Resurgent magma characteristics of a super-volcano, the Youngest Toba Tuff, northern Sumatra, inferred from zircon U-Pb geochronology

Abstract

Resurgent magma of the climactic Youngest Toba Tuff (YTT) super-eruption at ~74,000 years ago or ~0.074 million years ago (Ma), was investigated using zircons from a post-caldera lava dome. Here I reconfirmed that magmatic activity of the Toba Caldera Complex (TCC) started at ~1.3 Ma and that zircon-forming magmatic activity of YTT flared up at ~0.3 Ma and significantly declined at ~0.2 Ma, well before the ~0.074 Ma YTT eruption. Therefore, the climatic YTT eruption may not have been triggered by intensive/rapid magma supply at the time of eruption. The trigger may have been a small magmatic input or some other mechanisms. The remarkable accordance of zircon U-Pb age distribution between YTT and a post YTT lava dome indicates that post-caldera magmatic activity/resurgence occurred using essentially the same magma with YTT. A significant decline of magmatic inputs since ~0.2 Ma may indicate that another super-eruption is unlikely for at least hundreds of thousands of years to come in the TCC.