Preserved within the Glenelg River Complex of SE Australia is a sequence of metamorphosed late Neoproterozoic-early Cambrian deep marine sediments intruded by mafic rocks ranging in composition from continental tholeiites to mid-ocean ridge basalts. This sequence originated during breakup of the Rodinia supercontinent and is locally host to lenses of variably sheared and serpentinised mantle-derived peridotite (Hummocks Serpentinite) representing the deepest exposed structural levels within the metamorphic complex. Direct tectonic emplacement of these rocks from mantle depths is considered unlikely and the ultramafites are interpreted here as fragments of sub-continental lithosphere originally exhumed at the seafloor during continental breakup through processes analogous to those that produced the hyper-extended continental margins of the North Atlantic. Subsequent to burial beneath marine sediments, the exhumed ultramafic rocks and their newly acquired sedimentary cover were deformed and tectonically dismembered during arc-continent collision accompanying the early Paleozoic Delamerian Orogeny, and transported to higher structural levels in the hangingwalls of west-directed thrust faults. Thrust-hosted metasedimentary rocks yield detrital zircon populations that constrain the age of mantle exhumation and attendant continental breakup to be no later than late Neoproterozoic-earliest Cambrian. A second extensional event commencing ca. 490 Ma overprints the Delamerian-age structures; it was accompanied by granite magmatism and low pressure-high temperature metamorphism but outside the zone of magmatic intrusion failed to erase the original, albeit modified, rift geometry. This geometry originally extended southward into formerly contiguous parts of the Ross Orogen in Antarctica where mafic-ultramafic rocks are similarly hosted by a deformed continental margin sequence.

Presentation delivered on 8 March 2012 at the Tasman Frontier Petroleum Industry Workshop, 8-9 March 2012, Geoscience Australia, Canberra.

Speculation is increasing that Proterozoic eastern Australia and western Laurentia represent conjugate rift margins formed during breakup of the NUNA supercontinent and thus share a common history of rift-related basin formation and magmatism. In Australia, this history is preserved within three stacked superbasins formed over 200 Myr in the Mount Isa region (1800-1750 Ma Leichhardt, 1730-1670 Ma Calvert and 1670-1575 Ma Isa), elements of which extend as far east as Georgetown. The Mount Isa basins developed on crystalline basement of comparable (~1840 Ma) age to that underlying the Paleoproterozoic Wernecke Supergroup and Hornby Bay Basin in NW Canada which share a similar tripartite sequence stratigraphy. Sedimentation in both regions was accompanied by magmatism at 1710 Ma, further supporting the notion of a common history. Basin formation in NW Canada and Mount Isa both concluded with contractional orogenesis at ~1600 Ma. Basins along the eastern edge of Proterozoic Australia are characterised by a major influx of sediment derived from juvenile volcanic rocks at ~1655 Ma and a significant Archean input, as indicated by Nd isotopic and detrital zircon data. A source for both these modes is currently not known in Australia although similar detrital zircon populations are documented in the Hornby Bay Basin, and in the Wernecke Supergroup, and juvenile 1660-1620 Ma volcanism occurs within Hornby Bay basin NW Canada. These new data are most consistent with a northern SWEAT-like tectonic reconstruction in a NUNA assembly thus giving an important constraint on continental reconstructions that predate Rodinia.

The geological evolution of Australia is closely linked to supercontinent cycles that have characterised the tectonic evolution of Earth, with most geological and metallogenic events relating to the assembly and breakup of Vaalbara, Kenorland, Nuna, Rodinia and Pangea-Gondwana. Australia largely grew from west to east, with two major Archean cratons, the Yilgarn and Pilbara Cratons, forming the oldest part of the continent in the West Australian Element. The centre consists mostly of the largely Paleo-to Mesoproterozoic North and South Australian Elements, whereas the east is dominated by the Phanerozoic-Mesozoic Tasman Element. The West, North and South Australian Elements initially assembled during the Paleoproterozoic amalgamation of Nuna, and the Tasman Element formed as a Paleozoic accretionary margin during the assembly of Gondwana-Pangea. Australia's present position as a relatively stable continent resulted from the break-up of Gondwana. Australia is moving northward toward southeast Asia, probably during the earliest stages of the assembly of the next supercontinent, Amasia. Australia's resources, both mineral and energy, are linked to its tectonic evolution and the supercontinent cycle. Clusters of resources, both in space and time, are associated with Australia's tectonic history and the Earth's supercontinent cycles. Australia's most important gold province is the product of the assembly of Kenorland, whereas its major zinc-lead-silver deposits and iron-oxide-copper-gold deposits formed as Nuna broke up. The diverse metallogeny of the Tasman Element is a product of Pangea-Gondwana assembly and most of Australia's hydrocarbon resources are a consequence of the break-up of this supercontinent.

