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Record Search Query:

Measurements of the effects of debris on the mechanical behaviour (deformation and motion) of ice of the Taylor Glacier, Taylor Valley, Antarctica

Entry ID: K053_1992_2000_NZ_1

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Summary

Abstract: Debris-rich ice is a commonly observed basal ice facies found at the base of many temperate and polar glaciers and at the base of cores through major ice sheets. The effects of the presence of debris on the mechanical behaviour of ice was investigated and then the implication of those effects for the overall dynamics of ice masses was examined at the Taylor Glacier, Taylor Valley, Antarctica over ... three field seasons. 51 uniaxial compression tests, 30 shear strength tests, 120 point load tests and 31 Brazilian tensile strength tests were carried out on debris-laden ice samples, and 140 point load tests were carried out on clean ice samples. Debris laden and clean ice were sampled (blocks and cores) and analysed for characteristics and crystallography. Relative rates of deformation were determined by measuring over time the relative positions of a grid of metal pegs installed. The mechanical strength of debris-laden and clean ice in uncontrolled field conditions and in temperature controlled laboratory conditions (cold room laboratories at -5, -15 and -25°C) was measured to determine the effect of temperature on strength on both types of ice. Temperature data was collected from ice away from the glacier margin by placing a line of temperature sensors in a 10m long bore-hole and recording it to investigate the variation in the ice thermal regime away from the ice margin. Ice samples were obtained in situ for unconfined compressive strength testing and laboratory tests for triaxial and constant stress tests. The importance of deformation of the basal ice layer (with different characteristics) in the overall motion of the Taylor Glacier, was also assessed. A detailed map of stress fields and surface velocity over the lower part of the glacier was completed using GPS and GPR. The surface topography was obtained by GPS surveying comprising sampling along a series of approximately evenly spaced profiles. The bed topography was obtained by GPR. Surface velocities were obtained by establishing a network of about 70 surface markers extending approximately 5km up the glacier and repeatedly resurveying every 2-4 days. The role of sublimation in moisture loss from debris-laden ice at the margins of the glacier was determined by installing a climate station on the alluvial fan where the stream at the north side of the glacier runs into Lake Bonney and installing three small lysimeters on the debris-laden ice at the margin of the glacier to enable the moisture balance of a sample of surficial material to be evaluated. Basal ice was sampled for comparative testing in order to differentiate behaviours of different facies. The types and characteristics of basal ice facies found in the basal layer of the Taylor Glacier were determined by sampling and examining the physical, chemical and isotopic characteristics of the ice. To explore the hypothesis that clear basal ice forms by metamorphism of clean glacier ice, analysis and comparison of the included-gas compositions of clear basal ice facies and overlying glacier ice was carried out on collected samples. An array of markers was placed in a marginal ice cliff and was re-surveyed at regular intervals to determine if debris-laden ice deforms more rapidly in situ than overlying clean glacier ice.

Geographic Coverage

(Click for Interactive Map)

Spatial coordinates

N: -77.73

S: -77.73

E: 162.17

W: 162.17

Temporal Coverage

Start Date: 1992-12-14

Stop Date: 1993-01-16

Location Keywords

CONTINENT > ANTARCTICA

CONTINENT > ANTARCTICA > TAYLOR GLACIER

CONTINENT > ANTARCTICA > TAYLOR VALLEY

GEOGRAPHIC REGION > POLAR

Science Keywords

CRYOSPHERE > GLACIERS/ICE SHEETS > GLACIERS

CRYOSPHERE > GLACIERS/ICE SHEETS > GLACIER MASS BALANCE/ICE SHEET MASS BALANCE

CRYOSPHERE > GLACIERS/ICE SHEETS > GLACIER MOTION/ICE SHEET MOTION

ISO Topic Category

BIOTA

ENVIRONMENT

OCEANS

Platform

FIELD SURVEYS

LABORATORY

FIELD INVESTIGATION

Quality The values provided in temporal and spatial coverage are approximate only.

Taken from the 2008-2009 Progress Report:
Variations to work plan or objectives:
With greatly reduced field work possible in the 2008/09 season, the work plan for this project has been modified this year. The experiments planned to be conducted in situ in Antarctica over the 0809 summer season will ... now be done over the 2009 winter in the Ecotoxicology aquarium facilities at Kingston. The lack of project personnel and the short field season on station this past season will certainly result in changes to the future work plan, and attempts will be made to maximise time on station for several project personnel over the next 2 to 3 seasons to enable this project to be completed.

