The Antarctic region has profoundly affected the global climates of the past 50 million years, influencing sea levels, atmospheric composition and dynamics, and ocean circulation. A greater understanding of this region and the Antarctic cryosphere is crucial to a broader understanding of the global climates and palaeoceanography at all scales. Much of the information obtained during the last two decades derives from studies of sedimentary sequences drilled in and around Antarctica.

A new compilation of magnetic data over onshore and offshore Tasmania plus existing geological mapping and gravity data have provided the basis for the production of map illustrating the geometric distribution of the main basement units of the state. Significant aspects of the new interpretation map include: the delineation of the wide-spread sub-surface granite occurrences in Tasmania; identification of more extensive occurrences of Proterozoic rocks than previously known; mapping of the extent of the Dundas Trough and extensive northwestern and southeastern continuations of the Beaconsfield ultramafi rocks; definition of the areal distribution of Mesozoic sedimentary basins; and the control of Proterozoic lineaments, in particular the Arthur Lineament, on the development of the Mesozoic basins.

Palaeomagnetic, rockmagnetic and magnetic fabric results are presented for a Carboniferous (Visean to Westphalian) succession of felsic, mainly ignimbritic, volcanic and volcaniclastic rocks from the Rocky Creek Block of the northern Tamworth Belt, southern New England Orogen. Detailed thermal demagnetization of 734 samples from 64 sites has shown three groups of magnetic components with low (LT: up to 300 degrees C), intermediate (IT: 300 to 600 degrees C) and high (HT: mainly 500 to 680 degrees C) unblocking temperature ranges. Analysis and interpretation of component directions have established well-defined primary magnetization results fro 29 sites and evidence for four magnetic overprint phases.The overprints are of widespread (a,c) or localized (b,d) occurrence and are attributed to: a mid_tertiary weathering event (a: mainly LT); or to fluid movements (b,c,d) associated with either Late Cretaceous opening of the Tasman Sea (b: mainly HT); or to thrusting during the Middle Triassic main phase of the Hunter_Bowen Orogeny (c: mainly IT); or to latest Carboniferous - Early Permian formation of the Bowen-Gunnedah-Sydney Basin system (d: IT,HT). Rockmagnetic (Lowrie-Fuller test, IRM acquisition, Lowrie-test, low- and high-temperature susceptibility cycling) and palaeomagnetic analyses indicate predominance of magnetite carriers with main unblocking temperatures ranging from 400 to between 500 and 580 degrees C, and less prevalent presence of hematite carriers with unblocking temperature ranges generally up to 640 degrees C and for some sites up to 680 degrees C. Multidomain (MD-) magnetite is prevalent in the volcaniclastic rocks. Most of the volcanic rocks with well-defined primary magnetization components show evidence for single domain (SD-) magnetite with no, or only limited, presence of MD-magnetite. See paper for remainder of abstract

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The East Antarctic continental shelf has had very few studies examining the macrobenthos structure or relating biological communities to the abiotic environment. In this study, we apply a hierarchical method of benthic habitat mapping to Geomorphic Unit and Biotope levels at the local (10s of kilometers) scale across the George V Shelf between longitudes 1421E and 1461E. We conducted a multi-disciplinary analysis of seismic profiles, multibeam sonar, oceanographic data and the results of sediment sampling to define geomorphology, surficial sediment and near-seabed water mass boundaries.

Detailed analysis and modeling of regional gravity and magnetic data from the Stuart Shelf around the Olympic Dam iron oxide copper-gold (IOCG) deposit, constrained by geologic observations obtained from deep drill cores, show that the eastern Gawler craton basement at 1.61 to 1.59 Ga consisted of an Archean core with two sequences of successively younger supracrustal rocks stepping out eastward from it. These were overprinted by the tectonothermal Hiltaba event. Forward models of potential-field data show no convincing evidence for the presence of widespread mafic rocks or extensional basin systems developed immediately prior to, or during, IOCG mineralization. The high intrusive level and sill-like geometry of Hiltaba Suite plutons emplaced immediately prior to IOCG mineralization is difficult to explain in terms of a genetic association with a dominantly extensional tectonic setting. Instead, the tectonic setting inferred from the basement architecture during mineralization is one of low-strain shortening, consistent with regional field observations. A case can be made for intrusion of the Hiltaba Suite in localized accommodation zones in an overall orogenic setting. This style of low-strain shortening (<10%) is consistent with maximum rates and volumes of fluid flow in the upper crust, and access of these fluids to a variety of basement rock types to buffer metal-scavenging fluids. This fluid-driving mechanism does not necessitate a role for regional mafic magmatism and volcanism in the formation of IOCG deposits. Modeling of regional gravity and magnetic data is generally applicable to exploration for IOCG systems, and other mineral systems, in covered terranes that have distinctive geophysical signatures resulting from fluid-wall-rock redox geochemical reactions.

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