Darling-Curnamona-Delamerian

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The Darling-Curnamona-Delamerian project is one of three deep-dive projects under the Exploring for the Future program. By gathering and analysing geological and geophysical data and making the results publicly available, the program supports regional development and informed decision-making across Australia, resulting in jobs and growth.

The project is delivering new data and knowledge to assess mineral and groundwater potential and support water management across western New South Wales and Victoria, eastern South Australia and northwest Tasmania.

The Curnamona Province is a roughly circular block of ancient (Paleo-Mesoproterozoic) rocks that underlies the NSW-SA border, with many similarities to other geological regions with rich mineral wealth like the Gawler Craton and Mount Isa Block. The Curnamona Province hosts the world-class Broken Hill lead-zinc-silver-gold mine that has operated continually since 1885, underpinning much of the local economy, and numerous smaller ore deposits including gold, silver, lead, zinc, copper and critical minerals like cobalt. A geological province is a term used by geologists to describe a large area that encompasses a natural geological feature where the rocks have a common geological history, such as a sedimentary basin, a fold belt or a mountain range.

The Delamerian Orogen wraps around the eastern Curnamona Province in New South Wales and South Australia, and extends through Victoria into Tasmania. This is a slightly younger (Neoproterozoic to Early Paleozoic) continental collision zone that was a region of volcanism and mountain building, which has now eroded down and lies mostly under cover of younger sedimentary basins on the Australian mainland. The Delamerian Orogen also hosts high quality mineral deposits including gold, copper, lead and zinc within igneous (volcanic and granitic) and more weakly metamorphosed sedimentary rocks. This project is assessing the mineral potential undercover in the Curnamona Province and Delamerian Orogen. Orogen is a term used by geologists to describe a group of rocks with a common geological history, formed by geological mountain building events, which may now be eroded flat and buried.

The pastoral and agricultural sectors are important contributors to communities and the local economy in the region. In support of these, the project is also investigating the groundwater potential of overlying basins, including the Murray-Darling Basin, with a focus on the upper Darling River floodplain. In the Darling region, potable water supply to some towns is threatened during dry periods, and shallow saline groundwater threatens the ecosystem health of the Darling River. The project seeks to identify new groundwater resources and assess the potential for groundwater storage in the region to support groundwater management and improve drought resilience in communities.

Proposed project activities may include:

  • new multi-scale geophysical data acquisition, stratigraphic and groundwater drilling
  • sampling, geochemical analysis and age dating of groundwater, rock and sediment
  • integration of these new data with historical and state data to deliver geological framework understanding and resource potential assessments.

The project will involve extensive stakeholder engagement, including state and local government agencies, landholders and Traditional Owner groups. In-air data acquisition activities commenced in early 2021 with the eastern corridor AusAEM survey, and further in-air and on-ground acquisition activities are planned to continue to late 2023 as outlined below.

What we are doing

The project incorporates a number of study areas and proposed activities, including:

Upper Darling River floodplain groundwater study

The study is acquiring multi-scale airborne electromagnetic (AEM) data followed by non-intrusive surface geophysics (surface magnetic resonance), water monitoring bore drilling, groundwater hydrogeochemistry and borehole geophysics across the upper Darling River floodplain to assess groundwater quality and levels. Results will help build drought resilience by identifying potential new groundwater resources, managed aquifer recharge opportunities and augmenting salt interception schemes and weirs. This work will be conducted in collaboration with the NSW Department of Planning, Industry and Environment. For more information about the study, including active and planned data collection, please visit the Upper Darling River floodplain groundwater study page.

AEM infill

Airborne electromagnetic (AEM) surveys using fixed-wing aircraft or helicopters at a flight line spacing of approximately 5km to map near-surface geology.

Deep crustal reflection seismic

Seismic data will be acquired to map geology to the base of the Earth’s crust and help interpret the geological history of the project area.

This work module includes a carefully designed reflection seismic survey that will create an image of important crustal boundaries including the structure of the Delamerian margin, which runs through New South Wales, South Australia and Victoria, separating older rocks of the Gawler Craton and Curnamona Province from younger rocks of the Lachlan Fold Belt (Tasmanides).

Curnamona Cube Extension magnetotelluric survey

Magnetotelluric (MT) surveys measure the Earth’s natural magnetic and electric fields. These data help map the electrical structure of the Earth’s crust and complement the seismic and AEM data gathered in the region, as well as providing clues to places that are prospective for buried mineral systems.

This survey will acquire data at sites approximately 12.5 km – 25 km apart, continuing the grid of the AuScope Curnamona Cube Program eastwards from the Curnamona Province to provide better definition of deep-seated lower crustal conductivity anomalies under the Delamerian Orogen and their significance for mineral potential and geological structure.

Curnamona Geochemistry

A low impact geochemical sampling program of rocks, soils and groundwater across parts of the Curnamona Province to enable an integrated understanding of geochemical baselines, geochemical migration and mineral potential under cover.

Geological Framework, Mineral Potential Assessment and Stratigraphic Drilling

Integration of newly acquired geoscientific data with historical and state data to deliver new understanding of the regional geology and its evolution through geological time, and resource potential assessments for a range of commodities including copper, gold, lead, zinc and critical minerals important for economic development.

Targeted scientific drilling may be undertaken in one or more locations within the project area to fill knowledge data gaps in undercover geology, as part of the MinEx CRC National Drilling Initiative. The rocks will be analysed for geochemistry, structures and isotopic ages and the data used to inform the regional geological framework and mineral potential assessments.

Collaboration

Project collaborators include:

Outputs

All data produced by Geoscience Australia, including the data from this project, will be made publicly available after quality assurance has been performed at the Geoscience Australia Community and Education Portal.

We will work with communities to return the data in a useful format, through the Geoscience Knowledge Sharing project. Acquisition activities are not being undertaken on behalf of any exploration companies. All Geoscience Australia staff and contractors will comply with Geoscience Australia’s COVID-19 protocols, available upon request.