Eruptive history of Earth's largest Quaternary caldera (Toba, Indonesia) clarified

Single-grain laser-fusion (super 40) Ar/ (super 39) Ar analyses of individual sanidine phenocrysts from the two youngest Toba (Indonesia) tuffs yield mean ages of 73 + or -4 and 501 + or -5 ka. In addition, glass shards from Toba ash deposited in Malaysia were dated at 68 + or -7 ka by the isothermal plateau fission-track technique. These new determinations, in conjunction with previous ages for the two oldest tuffs at Toba, establish the chronology of four eruptive events from the Toba caldera complex over the past 1.2 m.y. Ash-flow tuffs were erupted from the complex every 0.34 to 0.43 m.y., culminating with the enormous (2500-3000 km (super 3) ) Youngest Toba tuff eruption, caldera formation, and subsequent resurgence of Samosir Island. Timing of this last eruption at Toba is coincident with the early Wisconsin glacial advance. The high-precision (super 40) Ar/ (super 39) Ar age for an eruption of such magnitude may provide an important marker horizon useful as a baseline for research and modeling of the worldwide climatic impact of exception-ally large explosive eruptions.