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 comparble 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, an 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. ¿ American Geophysical Union 1987 |