The Relation between the Volatilization Rates of Chlorine and Bromine Compounds from Volcanic Rocks on Heating

Abstract

Abstract Experiments on the volatilization rate of chlorine and bromine compounds from volcanic rocks were made at temperatures above 770°C in a stream of nitrogen, both in the presence of water vapor and without it. The rate of volatilization have been studied by following the change in the retained chlorine and bromine contents as a function of the heating time. Their contents retained in rocks during heating were estimated indirectly by determining their amounts evolved from rocks. The chlorine compounds are more volatile than those of bromine, regardless of the rock type. However, the difference in their volatility becomes quite small in the presence of water vapor. This fact suggests that there is little difference in the volatility between chlorine and bromine compounds in the presence of much water vapor, so the Br/Cl ratio in magma does not change very much during the crystallization process.