Formed throughout some 40% of the earth's history (>2500 Ma), Archaean cratons now comprise <10% of the continents, but contribute disproportionately to the world's mineral wealth. Remnant Archaean terrains vary in age from fragments as old as 3.6 to 4.0 Ga in age (e.g., Isua - Greenland, Acasta's Slave Province), to more common younger cratons (3.6 to 2.5 Ga) of various sizes, the largest being the Superior Province (1,572,000 km2), which alone constitutes greater than 20% of the total exposed Archaean (Thurston, 1991). Better known Australian examples include the small but well exposed (3.6 Ga and younger) Pilbara Craton (45,000 km2), and the significantly larger, but poorly outcropping Yilgarn Craton (>600,000 km2), both in Western Australia. Granitic rocks form the main component of most Archaean Cratons (e.g., ~70% of the Yilgarn). They occur as syn-volcanic and younger intrusive units within volcano-sedimentary assemblages (greenstone belts), as intrusive components of batholiths, and as components of high-grade gneiss terrains. Their compositional range is extensive and reflects both short-lived or local tectonic processes as well as longer-term process that relate to regional or global evolution.

This paper contains an interpretation of the structure of the continental margin of Enderby and Mac.Robertson Lands, east Antarctica, using the geophysical data acquired under the Australian Antarctic and Southern Ocean Profiling Project.

Elan Bank, a large western protrusion of the Kerguelen Plateau, is a microcontinent that originally lay between India and Antarctica in Gondwana. The acticle analyses seismic stratigraphy and crustal structure of the Elan Bank and discusses tectonic history of this feature. The paper contributes to understanding of dispersal and accretion of continental fragments in association with both plate tectonics and hotspot activity has likely been a significant process for much of Earth's history.

The IAG (International Association of Geodesy) Working Group (WG) on 'Regional Dense Velocity Fields' aims at densifying the ITRF (International Terrestrial Reference Frame) and creating a dense velocity field based on regional and global GNSS networks. With the goal to generate a high-quality solution for a core network, several newly reprocessed global and regional cumulative position and velocity solutions were submitted to the WG. In order to find a consensus on discontinuity epochs for stations common to several networks (an issue which was problematic in previous submissions), the new submissions were restricted to contain only the core networks over which the analyst has full control so that ITRF2008 discontinuities could be applied. The 3D-RMS of the agreement of the new solutions with the ITRF2008 (after outlier rejection) varies between 0.6 and 1.1 mm/yr; it is extremely good for some solutions, while others still require more iteration to reach the required level of precision. Generally the cause of these disagreements has been identified and they often originate in the use of different data time spans within the ITRF2008 and submitted solution. In a next step, the WG expects to generate and use a discontinuity database complementing the ITRF2008 one and identify/solve the sources of disagreements. In addition, several of the regional solutions will be reprocessed to imbed the regional network in a global network and reduce the error induced by the network effect. More details on the WG are available from http://epncb.oma.be/IAG/.

A database of 1075 high-precision geochemical analyses of ultramafic-mafic units, predominantly flows, was compiled for the Eastern Yilgarn Craton. Samples are divided into a high-Mg population at MgO-10-24 wt.% and a basaltic population where 4-MgO<10 wt.%. There are 8 groups based on (La/Sm)N and Nb/Th ratios. Four magma series are identified. Uncontaminated komatiitic-basalts have MgO ~ 11-23 wt.% and Nb/Th-8, whereas contaminated counterparts have Nb/Th<8 corresponding to siliceous high-Mg basalts (SHMB). A distinct magma series with MgO ~ 5-18 wt.% MgO has a narrow range of Nb/Th at 0.5-?2 over a range of (La/Sm)N from 0.7-5.5, unlike contaminated suites where (La/Sm)N and Nb/Th are correlated; this series corresponds to the enriched-Paringa basalt of the Kalgoorlie Terrane. A third high-Mg magma series has a narrow range of MgO at ~13-16 wt.%, extends to elevated TiO2 and Ni relative to komatiitic-basalts at that MgO range, and features (La/Sm)N ?2. Prevalent, crustally uncontaminated, tholeiitic basalts all have Nb/Th?8, span Mg-rich to fractionated Fe-rich counterparts, and range from LREE-depleted to mildly LREE enriched. Contaminated equivalents have Nb/Th<8. Two additional uncontaminated tholeiitic basaltic groups are defined respectively by high-Nb to 20 ppm akin to alkaline ocean island basalts, and elevated total-REE relative to the other basaltic groups. Contamination of all groups was dominantly by interaction with continental mantle lithosphere with a minor crustal component.

