IMMEDIATE SCIENCE REPORT
K047: Dating Relict Ice in the Dry Valleys
Antarctica New Zealand 2004/05
1 Popular Summary of Scientific Work Achieved
In the last 15 years, deep cores through the Antarctic ice sheet have provided a wealth of high resolution climate data, which have been invaluable for testing both regional and global climate models. Although ice core data only cover the last 500,000 years of earth history, the possibility of obtaining much older climate data is now recognized in a few select areas where ancient glacial ice has stagnated and lies buried beneath rock debris. Beacon Valley contains the best known relict ice, which if glacial has been dated by a volcanic ash layer as more than 8 million years old. This age remains controversial, but other occurrences of relict ice have recently been discovered in Pearse, Columnar, and Victoria Valleys and appear to be analogous to Beacon. The ongoing aim of this project is to understand the origin and paleoenvironmental significance of ice from these areas and place them in context with the Beacon Valley ice. Of particular value will be the independent dating of debris covering the ice. We will use a new method of beryllium-10 dating, which unlike exposure age methods, can extend back at least 20 million years.
2 Proposed Programme
Lower Victoria Valley (13 Nov – 1 Dec)
- Sample ice in modern glacial and lake environments at snout of Lower Victoria Glacier. Sample buried ice and ice cemented sediment down valley (stream) from Lower Victoria Glacier.
- Sample several soil profiles for Atm Be-10 on top of buried ice, down valley from Lower Vic Glacier.
- Survey profiles of meltwater channels around the Packard Glacier for a paper by Atkins and Dickinson entitled 'Landscape modification by meltwater channels at margins of cold-based glaciers'.
- Testing of resistivity soundings/profiling over known occurrences of ground ice (both massive and ice cemented sediment).
Beacon Valley (1 – 10 Dec)
- Sample ice in modern glacial and lake environments around Beacon Valley. Sample buried ice and ice cemented sediment in central Beacon Valley as well as one of the side valleys (University or Farnell). Also to sample the main body of ice in central Beacon Valley to look for spatial differences/variations since vertical variations are nil.
- Sample several soil profiles for Atm Be-10 on top of the buried ice.
- Testing of resistivity soundings/profiling over central Beacon Valley. These should follow the gravity and GPR lines of Ron Sletten.
3 Scientific Endeavours and Achievements
Summary
The four members of the event spent 17 days in Lower Victoria Valley from 13 Nov to 1 Dec and 9 days in central Beacon Valley from 1 Dec to 10 Dec. Ice and permafrost samples (Table 1), resistivity soundings, and topographic profiles were completed in both of these areas. Resistivity soundings may be useful in imaging subsurface ice in Beacon Valley. However, variable conditions (thawing) on the surface of the Lower Victoria Valley caused unstable resistivity readings and these yielded ambiguous results in this area.
Method
Sampling sites were selected for the occurrence of massive relict ice. At each site, a 1.5 square metre pit was dug into the ice free soil or sediment above the relict ice. In some areas ice cemented sediment was above the relict ice. This was sampled by means of a small gasoline powered hammer drill with a diamond or carbide core bit. Once into the relatively sediment-free relict ice, a sipre auger with carbide cutters was used to core to a depth of about one metre.
Ian Graham and co-workers at GNS, Lower Hutt, will carry out the dating method using atmospheric 10Be. The procedure will be similar to that used in previous studies (Dickinson et al. 2003b; Graham et al. 1995; Graham et al. 2002). To streamline the method, we will only process the >62 micron fraction of sediment which we believe contains most of the Be.
Samples of relict ice taken at 5cm intervals down the sipre auger cores were subsampled and sent to Ron Sletten at the University of Washington for chemical and isotopic analyses (see supporting letter).
Resistivity soundings (one dimensional, vertical profile) were made in selected locations where relic ice was sampled. The results are expected to help characterize the extent and depth of the relict ice. Previous attempts by A. Hubbard (pers. comm. 2001) and H. Conway (pers. comm. 2003) to define the depth of the ice by ground penetrating radar (GPR) have yielded ambiguous results because of salts that have accumulated in the soils and ice. Apart for these two surveys, other geophysical surveys to define the depth of the ice have not been conducted in Beacon Valley.
4 Publications
A paper on landscape modification by meltwater from the Packard Glacier will be submitted to the Journal of Glaciology in April 2005. Results from OSL sampling of Victoria Valley sediments will be published as a paper and poster for the 11th International Conference on Luminescence and Electron Spin Resonance Dating (LED 2005), at the University of Cologne, July 2005. Results from sampling the relict ice in Victoria Valley will first be published as an MSc thesis at Victoria University in 2006. Copies of these will be sent to Antarctica NZ. The resistivity data will be published as an Antarctic Research Centre Report in may 2005.
page 3Further publications of the scientific results will be published in international peer-reviewed scientific journals. Copies of this work will also be sent, when available, to Antarctica NZ.
