Petrography, mineral chemistry, and petrogenesis of Antarctic Shergottite LEW88516

Harvey, R. P.; Wadhwa, M.; McSween, H. Y.; Crozaz, G.

doi:10.1016/0016-7037(93)90199-7

Cited by 95 publications

(138 citation statements)

References 23 publications

Supporting

Mentioning

123

Contrasting

Unclassified

Order By: Relevance

“…maskelynite, pigeonite, augite, and whitlockite. The Fe-Mg-silicates of this suite of ultramafic rocks are much more magnesian than those of the basaltic shergottites, and an observed chemical disequilibrium between coexisting olivine and pyroxene gives evidence for non-linear cooling (Harvey et al, 1993). High concentrations of Fe 3+ in chromites suggest high oxygen fugacity during crystallization.…”

Section: Lherzolitic Shergottitesmentioning

confidence: 93%

See 1 more Smart Citation

Ages and Geologic Histories of Martian Meteorites

Nyquist

Bogard

Shih

et al. 2001

Space Sciences Series of ISSI

380

558

View full text Add to dashboard Cite

Abstract.We review the radiometric ages of the 16 currently known Martian meteorites, classified as 11 shergottites (8 basaltic and 3 lherzolitic), 3 nakhlites (clinopyroxenites), Chassigny (a dunite), and the orthopyroxenite ALH84001. The basaltic shergottites represent surface lava flows, the others magmas that solidified at depth. Shock effects correlate with these compositional types, and, in each case, they can be attributed to a single shock event, most likely the meteorite's ejection from Mars. Peak pressures in the range 15 − 45 GPa appear to be a "launch window": shergottites experienced ∼30 − 45 GPa, nakhlites ∼20 ± 5 GPa, Chassigny ∼35 GPa, and ALH84001 ∼35 − 40 GPa. Two meteorites, lherzolitic shergottite Y-793605 and orthopyroxenite ALH84001, are monomict breccias, indicating a two-phase shock history in toto: monomict brecciation at depth in a first impact and later shock metamorphism in a second impact, probably the ejection event.Crystallization ages of shergottites show only two pronounced groups designated S 1 (∼175 Myr), including 4 of 6 dated basalts and all 3 lherzolites, and S 2 (330 − 475 Myr), including two basaltic shergottites and probably a third according to preliminary data. Ejection ages of shergottites, defined as the sum of their cosmic ray exposure ages and their terrestrial residence ages, range from the oldest (∼20 Myr) to the youngest (∼0.7 Myr) values for Martian meteorites. Five groups are distinguished and designated S Dho (one basalt, ∼20 Myr), S L (two lherzolites of overlapping ejection ages, 3.94 ± 0.40 Myr and 4.70 ± 0.50 Myr), S (four basalts and one lherzolite, ∼2.7 − 3.1 Myr), S DaG (two basalts, ∼1.25 Myr), and S E (the youngest basalt, 0.73 ± 0.15 Myr). Consequently, crystallization age group S 1 includes ejection age groups S L , S E and 4 of the 5 members of S, whereas S 2 includes the remaining member of S and one of the two members of S DaG . Shock effects are different for basalts and lherzolites in group S/S 1 . Similarities to the dated meteorite DaG476 suggest that the two shergottites that are not dated yet belong to group S 2 . Whether or not S 2 is a single group is unclear at present. If crystallization age group S 1 represents a single ejection event, pre-exposure on the Martian surface is required to account for ejection ages of S L that are greater than ejection ages of S, whereas secondary breakup in space is required to account for ejection ages of S E less than those of S. Because one member of crystallization age group S 2 belongs to ejection group S, the maximum number of shergottite ejection events is 6, whereas the minimum number is 2.Crystallization ages of nakhlites and Chassigny are concordant at ∼1.3 Gyr. These meteorites also have concordant ejection ages, i.e., they were ejected together in a single event (NC). Shock effects vary within group NC between the nakhlites and Chassigny.The orthopyroxenite ALH84001 is characterized by the oldest crystallization age of ∼4.5 Gyr. Its secondary carbonates are ∼3.9 Gyr old, an age corresponding t...

show abstract

Section: Lherzolitic Shergottitesmentioning

confidence: 93%

“…They are composed of relatively coarse-grained anhedral to euhedral olivine and chromite enclosed by large orthopyroxene crystals (Harvey et al, 1993;McSween, 1994;Mikouchi and Miyamoto, 1997). Interstices are filled with accessory phases, i.e.…”

Section: Lherzolitic Shergottitesmentioning

confidence: 99%

Ages and Geologic Histories of Martian Meteorites

Nyquist

Bogard

Shih

et al. 2001

Space Sciences Series of ISSI

380

558

View full text Add to dashboard Cite

show abstract

“…3C). The parent melt compositions were calculated using both low and high-Ca pyroxene distribution coefficients (Lundberg et al 1990;Harvey et al 1993). …”

