Redox-induced isotope anomalies in the deep Earth

Abstract

A weakly temperature dependent isotope effect, i.e., the nuclear field shift, can produce isotope anomalies in the deep mantle due to redox condition changes. This effect can produce several to tens of ppm isotope anomalies or mass-independent fractionations at 2000 or even higher temperatures for many heavy metal isotope systems. This effect can be confirmed easily by comparing several isotope anomaly results of the same isotope system. For example, for W isotope anomalies, e.g., 180W and 183W, there are unique relationships between tthem if they are caused by the nuclear field shift effects. This work suggests a method to use heavy metal isotope systems as the tracers to detect the redox changes in the deep mantle.