Iridium‐bearing sublimates at a hot‐spot volcano (Piton De La Fournaise, Indian Ocean)

Abstract

Sublimates and incrustations derived upon the cooling of volcanic gases have been collected on various sites (Piton de la Fournaise, Poas, Momotombo, Etna, Ardoukoba and Erta‐Ale). They have been analysed for Ir and other volatile elements (Se, As, Cu, Au, Ag, Pb, Tl) by means of instrumental neutron activation analysis (INAA) and proton induced X‐Ray emission (PIXE). Among the investigated volcanoes, only Piton de la Fournaise is found to release detectable amounts of iridium. Ir in Piton de la Fournaise sublimates is associated with F‐minerals. This confirms its gaseous transport as a volatile fluoride compound. Iridium seems to be preferentialy released by hot‐spot type volcanoes, and its detection in Piton de la Fournaise sublimates provides a positive argument in favour of a volcanic hypothesis to explain the KTB events.