New occurrence of Youngest Toba Tuff in abyssal sediments of the Central Indian Ocean

Abstract

Volcanic glass and pumice found in siliceous abyssal sediments of the Central Indian Basin, south of the Equator, have previously been assigned various origins including intra-basin volcanism, Indonesian arc, and Krakatau. Rhyolitic glass shards dispersed from 8 cores that have examined are compositionally identical to those of fallout deposits of the Youngest Toba Tuff erupted at 74 ka from northern Sumatra. The correlation extends the distribution of coarse (> 63 mu m) glass shards some 1500 km south of the previously known fallout zone, and into the Southern Hemisphere (reaching latitudes of ca. 14 degrees S). This provides evidence for bi-hemispheric dispersal of the ash colud and supports global dispersal of gas and aerosods from the eruption. Such dispersal could have facilitated the global impact of the eruption