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Geoscience Australia's involvement in Antarctica has primarily been focused on the maintenance and enhancement of geodetic infrastructure within the Australian Antarctic Territory (AAT). Such infrastructure provides a fundamental reference frame for the region and supports earth monitoring science applications on local, regional and continental scales. These foundations have furthered the development of geodesy throughout the continent and provided information on the contemporary motion of the Antarctic plate for comparison with long-term geological records. Primary Antarctic geodetic control also contributes to a greater understanding of global earth movement though contribution to the International Terrestrial Reference Frame solutions. This report focuses on the field work undertaken during the 2010/11 Antarctic summer by Geoscience Australia surveyors at the Davis, Mawson and Macquarie Island research stations, as well as several remote sites in Eastern Antarctica. At each of the research stations, upgrades and local monitoring surveys were performed at the continuously operating reference stations (CORS), which form part of the Australian Regional GNSS Network and also contribute to the International GNSS Service. Remote GPS sites in the Grove Mountains, Bunger Hills, Wilson Bluff and Mt Creswell were also visited for equipment upgrades and data retrieval. Additional surveys were undertaken directed at enhancing the spatial infrastructure around both the Larsemann and Vestfold Hills. Support was also provided to a number of different Australian Antarctic Division projects.

The Bunger Hills area, which forms part of the East Antarctic Shield, consists predominantly of granulite facies orthogneiss (pyroxene-quartz-feldspar gneiss), with subordinate maficgranulite and garnet, sillimanite, and cordierite-bearing paragneiss. The igneous precursors of granodioritic orthogneiss crystallised about 1500 - 1700 Ma ago, whereas late Archaean (2640 Ma) tonalitic orthogneiss occurs in the Obruchev Hills, in the southwest of the area. Metamorphism reached a peak of about 750 - 800 ° C and 5 - 6 kb (Mj) 1190±15 Ma ago (U-Pb zircon age) and was accompanied by the first of three ductile deformation events (Dj). Voluminous, mainly mantle-derived plutonic rocks were emplaced between 1170 (during D 3 ) and 1150 Ma. They range in composition from gabbro, through quartz gabbro, quartz monzogabbro, and quartz monzodiorite, to granite. Abundant dolerite dykes, of at least four chemically distinct groups, were intruded at about 1140 Ma. Their intrusion was associated with the formation of shear zones, indicating at least limited uplift; all subsequent deformation was of brittle-ductile or brittle type. Alkaline mafic dykes were emplaced 500 Ma ago. Marked geochronological similarities with the Albany Mobile Belt of Western Australia suggest that high-grade metamorphism in both areas was the result of continental collision between the Archaean Yilgarn Craton of Australia and the East Antarctic Shield. However, Gondwana reconstructions and the composition of the plutonic rocks suggest that the Bunger Hills metamorphics may have formed in an Andean-type continental arc, with the actual collision zone having been to the east of the present Bunger Hills. Exposures west of the Denman Glacier are also mainly granulite-facies gneiss, intruded by a variety of mafic to felsic plutonic rocks. They differ from the Bunger Hills in being partly derived from Archaean protoliths (- 3000 Ma), in lacking isotopic evidence for a Mesoproterozoic high-grade event, and in not being intruded by dolerite dyke swarms. They also show evidence of much more extensive 500 - 600 M a (Pan-African) metamorphism and plutonism (syenite to granite), and in this regard they are comparable with the Leeuwin Block metamorphics of southwestern Australia, although these were derived from significantly younger protoliths (T^D model ages: 1100 - 1500 Ma). If this early Palaeozoic activity was also a consequence of continental collision, it would explain the markedly different geological history of the terranes on either side of the Denman Glacier and could account for the final uplift of the Bunger Hills. However, the compressional tectonic regime implicit in the collision hypothesis was followed by an extensional regime, which, in southwestern Australia, eventually resulted in the formation of the Perth Basin rift zone. This structure is aligned with the Denman Glacier trough on our preferred Gondwana reconstruction, suggesting that it may have extended well to the south before the breakup of Gondwana.

Mawson South Escarpment, Antarctica, geological map 1:250 000