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Victoria University Antarctic Research Expedition Science and Logistics Reports 1977-78: VUWAE 22

SCIENTIFIC ACHIEVEMENTS

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SCIENTIFIC ACHIEVEMENTS

A. Glacial Sediment Studies

Taylor Glacier, a plateau-fed 'polar' glacier, has been under investigation for the past 3 austral summer field seasons. During the 1977-78 season ice-velocity, ablation and temperature recordings were continued for a Taylor Glacier mass balance study. This was incorporated into the main programme involving detailed study of basal ice dynamics and sediment texture; and 'recent past' Taylor ice expansions into the surrounding Kennar, Turnabout, Beacon, Arena and Pearse Valleys.

Ice velocity measurements were undertaken during early November and late January with the aid of two surveyors (J. Palmer and N. Nalder, Lands and Survey Department). Interim results indicate movement similar to that measured during 1976-77. A maximum down-glacier movement of 5.5 meters year −1 in the snout region was recorded for that same period.

Ablation measurements (early Nov. - mid Jan.) are lower than those for the same period last year, by as much as 50 per cent. The effect of generally lower temperatures and high precipitation.

Ice temperature measurements in a 20-meter hole drilled into the glacier indicate a mean annual air temperature of approx. −20°C at c800 meters elevation. This closely approximates previously measured temperatures (Anderson, et al., 1977) and known atabatic lapse rates for the region.

A study of basal ice along the margins of Taylor Glacier revealed englacial sediment concentrations ranging from 0.4 to 60 per cent. Movement of this basal debris-rich ice was measured (using precision engineering dial gauges in a tunnel access) and found to be moving by internal deformation, that is, no basal slip occurs along the margins of the Taylor Glacier.

Further englacial and proglacial sediment sampling was undertaken. Basic textural sediment analysis will be done as part of a project to determine different sedimentary environments from sedimentological characteristics.

Anderson, et al., 1977. Immediate Report of Victoria University of Wellington Antarctic Expedition, 1976-77. Wellington.

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B. Geochemical Studies

1. Crystal Chemistry of the Erebus Lava Flows

Samples of Kenyte containing anorthclase and plagioclase feldspar crystals were collected from exposed lava flows at Cape Royds, Barne, Evans, Turks Head and the Dellbridge Islands. Structural studies by X-ray diffraction methods will be carried out on these feldspars to see if the Si/Al distribution in them can be determined, and if the crystallographic parameters can be used to correlate the flows.

2. Mössbauer Spectroscopic Study of Desert Varnish

Samples of dolerite, granite, sandstone and quartzite heavily stained with desert varnish were collected from appropriate outcrops in the Depot Nunatak, Kennar, Beacon, Pearse, lower Taylor Valleys, Labyrinth, Upper Wright Valley, and the Olympus range and Lake Vida areas of the Victoria Valley. The prevailing wind direction, and patterns of local snow accumulations, particularly in the Labyrinth, were noted to see if these were of significance to the distributions and nature of desert varnish coatings.

Mössbauer spectroscopy and nuclear microprobe methods will be used to study the iron mineralogy of these coatings to see if the different locations and bedrock types are of significance to their nature and formation.

3. Secondary Iron Oxide/Oxidehydroxide Mineralogy of Soils

"Soil" samples were also collected at the above-mentioned locations. Mössbauer spectroscopy will be used to determine the extent of weathering and soil formation in these locations.

4. Geothermometric Studies of Olivine Basalts

Olivine - containing samples were collected from Crater and Observation Hills, and from the cinder cones in the Lake Bonney areas of the Taylor Dry Valley.

Mössbauer spectroscopy will be used to determine the cation distribution and hence the cooling history of these olivines.

C. Beacon Studies

At Finger Mountain the Maya Erosion Surface proved to have steep local relief in excess of 56 meters. The Metschel Tillite comprises of fluvial and fluvioglacial sandstones, conglomerates and a thin sandy diamictite, infilling the Maya Erosion Surface fossil scarp. Paleocurrent data indicates an east-northeasterly transport direction.

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In the Kennar Valley the Maya Erosion Surface also has considerable relief. The mantling Metschel Tillite has undergone soft sediment deformation and exhibits large scale (including overturned) folds and both steep and horizontal thrusts. Facies of the Metschel Tillite include laminated mudstones and siltstones, silty sandstones interbedded with thin diamictites (flow tills), quartzite sandstones and massive diamictices.

The basal Weller Coal Measures overlie the Metschel with a local angular unconformity. These coal measures contain quartzo-feldspathic medium to very coarse sandstones with carbonaceous streaks, fissile carbonaceous shales and 3 thin (less than 1 meter thick) coal seams, laterally persistent over 200 meters.

Two small outcrops of well stratified Metschel Tillite out-wash sediments were located near the head of Beacon Valley at the base of the northeastern spur of Mount Feather.