Actividad magmática explosiva en el Campo Volcánico de Calatrava

Abstract

The Calatrava Volcanic Field (Ciudad Real, Spain) encloses near one hundred volcanic cones composed of basic and ultra- basic alkaline rocks. The proximal pyroclastic deposits suggest that the cones formed through Strombolian, violent Strom- bolian, and / or Hawaiian eruptions, or involving transitional dynamics between these explosive styles, characteristic all of them of active volcanoes that emit basic and ultrabasic magmas (e.g., Valentine and Greeg, 2008). Strombolian eruptions are represented by bomb tephras, locally agglomerates, associated with block and angular lapilli tephras generated by bombs fragmentation. Violent Strombolian eruptions are represented by angular- and / or fluid-shaped scoriaceous lapilli tephras, which include sparse bombs. Some discontinuous tuffs appear interbedded within these tephras. Hawaiian episodes are mainly represented by spatter deposits welded by agglutination and / or coalescence, which, in the latter case, may appear transformed into lava masses with apparently coherent aspect. Exceptionally, clastogenic lava flows and achnelithic tephras (e.g., Pele’s tears and hairs), as typical of Hawaiian-type eruptions, have been also identified. Several edifices include parti- cular tephras constituted by spherical pyroclasts with concentric inner structure and variable clast-sizes (from ash to bomb sizes), generated in the context of explosive eruptions whose dynamics remains speculative since active volcanoes that emit- ted this type of tephras are unknown.