This activity aims to undertake a series of airborne electromagnetic (AEM) surveys of a large region of northern Australia, using a broad line spacing of 20 km. It represents the largest AEM survey of its kind ever undertaken. The AEM technique enables mapping of the subsurface electrical conductivity of rocks, sediments and waters, to depths of up to several hundred metres, depending on factors such as the AEM system used and the electrical conductivity of the sub-surface.
AEM is a non-invasive testing technique that can detect variations in the conductivity of the ground to a depth of several hundred metres. The conductivity response in the ground is commonly caused by the presence of electrically conductive materials such as salt or saline water, graphite, clays and sulphide minerals.
The AusAEM data and derived products will be used to map the thickness and character of sedimentary and regolith cover in regions flanking crystalline basement outcrop. Previous surveys by Geoscience Australia using wide line spacing (e.g. 6 km) have shown the utility of the method in mapping cover thickness and its character. The survey results will also be used by the groundwater community to assess the potential for groundwater resources in Australia's arid zones to support remote communities in the survey areas.
The AusAEM surveys have been divided into blocks approximately based on 1:1 million map sheets, for flying during the northern dry season to maximise survey production rates. The multi-year survey program will be delivered in yearly instalments to ensure that regular scheduled data releases occur throughout the life of the program.
The data will be archived and released only when the data have passed all quality assurance and quality control checks and are thus deemed by Geoscience Australia's geophysicists as fit-for-purpose and use by the geophysical community. This process generally takes several months.
AusAEM Survey NT-WA 2019
Geoscience Australia is conducting a series of airborne electromagnetic (AEM) surveys across the Northern Territory and Western Australia in the 2019 field season.
The airborne survey will take place between May and November 2019 in northern Western Australia and south-west Northern Territory. More information about schedules and detailed flight lines will be released when available. Estimated dates are as follows:
- May-June: Broome, Fitzroy Crossing area
- June-July: Halls Creek, Lajamaun area
- July-November: Karratha, Marble Bar, Alice Springs area
A fixed-wing plane will fly quite low, about 120 m above ground. The flight path involves flying in parallel lines spaced widely, approximately 20 km apart, subject to weather and other logistic issues. There will be no ground disturbance.
Contact Geoscience Australia on 1800 091 964 for any questions about the airborne survey.
AusAEM Survey NT-QLD (completed)
A total of 60 000 line kilometres were acquired between the 2017 and 2018 field season. The AusAEM survey also includes over 2,200 line kilometres of infill flying at tighter line spacing, funded by private exploration companies, in certain infill blocks within the survey area.
The AEM data will be integrated with other datasets collected as part of the EFTF program (surface geochemistry, groundwater hydrochemistry, seismic, magnetotelluric, potential field, solid geology, isotopic mapping) to assist with stratigraphic drilling to characterise the under-cover geology.
This survey was led by Geoscience Australia in collaboration with the Northern Territory Geological survey and the Geological Survey of Queensland as part of the Exploring for the Future (EFTF) program.
All data acquired during 2017 and 2018 field season is available to download:AusAEM data and Em Flow® conductivity estimates
The data release package contains the final deliverables produced by the contractor CGG including:
- The survey logistics and processing report
- Final processed electromagnetic, magnetic and elevation point located line data
- Final processed electromagnetic, magnetic and elevation grids
- Conductivity estimates generated by the EM Flow® conductivity depth imaging algorithm
- Graphical multiplots of line data and EM Flow® conductivity sections
- Graphical stacked EM Flow® conductivity sections
Future data release packages will include further inversion and interpretation products.
Geoscience Australia is partnering with State and Territory government geoscience agencies to deliver the AusAEM program. Industry have subscribed to areas of infill in the first survey area as this approach was successfully used in a previous exploration initiative of the Commonwealth Government — the Onshore Energy Security Program (OESP). Industry benefits include low acquisition and zero mobilisation costs.
The infill line data are confidential for a period of twelve (12) months from the date the final survey data is provided to the subscriber. Upon expiry of this moratorium period the infill data will be released as soon as possible by Geoscience Australia to the public domain for use in the minerals, energy and groundwater sectors.