Section: Alh 77005mentioning

confidence: 99%

“…For other Martian meteorites, such as the slowly cooled intrusives, the lherzolitic shergottites, and the cumulate nakhlites, the assumption that early melt compositions can be accurately estimated using compositions of later crystallizing phases is less well demonstrated. These meteorites appear to have undergone significant crystal fractionation (e.g., McSween et al 1979;Harvey et al 1993) and their final bulk REE composition may no longer reflect the melts from which they crystallized. Although previous analytical studies have suggested that the bulk rock REE composition and the parent melt REE composition calculated by inverting the pyroxene core REE values are similar (Wadhwa et al 2004), direct measurements of parent melt composition for the lherzolitic shergottites and nakhlites are not readily available.…”

Section: Introductionmentioning

confidence: 99%

Expanding the application of the Eu‐oxybarometer to the lherzolitic shergottites and nakhlites: Implications for the oxidation state heterogeneity of the Martian interior

McCanta¹,

Elkins-Tanton²,

Rutherford³

2009

Meteorit & Planetary Scien

View full text Add to dashboard Cite

“…Attempts to use these and other martian igneous rocks, however, have been frustrated because they are cumulate rocks rather than bulk melt samples. To overcome this problem, estimates of bulk melt compositions have been made by trying to identify and subtract the compositions of suspected cumulate minerals (Stolper and McSween 1979;Smith and Hervig 1979;Treiman 1986;McSween et al 1988;McCoy et al 1992), by analyzing trapped melt inclusions (Johnson et al 1991;Harvey and McSween 1992;Harvey et al 1993;Treiman 1993), by interpreting phase equilibria constraints (Longhi and Pan 1989), and by using minor element compositions in pyroxene with equilibrium partition coefficients (Treiman and Sutton 1992). However, these attempts have produced often controversial and contradictory results.…”

Section: Introductionmentioning

confidence: 99%

Composition of the first bulk melt sample from a volcanic region of Mars: Queen Alexandra Range 94201

Kring

Gleason

Swindle

et al. 2003

Meteorit & Planetary Scien

View full text Add to dashboard Cite

Abstract-Antarctic meteorite Queen Alexandra Range (QUE) 94201 is a 12 g basaltic achondrite dominated by plagioclase (now maskelynite) and zoned low-and high-Ca pyroxene. Petrologic, geochemical, and isotopic analyses indicate that it is related to previously described basaltic and lherzolitic shergottites, which are a group of igneous meteorites that are believed to be from Mars. Unlike previous shergottites, however, QUE 94201 represents a bulk melt rather than a cumulate fraction, meaning it can be used to infer magmatic source regions and the compositions of other melts on Mars. This melt has much more Fe and P than basaltic melts produced on Earth and formed at a much lower oxygen fugacity. This has altered the crystallization sequence of the melt, removing olivine from the liquidus to produce a plagioclase and 2-pyroxene assemblage. If the high-phosphorus and low-oxygen fugacity conditions represented by QUE 94201 are common in magmatic regions of Mars, then olivine may be rare in martian basalts. No solar cosmic ray effects were seen in the concentrations of 10 Be, 26 Al, and 36 Cl with depth in the meteorite, implying at least 3 cm of ablation during entry to Earth. Significant excesses of neutron capture noble gas isotopes ( 80, 82 Kr and 128, 131 Xe) suggest that the QUE 94201 sample came from a depth >22 cm in a meteoroid of at least that radius. The meteorite also has very low 21 Ne/ 22 Ne, which would often be interpreted to mean little ablation (contradicting above evidence) but, in this case, appears to reflect a very low abundance of Mg (the principal target element for Ne) in the meteorite, consistent with our bulk chemical analyses.The meteorite has a terrestrial 36 Cl age of 0.29 ± 0.05 Myr and a 10 Be exposure age of 2.6 ± 0.5 Myr in a 4π geometry, implying an ejection age of 2.9 ± 0.5 Myr.

show abstract

Petrography, mineral chemistry, and petrogenesis of Antarctic Shergottite LEW88516

Cited by 95 publications

References 23 publications

Ages and Geologic Histories of Martian Meteorites

Ages and Geologic Histories of Martian Meteorites

Expanding the application of the Eu‐oxybarometer to the lherzolitic shergottites and nakhlites: Implications for the oxidation state heterogeneity of the Martian interior

Composition of the first bulk melt sample from a volcanic region of Mars: Queen Alexandra Range 94201

Contact Info

Product

Resources

About