Molecular modeling of the effects of Ar-40 recoil in illite particles on their K-Ar isotope dating

摘要

The radioactive decay of K-40 to Ar-40 is the basis of isotope age determination of micaceous clay minerals formed during diagenesis. The difference in K-Ar ages between fine and coarse grained illite particles has been interpreted using detrital-authigenic components system, its crystallization history or post-crystallization diffusion. Yet another mechanism should also be considered: natural Ar-40 recoil. Whether this recoil mechanism can result in a significant enough loss of Ar-40 to provide observable decrease of K-Ar age of the finest illite crystallites at diagenetic temperatures - is the primary objective of this study which is based on molecular dynamics (MD) computer simulations.