Cosmogenic records in Antarctic meteorites

https://doi.org/10.1016/0012-821X(83)90047-XGet rights and content

Abstract

Aliquot samples of twenty-nine Antarctic L and H chondrites were analyzed for their nuclear track records and53Mn activities. Track density in the analyzed samples range from 104 to ∼ 6×106 cm−2. An important finding is the observation of track-rich grains in a set of four L3 chondrites ALHA 77215, 77216, 77217 and 77252, suspected to belong to the same fall based on petrographic observations. An additional sample, ALHA 78105, a L6 chondrite, also contains track-rich grains.53Mn activity is at near saturation level in ∼65% of the analyzed samples indicating exposure ages > 10 m.y. in these cases. Very few H chondrites from the 7-m.y. exposure age peak are apparently sampled among the ones analyzed in this study. About 6% and 4% respectively of the Antarctic H and L chondrites, analyzed so far for their cosmogenic records, have precompaction irradiation features. Combined analysis of53Mn and nuclear track data allowed us to confirm or rule out the proposed pairing of several sets of Antarctic meteorites, and also to estimate the preatmospheric sizes of some of these meteorites. The results indicate that most of the small Antarctic meteorites (< 1 kg) have suffered high (> 95%) ablation mass-loss.

Reference (40)

  • NishiizumiK. et al.

    The extent of lunar regolith mixing

    Earth Planet. Sci. Lett.

    (1979)
  • FiremanE.L.

    14C and39Ar abundances in Allan Hills meteorites

  • FiremanE.L.

    Carbon-14 and argon-39 in ALHA meteorites

  • FiremanE.L. et al.

    Carbon-14 ages of Allan Hills meteorites and ice

  • FiremanE.L. et al.

    14C terrestrial ages of Antarctic meteorites with counters and with a Van de Graaff accelerator

    Lunar Planet Sci.

    (1982)
  • EvansJ.C. et al.

    26Al content of Antarctic meteorites: implications for terrestrial ages and bombardment history

  • TakaokaN. et al.

    Rare gas studies of Yamato-7301(j), -7305(k) and -7304(m)

    Mem. Natl. Inst. Polar Res.

    (1978)
  • NagaoK. et al.

    Rare gas studies of Antarctic meteorites

    Mem. Natl. Inst. Polar Res.

    (1979)
  • WeberH.W. et al.

    Noble gases in ten stone meteorites from Antarctica

    Z. Naturforsch.

    (1980)
  • TakaokaN. et al.

    Rare gas studies of twenty-four Antarctic chondrites

    Mem. Natl. Inst. Polar Res.

    (1981)
  • Cited by (0)

    View full text