This report provides a description of the activities completed during the Bynoe Harbour Marine Survey, from 3 May and 17 May 2016 on the RV Solander (Survey GA4452/SOL6432). This survey was a collaboration between Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and Department of Land Resource Management (Northern Territory Government) and the second of four surveys in the Darwin Harbour Seabed Habitat Mapping Program. This 4 year program (2014-2018) aims to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline information and developing thematic habitat maps that will underpin future marine resource management decisions. The program was made possible through funds provided by the INPEX-led Ichthys LNG Project to Northern Territory Government Department of Land Resource Management, and co-investment from Geoscience Australia and Australian Institute of Marine Science. The specific objectives of the Bynoe Harbour Marine Survey GA4452/SOL6432 were to: 1. Obtain high resolution geophysical (bathymetry) data for the deeper areas of Bynoe Harbour (<5 m), including Port Patterson; and, 2. Characterise substrates (acoustic backscatter properties, sub-bottom profiles, grainsize, sediment chemistry) the deeper areas of Bynoe Harbour (<5 m), including Port Patterson. Data acquired during the survey included: 698 km2 multibeam sonar bathymetry, water column and backscatter; 102 Smith-McIntyre grabs, 104 underwater camera drops, 29 sub-bottom profile lines and 34 sound velocity profiles.

This package contains presentations given during NT Resources week, at the Uncovering East Tennant workshop held in Darwin on September 3, 2019, and Mining the Territory, September 5, 2019. The presentation given by Andrew Heap at the Mining the Territory forum is a high level overview of the data collection and activities of GA and it's collaborative partners across Northern Australia in conjunction with the Exploring for the Future (EFTF) program. The workshop, held in collaboration with the Northern Territory Geological Survey, outlined new mineral exploration opportunities in the East Tennant area, which lies beneath the Barkly Tableland and extends approximately 250 km east of Tennant Creek. The East Tennant area has been the focus of geochemical, geological and geophysical data acquisition as part of Geoscience Australia's Exploring for the Future program. This free event showcased new science insights for the East Tennant area and how this under-explored region has opportunities for greenfield mineral discoveries.

AusAEM 02 Airborne Electromagnetic Survey, NT /WA, 2019-2020: TEMPEST® AEM data and conductivity estimates The accompanying data package, titled “AusAEM 02 WA/NT, 2019-20 Airborne Electromagnetic Survey: TEMPEST® airborne electromagnetic data and conductivity estimates”, was released on 10 August 2020 by Geoscience Australia (GA), the Geological Survey of Western Australia and the Northern Territory Geological Survey. The package contains processed data from the“AusAEM 02 WA/NT, 2019-20 Airborne Electromagnetic Survey" that was flown over the North-West part of the Northern Territory across the border and all the way to the coast into Western Australia. The regional survey was flown at a 20-kilometre nominal line spacing and entailed approximately 55,675 line kilometres of geophysical data. The survey was flown in two tranches during 2019, by CGG Aviation (Australia) Pty. Ltd. under contract to Geoscience Australia, using the TEMPEST® airborne electromagnetic system. CGG also processed the data. The survey also includes a further 6,450 line kilometres of infill flying that was funded by private exploration companies, acquired in certain blocks within the survey area. The data from these infill blocks have been processed in the same manner as the regional lines and are part of this release. Geoscience Australia commissioned the AusAEM 02 survey as part of the Exploring for the Future (EFTF) program, flown over parts of the Northern Territory and Western Australia. Geoscience Australia (GA) leads the EFTF program, in collaboration with the State and Territory Geological Surveys of Australia. The program is designed to investigate the potential mineral, energy and groundwater resources of Australia driving the next generation of resource discoveries. GA managed the survey data acquisition, processing, contract, the quality control of the survey and generating two of the three inversion products included in the data package. The data release package comntains 1. A data release package summary PDF document. 2. The survey logistics and processing report and TEMPEST® system specification files 3. ESRI shape files for the regional and infill flight lines 4. Final processed point located line data in ASEG-GDF2 format 5. Conductivity estimates generated by CGG’s EMFlow conductivty-depth transform -point located line data output from the inversion in ASEG-GDF2 format -graphical (PDF) multiplot conductivity sections and profiles for each flight line -Grids generated from CGG's inversion conductivty-depth transform in ER Mapper® format (layer conductivities) 6. Conductivity estimates generated by Geoscience Australia's inversion -point located line data output from the inversion in ASEG-GDF2 format -graphical (PDF) multiplot conductivity sections and profiles for each flight line -georeferenced (PNG) conductivity sections (suitable for pseudo-3D display in a 2D GIS) -GoCAD™ S-Grid 3D objects (suitable for various 3D packages)

