Over the last fifteen years, Geoscience Australia, through its Onshore Energy Security Program, in conjunction with Primary Industries and Resources South Australia (PIRSA), the Geological Survey of New South Wales (Industry & Investment NSW), the Australian Geodynamics Cooperative Research Centre, and the Predictive Mineral Discovery Cooperative Research Centre (pmd*CRC), has acquired several deep seismic reflection profiles, which, when combined, form an east-west transect about 870 km long in southeastern Australia. The seismic data vary from low-fold, dynamite-source to higher-fold, vibroseis-source data. The combined seismic profiles, from the western Eyre Peninsula to the Darling Basin, provide a near complete cross-section of the crust across the Gawler Craton, Adelaide Rift System, Curnamona Province, Koonenberry Belt and Darling Basin. The entire region is dominated by east-dipping faults, some of which originated as basin-bounding extensional faults, but most appear also to have a thrust sense of movement overprinting the extension. In the Gawler Craton, an inferred shallow, thin-skinned thrust belt occurs to the west of an inferred thick-skinned thrust belt. The boundary between the two thrust belts, the Kalinjala Mylonite Zone, was active at least during the Kimban Orogeny, with possible extensional movement at that time. The thrust movement possibly occurred during the ~1600 Ma Olarian Orogeny.

Until recently, tectonic reconstructions have been limited by (1) the assumption that tectonic plates do not deform, or (2) the inability of software packages to simulate deformation. The assumption that plates do not deform is based on the earliest ideas about plate tectonics. This assumption has led workers dealing with plate tectonic reconstructions to introduce new micro-plates to explain the inconsistencies observed in different place circuits (e.g. the Somalian plate). However, we now know that the oceanic and continental crust deform. Therefore, tectonic reconstructions must begin to address this point, without the need to invoke more and more micro-plates to resolve inconsistencies in rigid plate circuits. The second point, that software cannot simulate plate deformation is no longer an issue after the development of Pplates. Pplates is an open-source tectonic reconstruction package that allows geologists to build both classical (rigid) plate reconstructions as well as deformable plate reconstructions. To do this, the software uses one or meshes to move data back and forth in time. Each of these meshes is deformable in order to simulate deformation of the crust. This software also allows geologists to import and deform GIS data. Here we report the initial results of a deformable reconstruction of the Australian and Antarctic plates, from the timing of rifting prior to Gondwana break-up, to the present. This reconstruction also shows the timing of major fault development in the sedimentary basins along Australia's southern margin. Future work aims to simulate development of major crustal features on the Australian and Antarctic plates, and to incorporate palaeogeographical interpretations from the sedimentary record. Our ability to simulate extensional deformation associated with continental break-up has implications for both global tectonic reconstructions as well as reconstructions of individual sedimentary basins

This 78 page full colour booklet published by the United States Geological Survey (USGS) is a comprehensive review of plate tectonic theory for teachers, students and the general public. The fundamental concepts are explained using colour graphics and clear, detailed text. Topics include Australia's polar dinosaurs, deep ocean vents, magnetic anomalies, sea floor spreading, magnetic pole reversals, earthquake distribution, rift valleys and the types of plate margins. Individual essays review major scientific contributions to the development of plate tectonic theory and the impact on people of associated natural hazards. Suitable for secondary level Years 7-12.

Aspects of the tectonic event history of Palaeo- to Mesoproterozoic Australia are recorded by metasedimentary basins in the Mt Isa, Etheridge, and Coen Provinces in northern Australia and in the Curnamona Province of southern Australia. Based on similarities in depositional ages and stratigrapy, these basins are interpreted to have been deposited in a tectonically-linked basin system. However, in deformed and metamorphosed basins, field correlations are difficult, making independent data, such as Nd isotope data and detrital zircon U-Pb geochronology essential to discriminate tectonic setting and sediment provenance.

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.

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A deep seismic reflection profile was acquired in South Australia and Victoria in November 2009 by Geoscience Australia with project partners AuScope, Geoscience Victoria, and Primary Industries and Resources South Australia (PIRSA). Along with previously acquired deep seismic reflection data, this 145 km long line completes a continuous east-west transect across the eastern Delamerian Fold Belt into the western Lachlan Fold Belt. The project aims included determining tectonic vergence during and after amalgamation of the Gondwana Supercontinent, understanding the transition from passive margin (Rodinia breakup) to convergent margin (Tasmanides orogenesis), and locating the so-called 'Tasman Line', the extent of Proterozoic continental crust.

