14C terrestrial ages of nine Antarctic meteorites using CO and CO2 temperature extractions

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As a continuation of the work reported in R. P. BEUKENS et al. (Proc. NIPR Symp. Antarct. Meteorites, 1,224,1988), a suite of Yamato and Trans-Antarctic Mountains meteorites have been analyzed for their ^<14>C content, to give an estimate of their terrestrial age. Further information on the samples' terrestrial history may be obtained from analysis of separate carbon species evolved at different temperatures. We report on data obtained from CO and CO_2 separations from a low temperature (500℃ to 900℃) and high temperature (≈1600℃) fraction from each sample. Three Allan Hills meteorites, ALH-77232 (H4), ALH-78112 (L6) and ALH-78130 (L6), give terrestrial ages >29000 years, and probably represent limit ages due to in situ production. Three other Trans-Antarctic meteorites, BTN-78002 (L6), MET-78028 (L6) and RKP-78002 (H4), give finite ^<14>C ages between 15000 and 27000 years. Three Yamato meteorites, Y-8011 (L6), Y-81132 (H5) and Y-82095 (L3), give ages between 16000 and 22000 years. The low temperature components indicate that recent weathering and atmospheric exchange has taken place for at least four (and possibly six) of the meteorites; ALH-78112,ALH-78130 and Y-81132 have low temperature activities that suggest an earlier exposure and weathering.
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