Seismic reflection mapping, geochemical analyses and petroleum systems modelling have increased our understanding of the highly prospective Mesoproterozoic and Paleoproterozoic source rocks across northern Australia, expanding the repertoire of exploration targets currently being exploited in Proterozoic petroleum systems. Data collected during the Exploring for the Future program have enabled us to redefine and increase the extent of regional petroleum systems, which will encourage additional interest and exploration activity in frontier regions. Here, we present a review of the Paleoproterozoic McArthur and Mesoproterozoic Urapungan petroleum supersystems, and the most up-to-date interpretation of burial and thermal history modelling in the greater McArthur Basin (including the Beetaloo Sub-basin), South Nicholson Basin and Isa Superbasin. We also present potential direct hydrocarbon indicators imaged in the 2017 South Nicholson Deep Crustal Seismic Survey that increase the attractiveness of this frontier region for hydrocarbon exploration activities. <b>Citation:</b> MacFarlane, S.K., Jarrett, A.J.M., Hall, L.S., Edwards, D., Palu, T.J., Close, D., Troup, A. and Henson, P., 2020. A regional perspective of the Paleo- and Mesoproterozoic petroleum systems of northern Australia. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.

<p>Geoscience Australia (GA) generated a series of gravity and magnetic grids and enhancements covering Northern Australia. Several derivative gravity datasets have been generated 1) for the North-West Shield Western Australia region (approximately between latitudes 7‒26⁰ S and longitudes 110‒130⁰ E), 2) for the Northern Territory (approximately between latitudes 7‒26⁰ S and longitudes 125.5‒141⁰ E) and for Queensland (approximately between latitudes 7‒30⁰ S and longitudes 135‒160⁰ E). The magnetic dataset has been generated only for the North-West Shield Western Australia region (approximately between latitudes 7‒26⁰ S and longitudes 110‒130⁰ E). The magnetic and gravity data were downloaded from the Geophysical Archive Data Delivery System (GADDS), website (http://www.geoscience.gov.au/cgi-bin/mapserv?map=/nas/web/ops/prod/apps/mapserver/gadds/wms_map/gadds.map&mode=browse). Satellite Free-air (FA) gravity v27.1 (released March 11, 2019) and Satellite Topography v19.1 (released January 14, 2019) data were sourced from Sandwell et al. (2014) and downloaded from the Scripps Institution of Oceanography (SIO), National Oceanic and Atmospheric Administration (NOAA), U.S. Navy and National Geospatial-Intelligence Agency (NGA) (SIO Satellite Geodesy, website, http://topex.ucsd.edu/WWW_html/mar_grav.html). The Satellite Bouguer gravity grid with onshore correction density of 2.67 gcm-3 and offshore correction density of 2.20 gcm-3 was derived from the Free-air gravity v27.1 and Topography data V19.1. This Bouguer gravity grid was used for filling areas of data gaps in the offshore region. <p>Data evaluation and processing of gravity and magnetic data available in the area of interest resulted in the production of stitched onshore-offshore Bouguer gravity grid derived from offshore satellite Bouguer gravity grid and GA’s onshore ground and airborne gravity survey data and a stitched Total Magnetic Intensity (TMI) grid derived from airborne and shipborne surveys (Tables 1 and 5). A Reduction to the Pole (RTP) grid was derived from the stitched TMI grid. The TMI, RTP, FA and terrain corrected Bouguer gravity anomalies are standard datasets for geological analysis. The free-air gravity anomaly provides the raw and basic gravity information. Images of free-air gravity are useful for first-pass interpretation and the data is used for gravity modelling. Magnetic anomalies provide information on numerous magnetic sources, including deep sources as arising from the structure and composition of magnetic basement and shallow sources such as intra-sedimentary magnetic units (e.g. volcanics, intrusions, and magnetic sedimentary layers). A standard TMI image will contain information from all these sources. Geosoft Oasis montaj software was used throughout the data processing and enhancement procedure and the montaj GridKnit module was used to generate the stitched gravity and magnetic grids. <p>Enhancement techniques have been applied to the final processed Bouguer gravity and RTP magnetic grids to highlight subtle features from various sources and to separate anomalies from different source depths. These enhancement techniques are described in the next section. <p>Enhancement processing techniques and results <p>A summary of image processing techniques used to achieve various outcomes is described in Table 1. <p>Data type Filter applied Enhancement/outcome <p>Gravity/Magnetic First vertical derivative (1VD) Near surface features (e.g. intrabasinal) <p>Gravity/Magnetic Upward continuation Noise reduction in data <p>Gravity/Magnetic Low pass filter, or large distance upward continuation Enhancement of deep features (e.g. basement) <p>Gravity/Magnetic High pass filter Enhancement of shallow features (e.g. surface anomalies) <p>Gravity/Magnetic Tilt filter and 1VD Enhancement of structure (e.g. in basement) <p>Gravity/Magnetic ZS-Edgezone and ZS-Edge filters Enhancement of edges <p>Gravity/Magnetic horizontal modulus / horizontal gradient Enhancement of boundaries <p>Magnetic RTP (reduction to the pole), Compound Anomaly, and Analytic Signal filter Accurate location of sources

