THE NATURAL THERMOLUMINESCENCE OF METEORITES .7. ORDINARY CHONDRITES FROM THE ELEPHANT MORAINE REGION, ANTARCTICA

We report natural and induced thermoluminescence (TL) measurements for meteorites from the Elephant Moraine region (76 degrees 17'S, 157 degrees 20'E) of Antarctica. We use our data to identify fragmented meteorites (i.e., ''pairings''); our dataset of 107 samples represents at most 73 separate meteorite falls. Fairing groups are generally confined to single icefields, or to adjacent icefields, but a small proportion cross widely separated icefields in the region, suggesting that the fields can be considered as a single unit. Meteorites from this region have high natural TL levels, which indicates that they have small terrestrial surface exposure ages (<12,500 years). There do not appear to be significant differences in natural TL levels (and hence surface exposure ages) between individual blue icefields in the region. The proportion of reheated meteorites from the Elephant Moraine region is similar to that of other Antarctic sites and modern falls, consistent with the uniformity of the meteoritic flux in this regard. An unusual subset of H-chondrites, with high induced TL peak temperatures, is absent among the data for meteorites collected in the Elephant Moraine region, which stresses their similarity to modern falls. We suggest that the Elephant Moraine icefields formed through shallow ablation of the ice. Unlike the Allan Hills sites to the south, lateral transport is probably less important relative to the infall of meteorites in concentrating meteorites on these icefields.