This web service provides access to the Geoscience Australia (GA) ISOTOPE database containing compiled age and isotopic data from a range of published and unpublished (GA and non-GA) sources. The web service includes point layers (WFS, WMS, WMTS) with age and isotopic attribute information from the ISOTOPE database, and raster layers (WMS, WMTS, WCS) comprising the Isotopic Atlas grids which are interpolations of the point located age and isotope data in the ISOTOPE database.

The contemporary crustal stress regime in south-eastern Australia can be traced back to the terminal Miocene. Increased coupling of the Australian and Pacific Plate boundary at this time resulted in regional-scale tilting, local uplift and erosion, and in the formation of unconformities in southern Australian basins. In the onshore Gippsland Basin the unconformity surface is overlain by an extensive sheet of fluvial sediment known as the Haunted Hill Formation (HHF). Open folds and flexures developed within the HHF over blind reverse and reverse oblique faults provide a record of deformation spanning much of the neotectonic period. The predominance of flexures and folds rather than discrete faulting at the surface complicates the assessment of slip rates over the last few seismic cycles. However, ages from an undeformed fill terrace bordering the Morwell River and crossing the Morwell Monocline suggest that it has been a minimum of 70 ka since the last deformation event on at least this structure. Stream profiles crossing the Snake Ridge, Yallourn and Rosedale Monoclines similarly reveal no evidence for recent tectonic displacement. Cosmogenic radionuclide (10Be and 26Al) burial ages of siliceous sediments sampled from tectonically uplifted HHF on the Yallourn, Morwell and Snake Ridge Monoclines provide constraint on the long-term evolution of these structures. Combined with stratigraphic and tectonic records from the offshore Gippsland Basin, these data provide a basis for informed seismic hazard assessment.

Faults of the Lapstone Structural Complex (LSC) underlie 100 km, and perhaps as much as 160 km, of the eastern range front of the Blue Mountains, west of Sydney. More than a dozen major faults and monoclinal flexures have been mapped along its extent. The Lapstone Monocline is the most prominent of the flexures, and accounts for more than three quarters of the deformation across the complex at its northern end. Opinion varies as to whether recent tectonism, or erosional exhumation of a pre-existing structure, better accounts for the deeply dissected Blue Mountains plateau that we see today. Geomorphic features such as the abandoned meanders at Thirlmere Lakes illustrate the antiquity of the landscape and favour an erosional exhumation model. According to this model, over-steepened reaches developed in easterly flowing streams at the Lapstone Monocline when down-cutting through shale reached more resistant sandstone on the western side of the LSC. These over-steepened reaches drove headward (westerly) knick point retreat, ultimately dissecting the plateau. However, a series of swamps and lakes occurring where small easterly flowing streams cross the westernmost faults of the LSC, coupled with over-steepened reaches 'pinned' to the fault zones in nearby larger streams, imply that tectonism plays a continuing role in the development of this landscape. We present preliminary results from an ongoing investigation of Mountain Lagoon, a small fault-bound basin bordering the Kurrajong Fault in the northern part of the LSC.

Compressional deformation is a common phase in the post-rift evolution of passive margins and rift systems. The central west Western Australian margin, between Geraldton and Karratha, provides an excellent example of strain partitioning between inverting passive margin crust and adjacent oceanic and continental crust. The distribution of contemporary seismicity in the region indicates a concentration of strain release within the basins diminishing eastward into the cratons. Very few data exist to quantify uplift or slip rates, however this pattern can be qualitatively demonstrated by tectonic landforms which indicate that the last century or so of seismicity is representative of patterns of Neogene and younger deformation. Pleistocene marine terraces on the western side of Cape Range indicate uplift rates of several tens of metres per million years, with similar deformation resulting in sub-aerial emergence of Miocene strata on Barrow Island and elsewhere. In the southern Carnarvon Basin, marine strandlines of unknown age are displaced by a few tens of metres, indicating uplift rates an order of magnitude lower than further west. Relief production rates in the western Yilgarn Craton are lower still - numerous scarps (e.g. Mt Narryer) appear to relate individually to <10 m of displacement across Neogene strata. The en echelon arrangement of such features distinguish them from those representing strain concentration in the craton proper, where scarps are isolated and typically <5 m high. Quantitative analysis of time-averaged deformation preserved in the aforementioned landforms, including study of scarp length as a proxy for earthquake magnitude, has the potential to provide useful constraint on seismic hazard assessments in a region which contains major population centres and nationally significant infrastructure.

