Although there is general agreement that the western two-thirds of Australia was assembled from disparate blocks during the Proterozoic, the details of this assembly are difficult to resolve, mainly due to ambiguous and often conflicting data sets. Many types of ore deposits form and are preserved in specific geodynamic environments. For example, porphyry-epithermal, volcanic-hosted massive sulfide (VHMS), and lode gold deposits are mostly associated with convergent margins. The spatial and temporal distributions of these and other deposits in Proterozoic Australia may provide another additional constraints on the geodynamic assembly of Proterozoic Australia. For example, the distribution of 1805-1765 Ma lode gold and VHMS deposits in the North Australian Element, one of the major building block of Proterozoic Australia, supports previous interpretations of a convergent margin to the south, and is consistent with the distribution of granites with subduction-like signatures. These results imply significant separation between the North and South Australian elements before and during this period. Similarly, the distribution of deposits in the Halls Creek Orogen is compatible with convergence between the Kimberly and Tanami provinces at 1865-1840 Ma, and the characteristics of the deposits in the Mount Isa and Georgetown provinces are most compatible with extension at 1700-1650 Ma, either in a back-arc basin or as a consequence of the break-up of Nuna.

Over the last decade there have been significant advances in our understanding of the: stratigraphy; magmatism; deformation; metamorphism; and timing of mineralisation, in the Eastern Goldfields Superterrane (EGST) of Yilgarn Craton, WA. The integration of these disciplines has enabled a holistic review of the tectonic history of the EGST, thereby providing a para-autochthonous geodynamic context for its mineralisation. A significant advance has been the recognition of a ~2.81 Ga rifting event off the eastern margin of the Youanmi Terrane which set up the north-northwest trending architecture of the EGST, as expressed in the Nd TDM map. Rifting was followed by the establishment of a convergent margin characterised by a west dipping subduction zone to the east of the EGST. Subduction resulted in the deposition of the 2.715-2.67 Ga volcanic stratigraphy and the emplacement of voluminous TTG magmatism, which resulted in magmatic thickening of the crust. Volcanism was terminated by a ~5 Ma pulse of east-northeast contraction which triggering lithospheric and lower crustal delamination associated with mid-orogenic extension. The lack of ultra-high pressure metamorphism and the presence of high geothermal gradients preclude this event from recording a continent-continent collision. Mid-orogenic extension initiated at 2.665 Ga resulted in the introduction of metasomatised mantle melts (Mafic-granites and Syenites), deposition of late-stage siliciclastic basins (which record anticlockwise PTt paths) and the start of significant economic gold mineralisation in the EGST. The delamination associated with this event resulted in significant heat input into the base of the crust, which eventually led to the emplacement of Low-Ca (crustal melt) granites and cratonisation of the EGST.

We have used data recorded by a temporary seismograph deployment to infer constraints on the state of crustal stress in the Flinders Ranges in south-central Australia. Previous stress estimates for the region have been poorly constrained due to the lack of large events and limited station coverage for focal mechanisms. New data allowed 65 events with 544 first motions to be used in a stress inversion to estimate the principal stress directions and stress ratio.While our initial inversion suggested that stress in the region was not homogeneous, we found that discarding data for events in the top 2km of the crust resulted in a well-constrained stress orientation that is consistent with the assumption of homogeneous stress throughout the Flinders Ranges. We speculate that the need to screen out shallow events may be due to the presence in the shallow crust of either: (1) small-scale velocity heterogeneity that would bias the ray parameter estimates, or (2) heterogeneity in the stress field itself, possibly due to the influence of the relatively pronounced topographic relief. The stress derived from earthquakes in the Flinders Ranges show an oblique reverse faulting stress regime, which contrasts with the pure thrust and pure strike slip regimes suggested by earlier studies. However, the roughly E-W direction of maximum horizontal compressive stress we obtain supports the conclusion of virtually all previous studies that the Flinders Ranges are undergoing E-W compression due to orogenic events at the boundaries of the Australian and Indian Plates.

We compare GPS derived geodetic strain rates with estimates from seismic moment release for the Western Australian Seismic Zone. The geodetic strain rates were derived from occupations, in 2002 and 2006, of a 48 site regional network in the SW corner of Australia. The high precision nature of the experiment enabled us to identify 16 sites where antenna errors were the cause of the anomalous displacements. The cause of this is considered to be due to errors in the phase centre of three antennas. The ~1200 km2 study area is one of the most seismically active areas of mid-continental crust worldwide. The geodetic and seismic derived compressional strain-rates are 0.8±0.8 x10-9 yr-1 and 4.9 ±1.9 x10-9 yr-1 (±1) respectively. In effect, the geodetic strain rate would appear to be significantly less than the seismic rate which is amongst the highest of all mid-continental crust rates. With over 95% confidence we can exclude the geodetic and seismic strain rates being the same. This suggests that the contemporary seismic moment release it significantly higher than the long-term moment release. Thus the seismicity of this region is possibly not following the Poissonian behaviour normally observed for inter-plate earthquakes and may be episodic. Thus estimates of the long-term seismic hazard in this area based solely on the earthquake data are likely to be overestimates. Whether the geodetic stain rate reflects the Australian continental average or an intermediate value will require several repeat occupations.

