Chemical systematics of the shergotty meteorite and the composition of its parent body (Mars)

Laul, J. C.; Smith, Mary Ellen; Wänke, H.; Jagoutz, E.; Dreibus, G.; Palme, H.; Spettel, B.; Burghele, A.; Lipschutz, M. E.; Verkouteren, R. Michael

doi:10.1016/0016-7037(86)90373-x

Cited by 106 publications

(43 citation statements)

References 27 publications

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“…EET 79001 is derived from a source region that has been more severely modified via earlier melt extractions that left it more depleted in LREE. (Barrat et al, 2002), EET79001 (Laul et al, 1986), and lherzolitic shergottites. (LEW 88516: Dreibus et al, 1992;Yamato-793605: Warren and Kallemeyn, 1997;Northwest Africa 1950: Gillet et al, 2005.…”

Section: Validity Of the Ar-ar Agementioning

confidence: 99%

Concordant Rb–Sr, Sm–Nd, and Ar–Ar ages for Northwest Africa 1460: A 346Ma old basaltic shergottite related to “lherzolitic” shergottites

Nyquist¹,

Bogard²,

Shih³

et al. 2009

Geochimica et Cosmochimica Acta

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Multiple lines of evidence show that the Rb-Sr, Sm-Nd, and Ar-Ar isotopic systems individually give robust crystallization ages for basaltic (or diabasic) shergottite Northwest Africa (NWA) 1460. In contrast to other shergottites, NWA 1460 exhibits minimal evidence of excess 40 Ar, thus allowing an unambiguous determination of its Ar-Ar age. The concordant RbSr, Sm-Nd, and Ar-Ar results for NWA 1460 define its crystallization age to be 346 ± 17 Ma (2r). In combination with petrographic and trace element data for this specimen and paired meteorite NWA 480, these results strongly refute the suggestion by others that the shergottites are $4.1 Ga old. Current crystallization and cosmic-ray exposure (CRE) age data permit identification of a maximum of nine ejection events for Martian meteorites (numbering more than 50 unpaired specimens as of 2008) and plausibly as few as five such events. Although recent high resolution imaging of the Martian surface has identified limited areas of sparsely cratered terrains, the meteorite data suggest that either these areas are representative of larger areas from which the meteorites might come, or that the cratering chronology needs recalibration. Time-averaged 87 Rb/ 86 Sr = 0.16 for the mantle source of the parent magma of NWA 1460/480 over the $4.56 Ga age of the planet is consistent with previously estimated values for bulk silicate Mars in the range 0.13-0.16, and similar to values of $0.18 for the ''lherzolitic" shergottites. Initial e Nd for NWA 1460/480 at 350 ± 16 Ma ago was +10.6 ± 0.5, which implies a time-averaged 147 Sm/ 144 Nd of 0.217 in the Martian mantle prior to mafic melt extraction, similar to values of 0.211-0.216 for the ''lherzolitic" shergottites. These time-averaged values do not imply a simple two-stage mantle/melt evolution, but must result from multiple episodes of melt extractions from the source regions. Much higher ''late-stage" e Nd values for the depleted shergottites imply similar processes carried to a greater degree. Thus, NWA 1460/480, the ''lherzolitic" shergottites and perhaps EET 79001 give the best (albeit imperfect) estimate of the Sr-and Nd-isotopic characteristics of bulk silicate Mars. Published by Elsevier Ltd.

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Section: Validity Of the Ar-ar Agementioning

confidence: 99%

Concordant Rb–Sr, Sm–Nd, and Ar–Ar ages for Northwest Africa 1460: A 346Ma old basaltic shergottite related to “lherzolitic” shergottites

Nyquist¹,

Bogard²,

Shih³

et al. 2009

Geochimica et Cosmochimica Acta

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“…The patterns were depleted in LREE with CI-normalized Lu/La ratios of 11 and 21, respectively, and had large, positive Eu anomalies (Laul et al 1986). The results indicate a noticeable attack on pyroxenes, in contrast to our experiments under milder conditions.…”

Section: Zagamimentioning

confidence: 99%

“…We do not consider finds from hot deserts because of possible terrestrial REE contaminations, see Crozaz et al (2003). Our lithology of Zagami has a REE concentration of 9 × CI, that of Shergotty is 10 × CI (Laul et al 1986). Both have CI-normalized Lu/La ratios of 1.14.…”

