The petrologic estimation of volcanic degassing.

Abstract

Petrological estimates of degassing of sulphur, chlorine and fluorine and the total volcanic volatile mass from several eruptions are closely comparable with volcanic aerosol estimates based on total acidity in ice-cores and direct stratospheric satellite-based extinction measurements. The results of petrological studies of 20 eruptions indicate that three general types of volcanic degassing should be considered: 1) dominated by sulphuric acid from degassing of magma, 2) dominated by halogens (chlorine and lesser fluorine) from degassing of magma, and 3) formed by decomposition of sulphur-rich mineral phase, e.g. anhydrite, during eruption (El Chichon-type). (Authors' abstract)-C.N.