<p>The Mesoproterozoic South Nicholson Basin (SNB) in northern Australia extends across an area approximately the size of Tasmania. It is flanked by the resource rich Mt Isa Orogen and McArthur Basin. Limited outcrop and a dearth of drilling has hampered understanding of the evolution of the Basin, its relationship to other tectonic elements in northern Australia and its resource potential. The lack of any identified interbedded volcanic rocks within the studied sections has led us to concentrate on an extensive SHRIMP U-Pb detrital zircon geochronology program that so far exceeds 40 samples. In addition, we have undertaken SHRIMP U-Pb geochronology of authigenic xenotime. <p>Detrital zircon U–Pb maximum depositional ages (MDA) for the South Nicholson Group (SNG) are up to 100 My younger than previously reported [1]. The new MDA for the Constance Sandstone is ~1470 Ma and is the youngest so far recorded in the SNB. Additionally, it accords with an MDA for the underlying Crow Formation of ~1483 Ma. SHRIMP U–Pb xenotime analyses of authigenic overgrowths on detrital zircons from the Constance Sandstone gave an age of ~1266 Ma. This new data brackets the deposition of the SNG to between 1470 Ma and ~1266 Ma and provides the first evidence that the SNG is broadly contemporaneous with the 1500–1320 Ma Roper Group of the McArthur Basin. Using Multidimensional Scaling of the detrital age distributions has also added an extra dimension to our evolving understanding of the development of the SNB. <p>[1] Carson (2011) Queensland Geological Record 2011/03.

<p>The Northern Territory Geological Survey (NTGS) designed the Mount Peake-Crawford survey to provide high resolution magnetic, radiometric and elevation data in the area. It is anticipated that the data from the survey would help attract explorers into ‘greenfield’ terranes and contribute to the discovery of the next generation of major mineral and energy deposits in the Northern Territory. A total of 120,000 line km of regional data (200m line spacing) and additional infill data (100m line spacing), flown at 60m flight height were acquired during the survey between July and October 2019. The survey was managed by Geoscience Australia. <p>Various grids were produced from the Mount Peake-Crawford Airborne Magnetic and Radiometric Survey dataset and simultaneously merged into a single grid file. The final grid retains all of the information from the input data and is levelled to the national map compilations produced by Geoscience Australia. The merged grids have a cell size of 20m. <p>The following merged grids are available in this download: <p>• Laser-derived digital elevation model grids (m). Height relative to the Australian Height Datum. <p>• Radar-derived digital elevation model grids (m). Height relative to the Australian Height Datum. <p>• Total magnetic intensity grid (nT). <p>• Total magnetic intensity grid with variable reduction to the pole applied (nT). <p>• Total magnetic intensity grid with variable reduction to the pole and first vertical derivative applied (nT/m). <p>• NASVD-filtered potassium concentration grid (%). <p>• NASVD-filtered thorium concentration grid (ppm). <p>• NASVD-filtered uranium concentration grid (ppm).