Section: Zagamimentioning

confidence: 99%

The loss of K, REE, Th, and U from a Martian and a terrestrial basalt by acidic leaching

Dreibus

Haubold

Huisl

et al. 2008

Meteorit & Planetary Scien

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Abstract-The mobilization of K, rare earth elements (REE), Th, and U from Martian surface material upon contact with acidic solutions probably occurred extensively on Mars about 4 to 3.5 Ga ago and seems to have occurred locally in more recent times. We have studied the dissolution of these elements by leaching the basaltic shergottite Zagami and the terrestrial basalt BE-N at constant pH values ranging from 5 to 1 in the absence and presence of added salts. Potassium is nearly immobile in Zagami and mobilized readily from BE-N. The REE reside mostly in calcium phosphates and dissolve readily, with those in whitlockite of Zagami reacting slightly better than those in apatite of BE-N. Thorium and U also reside mostly in calcium phosphates. Both dissolve similarly for both basalts and less readily than the REE. The experiments indicate the extent of the mobilization of K, REE, Th, and U, when acidic water leached the surface of Mars. Potassium was released slowly and in a small relative amount. The REE, and particularly the LREE, became mobile readily and were possibly distributed over large areas before immobilization. Thorium and U dissolved more slowly than the REE and were distributed less widely.

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“…1 means and standard deviations CI-normalized concentrations (Lodders 2003) of our trace element suite for 14 lunar meteorites (Verkouteren et al 1983;Kaczaral et al 1986;Dennison et al 1987;Wang and Lipschutz 1990;Lindstrom et al 1991aLindstrom et al , 1991b; this study), along with those for 13 Martian (Biswas et al 1980;Smith et al 1984;Laul et al 1986;Paul 1988;Treiman et al 1994;Mittlefehldt et al 1997;Wang et al 1998; and this study) and 37 HED (Paul 1988;and Paul and Lipschutz 1990) meteorites. We list elements as: siderophile (Au and Sb), labile (Se, Te, Bi, Ag, In, Tl, Zn, and Cd), and lithophile (Rb, Cs, Ga, and U).…”

Section: Comparison Of Lunar With Martian and Hed Meteoritesmentioning

confidence: 99%

Labile trace elements in basaltic achondrites: Can they distinguish between meteorites from the Moon, Mars, and V‐type asteroids?

Wolf

Wang

Lipschutz

2009

Meteorit & Planetary Scien

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(DaG 476) and incorporate these into a comparative study of basaltic meteorites from the Moon, Mars, and V-type asteroids. Multivariate cluster analysis of data for these elements in 14 lunar, 13 Martian, and 34 howardite, eucrite, and diogenite (HED) meteorites demonstrate that materials from these three parents are distinguishable using these markers of late, low-temperature episodes. This distinguishability is essentially as complete as that based on markers of high-temperature igneous processes. Concentrations of these elements in 14 lunar meteorites are essentially lognormally distributed and generally more homogeneous than in Martian and HED meteorites. Mean siderophile and labile element concentrations in the 14 lunar meteorites indicate the presence of a CI-equivalent micrometeorite admixture of 2.6%. When only feldspathic samples are considered, our data show a slightly higher value of 3.4% consistent with an increasing micrometeorite content in regolith samples of higher maturity. Concentrations of labile elements in the 8 feldspathic samples hint at the presence of a fractionated highly labile element component, possibly volcanic in origin, at a level comparable to the micrometeorite component. Apparently, the process(es) that contributed to establishing lunar meteorite siderophile and labile trace element contents occurred in a system open to highly labile element transport.

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Chemical systematics of the shergotty meteorite and the composition of its parent body (Mars)

Cited by 106 publications

References 27 publications

Concordant Rb–Sr, Sm–Nd, and Ar–Ar ages for Northwest Africa 1460: A 346Ma old basaltic shergottite related to “lherzolitic” shergottites

Concordant Rb–Sr, Sm–Nd, and Ar–Ar ages for Northwest Africa 1460: A 346Ma old basaltic shergottite related to “lherzolitic” shergottites

The loss of K, REE, Th, and U from a Martian and a terrestrial basalt by acidic leaching

Labile trace elements in basaltic achondrites: Can they distinguish between meteorites from the Moon, Mars, and V‐type asteroids?

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