Experimental constraints on metal transport in fumarolic gases

Renggli CJ, Klemme S

Abstract

Metals are efficiently transported in a gas phase and the gas composition strongly affects transport rates of thesemetals in the gas phase. Here we present a new approach to systematically investigate metal transport and depositionfromvolcanic gases of different compositions: We test the effect of sulfur and chlorine on the volatilizationof 30 metal oxides and the phases deposited along a temperature gradient of 1250–300 °C in evacuated silicaglass tubes in water-free systems. In total, we observe 30 different deposited phases, including oxides, sulfidesand chlorides. The experimental results are compared with closed system and open system thermochemicalequilibrium calculations. The closed system calculations provide insights into the metal speciation in the gasphase, and the open system calculations provide thermodynamic predictions of the temperature ranges overwhich metals deposited fromthe gas phase. Both approaches only partially reproduce the experimental observationsof the deposited phases in the silica glass tubes. However, whenwe compare our experimental resultswithrecords from fumaroles on three different volcanoes (Kudriavy volcano, Russia, La Fossa crater on Vulcano, Italy,and Momotombo, Nicaragua), we find that our experiments agree very well with natural observations. We suggestthat similar experimental investigations are powerful tools in the study of metal transport in ore formingsystems involving gas phases, and results may be applied to various processes in terrestrial and planetaryenvironments.

Projects the publication originates from