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Results of the new 5G-1N ice core studies related to technology of Lake Vostok unsealing

Results of the new 5G-1N ice core studies related to technology of Lake Vostok unsealing. Vostok. V. Lipenkov , N. Vasiliev , A. Ekaykin , I. Alekhina AARI, St. Petersburg, St. Petersburg Mining University. RADARSAT CSA.

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Results of the new 5G-1N ice core studies related to technology of Lake Vostok unsealing

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  1. Results of the new 5G-1N ice core studies related to technology of Lake Vostok unsealing Vostok V. Lipenkov, N. Vasiliev, A. Ekaykin, I. Alekhina AARI, St. Petersburg, St. Petersburg Mining University RADARSAT CSA St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  2. Lake Vostok - an essential element of the Antarctic subglacial environments: Aquatic environments beneath the Antarctic ice sheet (>22,000 km3 of water in >370 sub-ice lakes) provide a unique natural laboratory for prolonged ecological experiments • Surface area ~16,000 km2 • Lake volume ~6,000 km3 (~25% of the total volume of water beneath the Antarctic ice sheet) • Water depth up to 1200 m • Thickness of the overlying ice sheet up to 4350 m • A deep depression (1600 m b.s.l.) in the southern part of the lake • Popov et al., 2011 Siegert at al., 2007 St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  3. Uncertainties , risks andproblems: Ice sheet thickness: 3720-3790 m (Popkov, 1998; Popov, 2003; Richter et al., 2008) Pressure melting temperature of ice: from -2.85 to -2.62 °C Concentration of gases in subglacial water: 0.09-2.7 liters (STP) of gas per kg of water (Lipenkov & Istomin, 2001) Is the ice sheet in hydrostatic equilibrium at the drilling site? (e.g., Wendt, 2005; Ewert et al., 2012) Potential for contamination Potential for degassing of lake water allowed to rise in the hole Fluid control: “the control of all inflows, outflows and movements of fluid at all points in the hole and the ability to stop an inflow of fluid “as desired” (Fleckenstein, 2006) 3740 3750 Lake Vostok and the Vostok drilling project Hole 5G setting Original plan for Lake Vostok unsealing Accreted (lake) ice 3720 3770 m Lake Vostok St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  4. Narrative of the deep drilling operations at Vostok Station since 2007 Madison, WI, USA 9-13 September 2013

  5. Penetration record from the last 5G-2 run Fluid outflow from the hole mouth started 1 min after the penetration and persisted for 5 min (total fluid loss through the hole mouth  1-2 m3) Rate of fluid rise ≤ 0.4 м/s Fluid level before drilling: 50 m Estimated fluid level during drilling: 25…30 m Fluid level 8 days after penetration: 43 m St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  6. #4 3608 m Beneath Vostok Station: Upwelling ≤ 0.1 mm/s Maximum size of particles in suspension  10-15 m 20 m LV 3D circulation model Kazko et al., 2012 The last ice core from hole 5G-2 #3 #3 St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  7. Ice core studies (5G-1N and 5G-3 holes) 3194 m – hole reaming start 3200 m – first cork of bright white hard material 3385 m – first crescent-shaped fragments of refrozen water ice 3415-3427 m – mixed clathrate hydrate of lake gases and hydrochloroflurocarbon densifier (HCFC-141b) fills ~ 30% of the hole volume Madison, WI, USA 9-13 September 2013

  8. Ice core studies (5G-1N and 5G-3 holes) 3424-3427 m – hydrate core inside refrozen water ice core  80  0 mm St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  9. Ice core studies (5G-1N and 5G-3 holes) • 3427-3458 m – “solid” water ice (refrozen lake water): • -radial ice structure with preferred horizontal orientation of c-axes • -concentric layering implies several stages in ice growth • many gas and liquid inclusions, concentration of which increases toward 5G-1 hole axis • refrozen water ice easily come off a hole wall (hydrate layer) St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  10. Ice core studies (5G-1N and 5G-3 holes) 5G-1 hole wall, depth 3436 m Obtained by redrilling 5G-1 (5G-1N) hole) 5G-1 hole wall, depth 3599 m Obtained by drilling branch hole 5G-2 St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  11. Water level fluctuation after lake unsealing St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  12. EDML 2006 Vostok 2012 b Ice-coated units of the drill pulled out from the borehole: EDML ice core Vostokice core

  13. Core with hydrate center Hydrate center 3426m St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  14. Refrozen water ice: Total concentration of DF components ~15 % (volume) Hydrate core: 4% of core volume: DF components ~15%, but HCFC-141b is increased by factor of 2 Meteoric ice Hydrate layer Refrozen water ice: Concentration of DF components ~16 mg/l Central channel: HCFC-141b ~15 mg/l Phenol congeners ~35 mg/l And NO KEROSENE! 3426 m 3436 m Drilling fluid components in the water ice core from hole 5G-1N Composition of the drilling fluid (sample from 3630 m depth), %: Aliphatic hydrocarbons - 45.0 Naphthene hydrocarbons -23.0 Aromatic hydrocarbons - 27.8 Hydrochloroflurocarbone (HCFC-141b) – 3.2 Ethylene glycol <0.03 Unidentified -1 = kerosene + densifier + St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

  15. Central channel Peripheral core part 3436 m 3450m Elemental analysis - increased concentrations of some elements (Na, Mg, Si, S, K, Fe – level of some mineral waters with low salt content) Concentration factor – 30-50 No any firm conclusions about the composition of the lake water. contamination samples with DF

  16. Electro conductivity of secondary lake ice Vicinity of central channel Central channel Central channel Vicinity of central channel Vicinity of central channel Midpoint of secondary frozen lake water core Voltage (V) Meteoric ice Transit to hydrate layer and meteoric ice Outer part of secondary frozen lake water Depth St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok»

  17. Summary • - Ice sheet thickness: 3759±3 m (Pice= 33.70±0.03 MPa) • - Pressure melting temperature at the bottom (most probable value): -2.67 °C • Concentration of dissolved gases in the surface layer of lake water (m.p.v): 0.7 litre/kg, far from the equilibrium with hydrate phase • Poor mixing of the source (melt) water with resident water of the main lake body • Hydrostatic imbalance, if exists, can not be resolved because of the large uncertainties of the drilling fluid pressure estimates • A series of reactions may occur between subgalcial water rising in the hole and different components of the drilling fluid • The unexpectedly high water rise in the hole can be explained by the suction effect, high level of the drilling fluid in the hole (and by degassing?) • Recommendations: • Buy a good pressure sensor and install it in the drill! • Keep fluid level low and density high (instead of other way round)! • Try to reduce suction effect St.Petersburg, 27-28 September 2013 Fr-Ru seminar «Vostok »

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