Magmatic enclaves distribution within the Khaggiar lava dome (Pantelleria, Italy): implication for magma chamber dynamics and eruption

A study integrating spatial distribution observations, petrographical and geochemical features of magma mixing structures occurring inside the Khaggtar endogenous lava dome outcropping on the island of Pantelleria (Italy) reveals that the intensity of magmatic interaction increases from the outer to the more internal layers of the dome. Based on these observations a model for a silicic magma chamber evolution, in which magmatic interaction processes occur, is advanced. During a first stage the magma chamber is characterized by the onset of plume like dynamics induced by the hotter and more volatiles-rich mafic magma leading to the eruption of the external layers of the dome. In this physical regime the magmatic interaction processes are limited by rheological contrasts and low velocity of ascending magma. Successively fluid dynamics and thermal perturbations induce more intense magmatic interaction processes leading to the eruption of the internal parts of the dome.