This database contains information on faults, folds and other features within Australia that are believed to relate to large earthquakes during the Neotectonic Era (i.e. the past 5-10 million years). The neotectonic feature mapping tool allows you to: * search and explore Australian neotectonic features * create a report for a feature of interest * download feature data and geometries as a csv file or kml file * advise Geoscience Australia if you have any feedback, or wish to propose a new feature.

The evolution of the Paleo- and Mesoproterozoic of Australia is controversial. Early tectonic models were largely autochthonous, in part driven by the chemical characteristics of Proterozoic felsic magmatism: overwhelmingly potassic, often with elevated Th and U contents, and with evolved isotopic signatures, consistent with crustal sources and the implication they were not generated within continental arcs. This model has been increasingly challenged over the last 30 years, driven by the recognition of the diversity of Proterozoic magmatism, of linear magmatic belts often with subduction-compatible geochemistry and juvenile isotopic signatures, and of across-strike trends in isotope signatures, all consistent with continental margin processes. These, and other geological evidence for crustal terranes, suggest subduction-related tectonic regimes and collisional orogenesis. Current tectonic models for the Australia Proterozoic invoke such processes with varying number of continental fragments and arcs, related to assembly/break-up of the Nuna Supercontinent. Problems still exist however as the observations of early workers still largely hold-much Proterozoic magmatism was intracratonic, and interpreted backarc magmatism largely lacks obvious related arcs. This has led to more recent hybrid arc-plume models. No one model is completely satisfactory, however, reflecting ambiguity of geochemical data and secular arguments (when did modern-style tectonics actually begin).

Interpretation of the Capricorn deep seismic reflection survey has provided images which allow us to examine the geodynamic relationships between the Pilbara Craton, Capricorn Orogen and Yilgarn Craton in Western Australia. Prior to the seismic survey, suture zones were proposed at the Talga Fault, between the Pilbara Craton and the Capricorn Orogen, and at the Errabiddy Shear Zone between the Yilgarn Craton and the Glenburgh Terrane, the southernmost component of the Capricorn Orogen. Our interpretation of the seismic lines indicates that there is a suture between the Pilbara Craton and the newly-recognised Bandee Seismic Province. Our interpretation also suggests that the Capricorn Orogen can be subdivided into at least two discrete crustal blocks, with the interpretation of a suture between them at the Lyons River Fault. Finally, the seismic interpretation has confirmed previous interpretations that the crustal architecture between the Narryer Terrane of the Yilgarn Craton and the Glenburgh Terrane consists of a south-dipping structure in the middle to lower crust, with the Errabiddy Shear Zone being an upper crustal thrust system where the Glenburgh Terrane has been thrust to the south over the Narryer Terrane.

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.

Detrital zircon age patterns are reported for sandstones from the mid-Permian-Triassic part of the accretionary wedge forming the Torlesse Composite Terrane in Otago, New Zealand and from the early Permian Nambucca Block of the New England Orogen, eastern Australia. In Otago, the Triassic Torlesse samples have a major (64%) age group of Permian-Early Triassic components ca. 240, 255 and 280 Ma, and a minor age group (30%) with a Precambrian-early Paleozoic range (ca. 500, 600 and 1000 Ma). In Permian sandstones nearby, the younger group is diminished (30%), and the older group also contains a major (50%) and unusual, Carboniferous group (components at ca. 330-350 Ma). This trend is similar in sandstones from the Nambucca Block, an early Permian extensional basin in the southern New England Orogen, in which Permian zircons are now minor (<20%), and the age patterns are also dominated (40%) by similar Carboniferous age components, ca. 320-350 Ma.

A short article describing the outcomes of the Tasman Frontier Petroleum Industry Workshop held at Geoscience Australia on 8 and 9 March 2012.