Sedimentological and Glacial Geological Studies at the Law Dome Ice Margin
Metadata record for data from ASAC Project 339 See the link below for public details on this project. From the abstracts of some of the referenced papers: This paper presents the results of a detailed study on the geomorphic and diagnetic processes of surface-layer formation and its subsequent prese...
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Australian Antarctic Data Centre
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| Online Access: | https://researchdata.ands.org.au/sedimentological-glacial-geological-ice-margin/700144 https://data.aad.gov.au/metadata/records/ASAC_339 http://nla.gov.au/nla.party-617536 |
| Summary: | Metadata record for data from ASAC Project 339 See the link below for public details on this project. From the abstracts of some of the referenced papers: This paper presents the results of a detailed study on the geomorphic and diagnetic processes of surface-layer formation and its subsequent preservation in the stratigraphic record. The study supplemented stratigraphic studies carried out along a 750km ANARE traverse route along the 69 deg South parallel between 112 deg and 131 deg East (which approximately follows the 2000m contour) in the katabatic wind zone of eastern Wilkes land. A 100 cane farm was established at GD03 (69 deg South 115 deg East; 1835m a.s.l.), adjacent to a 30m deep firn-core drill site. The cane farm was used to monitor seasonal changes in snow accumulation and the type, size, distribution and orientation of the surface micro-relief. The annual snow accumulation at GD03 is equivalent to 300kg m-2 of water. This annual layer is visibly marked by a multi-layered ice crust, typically 1-2mm thick, which is formed in autumn during a hiatus in snow supply. Within the annual layer, single-layered thin ice crusts were observed. These correspond to short hiatus periods, of the order of 2-3 weeks, during late winter to early spring, and radiation glazes formed during summer. Density and oxygen-isotope - depth profiles display annual cyclicity within the snow-pack. Considerable horizontal variation was found in a single annual-layer thickness, with respect to ice-crust thickness, snow-density and oxygen-isotope - depth values, and depth-hoar development, when traced in 21 2m cores drilled at 5m horizontal spacing. The observed changes in surface micro-relief distributions over the cane farm have enabled a greater understanding of vertical variations between annual layers observed in the 30m firn core. A jokulhlaup event of 6 months duration occurred near Casey Station, Law Dome, Antarctica, in late March (austral autumn) 1985. This was followed by sporadic outbursts during the austral autumn and winter of 1986. The event is the first recorded outburst of water from beneath a cold ice-cap terminus on Law Dome and, to the authors knowledge, in Antarctica. From the results of oxygen-isotope and solute analysis, the water was found to have originated as basal melt water. It contained a high total solute load with a dominant enrichment in alkalis, indicating that it had been squeezed through subglacial sediments for an extensive time period. Evidence from the subgalcial topography, basal ice exposures, and the presence of an ice-marginal subglacial reservoir as the jokulhlaup source. Snow accumulation and surface microrelief distributions, together with the surface katabatic wind pattern and elevation profiles, are presented for the eastern Wilkes Land katabatic wind zone. The broad scale net accumulation distribution displays a strong negative correlation with elevation but on the mesoscale there are significant variations with respect to the elevation profile. The accumulation distribution was found to be dependent on slope aspect. Higher accumulation rates were observed on the north-east (windward) slope than those on the north-west (leeward) slope for the elevation range of 1870 m - 2230 m. These higher accumulation rates are associated with the occurrence of longitudinal dunes deposited by precipitation, during synoptic events. The dependence of the accumulation distribution on aspect implies that synoptic and orographic processes are the major control on the depositional regime, and that maritime synoptic systems regularly penetrate eastern Wilkes Land to at least 2300 m elevation. |
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