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Victoria University Antarctic Research Expedition Science and Logistics Reports 2001-02: VUWAE 46

Ice Core Drilling

Ice Core Drilling

In order to collect, store and process a 200m core, a field ice core laboratory / clean room was excavated (Fig.3). In the process 90m3 (?20t) of snow were moved. The temperature in the storage compartments had to be kept below –20°C, a temperature that guarantees that the chemical and isotopic characteristics of the cores are conserved. At a depth of 2.70m we reached this temperature, a remanent of the cold winter wave that travels from the glacier surface downwards.

Fig.3 Field Ice Core Laboratory

Fig.3 Field Ice Core Laboratory

Once the preparation for the drilling was completed, the drilling crew and the ICDS/NSF supplied electromechanical drill were flown to Victoria Lower Glacier. The drilling system worked well and we reached a depth of 180m (Fig.4). The processing crew extracted the core from the core barrel in the field laboratory in order to avoid contamination. The cores were then cleaned from cuttings (Fig.5), packed in "layflat" tubing, measured (Fig.6), and finally logged (Fig.7) before stored in the 'freezer' compartments of the snow pit. The ice cores were flown out to the transitional ice core facilities at McMurdo Station.

Fig.4: Alex Pyne and Tony Kingan drilling at Victoria Lower Glacier

Fig.4: Alex Pyne and Tony Kingan drilling at Victoria Lower Glacier

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The core quality deteriorated somewhat below 50m, a depth that coincides with a sharp boundary in the ground penetrating radar profile. This indicates that the ice below 50m could be older than first assumed, which makes the air enclosed in the ice potentially very interesting. The ICDS head ice core driller, Mr. Bruce Koçi, visited us in order to discuss possibilities to improve the core quality. Although some progress was made, in order to recover core material that is suitable for air bubble analysis a wet drilling system (electromechanical drill with drilling fluid) will have to be employed for this in future. The quality of the recovered core is sufficient for the proposed water and dust analysis. At Crary Laboratory the cores were split and sent to New Zealand and our collaboration partner, Prof. Paul Mayewski in the USA.

Fig.5: Nora Patterson cleaning ice cores

Fig.5: Nora Patterson cleaning ice cores

Fig.6: Nora Patterson and Matt Hill processing ice cores

Fig.6: Nora Patterson and Matt Hill processing ice cores

Fig.7: Nancy Bertler logging ice cores

Fig.7: Nancy Bertler logging ice cores

The drill hole was cased and capped (Fig. 8) to preserve the hole for future measurements, such as borehole temperature, magnetic susceptibility, transmissivity of light amongst others.

Fig.8: Cased and capped drilling hole

Fig.8: Cased and capped drilling hole