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  • The Australian continent is actively deforming in response to far-field stresses generated by plate boundary interactions and buoyancy forces associated with mantle dynamics. On the largest scale (several 103 km), the submergence of the northern continental shelf is driven by dynamic topography caused by mantle downwelling along the Indo-Pacific subduction system and accentuated by a regionally elevated geoid. The emergence of the southern shelf is attributed to the progressive movement of Australia away from a dynamic topography low. On the intermediate scale (several 102 km), low-amplitude (c. 100–200 m) long-wavelength (c. 100–300 km) topographic undulations are driven by (1) anomalous, smaller-scale upper mantle convection, and/or (2) lithospheric-scale buckling associated with plate boundary tectonic forcing. On the smallest scale (101 km), fault-related deformation driven by partitioning of far-field stresses has modified surface topography at rates of up to c. 170 m Ma-1, generated more than 30–50% of the contemporary topographic relief between some of Australia’s highlands and adjacent piedmonts, and exerted a first-order control on long-term (104–106 a) bedrock erosion. Although Australia is often regarded as tectonically and geomorphologically quiescent, Neogene to Recent tectonically induced landscape evolution has occurred across the continent, with geomorphological expressions ranging from mild to dramatic.

  • Report on energy assessment of north Queensland as part of the Onshore Energy Security Program. As part of the Onshore Energy Security Program, Geoscience Australia has undertaken a series of energy potential assessments, both on a national scale and on a regional scale in association geological framework studies. These framework studies, which are designed to provide information on geodynamic and architectural controls on energy systems, are linked to the acquisition of deep seismic, magnetotelluric and airbourne electromagnetic data. The focus of fiscal year 2008-2009 was north Queensland, stretching from the Northern Territory border to the coast, between 17° and 22° south latitude. In addition to the seismic data acquisition and interpretation, these framework studies have included geochronological studies as well as uranium mineral system and geothermal system studied in collaboration with the Uranium and Geothermal Projects. The main goal of these studies is to provide background data that can be used by industry for exploration, however the data also provide new information that can be used in assessing the potential of north Queensland for uranium and geothermal resources using geosystems (i.e. mineral and geothermal systems) methodologies in a GIS environment. This report provides such an assessment in a qualitative to semi-quantitative way. One of the goals of this analysis is to define the extent of areas or regions with known deposits; another goal was to define areas with previously unrecognised potential.

  • Presentations from the GOMA (Gawler-Officer-Musgrave-Amadeus) Seismic and MT Workshop 2010.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

  • There are a number of factors which influence the direct consequence of flooding. The most important are depth of inundation, velocity, duration of inundation and water quality. Though computer modelling techniques exist that can provide an estimate of these variables, this information is seldom used to estimate the impact of flooding on a community. This work describes the first step to improve this situation using data collected for the Swan River system in Perth, Western Australia. Here, it is shown that residential losses are underestimated when stage-damage functions or the velocity-stage-damage functions are used in isolation. This is because the functions are either limited to assessing partial damage or structural failure resulting from the movement of a house from its foundations. This demonstrates the need to use a combination of techniques to assess the direct economic impact of flooding.

  • This map is part of the series that covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 513 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and 110 kilometres from north to south. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. The topographic map and data index shows coverage of the sheets. Product Specifications Coverage: The series covers the whole of Australia with 513 maps. Currency: Ranges from 1995 to 2009. 95% of maps have a reliability date of 1994 or later. Coordinates: Geographical and either AMG or MGA (post-1993) Datum: AGD66, GDA94, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Paper, flat and folded copies.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

  • Vertical height datums are necessary as a reference for height measurements over the Earth. However the choice of reference is dependant on the purpose for the height data. For terrestrial users (especially on the coast), heights above a Mean Sea Level (MSL) are desired, whilst marine uses that depend on under keel clearance, prefer a low water tidal datum. The result of these preferences has produced two different types of height datum in Australia. Topography heights are referenced to the Australian Height Datum (AHD), Roelse (1975), and bathymetry heights are referenced to Chart Datum (CD) or Lowest Astronomical Tide (LAT), calculated through a tidal observation. Both are not directly compatible with satellite based data in ellipsoidal heights, which span the land/sea interface. Users of these data sets are increasingly aware of difficulties in joining these adjacent datasets, primarily a result of datum disparities. The focus of the research in this report is to reconcile the various bathymetry datums to allow joining of bathymetry datasets. A methodology has been presented to calculate uncertainty for short span observation MSL's relative to a long term reference epoch. This will increase the number of available MSL observations around the coast, which will aid in the creation of an ellipsoidal MSL surface with uncertainties. Despite their inclusion in the original project scope, methodologies for computing uncertainties of the Lowest Astronomical Tide (LAT) and Highest Astronomical Tide (HAT) tidal planes have not been developed. Several alternative options for high water and low water tidal planes with associated uncertainties to define the intertidal zone about MSL in Australia will be presented for consideration.

  • Induction conductivity data, commonly referred to as conductivity logs, were acquired from nineteen boreholes during September 2008 in support of the Paterson airborne electromagnetic (AEM) survey, described in Roach (2010). The geophysical investigations were designed to deliver reliable, pre-competitive AEM data and scientific analysis of the energy resource potential of the Paterson region of Western Australia. The Paterson AEM survey was the first regional AEM survey conducted in the Onshore Energy Security Program (OESP) at Geoscience Australia (GA). The survey was flown by Fugro Airborne Surveys Pty. Ltd. (FAS), for Geoscience Australia, as a combined TEMPESTTM time-domain electromagnetic (TEM) and magnetic survey between the 10th of September 2007 and the 28th of October 2008. The Paterson AEM survey covers a total area of 49 000 km2 in the Paterson region of Western Australia. Induction conductivity log data were acquired from the boreholes across a number of widespread, different geological units within the Paterson AEM survey area. The conductivity logs were used to assist in generating reference models for geophysical inversions of the AEM data, as well as for assessing the results of the inversions as an independent dataset.

  • Recently acquired seismic reflection and gravity potential field data was used to investigate the distribution of volcanic facies and large scale structural architecture of the Mentelle Basin, located on the southwestern margin of Australia. Isochron and seismic facies maps were used to identify the thickness and distribution of volcanic facies. These maps show that volcanism is generally confined to the Western Mentelle Basin, with two distinct areas of thick volcanic deposits occurring to the centre and north of the area. Two and three dimensional gravity forward models were created in IGMAS+. Two dimensional gravity modelling shows that the crust is extremely thin in the Western Mentelle (c.10km), associated with two mantle highs observed to the north and centre of the Western Mentelle. The crust thickens from the Eastern Mentelle (>20km) towards mainland Australia and the Naturaliste Plateau. The two modelled mantle highs coincide with the two seismically defined areas of thick volcanic deposits. Analogue models indicate that rift related volcanism is generally confined to the locus of extension where the pressure is lowest. Thus results of gravity modelling and seismic interpretation in this study indicate that Jurassic - Cretaceous extension was focussed in the Western Mentelle. This conclusion conforms to models of rift related basin formation, where the flanks of the basin are uplifted; an angular unconformity in the Eastern Mentelle may support the occurrence of rift-flank uplift in this area as a result of asthenospheric rise and rifting while the deposition of volcanic material was focussed in the Western Mentelle.