This web service provides access to the Geoscience Australia (GA) ISOTOPE database containing compiled age and isotopic data from a range of published and unpublished (GA and non-GA) sources. The web service includes point layers (WFS, WMS, WMTS) with age and isotopic attribute information from the ISOTOPE database, and raster layers (WMS, WMTS, WCS) comprising the Isotopic Atlas grids which are interpolations of the point located age and isotope data in the ISOTOPE database.

This is a combined metamorphic and strain map of the Eastern Yilgarn Craton. Inset maps of different phases of metamorphism are also shown. <p>Related material<a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&catno=68806">Metamorphic Evolution and Integrated Terrane Analysis of the Eastern Yilgarn Craton: Rationale, Methods, Outcomes and Interpretation</a> - Geoscience Australia Record 2009/023.</p>

Ongoing developments in geodetic positioning towards greater accuracies with lower latency are now allowing the measurement of the dynamics of the Earth's crust in near real time. However, in the Australian circumstance a sparsity of geodetic infrastructure has limited the application of modern, geodetic science to broader geoscience research programs. Recent enhancements to the Australian geodetic infrastructure, through the AuScope initiative, offer opportunities for research into refinement of geodetic accuracies, as well as their application to measuring crustal deformation.

A deep seismic reflection profile and coincident refraction and magnetotelluric data were acquired across the northern Eyre Peninsula, Gawler Craton in 2008 to enhance the prospectivity of the Gawler Craton for uranium and geothermal energy, by establishing the regional geodynamic framework and improving our understanding of the crustal architecture. The seismic line crossed the western boundary of a region of elevated surface heat flow, termed the South Australian Heat Flow Anomaly (SAHFA). This broad zone correlates with elevated surface heat production values, predominantly associated with high heat producing granites, and thus the boundary is an isotopic and geochemical boundary. The seismic line crosses several tectonic domain boundaries in the Gawler Craton, including between the Archaean core of the craton and younger domains to the east and west. It also crossed the Kalinjala Shear Zone, which is a key structure in the southern and central Gawler Craton, defining a boundary between Hutchison Group sedimentary rocks and Donington Suite granites in the south. In the vicinity of the seismic section, this shear zone dips moderately to the east and appears to be a major crustal-scale fault which cuts through to the Moho; it separates mid to lower crust of differing seismic reflectivity, with strong reflectivity west of the fault, and a lower reflectivity to the east. The upper crust appears to be dominated by a series of thin-skinned thrust faults, most of which dip to the east. The seismic line also crossed the boundary between the Olympic Fe-oxide Cu-Au-U Province (host of Olympic Dam and Prominent Hill deposits) in the east, and the Central Gawler Au Province in the west, and tested the difference in crustal architecture between the two mineral provinces.

This web service provides access to the Geoscience Australia (GA) ISOTOPE database containing compiled age and isotopic data from a range of published and unpublished (GA and non-GA) sources. The web service includes point layers (WFS, WMS, WMTS) with age and isotopic attribute information from the ISOTOPE database, and raster layers (WMS, WMTS, WCS) comprising the Isotopic Atlas grids which are interpolations of the point located age and isotope data in the ISOTOPE database.

Seismic line 07GA-IG1, described here, forms part of the Isa-Georgetown-Charters Towers seismic survey that was acquired in 2007. The seismic line is oriented approximately northeast-southwest and extends from northwest of Cloncurry in the southwest to east of Croydon in the northeast (Figure 1). The acquisition costs for this line were provided jointly by Geoscience Australia and the Geological Survey of Queensland, and field logistics and processing were carried out by the Seismic Acquisition and Processing team from Geoscience Australia. Six discrete geological provinces have been interpreted on this seismic section (Figure 2). Two of these, the Numil and Abingdon Provinces, only occur in the subsurface. The Mt Isa Province occurs in the southwest, with the Kowanyama Province occurring on the middle of the section and the Etheridge province in the northeast. The Millungera Basin, first observed on two seismic lines in the 2006 Mt Isa seismic survey, occurs beneath shallow cover of the Jurassic-Cretaceous Carpentaria Basin and sits above the Kowanyama Province.