Yamato 74014 meteorite, Queen Fabiola Mts, Queen Maud Land, Eastern Antarctica, Antarcticai

Regional Level Types
Yamato 74014 meteorite	Meteorite Fall Location
Queen Fabiola Mts	Mountain Range
Queen Maud Land	Region
Eastern Antarctica	Region
Antarctica	Continent

Official name: Yamato 74014
Synonym: Y-74014
Observed fall: no
Found: 1974
Coordinates: 71°30'S, 35°40'E (Catalogue of Meteorites);
71°50'8"S, 36°18'10"E (recommended, Meteoritical Bulletin)
Approx. recovered weight: 2.37 kg
Chondrite, type H6

For Yamato-74014 chondrite, the exposure age of about 3 ～ 5 Myr can be evaluated, assuming the shallow burial depth of the sample, which has a fusion crust on one side. A small polished section with a fusion crust was etched to investigate the effect of the ablation heating. Cosmic-ray tracks were survived in olivine grains at the depth of more than 0.9 mm from the meteorite surface. According to the high-temperature annealing experiments, the temperature higher than 550°C had not continued for 1 sec. at the position. Pyroxene in chondrites usually contains much higher uranium contents and fossil tracks than in olivine. These tracks cannot be explained only by cosmic-ray and the spontaneous fission of ²³⁸U during 4.6×10⁹ yr. On the assumption that the excesses are due to the spontaneous fission of the presently extinct isotope, ²⁴⁴Pu (half-life 82 my), the time interval between the end of nucleosynthesis and the onset of track retention, ΔT, was calculated. For bronzite grains in this meteorite, ΔT is estimated to 8×10⁷ (Yabuki, 1978).

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References