DIFFUSION KINETICS OF SAMARIUM AND NEODYMIUM IN GARNET, AND A METHOD FOR DETERMINING COOLING RATES OF ROCKS

Experimental determinations of the diffusion coefficients of samarium and neodymium in almandine garnet and theoretical considerations show that one cannot assign a sufficiently restricted range of closure temp erature, T-c, to the samarium-neodymium decay system in garnet for the purpose of constraining the cooling rate. However, it is shown that t he samarium-neodymium cooling age of garnet can be used to calculate b oth cooling rate and T-c if the temperature and age at the peak metamo rphic conditions are known.