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  • Geochemical surveys conducted by BMR since 1980 in the southern Kakadu region have highlighted the natural occurrence in specific areas of well above crustal concentrations of uranium, thorium, arsenic, mercury and lead. The natural levels of concentration in the land and possibly the water systems of the South Alligator Valley area could constitute an environmental hazard. A large part of this area coincides with the area delineated as the "sickness country". SUBMISSION TO THE RESOURCE ASSESSMENT COMMISSION BY THE BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS.

  • This database contains geochemical data for samples analysed both for inorganic and organic geochemistry. Analytical data are sourced from Geoscience Australia's Inorganic Geochemistry Database (OZCHEM) and Organic Geochemistry Database (ORGCHEM), respectively. The data are joined on a unique sample number. Inorganic geochemical data cover the majority of the periodic table, with metadata on analytical methods and detection limits. Organic geochemical data include results of pyrolysis, derivative calculated values, and, where available, isotopic composition of carbonates (D13C) and isotopic composition of rock nitrogen (D15N). Further, there are provisions for delivery of isotopic data for kerogen (H, C, N) and oxygen (O) for carbonates. Where available, sample descriptions include stratigraphic unit names and ages, and lithology. Location information includes coordinates of the sampled feature (eg, borehole), coordinates of the sample and sample depth. Interpretation of the combined inorganic and organic geochemistry for organic-rich shales will facilitate comprehensive characterisation of hydrocarbons source rocks and mineral commodities source and trap environments. All are achieved within the frameworks of petroleum and mineral systems analysis. The initial data delivered by this service include 1785 samples from 35 boreholes from 14 geological provinces, including recently released data for 442 samples from the South Nicholson National Drilling Initiative Carrara 1 stratigraphic drill hole (Butcher et al., 2021; Carson et al., 2021). Many sampled boreholes are located within the polygon of the Exploring for the Future Barkly-Isa-Georgetown project. This dataset will be updated periodically as more data become available.

  • As part of the Onshore Energy Systems Group’s program, organic maturation levels were determined using polar compounds from potential source rocks from the Georgina and Canning basins. The Early Paleozoic organic matter is devoid of the vitrinite maceral so unsuitable of the measurement of the industry-standard vitrinite reflectance (Ro%) measurement.

  • This report presents key results from hydrogeological investigations in the Tennant Creek region, completed as part of Exploring for the Future (EFTF)—an eight year, $225 million Australian Government funded geoscience data and information acquisition program focused on better understanding the potential mineral, energy and groundwater resources across Australia. The EFTF Southern Stuart Corridor (SSC) Project area is located in the Northern Territory and extends in a north–south corridor from Tennant Creek to Alice Springs, encompassing four water control districts and a number of remote communities. Water allocation planning and agricultural expansion in the SSC is limited by a paucity of data and information regarding the volume and extent of groundwater resources and groundwater systems more generally. Geoscience Australia, in partnership with the Northern Territory Department of Environment and Natural Resources and Power and Water Corporation, undertook an extensive program of hydrogeological investigations in the SSC Project area between 2017 and 2019. Data acquisition included; helicopter airborne electromagnetic (AEM) and magnetic data; water bore drilling; ground-based and downhole geophysical data for mapping water content and defining geological formations; hydrochemistry for characterising groundwater systems; and landscape assessment to identify potential managed aquifer recharge (MAR) targets. This report focuses on the Tennant Creek region—part of the Barkly region of the Northern Territory. Investigations in this region utilised existing geological and geophysical data and information, which were applied in the interpretation and integration of AEM and ground-based geophysical data, as well as existing and newly acquired groundwater hydrochemical and isotope data. The AEM and borehole lithological data reveal the highly weathered (decomposed) nature of the geology, which is reflected in the hydrochemistry. These data offer revised parameters, such as lower bulk electrical conductivity values and increased potential aquifer volumes, for improved modelling of local groundwater systems. In many instances the groundwater is shown to be young and of relatively good quality (salinity generally <1000 mg/L total dissolved solids), with evidence that parts of the system are rapidly recharged by large rainfall events. The exception to this is in the Wiso Basin to the west of Tennant Creek. Here lower quality groundwater occurs extensively in the upper 100 m below ground level, but this may sit above potentially potable groundwater and that possibility should be investigated further. Faults are demonstrated to have significantly influenced the occurrence and distribution of weathered rocks and of groundwater, with implications for groundwater storage and movement. Previously unrecognised faults in the existing borefield areas should be investigated for their potential role in compartmentalising groundwater. Additionally a previously unrecognised sub-basin proximal to Tennant Creek may have potential as a groundwater resource or a target for MAR. This study has improved understanding of the quantity and character of existing groundwater resources in the region and identified a managed aquifer recharge target and potential new groundwater resources. The outcomes of the study support informed water management decisions and improved water security for communities; providing a basis for future economic investment and protection of environmental and cultural values in the Tennant Creek and broader Barkly region. Data and information related to the project are summarised in the conclusions of this report and are accessible via the EFTF portal (https://portal.ga.gov.au/).

