Abstract
ANALYTICALLY, the simplest example of isotope migration in a geological environment is afforded by the loss of radiogenic argon-40 (one of the daughter products of the potassium-40 decay scheme) from minerals in a thermal metamorphism. By suitably selecting the thermal source, and assuming that the argon is lost by a diffusion process having only a single activation energy (E) of argon release, a relatively simple mathematical model of the system can be constructed. The most probable value of E can be deduced by finding for what value of the parameters in the diffusion equation the theoretical argon losses approach closest to those observed. The significance of E is that it affords a convenient numerical criterion for the argon-retentivity of a mineral; the higher the value of E, the more firmly is the argon retained.
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WESTCOTT, M. Loss of Argon from Biotite in a Thermal Metamorphism. Nature 210, 83–84 (1966). https://doi.org/10.1038/210083a0
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DOI: https://doi.org/10.1038/210083a0
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