Volatiles (S-CO₂-H₂O-Cl-F) Behavior during the AD 1944 Eruption

Abstract

The AD 1944 is the last vulcanian-effusive eruption of Vesuvius volcano. I have reviewed most of the major and volatile elements in order to better understand the eruptive dynamic of this hazardous volcano. These volcanic products were basically formed by at least two main petrogenetic mechanisms: 1) mixing, 2) crystal fractionation. Crystal fractionation plays a major role in the evolution of the volcanic products of the AD 1944 eruption. According to the major elements data, several fractionation lines can be employed. Volatile data are analyzed in sequence. Indeed, the volatile data allow an insight into the exsolution and degassing processes occur during the growth and eruption of the AD 1944 eruption. Some inferences are also made on the exsolution and degassing depth. The volatile data illustrate a sequential order of exsolution for the AD 1944 eruption: Cl-H 2 O-CO 2 -S and finally as volatile phase degassed fluorine. The eruption has not interacted with external water. An early exsolution of Cl in Cl-rich magmas is also confirmed by experimental and geological studies (3 - 4 Kbars) coinciding with the deep magma reservoir.