The natural thermoluminescence of meteorites: I. Twenty‐three Antarctic meteorites of known 26Al content

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Abstract
The level of thermoluminescence (TL) naturally present in 23 Antarctic chondrites of known 26Al content has been measured as a means of exploring their thermal and radiation history. Antarctic meteorites tend to have lower natural TL than non‐Antarctic meteorites, presumably because of their generally longer terrestrial ages. Seventeen of the meteorites lie on a band of increasing natural TL and 26Al activity; meteorites with 26Al of 45–60 dpm/kg have natural TL values (normalized to the high temperature TL) of 2–4, whereas those with 26Al values of 30–45 dpm/kg have normalized natural TL values of 1–2, and ALHA 76008, with an 26Al content of 11 dpm/kg, has a TL value of 0.87 ± 0.01. This suggests that the “half‐life” for TL decay is comparable to that of 26Al. The six meteorites not lying on the TL‐26Al trend have much lower TL than others of comparable 26Al. For two of them (RKPA 79001 and RKPA 80202, which are tentatively paired) the low natural TL probably reflects a recent severe shock, while another (ALHA 77294) has previously been measured in this lab and had TL consistent with the TL‐26Al trend. The remaining three, ALHA 78006, ALHA 77296, and ALHA 77297 (of which the last two are probably paired), have suffered a recent reheating such as would be expected from orbits of unusually small perihelia.