Deep seismic survey uncovers Australia's secret past

26 September 2006

Fresh analysis of seismic data gathered in the Broken Hill region has revealed new information about the make up of the Australia continent indicating a previously unidentified merging of the Earth's crust.

In a presentation to the Broken Hill Exploration Initiative Conference, Geoscience Australia scientist, Dr Russell Korsch, said improved techniques in the interpretation of deep seismic data showed an anomaly occurring at between 42 and 54 kilometres below the surface.

Dr Korsch said the results show a strong correlation between the varying ages of rocks at the surface and a major joining of two very different pieces of the Earth's crust.

"The architecture at depth helps to explain the previously puzzling difference between the rocks of up to 1,720 million years in the Broken Hill region and the less than 600 million year old rocks in the more easterly Darling region," he said.

"The result provides a much clearer understanding of the geological architecture well beyond the Moho, or Mohorovicic discontinuity, and will help in the identification of possible mineralisation in the region.

"This is an exciting new period of discovery thanks to the wealth of pre-competitive geoscience information and new knowledge generated by the partners in the Broken Hill Exploration Initiative along with industry, and university researchers, " Dr Korsch said.

The deep seismic survey was a joint venture between Geoscience Australia and the predictive minerals discovery Cooperative Research Centre in conjunction with the NSW and South Australian resource agencies and Geological Surveys.

It was the first of its kind to transect the whole of a known mineral province at depth, extending more than 400 km from the Flinders Ranges to the Darling Basin in a continuous line which passed close to Broken Hill.

Known as the Curnamona geological province, the region already contains a number of important mines apart from Broken Hill, including the Beverley and newly approved Honeymoon uranium mines in South Australia.

Dr Korsch said the knowledge gained through the deep seismic survey will help with the identification of other potential mineralisation and energy sources, including uranium and hot rocks.

"Broken Hill type mineralisation occurs to the north and south of Broken Hill and exploration is currently being undertaken for copper, gold, uranium, nickel and platinum group elements by a range of junior explorers and major multinational mining companies," he said.

"The potential for copper and gold deposits in the Curnamona Province has been highlighted by advances in geological knowledge which show the similarities to major deposits in the Gawler region of South Australia and the Cloncurry district in North Queensland," Dr Korsch said.

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