Inferences into the volcanic system of Mt. Etna (Italy) through geochemical pattern classification of volcanic products erupted from 1995 to 2013

Abstract

In this paper, we present the results of the application of pattern classification to the bulk rock composition (based on 13 major and trace elements) of volcanic products erupted by Mt. Etna volcano, Italy. The software for pattern classification belongs to the data mining tools developed within the WP 5 - Task 5.1 “Characterization of the threatening phenomena from space and ground” of the European MEDiterrranean Supersite Volcanoes (MEDSUV) project. The analyzed samples are the products of Strombolian explosions, lava fountaining, and lava effusion during summit and flank eruptions from 1995 to 2013. The results of pattern classification allow us to visualize quickly in a single diagram changes in magma composition over the 18 years covered by these products, providing useful insights into magma dynamics within the plumbing system of the volcano and their possible relationship with the features of volcanic activity. In particular, our data highlight important compositional changes of products erupted during the long- lasting flank eruptions. According to literature data, these changes can be explained by the ascent of primitive, deep magma that mixes with the magma feeding the ongoing eruption, changing the composition of the erupted products. Concerning the summit activity at the four craters Bocca Nuova, Voragine, North-East- and South- East Crater, pattern classification indicates that no crater had a “typical” magma. This suggests that all the summit craters were fed by a common magmatic reservoir, and that magmatic processes (fractional crystallization) in limited portions of the shallow plumbing system likely drove the variations of magma composition in time. Finally, among the summit craters, the South-East Crater and its new cone, the New South-East Crater formed in 2011, were active almost continuously for a long time giving us the opportunity to investigate the magmatic processes that control the compositional variations of products erupted during the lava fountains in 2000, 2007-08, and from 2011 to 2013.