5 Acknowledgments
Thanks to the following:
Prof Peter Barrett, (Director, Antarctic Research Centre, VUW)
Dean Peterson, Paul Woodgate and Keith Springer, (Antarctica NZ)
All of the Scott Base personnel (Nov-Dec 2004)
Special thanks to NSF and personnel at the Crary Lab for use of freezer space and ice core storage
Websters Drilling, for equipment preparation and cargo handling
Funding and Support
Antarctica New Zealand,
University Grants Committee, VUW
Foundation of Research and Technology, NZ
Ident | Lat | Long | Location | Ice/sediment type | Type & Wt. (Kg) |
---|---|---|---|---|---|
VI1-1 | −77.3721 | 162.227 | valley floor - geophys site | clear ice pod in gravel lag | ice (10) |
VI1a | valley floor - geophys site | clear ice pod in gravel lag | ice (0.2) | ||
VI1b | valley floor - geophys site | clear ice pod in gravel lag | ice (0.2) | ||
VI1c | valley floor - geophys site | clear ice pod in gravel lag | ice (0.2) | ||
VI1d | valley floor - geophys site | clear ice pod in gravel lag | ice (0.2) | ||
VI2a | −77.3720 | 162.345 | Kaotica - Victoria Stream | massive clear ice | ice (0.2) |
VI2b | Kaotica - Victoria Stream | massive clear ice | ice (0.2) | ||
VI2c | Kaotica - Victoria Stream | massive clear ice | ice (0.2) | ||
VI2d | Kaotica - Victoria Stream | massive clear ice (~ 1m away from a,b,c) | ice (0.2) | ||
VI2e | Kaotica - Victoria Stream | massive clear ice (~ 1m away from a,b,c) | ice (0.2) | ||
VI2f | Kaotica - Victoria Stream | undeformed sediment-rich ice sample | sed-rich ice (0.2) | ||
VI2g | Kaotica - Victoria Stream | homogeneous sand bleb (OSL sample taken) | ice-cement sed (0.2) | ||
VI2h | Kaotica - Victoria Stream | homogeneous sand bleb (OSL sample taken) | ice-cement sed (0.2) | ||
VI2i | Kaotica - Victoria Stream | massive clear ice (above main outcrop) | ice (0.5) | ||
VI2j | Kaotica - Victoria Stream | homogeneous sand boudin (OSL sample taken) | ice-cement sed (0.2) | ||
VI2k | Kaotica - Victoria Stream | homogeneous sand boudin (OSL sample taken) | ice-cement sed (0.2) | ||
VI2l | Kaotica - Victoria Stream | homogeneous sand boudin (OSL sample taken) | ice-cement sed (0.2) | ||
VI3a | −77.3726 | 162.335 | Victoria Stream downstream from (VI2) | massive, clear ice in bank | ice (0.2) |
VI3b | Victoria Stream downstream from (VI2) | massive, clear ice in bank (few cm from a,c,d) | ice (0.2) | ||
VI3c | Victoria Stream downstream from (VI2) | massive, clear ice in bank | ice (0.2) | ||
VI3d | Victoria Stream downstream from (VI2) | massive, clear ice in bank | ice (0.2) | ||
VI4a | −77.3721 | 162.319 | Victoria Stream downstream from (VI3) | massive, clear ice in bank | ice (0.2) |
VI4b | Victoria Stream downstream from (VI3) | massive, clear ice in bank | ice (0.2) | ||
VI4c | Victoria Stream downstream from (VI3) | massive, clear ice in bank (~1m from a,b) | ice (0.2) | ||
VI5a | −77.3712 | 162.362 | Victoria Stream upstream from VI2 | massive, clear ice in bank | ice (0.2)page 4 |
VI5b | Victoria Stream upstream from VI2 | massive, clear ice in bank | ice (sed at base) (0.2) | ||
VI5c | Victoria Stream upstream from VI2 | massive, clear ice in bank (~5m away from a,b) | ice (sed at base) (0.2) | ||
VI5d | Victoria Stream upstream from VI2 | massive, clear ice in bank (~10 away from c) | ice (0.2) | ||
VI6a | −77.3710 | 162.381 | Victoria Stream upstream from VI5 | massive, clear ice in bank (~4m from c) | ice (0.2) |
VI6b | Victoria Stream upstream from VI5 | massive, clear ice in bank (~4m from c) | ice (0.2) | ||
VI6c | Victoria Stream upstream from VI5 | ice overlain by sed. then ice (OSL + algae taken) | ice (0.2) | ||
VI6d | Victoria Stream upstream from VI5 | ice overlain by sed. then ice (OSL + algae taken) | ice (0.2) | ||
VI6-1 | Victoria Stream upstream from VI5 | ice overlain by sed. then ice (OSL + algae taken) | ice (5) | ||
VI7a | −77.3704 | 162.401 | Victoria Stream upstream from VI6 | massive, clear ice in bank | ice (0.2) |
VI7b | Victoria Stream upstream from VI6 | massive, clear ice in bank | ice (0.2) | ||
