Mineral chemistry of the calcalkaline lavas from Marsili Seamount (southeast Tyrrhenian Sea): some magmatological and geodynamic considerations

Mineral chemistry data from lavas recovered over a large depth interval of the deep-water volcano of Marsili (Aeolian back-arc, SE Tyrrhenian Sea) are presented. The volcano is built up by products of calcalkaline affinity with the only exception of one outcrop of sub-alkaline, within plate basalts in the crestal area. On the whole, the calcalkaline lavas of Marsili have bimodal composition, and consist of basalts and andesites with, respectively, calcalkaline and high-K serial affinity. The andesites mark a change in the geodynamic conditions that is reflected by the clockwise rotation of the seamount rifting from the early NNE-SSE orientation, associated with the extrusion of the basalts, to a dominant tensional regime trending almost NE-SW. This evolution is discussed in the context of some magmatic-structural features in the southest Tyrrhenian volcanic area. -from Authors