Minerals Alert August 2009

  1. Reports and maps released on Australia's uranium mineral systems
  2. New gravity survey data added to the Australian National Gravity Database
  3. New gravity anomaly grids of the Australian Region
  4. Broken Hill Exploration Initiative Conference
  5. Update on geophysical data releases
  6. About Minerals Alert

1. Reports and maps released on Australia's uranium mineral systems

As part of the Onshore Energy Security Program, Geoscience Australia released two reports and a series of national-scale maps that provide a conceptual and empirical framework for uranium exploration at the AusIMM's International Uranium Conference in Darwin in June. The new products are available on the Uranium Systems Project webpage.

Geoscience Australia Record 2009/20, Uranium mineral systems: processes, exploration criteria and a new deposit framework, examines the key geological and geochemical processes controlling where and how uranium mineralisation occurs in Australia and globally. The report presents a revised conceptual framework for a fresh assessment of Australia's uranium mineral potential and provides key exploration criteria of practical value. Generalised models for families of uranium mineral systems with shared characteristics are presented. They are based on an understanding of the fundamental processes in uranium mineral systems and on descriptions of well-documented ore systems.

Geoscience Australia Record 2009/17, Uranium content of igneous rocks of Australia 1:5 000 000 maps: Explanatory notes and discussion describes and discusses the data presented in an accompanying series of three 1:5 million scale maps of Australia. The maps use whole-rock geochemical data compiled mainly from Geoscience Australia's OZCHEM database. Map 1. Igneous rock type: surface geology shows the uranium concentrations of igneous rock samples, plotted on igneous rock polygons from Geoscience Australia's new 1:1 million scale Surface Geology of Australia dataset. Map 2. Average uranium abundance: surface geology shows the average uranium content of each surface geology polygon. Map 3. Average abundance: solid geology uses a similar methodology, but shows average uranium contents for solid geology polygons. This map is expected to be useful in areas where the igneous rocks are concealed beneath a cover of sediments or regolith, which is the case for very large areas of the continent.

For further information, email roger.skirrow@ga.gov.au; or phone +61 2 6249 9442.

2. New gravity survey data added to the Australian National Gravity Database

Gravity data collected in conjunction with several seismic surveys have recently been added to the Australian National Gravity Database (ANGD). Total number of new stations is 3380.

Seismic surveys were carried out in 2008 and 2009 in South Australia (SA), the Northern Territory (NT) and New South Wales (NSW) funded through Geoscience Australia's Onshore Energy Security Program. The new datasets were collected to assist in identifying areas with potential for mineralisation, hot rock geothermal energy and/or hydrocarbons.

Gravity data collected along the seismic line located in NSW are situated on the Canberra 1:1 Million sheet area and the data collected along lines in SA are situated on the Oodnadatta, Tarcoola, Broken Hill, Port Augusta and Adelaide 1:1 Million sheet areas.

The NSW data were collected in 2009 along an extension to the 2008 Rankin Springs seismic survey lines. Data collected in SA were read along the 2008 Arrowie, Curnamona and Gawler seismic survey lines and the 2008 Gawler, Officer, Musgrave and Amadeus (GOMA) seismic line.

Open file data in the Australian National Gravity Database, can be obtained from the Geophysical Archive Data Delivery System (GADDS).

For further information, please email mario.bacchin@ga.gov.au; or phone +61 (0)2 6249 9308.

3. New gravity anomaly grids of the Australian Region

Geoscience Australia has recently released two new gravity anomaly grids of the Australian Region. These new grids replace those produced in 2008. They incorporate approximately 90 000 new gravity stations which have been added to the Australian National Gravity Database since the release of the 2008 grids.

One grid covers the region from 8°S to 52°S and 100°E to 170°E. Data for the offshore region were sourced from the Marine Gravity from Satellite Altimetry dataset available from Scripps Institution of Oceanography, California, United States of America. This grid is a combination of Spherical Cap Bouguer gravity anomaly values for the onshore stations and free air gravity anomaly values for the offshore region.

The second grid of Spherical Cap Bouguer gravity anomaly values covers Continental Australia only.

Both grids have a cell size of 0.008333333 degrees (approximately 800 m).

Apart from the extra 90 000 new stations used to create the 2009 grids, the other difference between the 2008 and 2009 grids is the exclusion of pre-1975 regional data in areas where high quality, closer-spaced data have been collected over the last 10 years. This was done to eliminate the 'spotty' artefacts evident in the 2008 grids in those regions containing both modern, closely-spaced data and pre-1975 data.

To assist users in deciding whether to include a gravity station in their own grids, a new field has been added to the point located data available for downloading. The new field called 'GRIDDING_FLAG' has a value of either zero or one. Zero indicates that the station has not been included in the 2009 grids and a value of one indicates it has been used.

The new grids can be obtained from the Geophysical Archive Data Delivery System (GADDS).

For further information, please email mario.bacchin@ga.gov.au; or phone +61 (0)2 6249 9308.

4. Broken Hill Exploration Initiative Conference

A conference will be held in Broken Hill from 29 September - 1 October 2009 to report on new insights into exploration geoscience in the Curnamona Craton and adjacent areas. This is being organised jointly by the NSW Department of Primary Industries, Primary Industries and Resources South Australia, and Geoscience Australia.

Further information on this conference is available from the NSW Department of Primary Industries; or email russell.korsch@ga.gov.au; or phone +61 2 6249 9495.

5. Update on geophysical data releases

The current status of Geoscience Australia's geophysical survey data acquisition is now available in a comprehensive table.

The South Yilgarn gravity survey which covers the Lake Johnston, Balladonia, Zantus and Naretha 1:250 000 map sheets commenced on 24 July 2009.

For further information, email murray.richardson@ga.gov.au; or phone +61 2 6249 9229.

6. About Minerals Alert

For more information contact Mike Huleatt on +61 2 6249 9087 or email mike.huleatt@ga.gov.au.

To view past editions of Geoscience Australia's Minerals Alert, visit the Minerals Alert Newsletter Archive.

Topic contact: media@ga.gov.au Last updated: October 4, 2013