Connections between South Africa and Antarctica can be traced as far back as the 1700s when European expeditions in search of the southern continent used Cape Town (and later Simonstown) as a base of operation. This link expanded considerably after formal British acquisition of the Cape of Good Hope in 1815, yet it was not until 1926 that an actual South African policy towards the Antarctic began to materialize. Once this policy was established it continued to be characterized by procrastination as well as resistance both from within and without South Africa. The history of South Africa's Antarctic policy can be divided into five periods: first, the commencement of the policy (focusing primarily on economic interests), 1926-1939; second, the pursuit of interests through the policy (focusing on political interests), 1944- 1958; third, the entrenchment of South Africa's interests in the Antarctic (by securing South Africa's position within the Antarctic Treaty System), 1958-1960; fourth, the expansion of and foreign assault on the policy (under the auspices of the Antarctic Treaty System), 1960-1988; and fifth, the defence of and future prospects for the policy (from United Nation's calls for South Africa's exclusion from the Antarctic Treaty System), since 1982. While resistance from inside and outside the government during the first two periods resulted from inadequacies in the South African Antarctic policy itself, resistance in the final two periods has centred upon non-Antarctic issues. As South Africa has faced ever-increasing exclusion from international governmental organizations over opposition to Its apartheid policies, organizations such as the Antarctic Treaty Organization have inevitably been drawn into the debate. As a result, the Consultative Parties of the Antarctic Treaty (of which South Africa is one of the original twelve) have been forced to deal with the following question: to what extent will political issues outside the scope of the management policies of the Antarctic Treaty Organization be allowed to affect the functioning of the Antarctic Treaty System? While the Consultative Parties continue to ponder this and the fact that South Africa's Consultative Status has become the most divisive factor within the Antarctic Treaty System, no final solutions to these issues appear likely before 1991.

Ocean warming near the Antarctic ice shelves has critical implications for future ice sheet mass loss and global sea level rise. A global climate model with an eddying ocean is used to quantify the mechanisms contributing to ocean warming on the Antarctic continental shelf in an idealized 2xCO(2) experiment. The results indicate that relatively large warm anomalies occur both in the upper 100 m and at depths above the shelf floor, which are controlled by different mechanisms. The near-surface ocean warming is primarily a response to enhanced onshore advective heat transport across the shelf break. The deep shelf warming is initiated by onshore intrusions of relatively warm Circumpolar Deep Water (CDW), in density classes that access the shelf, as well as the reduction of the vertical mixing of heat. CO2-induced shelf freshening influences both warming mechanisms. The shelf freshening slows vertical mixing by limiting gravitational instabilities and the upward diffusion of heat associated with CDW, resulting in the buildup of heat at depth. Meanwhile, freshening near the shelf break enhances the lateral density gradient of the Antarctic Slope Front (ASF) and disconnect isopycnals between the shelf and CDW, making cross-ASF heat exchange more difficult. However, at several locations along the ASF, the cross-ASF heat transport is less inhibited and heat can move onshore. Once onshore, lateral and vertical heat advection work to disperse the heat anomalies across the shelf region. Understanding the inhomogeneous Antarctic shelf warming will lead to better projections of future ice sheet mass loss.

