Toba eruption 74 ka : global synchronization of late-Quaternary records
- Astronomically calibrated 40Ar/39Ar age for the Toba supereruption and
global synchronization of late Quaternary records
Michael Storey, Richard G Roberts & Mokhtar Saidin 2012
PNAS 109:18684-8 doi 10.1073/pnas.1208178109 open access
The Toba super-eruption in Sumatra ∼74 ka was the largest terrestrial
volcanic event of the Quaternary.
Ash & sulfate aerosols were deposited in both hemispheres, forming a
time-marker horizon that can be used to synchronize late-Quaternary
We report an astronomically calibrated 40/39Ar age of 73.88 ± 0.32 ka for
sanidine crystals extracted from Toba deposits in the Lenggong Valley,
Malaysia, 350 km from the eruption source, 6 km from an archaeological
site with stone artifacts buried by ash.
If these artifacts were made by Hs, Hs had reached SE.Asia by ∼74 ka.
Our 40/39Ar age is an order-of-magnitude more precise than previous
estimates, resolving the timing of the eruption to the middle of the cold
interval between Dansgaard–Oeschger events 20 & 19, when a peak in sulfate
concentration occurred as registered by Greenland ice cores.
This peak is followed by a ∼10°C drop in the Greenland surface Tp over
∼150 yr, revealing the possible climatic impact of the eruption.
Our 40/39Ar age also provides a high-precision calibration point for other
ice, marine & terrestrial archives containing Toba sulfates & ash,
facilitating their global synchronization at unprecedented resolution for
a critical period in Earth & human history beyond the range of 14C dating.