South Nicholson Gravity Survey
The first pre-competitive data collected as part of the Exploring for the Future program is now available. Geoscience Australia conducted a gravity survey in July 2017 over the South Nicholson Basin in the Northern Territory, 350 kilometres east of Tennant Creek.
The survey delivered 2,724 new gravity stations at four kilometre spacing over an area of 43,330 square kilometres (larger than the area of Switzerland). This greenfields region has been largely under-explored by industry due to younger sediment cover over prospective rocks beneath. The data from the South Nicholson Gravity Survey will be used to determine the geological structure of the South Nicholson Basin and to assist with an assessment of the mineral and hydrocarbon resource potential of the survey area.
The data from a gravity survey measures small changes in the Earth’s gravity due to changes in the density of the rocks in the survey area and makes it possible to map the distribution of different rock types and the structure of the rocks.
As part of a comprehensive package, reflection seismic surveys have been carried out in the same area, and the processed data is expected to be available in March 2018. These surveys will form a suite of new information on the geology and resource potential of this region.
The data was collected using a Scintrex CG5 gravimeter and a high precision GPS system with transport provided by a Robinson R44 helicopter. The helicopter was navigated to predetermined locations by GPS, with the observer spending a couple of minutes taking a gravity reading before heading to the next site.
The survey commenced on 4 July 2017; data acquisition was completed on 28 July 2017. The data were then processed by the contractor and assessed as being fit-for-purpose by Geoscience Australia. When the GA assessment was completed the data were released to the public domain by Geoscience Australia on 15 September 2017.
The data is available for download through the Geophysical Archive Data Delivery System (GADDS).
GA partnered with the Northern Territory Geological Survey (NTGS) to procure the data for the South Nicholson Gravity Survey. The NTGS assisted by promoting and discussing with stakeholders and audiences the purposes and benefits of this activity.