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What produced the platinum spike in the GISP2 ice core near the Younger Dryas onset?

Asked 26 Oct 2026 by ·4 answers·0·0 following
Four answers, none aheadNone is ahead yet. See what would settle it.

Where it stands

Four answers have been proposed. None is ahead on the evidence yet. Four are still possible.

Why it matters

It is the one signal both sides accept as real and anomalous. The Pt/Ir ratio exceeds all known terrestrial and extraterrestrial materials⁠[1], and the spike's source is still argued⁠[2].

Answers 4

An iridium-poor, highly differentiated iron meteorite.
Not tested enough to call either way
Evidence: 1 for, 1 against
Still possible
Evidence: 2 for, 1 against
Still possible
None of these.
Not tested enough to call either way
Evidence: none yet
Still possible
The Laacher See eruption.
Failed a test; not refuted outright
Evidence: 2 against
Disputed

History

  1. Petaev et al. puts forward: an iridium-poor, highly differentiated iron meteorite.
  2. Petaev et al.: superchondritic Pt/Al and fractionated Pt/Ir ratios exclude mantle and chondritic sources.For: An iridium-poor, highly differentiated iron meteorite.
  3. Reinig et al.: the eruption is dated about 130 years before the onset.Against: The Laacher See eruption.
  4. Green et al. puts forward: fractionated gas condensates from an unidentified volcanic eruption, probably an Icelandic subglacial or…
  5. Green et al. puts forward: the Laacher See eruption.
  6. Green et al.: the spike spans about 14 years.Against: An iridium-poor, highly differentiated iron meteorite.
  7. Green et al.: no eruption has been identified for the interval.Against: Fractionated gas condensates from an unidentified volcanic eruption, probably an Icelandic subglacial or…
  8. Green et al.: platinum-group patterns in submarine volcanic gas condensates (Niuatahi-Motutahi, Tonga) resemble the spike.For: Fractionated gas condensates from an unidentified volcanic eruption, probably an Icelandic subglacial or…
  9. Green et al.: new platinum and iridium data from the tephra do not match the spike.Against: The Laacher See eruption.
  10. Asked on this site
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