Physical properties of ice sheets – implications for, and findings from deep ice core drilling

Physical properties of ice sheets – implications for, and findings from

deep ice core drilling

F. Wilhelms, S. Kipfstuhl, S. H. Faria,

I. Weikusat, D. Dahl-Jensen, S. G. Sheldon, H. Oerter, H. Miller

CA PI E

EUROPEANPROJ EC T F O R IC E C O RI N G I NA

NTA RC

TIC

A

DO ME

CO

N CO RD I AbottomD R O NN I NGMAUDLAND

2774.15 m 17.01.2006 Dronning Maud Land

The EDML vicinity

Aim: Drill a hole and bring the core in 3.5 m long sections up

The ice core production rate

50

40

30

20

10

da ily p ro du ct io n / m | w ee kl y av er ag e pr od uc ti on / (m /d )

0 20.01.2002 27.01.2002 03.02.2002 10.02.2002 17.02.2002 22.12.2002 29.12.2002 05.01.2003 12.01.2003 19.01.2003 26.01.2003 02.02.2003 09.02.2003 16.02.2003 07.12.2003 14.12.2003 21.12.2003 28.12.2003 04.01.2004 11.01.2004 18.01.2004 25.01.2004 01.02.2004 08.02.2004 27.11.2005 04.12.2005 11.12.2005 18.12.2005 25.12.2005 01.01.2006 08.01.2006 15.01.2006 22.01.2006 29.01.2006

local date and time (GMT Sundays 00:00 ticks labelled)

weekly production / m weekly average production daily production

2001/2002

2002/2003

2003/2004

12.087 132.140 173.345 19.940 54.805 169.320 172.580 270.940 208.140 225.730 3.550 56.700 138.845 82.270 165.855 157.755 135.430 105.410 51.230

7.915 106.075

2005/2006

0.065 16.190 46.627 43.420 26.955 34.050 35.045 5.610

10 9 8 7 6 5 4 3 2 1 0

number of core pieces

27.01.2002

03.02.2002

10.02.2002

22.12.2002

29.12.2002

05.01.2003

12.01.2003

19.01.2003

26.01.2003

02.02.2003

09.02.2003

14.12.2003

21.12.2003

28.12.2003

04.01.2004

11.01.2004

18.01.2004

25.01.2004

01.02.2004

08.02.2004 13.11.2005

20.11.2005

27.11.2005

04.12.2005

11.12.2005

18.12.2005

25.12.2005

01.01.2006

08.01.2006

15.01.2006

22.01.200

6

29.01.2006

local date and time (GMT)

100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800plumbing depth / m1900 2000 2100 2200 2300 2400 2500 2550 2552 2575 2600 2625 2650 2675 2700 2725 2774

2001/ 2002 2002/2003 2003/2004 2005/2006

Number of core pieces

Brittle zone

clathrate formation

boundaries

Logging temperature

3000 2500 2000 1500 1000 500 0

EDML dril ling de pth / m

-40 -30 -20 -10 0

temperature / °C Intersection at -1.915 °C

in 2778 m drillers depth, 2790 logging depth.

radar depth 2780 ± 5 m.

Final depth 2774.15 m.

Temperature

Pressure melting curve (Wagner et al. 1994)

extrapolated with gradient over the lowermost 50 m:

0.0281 °C/m Best available logging data:

1. Log beginning of season NOV05 2. Log during the season 24JAN06 down to 2687 m drilling depth

3. Log at end of season - less precise.

Lots of refrozen water at the

bottom

Ice Coring goes arts

2500 2000

1500 1000

500 0

EDML depth / m -5.0

-4.5 -4.0 -3.5 -3.0 -2.5 -2.0

pressuredifference to ice pressure / 0.1 MPa [bar]

Slight under-pressure over 2 years

1.00

0.99

0.98

0.97

0.96

0.95

relative diameter

2500 2000

1500 1000

500 0

depth / m

modelled according to Paterson measured hole closure

First log the hole

Surprise: was not under- pressured much ->

Deformation experiments

measured hole

closure according to Nye‘s

formula as quoted in

Paterson

250

200

150

100

50

0

p re ssu re / b a rs [ = 1 0

5

Pa ]

3000 2500

2000 1500

1000 500

0 EDML depth / m

1.0

0.8

0.6

0.4

0.2

0.0

EDML d e n sity / g cm

-3

10 9 8 7 6 5 4 3 2 1 p re ssu re d iffe re n ce / b a rs [ = 1 0

5

Pa ]

3000 2500

2000 1500

1000 500

Bore-hole Log January 1^st, 2006 (corrected to tuned bore hole)

ice density [Schytt + DEP + Hobbs]

ice pressure [from ice density]

liquid pressure pressure difference

liquid density from pressure measurement

'24JAN06_pu1'

Pressure later in the season

The winch moves the underground unit on a cable

By pulling they are forced

into the core, break and

hold it (in reality they are

much smaller compared to

the core

25002400 23002200 21002000 19001800 17001600 15001400 13001200 11001000 900800 700600 500400 300200 1000 -100-200 -300-400 -500 breaking strength / (N/(9.81 ms-2 ) [kg])