Building on newly acquired airborne electromagnetic and seismic reflection data during the Exploring for the Future (EFTF) program, Geoscience Australia (GA) generated a cover model across the Northern Territory and Queensland, in the Tennant Creek – Mount Isa (TISA) area (Figure 1; between 13.5 and 24.5⁰ S of latitude and 131.5 and 145⁰ E of longitude) (Bonnardot et al., 2020). The cover model provides depth estimates to chronostratigraphic layers, including: Base Cenozoic, Base Mesozoic, Base Paleozoic and Base Neoproterozoic. The depth estimates are based on the interpretation, compilation and integration of borehole, solid geology, reflection seismic, and airborne electromagnetic data, as well as depth to magnetic source estimates. These depth estimates in metres below the surface (relative to the Australian Height Datum) are consistently stored as points in the Estimates of Geophysical and Geological Surfaces (EGGS) database (Matthews et al., 2020). The data points compiled in this data package were extracted from the EGGS database. Preferred depth estimates were selected to ensure regional data consistency and aid the gridding. Two sets of cover depth surfaces (Bonnardot et al., 2020) were generated using different approaches to map megasequence boundaries associated with the Era unconformities: 1) Standard interpolation using a minimum-curvature gridding algorithm that provides minimum misfit where data points exist, and 2) Machine learning approach (Uncover-ML, Wilford et al., 2020) that allows to learn about relationships between datasets and therefore can provide better depth estimates in areas of sparse data points distribution and assess uncertainties. This data package includes the depth estimates data points compiled and used for gridding each surface, for the Base Cenozoic, Base Mesozoic, Base Paleozoic and Base Neoproterozoic (Figure 1). To provide indicative trends between the depth data points, regional interpolated depth surface grids are also provided for the Base Cenozoic, Base Mesozoic, Base Paleozoic and Base Neoproterozoic. The grids were generated with a standard interpolation algorithm, i.e. minimum-curvature interpolation method. Refined gridding method will be necessary to take into account uncertainties between the various datasets and variable distances between the points. These surfaces provide a framework to assess the depth and possible spatial extent of resources, including basin-hosted mineral resources, basement-hosted mineral resources, hydrocarbons and groundwater, as well as an input to economic models of the viability of potential resource development.

This report is the second of three reports that provide the scientific analyses and interpretations resulting from a four-year collaborative habitat mapping program undertaken within the Darwin and Bynoe Harbour region by Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and the Northern Territory Government Department of Environment and Natural Resources (DENR). This program was made possible through offset funds provided by the INPEX-operated Ichthys LNG Project to DENR, and co-investments from GA and AIMS.

To meet the increasing demand for natural resources globally, industry faces the challenge of exploring new frontier areas that lie deeper undercover. Here, we present an approach to, and initial results of, modelling the depth of four key chronostratigraphic packages that obscure or host mineral, energy and groundwater resources. Our models are underpinned by the compilation and integration of ~200 000 estimates of the depth of these interfaces. Estimates are derived from interpretations of newly acquired airborne electromagnetic and seismic reflection data, along with boreholes, surface and solid geology, and depth to magnetic source investigations. Our curated estimates are stored in a consistent subsurface data repository. We use interpolation and machine learning algorithms to predict the distribution of these four packages away from the control points. Specifically, we focus on modelling the distribution of the base of Cenozoic-, Mesozoic-, Paleozoic- and Neoproterozoic-age stratigraphic units across an area of ~1.5 million km2 spanning the Queensland and Northern Territory border. Our repeatable and updatable approach to mapping these surfaces, together with the underlying datasets and resulting models, provides a semi-national geometric framework for resource assessment and exploration. <b>Citation:</b> Bonnardot, M.-A., Wilford, J., Rollet, N., Moushall, B., Czarnota, K., Wong, S.C.T. and Nicoll, M.G., 2020. Mapping the cover in northern Australia: towards a unified national 3D geological model. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.