D.Sc / Neumayerskarvet forms a continuous outcrop of high-grade gneiss within the northern Kirwanveggen in western Dronning Maud Land, Antarctica. A detailed geological study was carried out to obtain an evolutionary history for Neumayerskarvet. The work involved field mapping to provide a structural framework for further metamorphic and isotopic investigations. U-Pb zircon SHRIMP analysis, Rb-Sr, Sm-Nd and Ar-Ar mineral analysis were used to provide absolute time constraints on different tectono-metamorphic periods and cooling histories. Petrographic investigations, coupled with mineral chemistry on kyanite-bearing leucogneisses, provided information on the P-T conditions. An understanding of the crustal evolution of the high-grade gneisses was obtained through whole-rock geochemistry and isotope analysis. The dominant lithotectonic unit preserved at Neumayerskarvet is biotite-garnet migmatite gneiss, which is inter-fingered with quartzofeldspathic gneisses and banded quartz-feldspar gneisses. Several magmatic phases have intruded these sequences. Three tectonometamorphic cycles have been established for the region. The first two cycles are assigned to a period between 1390 Ma and 970 Ma while the third cycle is constrained between 650 Ma and 450 Ma. An age of ca. 1390 Ma for the biotite-gamet migmatite gneiss provides a maximum age for the first tectono-metamorphic cycle. Zircon growth and magmatism during this tectonometamorphic cycle constrains deformation (D1a) between ca. 1160 Ma and ca. 1110 Ma. Deformation is marked by the development of a penetrative planar foliation and isoclinal recumbent folding. High-pressure metamorphic conditions during this cycle have been suggested from previous investigations but are not confirmed in this investigation as the kyanite-bearing leucogneisses intruded during the second tectono-metamorphic cycle. It is possible that the first and second tectono-metamorphic cycles are part of a progressive deformational cycle. The second tectono-thermal cycle represents a major period of magmatism and tectonism constrained between ca. 1110 Ma and ca. 970 Ma. Major folding occurred during this tectonic episode, represented by isoclinal recumbent folds, sheath folds and re-folded fold interference patterns (D1b). The structural fabric elements produced a complicated relationship of transposed coplanar and colinear composite fabrics. Fabric geometries suggest NNW-SSE tectonic transport directions. Garnet-kyanite-muscovite-biotite-quartz assemblages (Mn+1 (nkv)) provide P-T estimates of 710-760 °C and 7.8-8.5 kb. Later metamorphic assemblages of sillimanite-muscovite-high Ca-garnet-biotite-quartz (Mn+2 (nkv)) provide P-T estimates of 630- 690 °C and 6.0-7.4 kb. The whole-rock isotope data indicate that material accreted during the second tectono-metamorphic cycle experienced a short crustal residence time. The third tectono-metamorphic cycle is constrained by isotopic ages between 650 Ma and 450 Ma. Deformation (D2) that re-works earlier tectonic fabrics may represent signatures of this cycle, but the exact nature of the deformation remains enigmatic. Tectonic fabric styles and geometries are similar to the more dominant D1 tectonic episode, making recognition of temporal relationships difficult. Diffusional P-T data from garnet-biotite rims (Mn+3 (nkv)) provide P-T cooling estimates of 560-570 °C and 4.4-4.6 kb. Re-working of the high-grade gneisses during the third tectono-metamorphic cycle, with no addition or accretion of new crustal material is indicated by the isotopic data. A final tectonic episode (D3) comprising late brittle deformation and uplift is equated to Gondwana break-up.

Quantum yields (φ) were determined for the phytoplankton of four perennially ice-covered lakes of southern Victoria Land, Antarctica. The phytoplankton communities of these oligotrophic lakes are dominated by cryptophytes, unicellular chrysophytes and flagellated chlorophytes. Quantum yields were calculated using a suggested value for the spectral extinction coefficient of chlorophyll a (k_c)=0.016 and an empirical estimation of k_c= 0.0328. Quantum yields ranged from 0.0045 to 0.156 using k_c= 0.016, while φ were lower when calculated using k_c=0.0328, ranging from 0.0022 to 0.076. Values of φ were comparable to values reported for phytoplankton elsewhere. Light utilization efficiencies (ε) ranged from 0.006 to 1.46% and are among the lowest values yet reported from aquatic ecosystems. The estimations of φ indicate that the phytoplankton were efficient at trapping the low levels of photosynthetically active radiation present in these dimly lit lakes, while ε indicate that environmental conditions of these lakes are limiting their respective phytoplankton communities. Percent extracellular release (PER) of organic matter was greatest in the shallow depths studied in comparison to the mid-depths sampled. The shallower waters of these lakes were supersaturated with oxygen, brighter and probably nutrient limited. Photosynthesis in <i>Chlamydomonas subcaudata</i> Wille was 2.5 to 3.5 x less at supersaturated oxygen in comparison to saturated oxygen. The higher amount of PER in the shallow depths and the inhibition of photosynthesis in <i>C. subcaudata</i> by supersaturated oxygen indicates that the reduction of photosynthesis due to photorespiration might be limiting the development of the phytoplankton communities of these lakes. / M.S.

