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Toba eruption 74 ka : global synchronization of late-Quaternary records

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  • Marc Verhaegen
    Astronomically calibrated 40Ar/39Ar age for the Toba supereruption and global synchronization of late Quaternary records Michael Storey, Richard G Roberts &
    Message 1 of 1 , Nov 13, 2012
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      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
      records globally.
      ...
      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.
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