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  • 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.

  • Australia has a significant number of surface sediment geochemical surveys that have been undertaken by industry and government over the past 50 years. These surveys represent a vast investment and have up to now only been able to be used in isolation, independently from one another. The key to maximising the full potential of these data and the information they provide for mineral exploration, environmental management and agricultural purposes is using all the surveys together, seamlessly. These disparate geochemical surveys not only sampled various landscape elements and analysed a range of size fractions, but also used multiple analytical techniques, instrument types and laboratories. The geochemical data from these surveys require levelling to eliminate, as much as possible, non-geological variation. Using a variety of methodologies, including reanalysis of both international standards and small subsets of samples from previous surveys, we have created a seamless surface geochemical map for northern Australia, from nine surveys with 15,605 samples. We tested our approach using two surveys from the southern Thomson Orogen, which demonstrated the successful removal of inter-laboratory and other analytical variation. Creation of the new combined and levelled northern Australian dataset paves the way for the application of statistical and data analytics techniques, such as principal component analysis and machine learning, thereby maximising the value of these legacy data holdings. The methodology documented here can be applied to additional geochemical datasets as they become available.

  • This report presents the results of an elemental and carbon and oxygen isotope chemostratigraphy study on three historic wells; Kidson-1, Willara-1 and Samphire Marsh-1, from the southern Canning Basin, Western Australia. The objective of this study was to correlate the Early to Middle Ordovician sections of the three wells to each other and to wells with existing elemental and carbonate carbon isotope chemostratigraphy data from the Broome Platform, Kidson and Willara sub-basins, and the recently drilled and fully cored stratigraphic Waukarlycarly 1 well from the Waukarlycarly Embayment.

  • 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/).

  • Hydrochemistry data for Australian groundwater, including field and laboratory measurements of chemical parameters (electrical conductivity (EC), potential of hydrogen (pH), redox potential, and dissolved oxygen), major and minor ions, trace elements, nutrients, pesticides, isotopes and organic chemicals. <b>Value: </b>The chemical properties of groundwater are key parameters to understand groundwater systems and their functions. Groundwater chemistry information includes the ionic and isotopic composition of the water, representing the gases and solids that are dissolved in it. Hydrochemistry data is used to understand the source, flow, and interactions of groundwater samples with surface water and geological units, providing insight into aquifer characteristics. Hydrochemistry information is key to determining the quality of groundwater resources for societal, agricultural, industrial and environmental applications. Insights from hydrochemical analyses can be used to assess a groundwater resource, the impact of land use changes, irrigation and groundwater extraction on regional groundwater quality and quantity, assess prospective mineral exploration targets, and determine how groundwater interacts with surface water in streams and lakes. <b>Scope: </b>The database was inaugurated in 2016 with hydrochemical data collected over the Australian landmass by Geoscience Australia and its predecessors, and has expanded with regional and national data. It has been in the custodianship of the hydrochemists in Geoscience Australia’s Minerals, Energy and Groundwater Division and its predecessors. <b>To view the entire collection click on the keyword "HVC_144638" in the below Keyword listing</b> Explore the <b>Geoscience Australia portal - </b>

  • A regional hydrocarbon prospectivity study was undertaken in the onshore Canning Basin in Western Australia as part of the Exploring for the Future (EFTF) program, an Australian Government initiative dedicated to driving investment in resource exploration. As part of this program, significant work has been carried out to deliver new pre-competitive data including new seismic acquisition, drilling of a stratigraphic well, and the geochemical analysis of geological samples recovered from exploration wells. A regional, 872 km long 2D seismic line (18GA-KB1) acquired in 2018 by Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA), images the Kidson Sub-basin of the Canning Basin. In order to provide a test of geological interpretations made from the Kidson seismic survey, a deep stratigraphic well, Barnicarndy 1, was drilled in 2019 in a partnership between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA) in the Barnicarndy Graben, 67 km west of Telfer, in the southwest Canning Basin. Drilling recovered about 2100 m of continuous core from 580 mRT to the driller’s total depth (TD) of 2680.53 mRT. An extensive analytical program was carried out to characterise the lithology, age and depositional environment of these sediments. This data release presents organic geochemical analyses undertaken on rock extracts obtained from cores selected from the Barnicarndy 1 well. The molecular and stable isotope data carbon and hydrogen will be used to understand the type of organic matter being preserved, the depositional facies and thermal maturity of the Lower Ordovician sedimentary rocks penetrated in this well. This information provides complementary information to other datasets including organic petrological and palynological studies.