Indiana University-Purdue University Indianapolis (IUPUI) / U/Pb and (U-Th)/He (ZHe) dating of detrital zircons from glacial till samples in the Ross Embayment, Antarctica records cooling after the Ross/Pan-African orogeny (450-625 Ma) followed by a mid-Jurassic to mid-Cretaceous heating event in the Beacon basin. Zircons were extracted from till samples from heads of major outlet glaciers in East Antarctica, one sample at the mouth of Scott Glacier, and from beneath three West Antarctic ice streams. The Ross/Pan-African U/Pb population is ubiquitous in these Antarctic tills and many Beacon Supergroup sandstones, thus 83 grains were analyzed for ZHe to subdivide this population. Two ZHe age populations are evident in East Antarctic tills, with 64% of grains 115-200 Ma and 35% between 200-650 Ma. The older population is interpreted to be associated with the Ross/Pan-African orogeny including cooling of the Granite Harbour Intrusives and/or exhumation of the older basement rocks to form the Kukri Peneplain. The lag time between zircon U/Pb, ZHe and 40Ar/39Ar ages from K-bearing minerals show cooling over 200 My. Grains in East Antarctic tills with a ZHe age of 115-200 Ma likely reflects regional heating following the breakup of Gondwana from the Ferrar dolerite intrusions, subsidence within the rift basin, and a higher geothermal gradient. Subsequent cooling and/or exhumation of the Transantarctic Mountains brought grains below the closure temperature over a span of 80 My. This population may also provide a Beacon Supergroup signature as most of the tills with this age are adjacent to nunataks mapped as Beacon Supergroup and contain an abundance of vi Beacon pebbles within the moraine. Nine zircons grains from three Beacon Supergroup sandstones collected from moraines across the Transantarctic Mountains yield ages from 125-180 Ma. West Antarctic tills contain a range of ZHe ages from 75-450 Ma reflecting the diverse provenance of basin fill from East Antarctica and Marie Byrd Land. ZHe and U/Pb ages <105 Ma appear to be distinctive of West Antarctic tills. The combination of U/Pb, ZHe and 40Ar/39Ar analyses demonstrates that these techniques can be used to better constrain the tectonic evolution and cooling of the inaccessible subglacial source terrains beneath the Antarctic Ice Sheet.

No description available.

No description available.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A repeater is being designed to provide a telemetry and compressed video link from a remote robot located in the Dry Valleys Region of Antarctica, over a mountain range to California via McMurdo Antarctica. In return a command link is provided for control. A simple task normally, but a bit more difficult when considerations include the unforgiving elements of Antarctica itself. Even with a design using the most robust equipment, tradeoffs must always be made for the effects of the isolation and the weather. This paper describes one approach to the design of equipment capable of insuring the proper bandwidth, power output, and receive sensitivity that can use the energy provided by Mother Nature to continually charge the primary power source, and the engineering struggle to use electronic equipment in the severe and harsh environment of Antarctica.

