Volcanic Gas Controls the Alteration Mineral Assemblages in Tatun Volcano Group, Taiwan

Abstract

This study firstly applies the petrography and alteration mineral assemblages of rocks to study mineralogical facies transition under the gas-water-rock interaction in Longfengku and Liuhaungku of the Tatun Volcano Group (TVG). The results showed that the andesite consists of augite, hypersthene, hornblende, plagioclase and these samples far away from fumarolest; a partial altered andesite composes of opal, cristobalite and less plagioclase; and he andesite includes opal and a little plagioclase in the closer fumaroles area. The sulfur element does not exist in samples far away from fumaroles. In addition, the results of SEM, EDS and ED-XRF displayed that samples are well texture and lower silica content, and higher of aluminum and calcium elements of samples in the far away fumaroles area. Finally, this study infers to the sulfur component plays important role during alteration process.