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

Beginning in the Archean, the continent of Australia evolved to its present configuration through the accretion and assembly of several smaller continental blocks and terranes at its edges. Australia grew usually by convergent plate margin processes, such as arc-continent collision, continent-continent collision or through accretionary processes at subduction zones. The accretion of several island arcs to the Australian continent, through arc-continent collisions, played an important role in this process, and the geodynamic implications of some Archean and Proterozoic island arcs recognised in Australia will be discussed here.

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.

Continental rifting and the separation of Australia from Antarctica commenced in the Middle-Late Jurassic and progressed from west to east through successive stages of crustal extension, basement-involved syn-rift faulting and thermal subsidence until the Cenozoic. Early syn-rift faults in the Bight Basin developed during NW-SE directed extension and strike mainly NE and E-W, parallel to reactivated basement structures of Paleoproterozoic or younger age in the adjacent Gawler craton. This extension was linked to reactivation of NW-striking basement faults that predetermined not only the point of breakup along the cratonic margin but the position and trend of a major intracontinental strike-slip shear zone along which much of the early displacement between Australia and Antarctica was accommodated. Following a switch to NNE-SSW extension in the Early Cretaceous, the locus of rifting shifted eastwards into the Otway Basin where basin evolution was increasingly influenced by transtensional displacements across reactivated north-south-striking terrane boundaries of Paleozoic age in the Delamerian-Ross and Lachlan Orogens. This transtensional regime persisted until 55 Ma when there was a change to north-south rifting with concomitant development of an ocean-continent transform boundary off western Tasmania and the South Tasman Rise. This boundary follows the trace of an older Paleozoic structure optimally oriented for reactivation as a strike-slip fault during the later stages of continental breakup and is one of two major basement structures for which Antarctic equivalents are readily identified. Some ocean floor fracture zones lie directly along strike from these reactivated basement structures, pointing to a link between basement reactivation and formation of the ocean floor fabrics. Together with the two basement structures, these fabrics serve as an important first order control on palaeogeographic reconstructions of the Australian and Antarctic conjugate margins.

The origins of high heat production (HHP) granites - with high concentrations of the heat-producing elements Th, U and K (HPE) - is controversial, particularly large areas of such rocks. To constrain possible controls on HHP granites, we have investigated temporal changes in Th, U and K contents of Paleoarchean to Mesozoic granites in Australia, and how these relate to peri-ods of HHP magmatism. Australian HHP granites range in age from Mesoarchean to Triassic, but are most abundant in the Neoarchean, the Paleoproterozoic - early Mesoproterozoic, and the Carboniferous. HHP magmatism ranges from relatively short lived (<30 Ma) geographically-restricted events in the Neoarchean and Carboniferous, to geographically widespread, (possibly unrelated) repetitive events over an extended time period (ca. 1800 to 1500 Ma) for the Proterozoic.

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.

Developed in consultation with Emergency Management Australia (EMA), this kit defines and maps major hazards affecting Australia - earthquakes, tsunamis, landslides, volcanoes, severe storms, cyclones, bushfires, floods and droughts. This kit helps students and teachers recognise risks from different natural hazards and the practical steps we can all take to reduce their effects. The Australian Natural Hazards Education Map Kit contains: - eight colour A3 poster maps with descriptive text - eight blackline A4 map masters - background information on each hazard - student activities - Emergency Management Australia hazard action cards Suitable for primary years 5-6 and secondary years 7-8.

Late potassic granites are a characteristic feature of many Archean cratons, including the Yilgarn and Pilbara Cratons in Western Australia. In the Yilgarn Craton, these "low Ca" granites comprise over 20 percent by area of the exposed craton, are distributed throughout the entire craton and intruded at c. 2655-2620 Ma, with no evidence for significant diachroneity at the craton scale. In the Pilbara Craton, similar granites are concentrated in the East Pilbara Terrane, have ages of c. 2890-2850 Ma and truncate domain boundaries. Late potassic granites are dominantly biotite granites but include two mica granites. They are "crustally derived with high K2O/Na2O, high LILE, LREE, U, Th, variable Y and low CaO, Sr contents. They likely represent dehydration melting of older LILE-rich tonalitic rocks at low to moderate pressures. High HFSE contents suggest high temperature melting, consistent with a water-poor source. Models for their genesis must take into account that: 1. the timing of late potassic granites shows no relationship with earlier transitional-TTG plutonism; 2. there is no relationship to crustal age, with emplacement ranging from c. 100 m.y. (eastern Yilgarn) to c. 800 m.y. (eastern Pilbara) after initial crust formation; 3. the emplacement of late granites reflects a change in tectonic environment, from melting of thickened crust and/or slab for earlier TTG magmatism to melting at higher crustal levels; 4. at least in the Yilgarn, the late potassic granites were contemporaneous with mid-crustal high-grade metamorphism. Two models have been invoked for late potassic granites: melting driven by thermal influx following lithospheric delamination; and decompression melting resulting from orogenic collapse. There is no geophysical evidence for underplated or intraplated mafic magmas, typically invoked to provide extra-crustal heat, in either the Pilbara or Yilgarn. There is clearly older lithospheric mantle below the eastern Pilbara and central Yilgarn, making it difficult to invoke delamination prior to later crustal melting. Orogenic collapse following crustal thickening may be more appropriate. The late granites are post major compression in both cratons, coincident with extensional deformation and contemporaneous with syenitic granites (eastern Yilgarn). A similar time interval between compression and generation of crustal granites is present for all the Yilgarn regardless of crustal history. Independent of either model was the transfer of heat-producing elements from the lower crust into the upper crust, effectively cratonizing each province.

No abstract available

Regional geology of the Eastern Goldfields and component terranes; deformation history and structural architecture; previous seismic interpretations; granitoids; tectonics constraints imposed by greenstones; tectonic settings and models