Found 500 items for "geophysical anomaly maps" in Data & Publications
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Australia magnetic anomaly pixel map
Australia magnetic anomaly pixel map
Isostatic Gravity anomaly map
Gravity anomaly map of the Australian Region 3rd edition. This map is derived from an image which combined onshore Bouguer gravity anomaly and offshore freeair anomaly values. Onshore Bouguer gravity anomalies were calculated from over 1.4 million observations held in the the Australian National Gravity Database. Offshore freeair anomaly data were derived from satellite altimetry data available from Scripps Institution of Oceanography. This data is used to study the tectonic structure of Australia by mapping variations in the earth's gravimetric field. The 'hotter colours' (eg red) show areas of stronger gravity field and the 'cooler colours' (eg dark blue) show areas of weaker gravity field. Gravity data used to produce the Gravity Anomaly Map of the Australian Region are available for free download via the Geophysical Archive Data Delivery System (GADDS).
Australian Mines and Mineral Deposit Map on magnetic anomaly base, 1:5 000 000, July 2007 Version
Magnetic anomaly map of Australia 1:25 000 000
The file magmap_V5_2010 is a composite TMI grid of the Australian region with a grid cell spacing of ~3 seconds of arc (approximately 80 m). This grid only includes airborne-derived TMI data for onshore and near-offshore continental areas. Data used to compile this grid form the basis for the concurrent release of a new fifth edition of the Magnetic Anomaly Map of Australia. This edition is underpinned by the concept of a database of matched TMI grids, from which any map at any resolution can be extracted. Details of the specifications of individual airborne surveys can be found in the Eleventh Edition of the Index of Airborne Geophysical Surveys (Percival, 2010), which is included with the grid as a PDF document called magmap_V5_2010.pdf. This Index is also available online at http://www.ga.gov.au/minerals/research/methodology/geophysics/acquisition.jsp#reports. Further up to date information about individual surveys can also be obtained online from the Airborne Surveys Database at http://www.ga.gov.au/oracle/argus/. The grid results from a completely new compilation of TMI grid data, an updated method of matching the individual survey grids, and use of independent data to constrain long wavelengths. 795 individual grids have been matched and merged into the composite grids supplied here. The resolution of each grid is optimal for the specifications of the source survey line data (Briggs, 1974). Since the fourth edition was released in 2004 data from many new surveys have been added to the database, acquired mainly by the State and Territory Geological Surveys. It is estimated that 27 000 000 line-kilometres of survey data were acquired to produce the grid data, 8 000 000 line-kilometres more than for the previous edition. The index map (Figure 1) shows the distribution of original survey line spacings from which the grids are derived, Figure 2 shows the distribution of all survey line spacings, and Figure 3 shows the survey ownerships. Matching of the grids in the database was achieved using a program called Gridmerge, which was originally developed within Geoscience Australia and has now been commercialised. It uses statistics of the overlap regions between adjacent surveys to globally minimise the differences in the base levels of all surveys (Minty et al., 2003). There is also provision to remove higher-order surfaces from grids. To constrain long wavelengths, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of those survey grids which overlapped the AWAGS data (Milligan et al., 2009). The high-frequency differences between the grids were smoothed using a convolution operator. Very long wavelengths greater than 1000 km have been constrained by using the MF6 data derived from the CHAMP satellite (Maus et al., 2007). Grid downloads: The Magnetic Map of Australia grid can be downloaded using the Geophysical Archive Data Delivery System (GADDS) on the Australian Government's Geoscience Portal at http://www.geoscience.gov.au/bin/mapserv36?map=/public/http/www/geoportal/gadds/gadds.map File size: At full resolution, the Magnetic Map of Australia grid has 41876 rows and 50592 columns and has a file size of approximately 8.3 Gb in ERMapper format. Note that, because of GADDS file size limits, it is not possible for clients to download very large areas of the grid at full resolution. Clients wishing to do so should contact Geoscience Australia to make special arrangements to have the complete grid dataset provided on a user-supplied portable hard drive.
This edition of the Magnetic anomaly map of Australia results from a completely new compilation of Total Magnetic Intensity (TMI) grid data. It has been produced using a new method of matching the individual survey grids and the use of independent data to help constrain long wavelengths. 680 individual grids have been matched and merged into the composite used to produce this image, with the resolution of each grid optimal for the specifications of the source survey line data. Since the Third Edition (Milligan and Tarlowski, 1999), data from many new surveys have been added, acquired mainly by the State and Territory geological surveys. It is estimated that 19 million line-kilometres of survey data were acquired to produce the grid data, 10 million line-kilometres more than for the Third Edition. This data is used to study the tectonic structure of Australia by mapping variations in the earth's magnetic field. The 'hotter colours' (eg red) show areas of stronger magnetic field and the 'cooler colours' (eg dark blue) show areas of weaker magnetic field. Magnetic data used to produce the Magnetic Anomaly Map of Australia are available for free download via the Geophysical Archive Data Delivery System.
The major basement components within the Albany 1:1M Sheet area of southwestern Western Australia are defined from aeromagnetic anomalies and 10-40 km wavelength gravity anomalies, and are integrated with mapped geology to provide a geological model. Their structure (lithological banding), faults and dykes are determined from short-wavelength magnetic anomalies. The main tectonic elements are the Archaean Yilgarn Craton, the younger Albany Province to the south, and the Perth Basin with Proterozoic basement to the west. The Yilgarn Craton comprises an eastern zone with strike-extensive sinuous anomalies, typical of granite-greenstone terrane, and a western zone with sparse, short anomalies, characteristic of granite-gneiss terrane. Highly magnetised granulites along the eastern margin of the western zone correlate with outcrop of the Jimperding Metamorphic Belt in the north of the sheet. The eastern boundary of these granulites is parallel to a weak gravity gradient, and corresponds with a significant change in structural style; it is inferred to be a major intra-cratonic discontinuity. A north-northwest-trending gravity gradient within the western zone coincides with the Southwest Seismic Zone, and defines the eastward extent of thick, relatively dense crust defined by earlier studies of seismic refraction data. The Albany Province consists of a low-density southern zone with weakly sinuous magnetic banding, and a northern zone characterised by high-density, high-magnetisation, and linear magnetic banding. The southern margin of the Yilgarn Craton has been deformed for up to 50 km and demagnetised up to 20 km from the boundary. This deformation is inferred to have been caused by overthusting of the Albany Province during the Mid-Proterozoic. Subsequently, tectonism involving the Proterozoic crust beneath the Perth Basin deformed the western edge of the Yilgarn Craton and folded adjacent parts of the Albany Province southward. Greenstone and metamorphic belts are highly prospective and host many of the regions mineral deposits. Both the composition and geophysical characteristics of these belts contrast with those of more widespread granite and granite-gneiss terrane, which are of considerably lower economic interest. Analysis of the regional geophysical data sets in co njunction with outcrop geology leads to a more complete model of the Precambrian geology of the region than that derived from outcrop mapping alone.
These data comprises the 3D geophysical and geological map of the Georgina-Arunta region, Northern Territory. This 3D map summarises the key basement provinces of this region, including the geometric relationships between these provinces. Depth of cover data, and approximate thicknesses of key basins within the region are also provided. Supporting geophysical studies, including inversions of gravity and magnetic data, and seismic data and their corresponding interpretations acquired under the Australian Government's Onshore Energy Security Program, are included with this 3D map. Finally, additional data, such as topographic data, are also included.