Geophysical surveys
Geophysics is the study of the physical characteristics of surface and buried rocks such as their magnetic properties, electrical conductivity, density and natural radioactivity. Geophysical data can be collected by airborne surveys, surface measurements, and from boreholes.
Airborne surveys are particularly valuable and are now indispensable to the Geological Survey for its geological mapping programs as well as to the mining industry for mineral exploration. The most valuable surveys for regional geological mapping are those that measure the magnetic characteristics and natural radioactivity of the rocks. These surveys are used to assist geological mapping interpretation and to determine the nature and distribution of rock units both at the surface (radioelement data) and beneath the cover of soil, alluvium, or younger rocks (magnetic data).
The Geological Survey of NSW maintains archives of regional airborne geophysical surveys, regional gravity surveys and seismic surveys conducted as part of Geological Survey programs. Open file geophysical surveys resulting from exploration company activities are also archived for public access following title relinquishment.
Airborne geophysical surveys
Regional airborne geophysical surveys
The Geological Survey of NSW has conducted regional airborne geophysical surveys as an integral part of its mapping programs and as part of the Discovery 2000, Exploration NSW and New Frontiers initiatives. These regional surveys assist geological mapping and help gain an understanding of the nature and distribution of lithologies and structure beneath cover. Approximately 84% of NSW is now covered by high resolution airborne surveys.
The majority of surveys have acquired both total magnetic intensity data and radiometric data. Special purpose survey programs have been conducted to acquire FALCON® [1] Airborne Gravity Gradiometer data and HyMapTM[2] airborne hyperspectral imaging data in the Broken Hill region
Geophysical data are distributed as high quality colour images at 1:250 000 and 1:100 000 scales. Gridded and located regional airborne geophysical data can be either downloaded from the National Geoscience Web Portal via the Geophysical Archive Data Delivery System GADDS or available by project area on a DVD (inclusive of ecw images). The Broken Hill Falcon and Hymap datasets on DVD are also available for purchase.
All the geophysical datasets mentioned above can be ordered by contacting geophysics.products@industry.nsw.gov.au.
Open file airborne geophysical surveys data
Open file airborne geophysical data submitted as part of NSW exploration title reporting are indexed in the statewide AEROFIND database. It provides precise locations and metadata of most airborne geophysical surveys carried out for mineral exploration in the state. Currently, there are more than 800 airborne surveys indexed in this database.
MinView users can use the ‘Spatial Search’ facility to determine which surveys cover a specified area without having to download data and use a GIS system. Alternatively, the entire AEROFIND layer index can be downloaded from MinView as an ArcGIS shape file.
Gravity surveys
Regional gravity surveys have been conducted as part of the Discovery 2000, Exploration NSW and New Frontiers initiatives. These gravity data are included in the National Gravity Database. Gridded and located gravity data are available for download from the National Geoscience Web Portal via the Geophysical Archive Data Delivery System GADDS.
Seismic surveys
Several deep crustal seismic surveys have been conducted in NSW to assist in the understanding of specific mapping or structural trends in the geological mapping programs. Information concerning seismic survey locations, data availability and interpretations are to be addressed to geophysics.products@industry.nsw.gov.au
Geophysical images and data
Index map/list of available geophysical images and data
[1] FALCON® is a registered Trade Mark of BHP Billiton Innovation Pty Ltd
[2] HyMapTM is a registered Trade Mark of Integrated Spectronics Pty Ltd