Minerals Alert September 2008

  1. New Gravity Anomaly Map of the Australian Region
  2. New National Map for Nickel and Platinum Explorers
  3. Australian manganese resource map
  4. Gawler geochemical survey report released
  5. New Gravity Survey Data added to the Australian National Gravity Database
  6. Update on geophysical data releases
  7. About Minerals Alert

1. New Gravity Anomaly Map of the Australian Region

Geoscience Australia has recently released a new full-colour Gravity Anomaly Map of the Australian Region at a scale of 1:5 million. This third edition map replaces the previous map produced in 1997. The new map covers the region from 8o S to 52o S and 100 o E to 170o E the same geographic extents as the new grid used in the production of the map image. (See the August edition of Minerals Alert for details of the new grid). Data for the offshore region of the grid and hence the map were derived from the Marine Gravity from Satellite Altimetry available at Scripps Institution of Oceanography, California. The image in the map is a combination of spherical cap Bouguer anomalies onshore and Free-air anomalies offshore after application to the original grid of a high pass filter with a cut-off wavelength of 500 kilometres. To emphasize the expression of subtle anomalies, an artificial sun-angle illumination from the northeast was used to modify both the saturation and intensity of the original colour image.

Full resolution hardcopy prints of the map may be obtained at a cost of $9.90 from the Geoscience Australia Sales Centre or phone +61 (0)2 6249 9966.

Reduced resolution copies can be downloaded from Geoscience Australia's Maps of Australia web page.

For further information, email Mario Bacchin; or phone +61 (0)2 6249 9308.

2. New National Map for Nickel and Platinum explorers

Geoscience Australia has released a detailed, web-based map at 1:5 million and 1:10 million scales featuring Australian Proterozoic Mafic-Ultramafic Magmatic Events (Sheets 1 and 2). This is the third and final component of the Proterozoic magmatic event series which show for the first time the geographic extent and age relationships of Proterozoic mafic and ultramafic rocks, and associated mineral deposits throughout the continent.

Thirty major Proterozoic magmatic events are identified on the national map and a Time-Space-Event chart. Inset maps show the locations of mineral deposits and occurrences, and the distributions of Large Igneous Provinces (large volumes of coeval mafic magmatism). The new map will be of interest to those explorers searching for nickel, platinum-group elements, chromium, titanium, and vanadium. It will be a fundamental resource also for understanding the dynamic evolution of the Australian continent.

Geoscience Australia Record 2008/15 Guide to using the 1:5 million map of Australian Proterozoic mafic-ultramafic magmatic events by Hoatson, Claoue-Long, & Jaireth, is expected to be released in September.

For further information, email Dean Hoatson, or phone +61 (0)2 6249 9593.

3. Australian manganese resource map

Geoscience Australia has released a new 1:10 million scale map showing the distribution of Australia's manganese resources. The map shows the location of manganese deposits and occurrences. The deposits are shown according to their total contained metal and the regions in which they occur are classified according to the total contained metal. Total contained metal is the aggregate of past production and remaining resources in a deposit. The resource data used to prepare these maps was derived from publicly available company reports and other reports. The map is available as a free download in either PDF (2.5MB) or JPEG (2.8MB). Compilation of data for this map is ongoing and new editions are expected to be released periodically.

For further information, email Mike Huleatt or phone +61 (0)2 6249 9087.

4. Gawler geochemical survey report released

A report entitled Gawler Region Geochemical Survey, South Australia (CRCLEME OFR 211) is now available as a free download. The report describes the methods, results and preliminary interpretations from a pilot project applying low-density sampling of near-surface transported regolith in the central Gawler region of South Australia. Sediment samples were collected at two depths (0-10 centimetres and ~60-90 centimetres depth) near the outlets of 42 catchments over the area. Bulk parameters and the concentrations of more than 60 elements in the <180 um and <75 um fractions were measured. Analyses of various other grain-size fractions, heavy mineral separates and groundwater also were carried out at selected sites.

Geochemical patterns displayed by mapping the concentration distributions of elements in the regolith at both depths show the influence of buried bedrock and mineralisation in the study area, despite the common occurrence of a thick regolith cover, which in places has an important aeolian component. The concentrations of Chromium (Cr) and Zinc (ZN) in the regolith materials appear to relate to the presence of mafic/ultramafic (high Cr) and I-type igneous (low Zn) lithologies in the basement rocks, respectively. Gold (Au) concentrations above the regional median value are observed in many of the catchments containing known Au mineral occurrences. Several catchments, with no known Au mineralisation, also show high regolith Au concentrations and may be of interest to explorers.

The new data provides a layer of fundamental geochemical information for mineral exploration. Potential additional uses of this data set include land management, environmental monitoring and geohealth.

For further information, email Patrice de Caritat; or phone +61 (0)2 6249 9378.

5. New Gravity Survey Data added to the Australian National Gravity Database

Gravity data collected along the 2007 Mt Isa - Georgetown - Charters Towers seismic lines will become open file from 8 September 2008 and will be available to download using the on-line data delivery system. The gravity dataset consists of 2816 stations read at a spacing of 400 metres along the seismic lines.

In July 2008 the 519 gravity stations collected at 400 metres spacing along the 2008 Rankin Springs seismic lines were added to the Australian National Gravity Database and are now available.

A total of 16,949 open file company gravity stations located in Victoria, South Australia, Tasmania and the Northern Territory have been entered recently into the Australian National Gravity Database. These data have been passed onto Geoscience Australia by the respective State and the Northern Territory geological surveys.

For further information, email Mario Bacchin; or phone +61 (0)2 6249 9308.

6. Update on geophysical data releases

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

The Lower Macquarie River airborne electromagnetic survey was flown and processed by Fugro Airborne Surveys Pty Ltd. The survey comprises 35,189 line kilometres of airborne electro magnetic (TEMPEST time domain EM system) and magnetic data over the Lower Macquarie River catchment in central west New South Wales. Data acquisition commenced on 14th December 2006 and was completed on 19th April 2007. The survey was commissioned by the Australian Government Department of Agriculture, Fisheries and Forestry through the Bureau of Rural Sciences (BRS) and funded under the National Action Plan for Salinity and Water Quality. The data were released on DVD on Tuesday 26th August. Contact the Geoscience Australia Sales Centre. For further information on the DVD, please visit the BRS web site.

The River Murray Corridor airborne electromagnetic survey was flown and processed by Fugro Airborne Surveys Pty Ltd. The survey comprises 24,286 line kilometres of airborne electro magnetic (RESOLVE frequency domain EM system) and magnetic data over the arthe River Murray Corridor Salinity Mapping Project area in New South Wales and Victoria. Data acquisition commenced on 2nd February 2007 and was completed on 13th May 2007. The survey is part of the Australian Government's $20 million Community Stream Salinity and Salinity Mapping Program commitment to map salinity in the Murray Darling Basin. The Mallee, North Central, Murray and Lower Murray Darling Catchment Management Authorities are working in partnership with the Australian Government Department of the Environment and the Department of Agriculture, Fisheries and Forestry through the Bureau of Rural Sciences. Geoscience Australia was engaged to manage the technical aspects of the survey program. The data were released on DVD on Tuesday 26th August 2008. Contact the Geoscience Australia Sales Centre for further information on the DVD. Further information on the survey is available from the the River Murray Corridor Salinity Mapping Project.

For further information, email Murray Richardson or phone +61 (0)2 6249 9229.

7. 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