Regresar

Coexistence of HK and MK series in the pyroclastics related to the Ambrym caldera, Vanuatu - New Hebrides island arc

Abstract:

The pyroclastics associated with the Ambrym caldera formation show the simultaneous outpouring of two magmatic series, from basalts to dacites, one high-K (HK), the other one medium-K (MK). This duality is also found in the petrologic evolution of the volcano where post-caldera high-K lavas succeed to a pre-caldera medium-K series. The large volume of basalts implicated in the pyroclastic event and the coexistence of HK and MK magmas suggest that the caldera stage of the volcanological development corresponds also to a key step of the petrological and geochemical evolution. The problem of the origin of these variations is stated. There is an abridged English version. -English summary