简介：
Potassium (K) is a moderately volatile, fluid-mobile, and lithophile element concentrated in the crust and ocean, and is an essential metabolic element for both animals and plants. The relatively large mass difference (5%) between the two stable K isotopes (41K, 6.730% and 39K, 93.258%) leads to large mass-dependent fractionation in a variety of chemical and biological processes. Recent studies have shown that the hydrosphere, especially seawater, has a homogenous and overall heavy K isotopic composition, whereas continental crustal rocks have highly heterogeneous and, on average, light K isotopic compositions than the mantle. This large K isotopic difference between the hydrosphere and continental crust result from multiple processes including continental weathering, seafloor alteration, biological activities etc. This review will focus on the basics of K isotope geochemistry, followed by the distribution of K isotopes in major reservoirs, and finally the applications of K isotopes in constraining major geological events in the formation and evolution of the Earth.
