Thermal cycling of lunar basalt analogs between liquid nitrogen temperature (-196 ¿C) and room temperature has no apparent influence on their remanent coercivity spectra. Initially, samples were cycled up to 100 times in a refrigerator over a period of about 30 min. per cycle. In a second set of experiments, samples were dipped directly into liquid nitrogen up to 100 times at about 1 min. per cycle. Comparison of AF demagnetization curves of weak field anhysteretic remanent magnetization (ARM) before and after cycling revealed no systematic differences. Calculations based on a model of spherical iron grains within olivine or troilite indicate that it is unlikely that the iron will crack under thermal stress. Thus, thermal cycling does not appear to provide an explanation for increasing the stability of remanence in samples from the lunar surface. |