The Jurassic Ferrar large igneous province of Antarctica contains significant mafic volcaniclastic deposits, underlying the Kirkpatrick flood basalts. In South Victoria Land, the mafic volcaniclastics are referred to as the Mawson Formation. At Coombs Hills, the Mawson is interpreted as filling a large vent complex, which was re-examined in detail to better understand vent-forming processes. Two contrasting types of cross-cutting volcaniclastic bodies were found in the complex, both of which are interpreted to have been forcefully emplaced from below into existing, non-consolidated debris. The first type consists of country rock-rich lapilli-tuff pipes. These are interpreted as fossilized remnants of subterranean debris jets which originated when phreatomagmatic explosions occurred near the walls or floor of the vent complex, causing fragmentation of both magma and country rock. The second type of cross-cutting body consists of basalt-rich tuff-breccias and lapilli-tuffs, some of which could have been generated by explosions taking place within pre-existing basalt-bearing debris, well away from the vent walls. Other basalt-rich zones, accompanied by domains of in situ peperite and coherent basalt, are inferred to have originated by less violent processes. At nearby Allan Hills, the Mawson can be divided into two informal members, m₁ and m₂. Member m₁ is exposed only at central Allan Hills, consists essentially of sedimentary material from the underlying Beacon Supergroup, and is interpreted as a [less than or equal to]180 m-thick debris avalanche deposit. Most megablocks in m₁ were derived from the late Triassic Lashly Formation, parts of which were probably only weakly consolidated in the Jurassic. Sandstone breccias dominate volumetrically over megablocks within the deposits. This indicates pervasive and relatively uniform fragmentation of the moving mass, and probably reflects the weak and relatively homogeneous nature of the material involved. The avalanche flowed into a pre-existing topographic depression carved into the Beacon sequence, and flow indicators reveal a northeastward movement. Sparse globular basaltic megablocks suggest that Ferrar intrusions played a role in triggering the avalanche. Member m₂, which is exposed at both central and southern Allan Hills, consists predominantly of metre-thick basaltic volcaniclastic layers that fall into three broad categories: (1) poorly sorted, coarse lapilli-tuff and tuff-breccia; (2) block-rich layers; (3) tuff and fine lapilli-tuff. The former type is interpreted as the deposits of high-concentration pyroclastic density currents (PDCs), probably formed during the collapse of phreatomagmatic eruption plumes. Occasional block-rich layers probably were formed by both ballistic fall from local vents and pyroclastic flows, and the finer-grained layers were probably deposited by dilute PDCs. Dilute, moist turbulent currents were also likely responsible for the generation and deposition of large ([less than or equal to]4.5 cm) rim-type accretionary lapilli. The thick layers are locally underlain by or interbedded with thin tuff ring-style volcaniclastic layers, and all the layers are underlain and invaded by basalt-rich tuff-breccias and lapilli-tuffs. COMPLETE REFERENCE: Ross, P.-S. (2005) Volcanology of the Mawson Formation at Coombs and Allan Hills, South Victoria Land, Antarctica. PhD Thesis, University of Otago, Dunedin, New Zealand, 400 pages, 46 tables, 162 figures, plus appendices.

Drainage systems on cold-based glaciers are often thought to be simple systems that can be approximated from the supraglacial components of temperate glaciers. Most studies concerning cold-based glacier drainage systems have only considered one facet of the system, with little regard for how the system components interact. Studying each component independently of the whole system constrains our ability to model drainage system function and development. This in turn restricts our potential to predict how drainage systems of cold glaciers may respond to environmental change. The overarching aim of this thesis was to understand drainage system development of a cold-based glacier, and to assess whether our current understanding of supraglacial hydrological systems is consistent with the drainage systems that form on cold-based glaciers. This thesis evaluated the drainage system of the Wright Lower Glacier, McMurdo Dry Valleys, Antarctica, during the 2004/05, 2005/06 and 2006/07 ablation seasons. The study incorporated field, laboratory and numerical analyses, which resulted in a deeper understanding of the spatial and temporal variability of meltwater generation, drainage pathways, water stores and bulk discharge from the glacier. The findings showed that melt variability was driven by sediment and topographic variations, and that water storage in the form of cryoconite holes, intergranular flow, supraglacial ponds and refreezing dictated meltwater transmission to the glacier outlet. These results indicated that the structure, function and variability of the drainage system were inherently more complex than previous studies on supraglacial drainage systems had suggested. These new insights were combined together to construct a new conceptual model of the drainage system structure of a cold-based glacier. However, before the conceptual model can be used to produce a numerical model of drainage system function or development on cold-based glaciers, several issues need to be addressed. These include: refined methods for quantifying meltwater generation in cold, arid environments; methods to measure water storage on and under the glacier surface; further understanding of the development of permeable ice; and a better technique to quantify cryoconite hole connectivity.