Thin-plate finite element models of the neotectonic deformation of the Australian plate have been calculated in order to estimate the stress and strain-rate within the plate, specifically concentrating on the Australian continent. The model includes plate-bounding faults, an anelastic brittle-ductile layered rheology and the option of laterally varying elevation and heat-flow. The results of the models are compared to: (a) the velocity of geodetic benchmarks on the Australian plate, (b) the spreading rate of the mid-oceanic ridges along the Australian plate's margins, (c) the direction of the maximum horizontal principal stress, (d) the stress regime within the plate and (e) the crustal thickness estimated from the depth to the base of Mohorovicic discontinuity's transition zone. A variety of models are tested with a wide range of input parameters. The model with the smallest misfit with observations predicts that the strain rate for most of the Australian continent is approximately 10^{-17}s^{-1}. This model has a slightly lower strain rate in the central Australia and is higher off the northern coast of Australia than for the rest of the continent. Strain rates of this magnitude would be difficult to observe from geodetic or geologic data for most parts of of Australia, but would be enough to generate much of the seismicity that has been observed over the last century.

Archaean TTGs, as originally defined comprise intermediate to felsic rocks characterised by high Na2O/K2O, low to moderate LILE contents and no potassium-enrichment with increasing differentiation. The majority of such rocks also carry a high-pressure signature, identified by elevated Sr (i.e., are Sr-undepleted) and Eu, fractionated REEs, with low HREE (Y- and HREE-depleted), and high Sr/Y. These latter characteristics are also often used to define TTGs and are commonly thought to reflect an origin via slab melting (with or without mantle-wedge interaction), largely as a necessary corollary of a warmer Archaean mantle. Our work, however, shows that within many Archaean terranes there exists a subclass of granites (which we call transitional TTGs), that when compared to `true? TTGs have higher LILE contents, show strong enrichment in LILEs (e.g., K2O) with increasing differentiation, and tend towards more siliceous compositions (68-77% SiO2), but still possess a similar high-pressure signature. Such transitional TTGs are contemporaneous with, or postdate true TTGs but where present also grade to more mafic compositions that overlap with true TTGs. These Transitional TTGs dominate some cratons, the best example being the Yilgarn Craton where true TTGs form only a small percentage of total granites. Sm-Nd isotopic and inherited zircon data indicate that the petrogenesis of most transitional TTGs requires the involvement of pre-existing crust. What is not clear, given the difficulty in reconstructing tectonic environments in the Archaean, is whether this crustal component represents input via the subduction process (e.g., subducted sediments), represents a response to thicker pre-existing crust (AFC processes), or whether these rocks form from pure crustal melts in thickened Archaean crust. Comparison of both TTG-types with ?apparent? modern-day TTG analogues ? adakites ? shows somewhat similar groupings. The major adakite group (group 1, mostly 58-68% SiO2), is characterised by a narrow range in La/Sm (5.5-3.0), and Sm/Yb (1.5-3.5), moderate Sr (400-700 ppm) and low to moderate LILE. This group overlaps significantly with true TTGs although the latter tend to have higher La/Sm (up to 9) and Sm/Yb (up to 10+). The second adakite group has higher Sm/Yb (6-10), La/Sm (6-9) and Sr (<500 to 1500 ppm), and typically higher LILE contents, and appears to be confined to continental arc regimes and is most similar to transitional TTGs. Notably both TTG-types extend to significantly more silica and LILE-rich compositions than seen in the majority of adakites. A distinctive, significantly more mafic (50-60+% SiO2) adakite group with high to very high Sr (up to 1500-2500 ppm), and high Sm/Yb (to 10-12), appears distinct from all Archaean TTGs. Group 1 adakites are most consistent with melting of a MORB source leaving an amphibole-bearing (i.e., non-eclogitic) residue, while group 2 adakites are interpreted to represent either melting at higher pressure or greater degrees of slab melting (leaving an eclogitic residue), with their higher LILE contents reflecting either subducted sediment input or processes related to the presence of continental crust (e.g., AFC). In contrast, the range in La/Sm and Sm/Yb in true TTGs suggests greater involvement of garnet during melting in Archaean times (garnet amphibolite to eclogite residue) relative to modern day (group 1) adakites, perhaps reflecting a greater depth of generation or drier melting. Importantly, although pure crustal melting can not be ruled out, analogies with group 2 adakites shows that transitional TTGs can be produced as slab melts particularly in continental arc environments ? both models maybe applicable and may have varied in relative importance through time. Further, the presence of transitional TTGs in Archaean cratons can be used to infer significant pre-existing continental crust. (THIS ABSTRACT MODIFIED FROM ORIGINAL).