Abstract
The magmatic history of the Oldest Toba Tuff (OTT), the second largest in volume after the Youngest Toba Tuff (YTT), northern Sumatra, Indonesia, was investigated using U–Pb zircon dating by LA-ICP-MS. Zircon dates obtained from surface and interior sections yielded ages of 0.84 ± 0.03 Ma and 0.97 ± 0.03 Ma, respectively. The youngest OTT zircon ages were in accordance with the 40Ar/39Ar eruption age of ~ 0.8 Ma, whereas the oldest zircon dates were ~ 1.20 Ma. Therefore, the distribution of zircon U–Pb ages is interpreted to reflect protracted zircon crystallization, suggesting that the estimated 800–2,300 km3 of OTT magma accumulated and evolved for at least 400,000 years prior to eruption. This result is comparable to the volume and timescales of YTT magmatism. The similarities of both magmatic duration and geochemistry between OTT and YTT may indicate that they are similar in size and that the caldera collapse that generated OTT might be much larger previously interpreted.
Highlights
The Toba Caldera Complex (TCC) (Fig. 1), northern Sumatra, Indonesia, is identified as the site of supereruptions that may have severely affected the Earth’s climate and human e volution[1]
Reid and V azquez[7] showed that Youngest Toba Tuff (YTT) zircons nucleated episodically and persisted over 500,000 years at the cool and wet eutectic conditions well before the ~ 0.074 Ma super-eruption based on U–Th–Pb ages measured by secondary ion mass spectrometry (SIMS) collected on both surface and interior of zircon crystals
The cataclysmic ~ 0.074 Ma YTT produced 2,800 km[3] of non-welded to densely welded ignimbrite and associated ashfall d eposit[5,6], which exceeds the eruptive volume from the three preceding ignimbrites: the ~ 1.2 Ma (~ 35 km3) Haranggaol Dacite Tuff (HDT)[20], the ~ 0.8 Ma (~ 800 to 2,300 km3) OTT2,3, and the ~ 0.5 Ma (≥ 60 km3) Middle Toba Tuff (MTT)[15]
Summary
The Toba Caldera Complex (TCC) (Fig. 1), northern Sumatra, Indonesia, is identified as the site of supereruptions that may have severely affected the Earth’s climate and human e volution[1]. Reid and V azquez[7] showed that YTT zircons nucleated episodically and persisted over 500,000 years at the cool and wet eutectic conditions well before the ~ 0.074 Ma super-eruption based on U–Th–Pb ages measured by secondary ion mass spectrometry (SIMS) collected on both surface and interior of zircon crystals. The TCC is a 100 × 30 km topographic depression of several overlapping calderas that collapsed as a result of four major eruptions during the Q uaternary[14,15] (Fig. 1). It is the largest resurgent Quaternary caldera on Earth[15,16,17,18] and elongated in a NW–SE direction parallel to the active volcanic front of Sumatra. Of the cauldron block at Lake Toba (Fig. 1) and the seismically imaged sill-like magmatic complex below it22, the associated intrusive volume is likely batholithic in scale[7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
