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The oldest ice challenge: potential sites and new drilling technology

The oldest ice challenge: potential sites and new drilling technology Jérôme Chappellaz and the Ice&Lasers/Subglacior team Laboratoire de Glaciologie et Géophysique de l’Environnement, Grenoble, France. 100 kyr periodicity. 40 kyr periodicity. The “Oldest Ice“ challenge.

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The oldest ice challenge: potential sites and new drilling technology

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  1. The oldest ice challenge: potential sites and new drilling technology Jérôme Chappellaz and the Ice&Lasers/Subglacior team Laboratoire de Glaciologie et Géophysique de l’Environnement, Grenoble, France

  2. 100 kyr periodicity 40 kyr periodicity The “Oldest Ice“ challenge • Climate and CO2 record covering the last 1.5 million years to evaluate climate sensitivity • One shot with conventional ice core drilling operations : too risky and costly Continental ice volume from δ18O stack of benthic foraminifera Lisiecki & Raymo, 2005

  3. Where to find such old ice in Antarctica? Pattyn, 2010

  4. IPICS Oldest Ice workshop, 6-7 October 2012, France

  5. Best guess: • 2500-m thickness max. • Smooth bedrock • Close to current domes or saddles • Simple ice flow regime

  6. Where to find such old ice in Antarctica? Basal temperature • Current requirements : • High-resolution 3D radar reconstructions • 3D ice-flow modelling • Shallow-intermediate drilling and snow radar for accumulation rate steadiness • Rapid access drilling Van Liefferinge and Pattyn, 2013

  7. VANISH / EXPLORE 2011/2012 traverse L. Arnaud, O. Alemany , J. Chappellaz, E. Lefebvre, M. Lemeur, G. Teste (LGGE), M. Bes de Bec (IPG Strasboug), M. Schneebeli (SLF, Davos) A. Vende, D. Colin, A. Leluc (IPEV) M. Fily (LGGE métropole) Vostok Point Barnola Concordia

  8. S1B DC Example of isochrones between Concordia and S1B S4 S3 • Mean accumulation over the last 300 years: • DC : 2.5 cm H2O/yr • Point Barnola : 2.3 cm • S2 : 2.1 cm • S3 : 1.6 cm • S4 : 1.6 cm S2 Point Barnola DC Lemeur et al., à soumettre

  9. Bedrock: Texas radar

  10. Innovativeapproach : in-situ probe withembedded OF-CEAS to qualifypotential sites • Run in a single fieldseason down to bedrock • Check statigraphiccontinuitywithin the icesheet • Real-time in-situ measurement of water isotopes (climate) and greenhousegases (CH4, maybe more) Design : O. Alemany

  11. PZT O.F. PDsignal LD current ramp Variable attenuator translation DFB diode laser PDref Optical Feedback CavityEnhanced Absorption Spectroscopy (OF-CEAS) Optical self-locking and narrowing of the laser frequency to the very narrow cavity transmission peaks Morville et al., Patent 2005 • Advantages: • Simple optical layout with few components • Small cavity (~ 10 cc), small sample size • Built-in frequency scale calibration (determined by cavity) • High light transmission • Switch between CEAS and CRDS modes for absorption calibration

  12. Semi-continuous CH4profile from NEEM using OF-CEAS technology and CFA Chappellaz et al., 2013

  13. How to handle the drilling chips ?

  14. Winch and hose A 3500 hose pipe in one piece Certified to -40°C (to be tested up to -50°C) One winch for the hose One winch for the main cable (power, data)

  15. OF-CEAS probe instrument Laser Lens1 PD ref Attenuator Wedge Lens2 Cavity PD sig 50 mm external diameter!!! 50 mm external diameter!!! R. Grilli, unpublished

  16. OF-CEAS probe instrument housing Second insulation First insulation Spectro housing Gas exit/vacuum Fluid channel x3

  17. Conclusions • The Oldest Ice challenge requires a lot of parallel tasks to reach success : snow radar, bedrock radar, modelling, rapid access drilling • We hope that the Subglacior probe will be able to qualify sites and to provide the primary information (climate, GHG), notably in the vicinity of Concordia • The LIA Vostok can frame the technological collaboration between the LGGE and Mining Institute, and future prospects south of Vostok

  18. Thanks !

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