  • Small-angle neutron scattering (SANS) measurements were performed on 32 rock samples from the southern Georgina Basin, central Australia to assess nanopore anisotropy. Anisotropy can only be determined from oriented core material, hence the samples were cut perpendicular to bedding in cores selected from three wells that intersect the base of the hydrocarbon-bearing, organic-rich middle Cambrian Arthur Creek Formation; the latter is the source rock for both unconventional and conventional plays in the basin. The evolution of anisotropy of two-dimensional SANS intensity profiles with depth (for pore diameters ranging from 10 nm to 100 nm) was quantified and correlated with SANS intensity and total organic carbon (TOC) content. Our results confirm hydrocarbon generation at the base of the Arthur Creek Formation. The nanopore anisotropy in the basal Arthur Creek Formation at the well locations CKAD0001 (oil generation window) and MacIntyre 1 (late oil generation window) varies roughly according to normal compaction. When the Arthur Creek Formation is in the gas window, as sampled at Baldwin 1, there is a strong (negative) correlation between the average vertical-to-horizontal pore shape anisotropy and SANS intensity. The results indicate that unconventional gas production from organic-rich regions of over mature shale may be adversely affected by abnormal pore compaction.

  • We present a new geological map of Warrumbungle Volcano created from volcanic facies field mapping, new geophysical, geochemical, and geochronological data as well as data from previous studies. Field mapping and petrography defined 19 volcanic and 2 mixed volcanic-sedimentary facies. Facies identification and distribution in conjunction with geochemical analyses indicate an early shield-forming phase of predominantly mafic and intermediate lavas and pyroclastic deposits, and minor felsic lavas deposited on an irregularly eroded basement of Surat and Gunnedah basin rocks. The shield was subsequently intruded by felsic intermediate to felsic magmas that formed dykes and other intrusions including possible cryptodomes, and also erupted as lava domes and block-and-ash-flow deposits. A radial dyke swarm cross-cuts most units, although is concentrated within basement sandstone surrounding the central area of the volcano, suggesting late inflation accompanied by dyke emplacement. Geochemistry indicates differentiation of a single although repeatedly recharged alkaline magmatic suite. Fractionation of olivine, Ti-magnetite and clinopyroxene occurred in mafic magmas, and after reaching 62 wt% SiO2 crystallisation of apatite and alkali feldspar took place. A new U-Pb zircon SHRIMP magmatic crystallisation age of 16.25 +/- 0.12 Ma on a felsic block-and-ash flow deposit is in agreement with the recalculated 40Ar/39Ar isochron dates of previous workers. Based on our mapping and the use of volcanic facies to define mappable units, we recommend the previous Warrumbungle Volcanics be elevated from formation to group status and renamed the Warrumbungle Volcanic Complex.

  • NDI Carrara 1 is a deep stratigraphic drill hole (~1751m) completed in 2020 as part of the MinEx CRC National Drilling Initiative (NDI) in collaboration with Geoscience Australia and the Northern Territory Geological Survey. It is the first test of the Carrara Sub-basin, a depocentre newly discovered in the South Nicholson region based on interpretation from seismic surveys (L210 in 2017 and L212 in 2019) recently acquired as part of the Exploring for the Future program. The drill hole intersected approximately 1100 m of Proterozoic sedimentary rocks uncomformably overlain by 630 m of Cambrian Georgina Basin carbonates. This report presents inorganic geochemical analyses undertaken by Geoscience Australia on selected rock samples, collected at roughly 4 m intervals.

  • The Exploring for the Future program is an initiative by the Australian Government dedicated to boosting investment in resource exploration in Australia. The initial phase of this program led by Geoscience Australia focussed on northern Australia to gather new data and information about the potential mineral, energy and groundwater resources concealed beneath the surface. The northern Lawn Hill Platform is an intracratonic poly-phased history region of Paleoproterozoic to Mesoproterozic age consisting of mixed carbonates, siliciclastics and volcanics. It is considered a frontier basin with very little petroleum exploration to date, but with renewed interest in shale and tight gas, that may present new exploration opportunities. An understanding of the geochemistry of the sedimentary units, including the organic richness, hydrocarbon-generating potential and thermal maturity, is therefore an important characteristic needed to understand the resource potential of the region. As part of this program, Rock-Eval pyrolysis analyses were undertaken by Geoscience Australia on selected rock samples from 2 wells of the northern Lawn Hill Platform.