In July 2009, Geoscience Australia initiated a new project within the Geospatial and Earth Monitoring Group to update the national earthquake hazard map using current methods and data. The map is a key component of Australia's earthquake loading code. As part of developing the project, between the 20th and 22nd of October 2009 Geoscience Australia hosted a workshop with Australian experts in seismic hazard assessment. The aim of the workshop was to scope out the short and long term direction of the earthquake hazard project and the national map. This report was developed from the input and advice received from that workshop.

The Asia-Pacific Reference Frame (APREF) project is an initiative that recognizes the importance of improving the regional geodetic framework in the Asia-Pacific region. A substantial number of state-of-the-art GNSS networks, operated by national mapping agencies and private sector organizations, are available in the region. In the APREF initiative these networks are combined to realize a high-standard regional reference frame. The GNSS data of the network are processed by different Analysis Centres (ACs). The contributions of the different ACs are combined into a weekly solution by the APREF Central Bureau. This weekly solution is the core product of the APREF; it contains weekly estimates of the coordinates of the participating Asia-Pacific GNSS tracking stations and their covariance information. The APREF products, which have been available since the first quarter of 2010, gives a reliable time-series of a regional reference frame in the International Terrestrial Reference Frame and a quality assessment of the performance of the GNSS CORS stations included in the network. This contribution gives an overview of the current status of the APREF network and an analysis of the first APREF products.

Collation of extended abstracts presented at the pmd*CRC conference 11-12 June 2008

This report presents the results of a geodynamic synthesis of South Australia, focusing predominantly on the Archean to Mesoproterozoic of the Gawler Craton and Curnamona Province in terms of geodynamic setting, architecture, and age, using results of a geological synthesis, seismic interpretation, sequence stratigraphy, geochronology and geochemistry. This was undertaken with the dual aims: 1. To better understand the tectonic and geodynamic setting of the Gawler Craton and Curnamona Province 2. To accompany the interpretation of recently-acquired seismic reflection transects (see related product below), and to highlight new geochemical and geochronological data collected from South Australia.

The western two-thirds of Australia is underlain by Precambrian rocks that are divisible into three Archean to Paleoproterozoic cratons, the West Australian, North Australian and South Australian cratons, separated by Paleoproterozoic to Mesoproterozoic orogens. The temporal and spatial record of Proterozoic rock units and orogenic events documents accretion and assembly of Precambrian, proto-Australia. The Archean Yilgarn and Pilbara cratons were assembled into the West Australian Craton along the Capricorn Orogen during the late Paleoproterozoic (2000 Ma) Glenburgh Orogeny, which then combined with the North Australian Craton along the Rudall Orogen during the 1800-1765 Ma, Yapungku Orogeny. Prior to about 1500 Ma the North and South Australian cratons show a similar geological history and are herein assumed to have evolved as a single entity, termed the North-South Australian Craton. It was bounded throughout most of the late Paleoproterozoic to earliest Mesoproterozoic by subduction zones along its south western and north eastern margins such that much of the craton occupied an upper plate, back arc basin environment. After ~1500 Ma the craton differentiated into the North Australian and South Australian cratons through rotation and lateral translation of the latter, resulting in convergence and collisional suturing with the West Australian craton along the 1345-1140 Ma Albany-Fraser Orogen. The Pinjarra Orogen developed along the margin of the West Australian Craton and records late Mesoproterozoic to Neoproterozoic strike-slip juxtaposition of India within an assembling Gondwana. The Neoproterozoic record of the Terra Australis Orogen, which extends along the eastern side of Precambrian Australia, records rifting and continental breakup within the supercontinent of Rodinia. Australian Proterozoic rocks host significant mineral resources, including world class banded iron-formations in the West Australian craton (Hamersley), and iron oxide copper gold deposits (Olympic Dam), Pb-Zn-Ag systems (Mount Isa and Broken Hill) and uranium deposits in the North-South Australian Craton.

We use seismic-reflection and rock-sample data to propose that the first-order physiography of New Caledonia Trough and Norfolk Ridge formed in Eocene to Miocene time, and was associated with the onset of subduction and back-arc spreading at the Australia-Pacific plate boundary. Our tectonic model involves an initial Cretaceous rift that is strongly modified by Cenozoic subduction initiation and hence we are able to explain: complex sedimentary basins of inferred Mesozoic age; a prominent unconformity and onlap surface of Middle Eocene to Early Miocene age at the base of flat-lying sediments beneath the axis of New Caledonia Trough; gently-dipping, variable thickness, and locally deformed Late Cretaceous strata along the margins of the trough; platform morphology and unconformities on either side of the trough that indicate a phase of Late Eocene to Early Miocene uplift to near sea level, followed by rapid Oligocene and Miocene subsidence of c. 1100-1800 m; and seismic-reflection facies tied to boreholes that suggest absolute tectonic subsidence at the southern end of New Caledonia Trough by 1800-2200 m since Eocene time. The Cenozoic part of the model involves delamination and subduction initiation followed by rapid foundering and rollback of the slab. This created a deep (>2 km) enclosed oceanic trough c. 2000 km long and 200-300 km across in Eocene and Oligocene time as the lower crust detached, with simultaneous uplift and local land development along basin flanks. Disruption of Late Cretaceous and Paleogene strata was minimal during this Cenozoic phase and involved only subtle tilting and local reverse faulting or folding. Basin formation was possible through the action of at least one detachment fault that allowed the lower crust to either be subducted into the mantle or exhumed eastward into Norfolk Basin. We suggest that delamination of the lithosphere, with possible mixing of the lower crust back into the mantle, is more widespread than previously thought.