Iridium and hot‐spot volcanos

Abstract

Condensed gases from a volcano produced by the same hot spot that spilled the Indian Deccan flood basalts at the boundary of the Cretaceous and Tertiary periods contain iridium, according to a new study.Jean‐Paul Toutain of the Observatoire Volcanologiques and Georges Meyer of the Institut de Physique du Globe, both in Paris, made measurements on sublimates and incrustations around active vents of arc, intracontinental, continental rift, and hot‐spot volcanic environments. In a paper published in the December 1989 issue of Geophysical Research Letters, the researchers claimed that the composition of the deposits represents that of gases emitted by the volcanos. Toutain and Meyer found that only sublimates from the hot‐spot volcano Piton de la Fournaise on Reunion Island in the southwest Indian Ocean contained measurable amounts of of the platinum‐group element iridium; they measured up to 7.5 ppb of the element in sublimates deposited at 250–450°C.