Search results

Found 500 items for "geophysical anomaly maps" in Data & Publications

Try searching for "geophysical anomaly maps" in Website

Data & Publication Results

Showing 1 of 50 pages

Australia magnetic anomaly pixel map

Australia magnetic anomaly pixel map

Australia magnetic anomaly pixel map

Australia magnetic anomaly pixel map

Gravity Anomaly Map of the Australian Region, 3rd edition, 2008

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, July 2007

Australian Mines and Mineral Deposit Map on magnetic anomaly base, 1:5 000 000, July 2007 Version

Australian Gravity Anomalies Image cached map service (Web Mercator) WMS

This image represents gravity anomalies of the Australian region. The grid combines accurate onshore gravity measurements, with satellite data over the offshore region. The cell values represent simple Bouguer anomalies at a density of 2.67 tonnes per cubic metre onshore and free-air anomalies offshore. The grid cell size is 0.5 minutes of arc, which is equivalent to about 800 metres.

Australian Gravity Anomalies Image cached map service (Web Mercator)

This image represents gravity anomalies of the Australian region. The grid combines accurate onshore gravity measurements, with satellite data over the offshore region. The cell values represent simple Bouguer anomalies at a density of 2.67 tonnes per cubic metre onshore and free-air anomalies offshore. The grid cell size is 0.5 minutes of arc, which is equivalent to about 800 metres.

Magnetic anomaly map of Australia 1:25 000 000

Magnetic anomaly map of Australia 1:25 000 000

Geoscience Australia National Airborne Geophysics Map Service

This map service was created to replace the GA National Geoscience Datasets service: to that end it should be used in conjunction with other GA map services. It contains: a floating-point Total Magnetic Intensity raster for the Australian region (2010); , a floating-point onshore Bouguer gravity raster (2010); a floating-point onshore and offshore gravity anomaly raster (2010); RGB Gravity and TMI images (2009 and2010); as well as outlines of GA airborne surveys

Magnetic Anomaly Map of Australia, 5th edition, 1:5 million scale, 2010

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.