Beryllium-10 contents of shergottites, nakhlites, and Chassigny

Pal, D. K.; Tuniz, Claudio; Moniot, R. K.; Savin, W.; Kruse, T. H.; Herzog, G. F.

doi:10.1016/0016-7037(86)90022-0

Cited by 24 publications

(10 citation statements)

References 18 publications

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“…This value, when combined with the averaged terrestrial age of 0.13±0.12 Myr, yields T ej = 0.73 ± 0.15 Myr (Table IV). A significantly higher value of 1.22 ± 0.24 Myr would be obtained, however, by combining the 10 Be-21 Ne CRE age of 0.90 ± 0.17 Myr for EET79001 lithology B (Pal et al, 1986) with the terrestrial age of 0.32±0.17 Myr reported for EET79001 (Sarafin et al, 1985). This is the highest value derivable from the EET79001 data and is in good agreement with the preferred ejection age of DaG476 (Table IV).…”

Section: Crystallization and Ejection Agessupporting

confidence: 70%

“…data (see Schultz and Franke, 2000); o Nishiizumi and Caffee (1996); p Nishiizumi et al (1986); q Pal et al (1986); r Schultz and Freundel (1984); s Evans et al (1992); t Miura et al (1995); u Nishiizumi et al (1992); v Jull et al (1994); w Treiman et al (1994); x Becker and Pepin (1993); z Ott and Löhr (1992); A Nishiizumi and Caffee (1997); B Nagao et al (1997); D Bogard (1995); E Lancet and Lancet (1971); F Schultz and Signer (1973), unpublished; G Swindle et al (1995); H Zipfel et al (2000); J Stauffer (1962); K Jull and Donahue (1988); L Sarafin et al (1985); M Becker and Pepin (1984), for R=35 to >1000 and d=6-80 g/cm 2 ; N Swindle et al (1986); P Bogard and Husain (1977); Q Swindle et al (1989); R Ganapathy and Anders (1969); T Folco et al (1999), same production rates used as for DaG476; U Jull et al (1997); Y Jull et al (1995); α Nishiizumi et al (1999; same T terr for the paired meteorites DaG476/489); β 21 Ne and 10 Be data from Garrison and Bogard (2000) and Nishiizumi and Masarik (2000), respectively; γ Lorenzetti and Eugster (2001); δ Shukolyukov et al (2000); Paetsch et al (2000); ζ Eugster (1994).…”

Section: Ejection Ages and Eventsmentioning

confidence: 99%

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Ages and Geologic Histories of Martian Meteorites

Nyquist

Bogard

Shih

et al. 2001

Space Sciences Series of ISSI

380

558

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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...

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Section: Crystallization and Ejection Agessupporting

confidence: 70%

Section: Ejection Ages and Eventsmentioning

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

“…Cosmic-ray exposure (CRE) ages for NWA 1950, based on stable noble gas isotopes 38 Ar, 21 Ne, and 3 He, are 2.3 ± 1.0 Myr, 3.5 ± 0.8 Myr, and 5.3 ± 3.0 Myr, respectively (Gillet et al 2005). The reported CRE ages span those previously reported for other lherzolitic shergottites: 2.5-3.4 Myr for ALH 77005 (Bogard et al 1984;Nishiizumi et al 1986;Pal et al 1986;Miura et al 1995;Eugster et al 1996); 3.0-4.1 Myr for LEW 88516 (Treiman et al 1994;Eugster et al 1996); and 3.9-5.4 Myr for Y-793605 (Terribilini et al 1998;Eugster and Polnau 1997;Nagao et al 1997Nagao et al , 1998. This spread in CRE ages (2.3-5.4 Myr) may be the result of a complex exposure history, including a contribution from solar cosmic rays (Gillet et al 2005) or irradiation by cosmic rays at the surface of Mars (Nagao et al 1997).…”

Section: Introductionsupporting

confidence: 72%

Localized shock melting in lherzolitic shergottite Northwest Africa 1950: Comparison with Allan Hills 77005

Walton

Herd

2007

Meteorit & Planetary Scien

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) and chromite, embedded in an Fe-rich, Al-poor basaltic to picro-basaltic glass. Within the melt pockets strong thermal gradients (minimum 1 °C/μm) existed at the onset of crystallization, giving rise to a heterogeneous distribution of nucleation sites, resulting in gradational textures of olivine and chromite. Dendritic and skeletal olivine, crystallized in the melt pocket center, has a nucleation density (1.0 × 10 3 crystals/mm 2 ) that is two orders of magnitude lower than olivine euhedra near the melt margin (1.6 × 10 5 crystals/mm 2 ). Based on petrography and minor element abundances, melt pocket formation occurred by in situ melting of host rock constituents by shock, as opposed to melt injected into the lherzolitic target. Despite a common origin, NWA 1950 is shocked to a lesser extent compared to Allan Hills (ALH) 77005 (45-55 GPa). Assuming ejection in a single shock event by spallation, this places NWA 1950 near to ALH 77005, but at a shallower depth within the Martian subsurface. Extensive shock melt networks, the interconnectivity between melt pockets, and the ubiquitous presence of highly vesiculated plagioclase glass in ALH 77005 suggests that this meteorite may be transitional between discreet shock melting and bulk rock melting.

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“…Table 4 compares the cosmic-ray exposure age of GRV 99027 with related lherzolitic shergottites. The exposure histories of ALHA77005 is relatively well studied: from 10 Be Nishiizumi et al [17] calculated an exposure age of 2.5 ± 0.3 Ma, Pal et al [18] obtained an age of 2.8 ± 0.6 Ma; from concentrations of cosmogenic noble gases the calculated ages are 2.9 ± 0.7 Ma [19] , 2.6 Ma [20] , and 3.3 ± 0.6 Ma [21] . From cosmic ray tracks and the existence of extra 26 Al, Nishiizumi et al [17] inferred that the radius of ALHA77005 before entering the Earth's atmosphere was 5-6 cm.…”

Section: Discussionmentioning

confidence: 99%

Cosmic-ray exposure age of Martian meteorite GRV 99027

et al. 2007

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We have determined the concentrations of 10 Be and 26 Al in GRV 99027 recovered by the 16th Chinese Antarctic expedition team, which are 14.1 ± 0.6 dpm/kg and 67.5 ± 3.4 dpm/kg, respectively. From the concentration of 10 Be, we calculate a cosmic-ray exposure age of 4.4 ± 0.6 Ma for GRV 99027. The concentration of 26 Al is too high compared to the 10 Be exposure age, indicating extra production from solar ray. The exposure ages, petrologic and geochemical characteristics of mantle-derived Martian meteorites GRV 99027, LEW 88516, Y-793605, NWA 1950 and ALHA77005 are very similar, suggesting that these meteorites most probably were ejected from Mars in the same impact event.

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Beryllium-10 contents of shergottites, nakhlites, and Chassigny

Cited by 24 publications

References 18 publications

Ages and Geologic Histories of Martian Meteorites

Ages and Geologic Histories of Martian Meteorites

Localized shock melting in lherzolitic shergottite Northwest Africa 1950: Comparison with Allan Hills 77005

Cosmic-ray exposure age of Martian meteorite GRV 99027

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