Thallium Isotope Fractionation During Magma Degassing: Evidence From Experiments and Kamchatka Arc Lavas

Thallium (Tl) isotope ratios are an emerging tool that can be used to trace crustal recycling processes in arc lavas and ocean island basalts (OIBs). is a highly volatile metal enriched volcanic fumaroles, but it unknown whether degassing of Tl from subaerial has significant effect on their residual compositions. Here, we present concentration data experiments best explained by Rayleigh kinetic fractionation during loss. Our closely follow predicted models which TlCl the primary degassed species where loss controlled diffusion natural convection, consistent with slow gas advection velocity utilized our experiments. We calculate into air should associated net factor ?net = 0.99969 for convection (low velocities) 0.99955 forced (high velocities). also show three volcanoes Kamchatka exhibit patterns plot between two different regimes, implying played important role controlling observed compositions these volcanoes. Literature inspection reveals majority appear only minorly affected degassing, although few samples both OIBs identified likely experienced some degassing.