Volcanic eruptions in subaqueous settings have been traditionally characterized by the study of ancient deposits and, more recently, by indirect observation of the sea floor with different geophysical means. Subaqueous volcanism is largely governed by the physical properties of water and the way water interacts with magma. Among the characteristic products of subaqueous volcanism are hyaloclastite breccias of dense clasts and of pumiceous clasts produced by the quench fragmentation of hot magma in effusive eruptions. Pumice breccias driven by fragmentation of magma in explosive eruptions are not infrequent. The Miocene volcanic zone of Cabo de Gata in southeastern Spain provides excellent exposures where to test the current understanding on subaqueous volcanism. In particular, submarine lavas with a coherent core and an outer carapace of vesicular hyaloclastite together with pumice breccias and crystal tuffs of the El Barronal Formation provide clues to understand transient conditions during explosive and effusive eruptions. Debris avalanches deposits are rather common in Cabo de Gata, such as those of the Los Frailes Formation and the Cerro Estorvillas Formation, and help to understand the instability processes of submarine volcanic edifices and the resultant mass flows. Interbedding of volcanic rocks with shallow water sedimentary rocks allows inferring water depth conditions for volcanism and the subsidence history of the volcano-sedimentary basin.

This research has been partly funded by project 2014SGR1595 and by grant PRX14/00303 to Carles Soriano.

Peer reviewed