Volcanological and geochemical features of the products of the Fiumicello eruption, Procida island, Campi Flegrei (southern Italy)

A volcanological and geochemical characterization of the products of the Fiumicello eruption is here proposed. The volcanological features of the deposits, representing both a "proximal" and a "distal" facies, suggest that the eruption dynamics were quite similar to those of many other Campi Flegrei events, being characterized by both purely magmatic and phreatomagmatic phases. The physical parameters of the eruption, like its relatively low magnitude, the height of the eruption column and the dispersion of the products, are still comparable to those of many other events which characterized Campi Flegrei's volcanological evolution. The mafic composition of the products of the Fiumicello eruption is rather unusual within the context of the Campi Flegrei district, largely dominated by highly evolved products. Therefore, the study of the products of this eruption gives an almost unique opportunity to investigate Campi Flegrei's plumbing system. Anyway, major- and trace element geochemistry, as well as mass-balance results, show that Fiumicello products can not be considered as representative of primary melts compositions. The geochemical vertical variations observed within the products of the eruption suggest that the Fiumicello event was fed by a density stratified magma chamber. The existence of such reservoir structures has already been proposed for other Campi Flegrei eruption and, therefore, their development seems to be a very important process in the framework of the evolution of the Campi Flegrei magmatic system.