The WA Array project will accelerate the acquisition of passive seismic data across Western Australia to identify areas of higher prospectivity under deep cover, which will assist in evaluating future competing land uses and maximise Western Australia’s opportunities in the State’s transition to net zero emissions. The program is a major logistical undertaking, representing one of the largest of its type completed anywhere in the world.
The project is funded by the State Government over a period of 10 years and will be run by the Geological Survey of Western Australia. The project will involve the deployment of an array of 165 seismometers arranged in a grid pattern spaced at 40 km intervals, with the entire State mapped over 10 years by relocating the instruments annually between nine regional areas. Each station requires deployment, servicing, retrieval and rehabilitation. About 52% of the stations will require transport via helicopter, the rest will be accessed by road. As data is generated, it will be subject to a rigorous quality assessment process and review by seismologists before being made freely available to explorers, researchers and the community through the national AusPASS portal. Derivative spatial and 3D products will be available through DMIRS online geoscience data platforms.
The roll out of the program will prioritise regions according to areas of greatest expected resource development potential, with data being progressively released.
The net-zero challenge
The global transition to a low-carbon economy will support ongoing high demand for critical minerals to keep pace with investment in renewable energy generation and storage technologies. Western Australia’s future requires optimal strategic planning that balances the competing land uses required for the State’s transition to a low-carbon economy. Locations for renewable energy projects, including a future renewable hydrogen export industry, must be balanced against exploring and developing future mines and associated potential downstream processing operations.
Western Australia is home to one of the most diverse and successful resource sectors in the world. It is a leading global producer of key industrial commodities such as iron ore and gold, and critical minerals such as lithium, nickel and alumina; however, the declining rate of discovery of major new mineral resources has the potential to impact our ability to keep up with demand.
The issue is not so much a lack of resources, but rather that most of the known and mined mineral deposits occur in areas that are either close to the surface, or were otherwise ‘easy to find’ (see map below). One of the key impediments to mineral exploration success is the blanket of sediments and weathered rock that conceals about 70% of prospective basement rocks.
The key to helping exploration companies pinpoint the probable location of these resources is through the application of geoscience technology like WA Array that can provide imaging of the State’s geology at sufficient depths beneath the surface.
Locating prospective areas under cover
Continents are made up of blocks of lithosphere that have come together as the continents assembled through time. The sutures between these lithospheric blocks are fundamental structures of interest in the hunt for new mineral discoveries. ‘Ambient’ seismic noise from ocean waves and storms, and receiver functions (how an earthquake signal is shaped by its passage through the crust underneath the seismometer), can be used to ‘image’ the velocity structure and composition of the Earth down to the core.
The lithosphere/asthenosphere boundary is regarded as the bottom of the continental plate, and is a key and fundamental feature used for predicting the location of mineral deposits near the surface. Passive seismic studies with sufficient resolution are able to map this boundary in detail and therefore provide critical information to mineral explorers.
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