VI8a | −77.3669 | 162.402 | Victoria Lower Glacier front (south) | clear ice within pod of lake sed in glacier (OSL) | ice (0.2) |
VI8-1 | Victoria Lower Glacier front (south) | glacier ice | ice (5) | ||
VI8-2 | Victoria Lower Glacier front (south) | glacier ice | ice (5) | ||
VI9-1 | −77.3669 | 162.409 | VLG apron/front (south) | ice-cored mound in apron | ice (5) |
VI9-2 | VLG apron/front (south) | ice-cored mound in front ~ 4m upslope from VI91 | ice (5) | ||
VI9-3 | VLG apron (south) | wedged-up pro-glacial lake | ice (5) | ||
VI10 | −77.3626 | 162.355 | VLG (north) geophys site | wedged-up pro-glacial lake (sed in core at 108cm) | ice (5) |
VI11a | −77.3672 | 162.415 | VLG (south) | ice-cored mound ~ 50m in front of glacier | ice (0.2) |
VI11b | VLG (south) | ice-cored mound ~ 50m in front of glacier | ice (0.2) | ||
VI11c | VLG (south) | ice-cored mound ~ 50m in front of glacier | ice (0.2) | ||
VI12 | −77.3679 | 162.421 | VLG (south) | linear lines of ice outcropping ~ 70m in front of glacier | ice (8) |
VI13a | −77.3677 | 162.384 | VLG (south) stream bank | clear, massive ice (with assicated contortions) | ice (0.2) |
VI13b | VLG (south) stream bank | clear, massive ice (with assicated contortions) | ice (0.2) | ||
VI14-1 | −77.3664 | 162.377 | VLG apron (middle) | glacier apron ice | ice (5) |
VI15-1 | −77.3597 | 162.358 | VLG (north) by ice cave | ice-cored moraine ~ 20m from glacier cliff | ice (5) |
VI16-1 | −77.3594 | 162.357 | VLG (north) by ice cave | lake over glacier ice in ice-cored moraine | ice (5) |
VI17-1 | VLG (north) by ice cave | glacier ice from ice cliff (ice cave blocks) | ice (3) | ||
VI18a | −77.3775 | 162.152 | Victoria Stream (north) west of camp | clear, massive ice in stream bank (OSL taken) | ice (0.2) |
VI18b | Victoria Stream (north) west of camp | clear, massive ice in stream bank (OSL taken) | ice (0.2) | ||
VI18c | Victoria Stream (north) west of camp | clear, massive ice in stream bank (OSL taken) | ice (0.2) | ||
VI19 | −77.3603 | 162.190 | Packard glacier cliff (west) | glacier ice from ice cliff by sed bleb | ice (3) |
VI20 | −77.3587 | 162.198 | Packard glacier cliff (east) | glacier ice from cave behind icicles | ice (3) |
VI21 | Lake Vida ice sample | ice (3) | |||
VI22 | −77.3600 | 162.350 | Victoria Stream (north) west of camp | clear, massive ice (with assicated contortions) | ice (0.2) |
BI1a | −77.8484 | 160.603 | Polygon by weather station | profile in shoulder | dirty ice (5) |
BI1b | Polygon by weather station | profile in shoulder - taken from below sample BI1a | dirty ice (0.2) | ||
BI1c | Polygon by weather station | profile in shoulder - taken from below sample BI1a | dirty ice (0.2) | ||
BI1d | Polygon by weather station | profile in shoulder - taken from below sample BI1a | dirty ice (0.2) | ||
BI1e | Polygon by weather station | profile in shoulder - taken from below sample BI1a | dirty ice (0.2) | ||
BI2a | −77.8484 | 160.603 | Polygon by weather station | profile in top | ice-cemented (0.2) |
BI2b | Polygon by weather station | profile in top (melted and refrozen) | ice-cemented (0.2) | ||
BI2c | Polygon by weather station | profile in top | ice-cemented (0.2)page 5 | ||
BI2d | Polygon by weather station | profile in top | ice-cemented (0.2) | ||
BI2e | Polygon by weather station | profile in top | ice-cemented (0.2) | ||
BI3a | −77.8484 | 160.603 | Polygon by weather station | profile in side (clockwise from BI1 looking upvalley) | dirty ice (10) |
BI4a | −77.8484 | 160.603 | Polygon by weather station | profile in side (clockwise from BI3 looking upvalley) | dirty ice (10) |
BI4b | Polygon by weather station | profile in side (clockwise from BI3 looking upvalley) | ice-cemented (5) | ||
BI5 | −77.8595 | 160.570 | 600m across valley from camp | profile in side | dirty ice (10) |
BI6 | −77.8560 | 160.556 | 1100m across valley from camp | profile in side | dirty ice (10) |
BI7 | −77.8532 | 160.547 | 1500m across valley from camp | profile in side | dirty ice (10) |
BI8 | −77.8844 | 160.560 | slope up to Mullen's Valley | shoulder, by triple junction | dirty ice (10) |