Head of CSIRO's exploration research, DR ROB HOUGH, writes about why research into Western Australia’s largely unexplored and deeply covered Capricorn region holds much promise for future prospectivity.
Article from resourceful: Issue 9, March 2016.
Of the many projects within the UNCOVER vision, one stands out as being of paramount importance. The Capricorn project in northern Western Australia is UNCOVER’s foremost testing ground.
The region was selected because it's a great unknown – a greenfield site that lies between two proven areas of mineralogical wealth – the Yilgarn and Pilbara cratons.
The Capricorn project will help us to determine the geological and geochemical signatures that point to the prospective mineral systems clusters that we know of in the region and possibly to others that we have yet to see.
It's not just about potential mineral finds, but about finding the right pathways towards minerals discovery, we want to be able to navigate and prospect the subsurface.
The $17.3 million project – a collaboration between CSIRO, The University of Western Australia and Curtin University, together with the Geological Survey of Western Australia and nine exploration companies – has been running for two years now.
The project has funding from the Science and Industry Endowment Fund as well as from the Minerals Research Institute of Western Australia. It's a rare opportunity for young researchers to work closely with industry, starting from a tabula rasa, a virtually unknown stretch of land.
The research team incorporates 25 full-time researchers and another 25 students from a wide variety of backgrounds and disciplines.
There are six teams incorporating expertise in geophysics, mineralogy, structural geology, geochemistry and geochronology. Each team is working on specific themes, which include structural geology, geochemistry and geochronology; mineral systems evolution; cover characterisation; how mineral hosts can act as distal footprints; the hydro-geochemistry for deep geological sensing; the geochemical mapping for lithospheric evolution and predictive targeting.
We also have a team putting together a 3D digital model using virtual environments for data integration and visualisation.
We do know something of the geology of the Capricorn region already and there are a small number of working gold and base metal mines there, but because it's around 800 kilometres from one end of the region to the other, much of it remains largely under-explored.
The research teams, together with the industry explorers on site, are using the latest analytical equipment to understand the chemistry and ages of the rocks below, as well as the chemical pathways of rocks and the potential ore-bearing fluids around them. Some of the most exciting new science being done in the Capricorn is about understanding the chemistry of individual mineral grains, which can act as orientation tools towards mineral systems.
We're also using magnetotelluric and passive seismic sensors, both of which are geophysical imaging tools using sound that can produce images to a depth of 60 kilometres. As a result, we're now seeing evidence of a thicker crust than first anticipated through imaging the older, colder rocks against the warmer, younger rocks.
What will we develop from the Capricorn? By the end of the project in January 2018, we intend to have a tool kit for footprints of mineralising systems, which could be applied in similar geological environments across Australia – and possibly globally.
If it's successful, there's every chance we can take this elsewhere. What happens if we go under the Nullarbor Plain or if we look at parts of the central Australian sedimentary basin and venture deep beneath the Northern Territory and far north Queensland? The point is, if we have the tool kits to do this, we can go into increasingly more complex geological environments with a strong confidence that we can reduce the risk and help with navigating the subsurface.
We will be supporting Australia to be as prosperous from its under cover geology as it has been from its surface geology for the last 120 years. The Capricorn is just the start of a revolution in exploration technology that aims to position Australia for the next 120.
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