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Penultimate deglacial sea level timing from U/Th dating of Tahitian corals

Penultimate deglacial sea level timing from U/Th dating of Tahitian corals. Alex L. Thomas, Gideon M. Henderson, Pierre Deschamps, Yusuke Yokoyama, Andrew J. Mason, Edouard Bard, Bruno Hamelin, Nicolas Durand, and Gilbert Camoin. Outline. TII Timing IODP Expedition 310 “Tahiti Sea Level”

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Penultimate deglacial sea level timing from U/Th dating of Tahitian corals

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  1. Penultimate deglacial sea level timing from U/Th dating of Tahitian corals Alex L. Thomas, Gideon M. Henderson, Pierre Deschamps, Yusuke Yokoyama, Andrew J. Mason, Edouard Bard, Bruno Hamelin, Nicolas Durand, and Gilbert Camoin

  2. Outline • TII Timing • IODP Expedition 310 “Tahiti Sea Level” • My Results

  3. Testing Milankovich’s Hypothesis… Now 0 ka LGM 21 ka ICE-5G Peltier 2004

  4. …with Absolute Chronology 12 ka Broecker & van Donk 1970

  5. Controversy Surrounding the Timing of Termination II Depth mbsl 128 ka 100 Age ka 150 • Direct U/Th dating of marine sediments. • Timing of TII too early to have same phasing as TI with respect to NHI. • Dating 18O Terminations in speleothems is not sea level • Highstand coral ages also constrain timing. Thompson & Goldstein 2006 Open system corrected coral ages Henderson & Slowey 2002

  6. IODP Expedition 310 Tahiti Tiarei M0009 Faaa M0019 M0020 Maraa M0005 149°W • Objectives of Exp 310 to constrain postglacial: sea level rise; SSTs; and reef geometry response. • Of 37 holes, 28 penetrated Pre-LGM material 18°S

  7. The Most Recent Deglaciation MWP-1A Barbados Stanford et al 2006 IODP EXP325 GBREC Deschamps et al. in prep

  8. Is there a dipstick for sea level? Milne & Mitrovica 2008 QSR

  9. Termination II coral data

  10. New data from IODP Exp 310

  11. Timing constraint

  12. Fit timing of continuous records to coral chronology

  13. An Alternative Sea Level Curve

  14. Insolation Forcing of Sea Level Rise Northern H Summer Southern H Summer Fuji 18O N. Atlantic 18O

  15. Timing of sea level rise is not out of phase with CO2 All Ice-core data are on the Dome Fuji timescale of Kawamura et al 2007 CO2 Fuji CO2 Vostok 18Oatm Vostok

  16. Can we get more from the corals?

  17. Drowning of Reefs IODP EXP325 GBREC Deschamps et al. in prep

  18. Paleodepths suggest a fall in sea level during the deglaciation

  19. Widespread evidence of millennial–scale lowstand Andrews et al 2007 (Gulf of Corinth) Siddall et al 2006 (Red Sea) Esat et al 1999 (PNG)

  20. Conclusions • Expedition 310 “Tahiti Sea Level” has been a great success, for drilling operations and for science • Sea level rise at the penultimate deglaciation was early with respect to phasing with NHI seen at TI • Sea level, and CO2, rise are not out of phase. • There is a substantial fall in global sea level during the penultimate deglaciation, indicating a readvance of ice sheets during a period of CO2 rise and warming.

  21. Shameless Self Promotion Out now online, and in print soon alext@earth.ox.ac.uk

  22. Effect of GIA on Timing Early Late Early Late Initial rise starts synchronously Milne & Mitrovica 2008 QSR

  23. Source of MWP-1A

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