27.01.2002

03.02.2002

10.02.2002

22.12.2002

29.12.2002

05.01.2003

12.01.2003

19.01.2003

26.01.2003

02.02.2003

09.02.2003

14.12.2003

21.12.2003

28.12.2003

04.01.2004

11.01.2004

18.01.2004

25.01.2004

01.02.2004

08.02.2004 13.11.2005

20.11.2005

27.11.2005

04.12.2005

11.12.2005

18.12.2005

25.12.2005

01.01.2006

08.01.2006

15.01.2006

22.01.200

6

29.01.2006

local date and time (GMT)

100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800plumbing depth / m1900 2000 2100 2200 2300 2400 2500 2550 2552 2575 2600 2625 2650 2675 2700 2725 2774

2001/ 2002 2002/2003 2003/2004 2005/2006

core breaking strength cable weight correction

The breaking strength

25x10³

20

15

10

5

0

breaking force / N

3000 2500

2000 1500

1000 500

0

EDML depth / m

breaking force

error 6% full scale systematic standard deviation of the mean

2500

2000

1500

1000

500

0

breaking load / kg

3000 2500

2000 1500

1000 500

0

EDML depth / m

core breaking load weight of cable

25x10³

20

15

10

5

0

breaking force / N

3000 2500

2000 1500

1000 500

0

EDML depth / m

breaking force

The breaking force

14x10 ³ 12 10 8 6 4 2 0

EDML brea k st ren gth / N

270 260

250 240

230

EDML temperature / K

1.5x10 ⁶

1.0

0.5

0.0

fracture st ress / Pa

52 4.7 6

72 5.1 8 92 6.5 4

11 28 .1 13 24 .9

14 24 15 23 .4

16 26 .5 17 26 .2

18 24

19 26

20 24 .3

21 29

22 25 .1 23 25 .2

24 23 .9 24 76 .5 25 29 .3

26 24 .2 26 78 .3 27 55 .8 EDML depth / m

Fits at -10 °C for approx. crystal size No indication of being dominated by crystal size change

No indication of being dominated by fabrics

Fracture stress

Crystal size generally growing Decreasing with

crystal size

Increasing with

crystal size

This fits my practical experience of

changing from brittle …

…. to ductile

Conclusions

• Ice Drilling Community: log as much of the parameters as possible: any core break is a stress test, any unbalanced hole is a

deformation test

• Physical Properties of Ice Community:

discuss mechanical design to get maybe

even better defined experimental set-up

Something to take away

14x10³ 12 10 8 6 4 2 0

EDML break strength / N

270 260

250 240

230

EDML temperature / K

1.5x10⁶

1.0

0.5

0.0

fracture stress / Pa

524.76

725.18 926.54

1128.1 1324.9

1424 1523.4

1626.5 1726.2

1824

1926

2024.3

2129

2225.1 2325.2

2423.9 2476.5 2529.3 2624.2 2678.3

2755.8 EDML depth / m

fracture stress / Pa = 3410 + 1.1e-19* exp(temperature/5.17 K)

Wilhelms, F. , Sheldon, S. G. , Hamann, I. and Kipfstuhl, S. (2007)

IMPLICATIONS FOR AND FINDINGS FROM DEEP ICE CORE DRILLINGS AN EXAMPLE: THE ULTIMATE TENSILE

STRENGTH OF ICE AT HIGH STRAIN RATES , Physics and Chemistry of Ice (The proceedings of the International Conference on the Physics and Chemistry of Ice held at Bremerhaven, Germany on 23-28 July 2006) The Royal Society of Chemistry Special Publication No. 311, p., pp. 635-639 , http://epic.awi.de/15765/

WILHELMS, F. , MILLER, H. , GERASIMOFF, M. D. , DRÜCKER, C. , FRENZEL, A. , FRITZSCHE, D. , GROBE, H. , HANSEN, S. B. , HILMARSSON, S. Æ. , HOFFMANN, G. , HÖRNBY, K. , JAESCHKE, A. , JAKOBSDÓTTIR, S. S. , JUCKSCHAT, P. , KARSTEN, A. , KARSTEN, L. , KAUFMANN, P. R. , KARLIN, T. , KOHLBERG, E. , KLEFFEL, G. , LAMBRECHT, A. ,

LAMBRECHT, A. , LAWER, G. , SCHÄRMELI, I. , SCHMITT, J. , SHELDON, S. G. , TAKATA, M. , TRENKE, M. , TWARLOH, B.

, VALERO-DELGADO, F. and WILHELMS-DICK, D. (2014)

The EPICA Dronning Maud Land deep drilling operation , Annals of Glaciology, 55 (68), pp. 355-366 . doi:10.3189/2014AoG68A189 , hdl:10013/epic.45066 , http://epic.awi.de/37370/

Weikusat, I. , Jansen, D. , Binder, T. , Eichler, J. , Faria, S. H. , Wilhelms, F. , Kipfstuhl, S. , Sheldon, S. , Miller, H. , Dahl-Jensen, D. and Kleiner, T. (2017) Physical analysis of an Antarctic ice core—towards an integration of micro- and macrodynamics of polar ice , Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 375 (2086), p.

20150347 . doi:10.1098/rsta.2015.0347 , http://epic.awi.de/42978/