  • This animation shows how passive seismic surveys Work. It is part of a series of Field Activity Technique Engagement Animations. The target audience are the communities that are impacted by our data acquisition activities. There is no sound or voice over. The 2D animation includes a simplified view of what passive seismic equipment looks like, what the equipment measures and how the survey works.

  • Well and seismic correlation schemes exist for the Western Australian and South Australian parts of the Officer Basin but there are inconsistencies between the western and eastern regions. Hence, as part of the Exploring for the Future Officer-Musgrave Project, a chemostratigraphic correlation has been determined for the sedimentary fill of the Officer Basin with emphasis on Neoproterozoic to Cambrian rocks. The correlations have been developed on whole rock inorganic geochemical data obtained from the analysis of 10 study wells which span the basin from Western Australia and into South Australia. A total of 8 chemostratigraphic mega-sequences (MS) are recognised across the basin, that in turn are subdivided into a total of 24 chemostratigraphic sequences. MS1 to MS6 include the Neoproterozoic to Cambrian sedimentary rocks and are the focus of this study. The Neoproterozoic–Cambrian mega-sequences MS1 to MS4 broadly correspond to the previously defined Centralian supersequences CS1 to CS4 and provide robust well-control to the regional seismic correlations. Confidence in the correlation of these old rocks are important since they contain both potential source and reservoir rocks for petroleum generation and accumulation. MS7 is equivalent to the Permian Paterson Formation, while MS8 is equivalent to the Mesozoic section. The elemental data has also been used to elucidate aspects of the petroleum system by characterising reservoirs and identifying fine-grained siliciclastics deposited in anoxic environments which may have source potential. This work is expected to further improve geological knowledge and reduce the energy exploration risk of the Officer Basin, a key focus of this program. <b>Citation:</b> Edwards D.S., Munday S., Wang L., Riley D. & Khider K., 2022. Neoproterozoic and Cambrian chemostratigraphic mega-sequences of the Officer Basin; a regional framework to assist petroleum and mineral exploration. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://dx.doi.org/10.26186/146285

  • Australia has been, and continues to be, a leader in isotope geochronology and geochemistry. While new isotopic data is being produced with ever increasing pace and diversity, there is also a rich legacy of existing high-quality age and isotopic data, most of which have been dispersed across a multitude of journal papers, reports and theses. Where compilations of isotopic data exist, they tend to have been undertaken at variable geographic scale, with variable purpose, format, styles, levels of detail and completeness. Consequently, it has been difficult to visualise or interrogate the collective value of age and isotopic data at continental-scale. Age and isotopic patterns at continental scale can provide intriguing insights into the temporal and chemical evolution of the continent (Fraser et al, 2020). As national custodian of geoscience data, Geoscience Australia has addressed this challenge by developing an Isotopic Atlas of Australia, which currently (as of November 2020) consists of national-scale coverages of four widely-used age and isotopic data-types: 4008 U-Pb mineral ages from magmatic, metamorphic and sedimentary rocks 2651 Sm-Nd whole-rock analyses, primarily of granites and felsic volcanics 5696 Lu-Hf (136 samples) and 553 O-isotope (24 samples) analyses of zircon 1522 Pb-Pb analyses of ores and ore-related minerals These isotopic coverages are now freely available as web-services for use and download from the GA Portal. While there is more legacy data to be added, and a never-ending stream of new data constantly emerging, the provision of these national coverages with consistent classification and attribution provides a range of benefits: vastly reduces duplication of effort in compiling bespoke datasets for specific regions or use-cases data density is sufficient to reveal meaningful temporal and spatial patterns a guide to the existence and source of data in areas of interest, and of major data gaps to be addressed in future work facilitates production of thematic maps from subsets of data. For example, a magmatic age map, or K-Ar mica cooling age map sample metadata such as lithology and stratigraphic unit is associated with each isotopic result, allowing for further filtering, subsetting and interpretation. The Isotopic Atlas of Australia will continue to develop via the addition of both new and legacy data to existing coverages, and by the addition of new data coverages from a wider range of isotopic systems and a wider range of geological sample media (e.g. soil, regolith and groundwater).

