Geophysical Projects

Recent Surveys

2009 Barkly Gravity Survey - (Preliminary)

The Northern Territory Geological Survey, in conjunction with Geoscience Australia, is acquiring/has acquired a 4 km ground gravity survey over the Barkly Tableland. It replaces gravity readings approximately 11 km apart, acquired using barometer heightings, in the 1960s and 1970s.

The survey, funded by the Northern Territory Government's "Bringing Forward Discovery" Initiative, involves helicopter-supported acquisition and processing of 9818 new gravity stations on a 4 km x 4 km grid by Atlas Geophysical Ltd.

The primary value of this new data will be in delineating deep structures under the Barkly Tableland, seeking extensions of the better-known structures under the Tennant Creek and Mount Isa mineral provinces. Explorers will be able to infill the grid to resolve questions arising from the new knowledge.

The complete data of the 4 km grid will be available for download from this website in December 2009.

Images of the Bouguer gravity are available on the GIWS. The final gridded and point located data will be available from the InfoCentre in December 2009.
 

Geophysical and Remote Sensing Data

• Geophysical Data
• Open File Company Geophysical Surveys
• Remote Sensing Data
   

Regional Gravity

Background:

NTGS has commenced a program of semi-regional gravity surveys over selected areas that have unresolved geological problems and unrealised mineral potential. There is growing awareness in the exploration industry that semi-regional gravity surveys can assist greatly in understanding rock distribution in the mineable zone.

Territory-Wide Gravity:

NTGS has extracted all onshore gravity stations for the Northern Territory from the 2002 Geoscience Australia National Gravity Database. Over 2000 stations have been added to this dataset in the southern Georgina Basin region, from previously unrecovered open file data and several new regional traverses. The resultant point located and gridded data sets (5MB zip file) can be downloaded here.

Located Bouguer Gravity images for the whole of the Northern Territory can be viewed on Geophysical Image Web Server.

Airborne surveys 

Background:

Since 1981, NTGS has been flying magnetic and radiometric surveys over mineral fields and basement terrains. These surveys progressively replaced the old reconnaissance magnetic coverage by the Bureau of Mineral Resources (BMR, now Geoscience Australia). Early surveys were acquired on 500 m line spacing and collected four windows of radiometrics, without the benefit of precise control in x-y-z. These surveys evolved in the early 1990s into a standard specification of high-resolution 400 m line spacing, with precise location control by DGPS, collection of elevation data and 256 channel radiometrics. As of mid 2007, over 96% of the Northern Territory is covered by 57 separate surveys, including 3 surveys flown by Geoscience Australia.

Policy:

The strong historical emphasis on high-resolution surveys, combined with modern zero-pricing enables uniquely facilitating policies:

• NTGS takes note of industry requests in planning its flying projects.
• Exploration companies are invited to undertake simultaneous infill surveys, with finer line spacing.
• NTGS incorporates selected open file and open range private sector airborne surveys into the Territory-wide coverage.

Consequently NTGS now supplies the most extensive coverage of uniformly high-quality datasets available in Australia free-of-charge.

Existing Datasets:

Existing NTGS and Geoscience Australia high-resolution surveys are shown on the NTGS airborne geophysical index map. The index map provides:

• survey specifications
• high quality located images for each survey, via the NTGS Geophysical Image Web Server
• an order form.

Alternatively, you can download the spatial index in either MapInfo or ArcView format.

Individual NTGS and Geoscience Australia surveys are supplied free of charge as located data and magnetic, radiometric and elevation grids (ER Mapper .ERS) on a CD-ROM from the InfoCentre.

Information on the Magnetic, Radiometric and Elevation Maps of the Northern Territory can be accessed via the Geophysical Image Web Server.