Constraints on the petrogenesis of Martian meteorites from the Rb-Sr and Sm-Nd isotopic systematics of the lherzolitic shergottites ALH77005 and LEW88516

Borg, L. E.; Nyquist, L. E.; Wiesmann, H.; Reese, Y.

doi:10.1016/s0016-7037(02)00835-9

Cited by 105 publications

(116 citation statements)

References 30 publications

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“…Pb is from Stacey and Kramers (1975) and Antarctic ice is from Vallelonga et al (2005). Borg and Draper (2003), which were calculated using data from Blichert-Toft et al (1999), Borg et al (1997;2002), Nyquist et al (1979;1995;2000;2001) and Wooden et al (1982), with the exception of Y79, which are from Borg et al (2003) and Misawa et al (2006). Calculations of µ values of shergottite and Nakhla sources are described in the text and use data from Chen and Wasserburg (1986a;1986b;1993), Misawa et al (1997), Borg et al (2005) 1986;McKenzie and O'Nions, 1991;Beattie, 1993;Ewart and Griffin, 1994;Hauri et al, 1994).…”

Section: Resultsmentioning

confidence: 99%

Uranium–lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

Gaffney

Borg

Connelly

2007

Geochimica et Cosmochimica Acta

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Section: Resultsmentioning

confidence: 99%

Uranium–lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

Gaffney

Borg

Connelly

2007

Geochimica et Cosmochimica Acta

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“…Primarily on the basis of the similarity of REE patterns, Barrat et al (2002) suggested NWA 480/1460 and the ''lherzolitic" shergottites may have had similar parent liquids, or at least came from similar mantle sources. However, the $346 Ma age of NWA 1460 is greater than the $185 Ma age of ''lherzolitic" shergottites (Morikawa et al, 2001;Borg et al, 2002;Misawa et al, 2006), so these diabasic and ''lherzolitic" shergottites could not have shared the same parent liquid. Furthermore, the CRE ages of the two shergottite types are resolved, showing that they must have originated from different places on Mars.…”

Section: Validity Of the Ar-ar Agementioning

confidence: 97%

“…This plot of e Nd vs. age shows that time-averaged Sm/Nd in the NWA 1460 source was similar to that in the source for ''lherzolitic" shergottites. Borg et al, 2002), EET 79001 Nyquist et al, 2001c), and nakhlites (Shih et al, 2005(Shih et al, , 2006 Borg et al, 2002a), EET 79001 Nyquist et al, 2001c), and nakhlites (Shih et al, 2005(Shih et al, , 2006. Here l = ( 147 Sm/ 144 Nd) S in Martian mantle source regions.…”

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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“…A second, more enriched reservoir must also exist because some shergottites have flatter REE profiles (higher La/Lu ratios) and Sm-Nd systematics that indicate prolonged incompatible element enrichment. This enriched reservoir may reside in the crust (e.g., Borg et al, 2002) and/or in the mantle as primitive, undepleted domains (e.g., Jones, 1989) or as the product of latest-stage melts from the solidification of the primordial magma ocean (e.g., Borg and Draper, 2003).…”

Section: Introductionmentioning

confidence: 99%

The evolution of a heterogeneous Martian mantle: Clues from K, P, Ti, Cr, and Ni variations in Gusev basalts and shergottite meteorites

Schmidt

McCoy

2010

Earth and Planetary Science Letters

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Constraints on the petrogenesis of Martian meteorites from the Rb-Sr and Sm-Nd isotopic systematics of the lherzolitic shergottites ALH77005 and LEW88516

Cited by 105 publications

References 30 publications

Uranium–lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

Uranium–lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

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

The evolution of a heterogeneous Martian mantle: Clues from K, P, Ti, Cr, and Ni variations in Gusev basalts and shergottite meteorites

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