  • This Record presents 40Ar/39Ar chronologic results acquired in support of collaborative regional geoscientific investigations and mapping programs conducted by Geoscience Australia (GA) and the Northern Territory Geological Survey (NTGS). Argon isotopic data and interpretations from hornblende, muscovite, and biotite from seven samples collected from the Aileron Province in ALCOOTA , HUCKITTA, HALE RIVER, and ILLOGWA CREEK in the Northern Territory are presented herein. The results complement pre-existing geochronological constraints from U–Pb zircon and monazite analyses of the same or related samples, and provide new constraints on the thermal and deformation history of the Aileron Province. Three samples (2003082017, 2003082021, 2003083040) were taken from ALCOOTA in the northeastern portion of the Aileron Province. Biotite in sample 2003082017 from the ca 1.81 Ga Crooked Hole Granite records cooling below 320–280°C at 441 ± 5 Ma. Biotite in sample 2003082021 from the ca 1.73 Ga Jamaica Granite records cooling below 320–280°C at or after 414 ± 2 Ma. Muscovite in sample 2003083040 from the Delny Metamorphics, which were deposited after ca 1.82 Ga and preserve evidence for metamorphism at ca 1.72 Ga and 1.69 Ga, records cooling below 430–390°C at 399 ± 2 Ma. The fabrics preserved in the samples from the Crooked Hole Granite and Delny Metamorphics are interpreted to have formed due to dynamic metamorphism related to movement on the Waite River Shear Zone, an extension of the Delny Shear Zone, during the Palaeoproterozoic. Portions of the northeastern Aileron Province are unconformably overlain by the Neoproterozoic–Cambrian Georgina Basin, indicating these samples were likely at or near the surface by the Neoproterozoic. Together, these data indicate that rocks of the Aileron Province in ALCOOTA were subjected to heating above ~400°C during the Palaeozoic. Two samples (2003087859K, 2003087862F) of exoskarn from an indeterminate unit were taken from drillhole MDDH4 in the Molyhil tungsten–molybdenum deposit in central HUCKITTA. The rocks hosting the Molyhil tungsten–molybdenum deposit are interpreted as ca 1.79 Ga Deep Bore Metamorphics and ca 1.80 Ga Yam Gneiss. They experienced long-lived metamorphism during the Palaeoproterozoic, with supersolidus metamorphism observed until at least ca 1.72 Ga. Hornblende from sample 2003087859K indicates cooling below 520–480°C by 1702 ± 5 Ma and may closely approximate timing of skarn-related mineralisation at the Molyhil deposit; hornblende from sample 2003087862F records a phase of fluid flow at the Molyhil deposit at 1660 ± 4 Ma. The Salthole Gneiss has a granitic protolith that was emplaced at ca 1.79 Ga, and experienced alteration at ca 1.77 Ga. Muscovite from sample 2010080001 of Salthole Gneiss from the Illogwa Shear Zone in ILLOGWA CREEK records cooling of the sample below ~430–390°C at 327 ± 2 Ma. This may reflect the timing of movement of, or fluid flux along, the Illogwa Shear Zone. An unnamed quartzite in the Casey Inlier in HALE RIVER has a zircon U–Pb maximum depositional age of ca 1.24 Ga. Muscovite from sample HA05IRS071 of this unnamed quartzite yields an age of 1072 ± 8 Ma, which likely approximates, or closely post-dates, the timing of deformation in this sample; it provides the first direct evidence for a Mesoproterozoic episode of deformation in this part of the Aileron Province.

  • Soil geochemistry has been used to discover many mineral deposits in Australia. Further, it places first-order controls on soil fertility in agriculture and can be used to monitor the environment. With this utility in mind, an extensive soil sampling survey was undertaken as part of the Exploring for the Future program across the vast prospective exploration frontier between Tennant Creek and Mount Isa, dubbed the Northern Australia Geochemical Survey (NAGS). In all, 776 stream sediment outlet samples were collected at a depth of 0–10 cm, improving the density of the National Geochemical Survey of Australia by an order of magnitude, to one sample per ~500 km2. Two size fractions from each sample were analysed for a comprehensive suite of chemical elements after total digestion, Mobile Metal Ion™ (MMI) and aqua regia extractions, and fire assay. Here, we highlight the applicability of these results to base metal exploration, evaluation of soil fertility for agriculture and establishment of geochemical baselines. Our results reveal an association between elevated concentrations of commodity or pathfinder elements in the same or downstream catchments as known mineral deposits. Similar features elsewhere suggest new areas with potential for base metal discovery. <b>Citation:</b> Bastrakov, E.N. and Main, P.T., 2020. Northern Australia Geochemical Survey: a review of regional soil geochemical patterns. 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.

  • Petroleum geochemical datasets and information are essential to government for evidence-based decision making on natural resources, and to the petroleum industry for de-risking exploration. Geoscience Australia’s newly built Data Discovery Portal (https://portal.ga.gov.au/) enables digital discoverability and accessibility to key petroleum geochemical datasets. The portal’s web map services and web feature services allow download and visualisation of geochemical data for source rocks and petroleum fluids, and deliver a petroleum systems framework for northern Australian basins. The Petroleum Source Rock Analytics Tool enables interrogation of source rock data within boreholes and field sites, and facilitates correlation of these elements of the petroleum system within and between basins. The Petroleum Systems Summary Assessment Tool assists the user to search and query components of the petroleum system(s) identified within a basin. The portal functionality includes customised data searches, and visualisation of data via interactive maps, graphs and geoscientific tools. Integration of the petroleum systems framework with the supporting geochemical data enables the Data Discovery Portal to unlock the value of these datasets by affording the user a one-stop access to interrogate the data. This allows greater efficiency and performance in evaluating the petroleum prospectivity of Australia’s sedimentary basins, facilitating and accelerating decision making around exploration investment to ensure Australia’s future resource wealth <b>Citation:</b> Edwards, D.S., MacFarlane, S.K., Grosjean, E., Buckler, T., Boreham, C.J., Henson, P., Cherukoori, R., Tracey-Patte, T., van der Wielen, S., Ray, J. and Raymond, O., 2020. Australian source rocks, fluids and petroleum systems – a new integrated geoscience data discovery portal for maximising data potential. 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.