise to these rocks may have been generated at significantly different conditions in the Martian mantle than those derived from previously studied rocks. Here we build upon our previous models of basalt formation based on rocks analyzed in Gusev Crater and Meridiani Planum to the new models of basalt formation for compositions from Gale Crater and a clast in meteorite NWA 7034. Estimates for the mantle potential temperature, T P based on Noachian age rock analyses in Gale Crater, Gusev Crater, and Bounce Rock in Meridiani Planum, and a vitrophyre clast in NWA 7034 are within error, which suggests that the calculated average T P of 1450 ± 70°C may represent an average global mantle temperature during the Noachian. The T P estimates for the Hesperian and Amazonian, based on orbital analyses of the chemistry of the crust, are lower in temperature than our estimates for the Noachian, which is consistent with simple convective cooling of the interior of Mars. However, the T P estimates from the young meteorites are significantly higher than the estimates based on surface chemistry and are consistent with localized "hot spot" melting and not heating up of the interior.

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Section: Calculated Resultsmentioning

confidence: 93%

Constraints on the depth and thermal vigor of melting in the Martian mantle

Filiberto

Dasgupta

2015

JGR Planets

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“…; Balta et al. ; Balta and McSween ) or any clinopyroxenes. It is surprising, then, that we observe augites with these low Ti/Al ratios (Figs.…”

Section: Discussionmentioning

confidence: 97%

Petrology and geochemistry of olivine‐phyric shergottites LAR 12095 and LAR 12240: Implications for their petrogenetic history on Mars

Dunham

Balta

Sharp

et al. 2019

Meteorit & Planetary Scien

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Larkman Nunatak (LAR) 12095 and LAR 12240 are recent olivine‐phyric shergottite finds. We report the results of petrographic and chemical analyses of these two samples to understand their petrogenesis on Mars. Based on our analyses, we suggest that these samples are likely paired and are most similar to other depleted olivine‐phyric shergottites, particularly Dar al Gani (DaG) 476 and Sayh al Uhaymir (SaU) 005 (and samples paired with those). The olivine megacryst cores in LAR 12095 and LAR 12240 are not in equilibrium with the groundmass olivines. We infer that these megacrysts are phenocrysts and their major element compositions have been homogenized by diffusion (the cores of the olivine megacrysts have Mg# ~70, whereas megacryst rims and groundmass olivines typically have Mg# ~58–60). The rare earth element (REE) microdistributions in the various phases (olivine, low‐ and high‐Ca pyroxene, maskelynite, and merrillite) in both samples are similar and support the likelihood that these two shergottites are indeed paired. The calculated parent melt (i.e., in equilibrium with the low‐Ca pyroxene, which is one of the earliest formed REE‐bearing minerals) has an REE pattern parallel to that of melt in equilibrium with merrillite (i.e., one of the last‐formed minerals). This suggests that the LAR 12095/12240 paired shergottites represent the product of closed‐system fractional crystallization following magma emplacement and crystal accumulation. Utilizing the europium oxybarometer, we estimate that the magmatic oxygen fugacity early in the crystallization sequence was ~IW. Finally, petrographic evidence indicates that LAR 12095/12240 experienced extensive shock prior to being ejected from Mars.

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“…Plagioclase crystallization does not begin until 1060 °C. Spinel (Cr‐Fe‐Mg‐Al) crystallization occurs throughout and is never more than 3 wt %, but spinel stability is typically overestimated using MELTS for Martian bulk compositions (Balta & McSween, ). The calculated mineralogy just above the solidus (at 1000 °C) is 42 wt % pigeonite, 42 wt % augite, 3 wt % spinel, and 6 wt % plagioclase.…”

Section: Discussionmentioning

confidence: 99%

Shergottite Northwest Africa 6963: A Pyroxene‐Cumulate Martian Gabbro

et al. 2018

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Northwest Africa (NWA) 6963 was found in Guelmim‐Es‐Semara, Morocco, and based on its bulk chemistry and oxygen isotopes, it was classified as a Martian meteorite. On the basis of a preliminary study of the textures and crystal sizes, it was resubclassified as a gabbroic shergottite because of the similarity with terrestrial and lunar gabbros. However, the previous work was not a quantitative investigation of NWA 6963; to supplement the original resubclassification and enable full comparison between this and other Martian samples; here we investigate the mineralogy, petrology, geochemistry, quantitative textural analyses, and spectral properties of gabbroic shergottite NWA 6963 to constrain its petrogenesis, including the depth of emplacement (i.e., base of a flow versus crustal intrusion). NWA 6963 is an enriched shergottite with similar mineralogy to the basaltic shergottites but importantly does not contain any fine‐grained mesostasis. Consistent with the mineralogy, the reflectance (visible/near‐infrared and thermal infrared) spectrum of powdered NWA 6963 is similar to other shergottites because they are all dominated by pyroxene, but its reflectance is distinct in terms of albedo and spectral contrast due to its gabbroic texture. NWA 6963 represents a partial cumulate gabbro that is associated with the basaltic shergottites. Therefore, NWA 6963 could represent a hypabyssal intrusive feeder dike system for the basaltic shergottites that erupted on the surface.

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Application of the MELTS algorithm to Martian compositions and implications for magma crystallization

Cited by 34 publications

References 103 publications

Constraints on the depth and thermal vigor of melting in the Martian mantle

Constraints on the depth and thermal vigor of melting in the Martian mantle

Petrology and geochemistry of olivine‐phyric shergottites LAR 12095 and LAR 12240: Implications for their petrogenetic history on Mars

Shergottite Northwest Africa 6963: A Pyroxene‐Cumulate Martian Gabbro

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