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Geologists have just taken a long overdue glimpse of the basement rocks from under the Nullarbor Plain, in the far west of South Australia. The first drill hole of the $3 million PACE Copper Coompana Drilling Program has now been completed. Aimed at providing new insights into the geology beneath the Nullarbor Plain the program will drill up to 18 holes between now and the end of 2017 collecting valuable samples, new data and information in one of the state’s (if not Australia’s) greatest geological frontiers.

If you are one of the few people to drive across the Nullarbor Plain it is fascinating to simply contemplate what lies beneath this vast area of Australia – new steps have now been made to provide the facts for answering that question.

The Nullarbor Plain is one of Australia’s most distinctive landforms but little has been known about what rocks lie beneath the limestones of this uplifted sea floor. These deeply buried rocks are thought to hold critical clues on the ancient history of how the Australian continent has formed, as well as its buried natural resources. The Coompana Drilling Program utilises new information on the geology of this region, incorporating earlier geophysical and geochemical imaging of these buried rocks.

In using an analogy with medical practice, after several years of scanning the Earth’s crust it finally became time to ‘operate’, and drill and retrieve samples for analysis and see first-hand what is down there. For geologists this is a once in a generation opportunity to see these rocks and piece them into the geological history of our continent. Then comes the decision as to how they might link this to the formation of mineral deposits and groundwater reservoirs.  

The first hole has been drilled to a depth of just over 500 metres and has revealed samples of a granite type rock known as diorite. These rock samples will now be tested and analysed, to determine their detailed geochemical and mineral compositions, as well as geochronological assessments (telling how old the rocks are). These samples will then be stored for further examination by future generations of geologists in the South Australia Drill Core Reference Library within the Tonsley Precinct.  

The Coompana Drilling Program is being run in partnership with Geoscience Australia under the National Collaboration Framework’s Exploring for the Future program. The Geological Survey of South Australia (GSSA) within the Department of the Premier and Cabinet recently awarded the drilling contract to South Australian based Boart Longyear Australia Pty Ltd after a competitive tender process.

The PACE Copper Coompana Drilling Program will not only help to fill in the remaining gaps of our State’s geological story but will provide regional jobs and economic opportunities through the engagement of local businesses in Ceduna, Border Village and Nullarbor.

Stay tuned for further updates as more holes are drilled and samples analysed. More results will also be released during the annual Geological Survey of South Australia Discovery Day to be held on 7 December at the Adelaide Convention Centre – registration is free.

Coompana drilling program TMI imageFoliated diorite

Regional geophysical data can be accessed via the South Australian Resources Information Gateway (SARIG)