Models for the crustal evolution of the Yilgarn Craton have changed in the last 25 years from generally autochthonous greenstone development on sialic crust (Gee et al. 1981, Groves & Batt 1984) to alloch-thonous models that highlight the importance of accretionary tectonics (Myers 1995). Recent models highlight the importance of mantle plumes and long-lived convergent margins for both Au and Ni (Barley et al. 1998). The role of sialic crust in the development of the abundant mineral systems in the Yilgarn, and Archaean cratons in general, however, remains problematic. Felsic rocks from across the Yilgarn Craton are used as crustal probes, with their geochronology, zircon inheritance and Nd isotopic character used to constrain the age and extent of basement terranes. The studies reveal a collage of crustal fragments and implicate both autochthonous and allochthonous crustal development, with increasing importance of accretionary tectonics, particularly after 2.8 Ga. The crustal evolution places significant constraints on the development of metallogenic associations.

A model for lithospheric-scale rifting and deformation history is proposed for the conjugate margins of Australia (Great Australian Bight) and Antarctica (Terre Adélie), based on the two-dimensional sequential restoration of the margins. The model scenario highlights the initial symmetric pattern of stretching, which progressively evolves to completely asymmetric shearing along a single south dipping detachment at the scale of the lithosphere. The detachment accounts for the exhumation of the mantle part of the Australian lithosphere, and the isolation of a crustal klippe. Antarctica plays the role of the upper plate with the formation of an external crustal high separated from the unstretched continent by a highly extended zone. The geometry of the rifted margins is comparable to other asymmetric magma-poor rifted margin such as the Newfoundland-Iberia margin or the exhumed Alpine sea margin exposed in the Central Alps. Although the early geometric evolution of the margins appears mostly controlled by the inherited geometry of the continental crust, its later evolution is thought to relate to the mechanical evolution of the crustal and mantle material during exhumation

Comparison of Pb and Nd isotopes of the well-endowed Abitibi-Wawa Subprovince with the poorly endowed Eastern Goldfields Province implies that volcanic-hosted massive sulfide (VHMS) endowment in Archean terrains is controlled by crustal character. The Abitibi-Wawa Subprovince contains mostly primitive crust formed in a wide extensional environment. The high heat flow, promoted by thin crust and high level intrusions, and the extensional structures that characterize such an environment encouraged the formation of extensive VHMS deposits. In contrast, extensional environments are limited to a relatively narrow zone in the Eastern Goldfields Province. Although this zone contains VHMS deposits, they are not abundant enough to create high endowment. Provinciality of Pb isotopes in lode Au deposits from near Leonora in the Eastern Goldfields Province supports the concept of a rift-like zone.

New seismic, gravity and magnetic data over the Capel and Faust basins have allowed improved resolution of the basin architecture and a better appreciation of the stratigraphy, terrane evolution and palaeogeography. Preliminary interpretation suggests that the Capel Basin contains several depocentres with up to 4 seconds two-way time (s TWT) sediment thickness, up to 150 km long and 40 km wide. Grabens appear to contain Lower Cretaceous syn-rift volcanics, Turonian-Maastrichtian syn-rift clastic megasequences and a Maastrichtian-Recent bathyal post-rift phase. There may also be a Lower-Middle Jurassic pre-rift sequence, possibly an equivalent of the Clarence-Moreton coal measures. Total Jurassic-Recent sediment thickness may be as much as 6-7 km. A number of smaller grabens characterise the Faust Basin to the east and the southern part of the Capel Basin. Stratigraphic complexity was driven by multiple extension events. Subsequent discrete seafloor spreading events resulted in the sequential formation of the Tasman Sea, and possibly the Middleton Basin, proto-Loyalty Basin, and central New Caledonia Basin. Plate reconstructions indicate that the Capel Basin was located adjacent to the northern edge of the Sydney Basin prior to breakup. The junction between the Capel and Faust Basins is a major fault system, which may have exploited a Middle Triassic collision suture between the New England Orogen and equivalents of the Maitai Murihiku terranes of New Zealand. The interpreted Lower Cretaceous volcanics are expected to correlate with the Lower Cretaceous igneous complexes and associated volcanogenic sediments in Queensland, Bass Strait and New Zealand. Sediment analogues of the mid-Cretaceous rift fill in the Capel-Faust area can possibly be found in Gippsland and the Great South Basin, but exact correlations will be difficult because of the diachronous breakup of Tasman continental ribbons. The Capel Basin in particular may contain sediments capable of generating gas and perhaps some liquids such as those seen in Clarence-Moreton and Great South basins.

Describes boninites from the Whundo belt, Pilbara Craton, and compares and contrasts these with other Archaean boninites and modern boninites. Results include recognition of 2 types of Archaean boninites - one similar to modern-day counterparts, and another type restricted to the Archaean.