Precise Rb-Sr dating of binary isotopic mixing during hydrothermal wall rock alteration

摘要

A method is presented that enables to precisely date binary isotopic paleo-mixing events by iterative reconstruction and regression of corresponding two-component mixing lines from conventional Rb-Sr data. This approach was applied to clay-bearing granulometric fractions of hydrothermally overprinted wall rocks associated with low-temperature vein mineralization. In contrast to conventional Rb-Sr isochron regressions, the mixing line calculations in these cases generally yield statistically well defined and very precise model ages. The mixing model turns out to be a successful dating concept for isotopic disequilibrium processes resulting in binary mixing, especially during low-temperature wall rock alteration.