Fumarolic Gases. They can occur as holes, cracks, or fissures near active volcanoes or in areas. The data 4 he ratios in the fumarolic gases are plotted in figure 6 ( ja7, jb7, jb8.

The fumarolic mineralogy of the icelandic active volcanoes, the tyrrhenian volcanic belt (italy) and the aegean active arc (greece) is investigated, and literature data surveyed in order to define the characteristics of the. The data 4 he ratios in the fumarolic gases are plotted in figure 6 ( ja7, jb7, jb8.