Field work:
A short field season of approximately 5 weeks was conducted at Casey in 2008/09 with a team of 6 scientists working together on an intensive marine sampling program under TRENZ (AAS project 2948, CI Stark) in support of 5 different AAS projects including this one. Sampling of live invertebrates for this project was done in various habitats at several locations on the coast close to Casey. Sampling was done by dip netting, grab samples, dredges, traps, and by snorkellers. No in situ experimental field work was possible over this short season with such a small team. Hopefully berths on station will be less limited over the next 2 to 3 seasons, the Marine Ecotoxicology aquarium field module will be completed and taken south as cargo, and the dive program will take place at Davis station. With a larger team available to work on this project, and more time allocated to be on station, we should be able to generate the data required to complete this project over the next few years. It is anticipated that our project team will spend 4-6 months at Davis station this year working with the dive team and using the field aquarium module currently being built by the STS workshop.

Laboratory activity/analysis:
Laboratory experiments were not possible at Casey this season for reasons discussed previously. Experiments with live invertebrates will therefore be conducted in the marine ecotoxicology aquarium here at Kingston over the next months prior to the 2009/10 field season. It is anticipated that with the capability of the Ecotoxicology aquarium here at Kingston and the Marine Ecotoxicology aquarium field module that laboratory based toxicity tests will be able to be run almost year, so long as adequate support is provided to the maintenance of these aquarium facilities in the future.

Difficulties affecting project:
The main difficulty experienced in this project was the lack of available berths for the 2008/09 (and the previous 2007/08) season. While this has delayed progress, it is unlikely to affect the overall outcomes of the project in the long term and has not resulted in significant changes to the project objectives or design. In addition, we have modified the project to include more use of the cold water facilities at Kingston which hopefully when fully developed will enable experiments to be carried out year round.

Taken from the 2009-2010 Progress Report:
Field work:
A field season was conducted at Davis in 2009/10 with 2 project personnel. Sampling of live invertebrates for this project was done in various habitats at several locations on the coast close to Davis. Sampling sites were accessed either by IRB, helicopter or on foot. Sampling was done by dip netting and by snorkellers.

Laboratory activity/analysis:
Laboratory experiments were conducted at Davis this season using live invertebrates. Unfortunately the decommissioning of the Ecotoxicology Lab at Kingston means that laboratory experimentation will be limited to field seasons in the immediate future until upgrades and modifications can be competed.

Access Constraints Data (if available) are accessible via the child records.

Use Constraints This data set conforms to the PICCCBY Attribution License
(http://creativecommons.org/licenses/by/3.0/).

Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_2933 when using these data.

Ancillary Keywords

pollution

marine environments

remediation

Data Set Progress

IN WORK

Data Center

Australian Antarctic Data Centre, Australia

Data Center URL: http://data.aad.gov.au

Data Center Personnel
Name: DATA OFFICER AADC Phone: +61 3 6232 3244 Fax: +61 3 6232 3351 Email: metadata at aad.gov.au Contact Address: Australian Antarctic Division 203 Channel Highway City: Kingston Province or State: Tasmania Postal Code: 7050 Country: Australia

Personnel

CATHERINE KING

Role: INVESTIGATOR

Role: TECHNICAL CONTACT

Phone: +61 3 6232 3515

Email: cath.king at aad.gov.au

Contact Address:

Australian Antarctic Division

203 Channel Highway

City: Kingston

Province or State: Tasmania

Postal Code: 7050

Country: Australia

DAVE CONNELL

Role: DIF AUTHOR

Phone: +61 3 6232 3244

Fax: +61 3 6232 3351

Email: dave.connell at aad.gov.au

Contact Address:

Australian Antarctic Division

203 Channel Highway

City: Kingston

Province or State: Tasmania

Postal Code: 7050

Country: Australia

Publications/References

Hill NA, King CK, Perrett L, Johnston EL (200), Contaminated suspended sediments toxic to an Antarctic filter feeder: Aqueous and particulate-phase effects., Environ. Toxicol. Chem., 2, 28, 4109-417

Creation and Review Dates

DIF Creation Date: 2009-04-23

Last DIF Revision Date: 2011-05-24

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