b'AEGC 2021Short abstractsbedrock conductors associated with possible mineralisation,The Exploring for the Future Programme facilitated the palaeo-channels and anthropogenic anomalies. Theacquisition of major geoscience datasets in northern Australia, geological interpretation has utilised GA layered Earthwhere rocks are mostly undercover and the basin evolution, inversions, probabilistic inversions and 2-5D inversions. AEMmineral, energy and groundwater resource potential are, in conductivitydepth sections were integrated with drillingplaces, poorly constrained. In an effort to support sustainable, information and other datasets using 3D geological modellingregional economic development and build stronger applications. This presentation will summarise results from ancommunities in these frontier areas, integration of new and interpretation report released earlier this year. legacy data within a consistent sub-surface platform could enhance the recognition of cross-disciplinary synergies.80: The North Australian Craton 3D gravity andHere we present a case study in the South-Nicholson magnetic inversion models - A trial for first passBasin, located in a poorly exposed area between the highly modelling of the entire continent prospective Mt Isa Province and the McArthur Basin. Both regions host major base metal deposits, contain units Dr James Goodwin 1 and Mr Richard Lane1 prospective for hydrocarbons, with significant groundwater resources in the overlying Georgina Basin. In this study we 1 Geoscience Australia interpret a subset of new large-scale data, which include As part of the Exploring for the Future initiative, whole-of-crust~1 900 km of deep seismic reflection data and 60 000 line 3D gravity and magnetic inversion models have been producedkilometers of AusAEM1 airborne electromagnetic survey, for an area encompassing the North Australia Craton (NAC).with legacy information and new tools. This interpretation These models were created to aid 3D geological mapping andrefines a semi-continental geological framework, as input to identification of large-scale mineral systems such as iron oxidenational coverage databases and inform decision-making for copper-gold (IOCG) systems. exploration and groundwater resource management.The inversion models were derived using the University ofThis study provides a 3D chronostratigraphic cover model down British Columbia Geophysical Inversion Facility (UBC-GIF)to the Paleoproterozoic basement. We mapped the depth to the MAG3D and GRAV3D programs. We used reference models thatbase of geological eras, as well as deeper pre-Neoproterozoic had layers for Phanerozoic sediments, Proterozoic sediments,Superbasin sequence boundaries to refine the cover model. The undifferentiated crust and the mantle. The reference modeldepth estimates are based on the compilation, interpretation for the magnetic inversion incorporated a Curie depth surfaceand integration of geological and geophysical datasets that below which magnetic susceptibility was set to zero. inform on the basement architecture control on the basin evolution with the key outcomes:To facilitate cross-referencing of the density and magnetic1) expanded the size of the basin, increasing prospectivity for susceptibility models, we used identical meshes for the twohydrocarbons and basin-hosted mineralisation, 2) correlation inversions. The spacing of the available gravity data dictatedof stratigraphic units across the region, 3) identified major a horizontal cell size of 1 km. We used 61 vertical layers ofcrustal boundaries and structures associated with localisation thickness increasing with depth. The area of interest wasof springs and mineralisation resulting from crustal fluid flow, 2450 km by 1600 km which meant that the mesh for the NAC4) support future investigation of groundwater resources in models had ~240 million cells. shallow and deeper aquifers.It was not possible to invert a model of this size. Instead, we broke the problem down into a grid of overlapping tiles with 882: Overburden measurement for coal mine rows and 10 columns. Each tile was independently inverted. management with 3D high resolution compressional When the overall model was reconstructed using the core region ofand shear velocity seismic inversioneach tile, some low-level edge effects were observed, increasing in significance with depth. These effects were satisfactorily attenuatedDr Claudio Strobbia1, Mr Martin Bayly 2, Dr Tim Dean3, Mr Denis by applying cosine weighting from the centre of each tile out to theSweeney2, Mr Matthew Grant3 and Mrs Margarita Pavlova3edge of the data padding zone during reconstruction. 1 RealtimeseismicThe success of the NAC modelling exercise has given us2 SuperSeisconfidence that we can expand the coverage to produce3 BHPcoincident gravity and magnetic inversion models for the entireHigh resolution surface seismic surveys can provide useful Australian region. images of coal bed reflections to depths as shallow as 50 to 100 metres. There is also a need, to gain information of the 81: Towards a 3D model of the South-Nicholson Basinoverburden properties above these depths. This information region, Northern Australia, for mineral, energy andgap can be addressed by inversion of both the refractions groundwater assessment and surface waves (ground-roll, normally considered to be noise) generated along with reflections as part of the regular Dr Nadege Rollet 1, Dr Michael Doublier1, Mr Chris Southby1, Mrsurvey acquisition. Recent advances in acquisition such as finer Ross Costelloe1, Dr Tanya Fomin1, Ms Lidena Carr1, Dr Marie- spatial sampling, single sensor recording and lower frequency Aude Bonnardot1, Dr John Wilford1, Mr Sebastian Wong1, Mrvibroseis sweeps all serve to improve the quality and utility of Malcolm Nicoll1, Dr Karol Czarnota1, Dr Donna Cathro1 and Mrthese data.Stephen Hostetler1In addition to their direct use to infer the petrophysical 1 Geoscience Australia and hydrodynamic properties of the overburden prior to AUGUST 2021 PREVIEW 74'