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    Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the Murrindal, Vic, 1996 VIMP Survey (GSV3060) survey were acquired in 1995 by the VIC Government, and consisted of 15589 line-kilometres of data at 200m line spacing and 80m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.

  • Geochemical surveys deliver fundamental data, information and knowledge about the concentration and spatial distribution of chemical elements, isotopes and compounds in the natural environment. Typically near-surface sampling media, such as soil, sediment, outcropping rocks and stream or groundwater, are used. The application of such datasets to fields such as mineral exploration, environmental management, and geomedicine has been widely documented. In this presentation I reflect on a sabbatical experience with the Australian Federal Police (AFP) in 2017-2018 that allowed me to extend the interpretation of geochemical survey data beyond these established applications. In particular, with my collaborators we explore ways in which geochemical survey data and maps can be used to indicate the provenance of an evidentiary sample collected at a crime scene or obtained for instance from items belonging to a suspect intercepted at border entry. Because soils are extremely diverse mineralogically, geochemically and biologically, it should theoretically be possible to exclude very large swathes of territory (>90%) from further provenancing investigation using soil data. In a collaboration between Geoscience Australia (GA), the AFP and the University of Canberra (UC), a recent geochemical survey of the urban/suburban Canberra region in southeastern Australia is being used as a testbed for developing different approaches to forensic applications of geochemical surveys. A predictive soil provenancing method at the national scale was also developed and tested for application where no actual detailed, fit-for-purpose geochemical survey data exist. Over the next few years, GA, AFP and UC are collaborating with Flinders University to add biome data from soil and soil-derived dust to further improve the provenancing technique. This Abstract was presented at the 2021 Goldschmidt Conference (https://conf.goldschmidt.info/goldschmidt/2021/meetingapp.cgi)

  • We collected 38 groundwater and two surface water samples in the semi-arid Lake Woods region of the Northern Territory to better understand the hydrogeochemistry of this system, which straddles the Wiso, Tennant Creek and Georgina geological regions. Lake Woods is presently a losing waterbody feeding the underlying groundwater system. The main aquifers comprise mainly carbonate (limestone and dolostone), siliciclastic (sandstone and siltstone) and evaporitic units. The water composition was determined in terms of bulk properties (pH, electrical conductivity, temperature, dissolved oxygen, redox potential), 40 major, minor and trace elements as well as six isotopes (δ18Owater, δ2Hwater, δ13CDIC, δ34SSO4=, δ18OSO4=, 87Sr/86Sr). The groundwater is recharged through infiltration in the catchment from monsoonal rainfall (annual average rainfall ~600 mm) and runoff. It evolves geochemically mainly through evapotranspiration and water–mineral interaction (dissolution of carbonates, silicates, and to a lesser extent sulfates). The two surface waters (one from the main creek feeding the lake, the other from the lake itself) are extraordinarily enriched in 18O and 2H isotopes (δ18O of +10.9 and +16.4 ‰ VSMOW, and δ2H of +41 and +93 ‰ VSMOW, respectively), which is interpreted to reflect evaporation during the dry season (annual average evaporation ~3000 mm) under low humidity conditions (annual average relative humidity ~40 %). This interpretation is supported by modelling results. The potassium (K) relative enrichment (K/Cl mass ratio over 50 times that of sea water) is similar to that observed in salt-lake systems worldwide that are prospective for potash resources. Potassium enrichment is believed to derive partly from dust during atmospheric transport/deposition, but mostly from weathering of K-silicates in the aquifer materials (and possibly underlying formations). Further studies of Australian salt-lake systems are required to reach evidence-based conclusions on their mineral potential for potash, lithium, boron and other low-temperature mineral system commodities such as uranium. <b>Citation:</b> P. de Caritat, E. N. Bastrakov, S. Jaireth, P. M. English, J. D. A. Clarke, T. P. Mernagh, A. S. Wygralak, H. E. Dulfer & J. Trafford (2019) Groundwater geochemistry, hydrogeology and potash mineral potential of the Lake Woods region, Northern Territory, Australia, <i>Australian Journal of Earth Sciences</i>, 66:3, 411-430, DOI: 10.1080/08120099.2018.1543208

  • Waukarlycarly 1 is a stratigraphic well drilled in the southern part of the Canning Basin’s Waukarlycarly Embayment under Geoscience Australia’s Exploring for the Future program in collaboration with the Geological Survey of Western Australia to provide stratigraphic data for this poorly understood tectonic component. The well intersects a thin Cenozoic section, overlying Permian–Carboniferous fluvial clastics and glacial diamictites, with a thick pre-Carboniferous succession (855–2585 mRT) unconformably overlying the Neoproterozoic metasediments. Three informal siliciclastic intervals were defined based on the data from core lithology, well logs, fluid inclusions, chemical and mineral compositions; an Upper Sandstone (855–1348.1 mRT), a Middle Interval (1348.1–2443.4 mRT) and a Lower Sandstone (2443.4 –2585 mRT). The Middle Interval was further divided into six internal zones. Conventional methods were applied to interpret effective porosity, water saturation and elastic properties (Poisson’s ratio and Young’s modulus). Artificial neural network technology was employed on well logs to interpret the total organic carbon (TOC) content, pyrolysis products from the cracking of organic matter (S2), permeability, and mineral compositions. In the Upper Sandstone, average sandstone porosity and permeability are 17.9% and 464.5 mD and, 6.75 % and 10 mD in the Lower Sandstone. The Middle Interval claystone has an average porosity and permeability of 4.17 % and 0.006 mD, and average TOC content and S2 of 0.17 wt% and 0.047 mg HC/g rock with maximum values of 0.66 wt% and 0.46 mg HC/g rock. Average Poisson’s ratio and Young’s modulus of the claystone are 0.154 and 9.81 GPa. Correlations of mineral compositions, petrophysical, geomechanical and geochemical properties of the Middle Interval have been conducted. Young’s modulus and Poisson’s ratio are well correlated with the contents of key minerals, including Quartz, carbonates and TotalClay. Although TOC content is low at Waukarlycarly 1, hydrocarbon generation and migration have occurred elsewhere in the Waukarlycarly Embayment. The helium response just above the Neoproterozoic basement in the FIS profile is not associated with the hydrocarbon responses implying that these fluids have different sources.

  • AusAEM (WA) 2020-21, Eastern Goldfields & East Yilgarn Airborne Electromagnetic Survey The accompanying data package, titled “AusAEM (WA) 2020-21, Eastern Goldfields & East Yilgarn Airborne Electromagnetic Survey Blocks: TEMPEST® airborne electromagnetic data and GALEI conductivity estimates”, was released on 4 February 2021 by Geoscience Australia (GA) and the Geological Survey of Western Australia. The data represents the first phase of the AusAEM2020 (WA) survey flown with a fixed-wing aircraft by CGG Aviation (Australia) Pty. Ltd. under contract to Geoscience Australia, using the TEMPEST® airborne electromagnetic system. The survey was flown at a 20-kilometre nominal line spacing over the most eastern part of the state and down to the southern coast of Western Australia. The total area encompasses close to 32,680 line kilometres of newly acquired airborne electromagnetic geophysical data. CGG also processed the data. This package contains 18,482 line kilometres of the survey data, which have been quality-controlled, processed and inverted. The East Yilgarn Block entailed approximately 12,590 line kilometres and the Eastern Goldfields 5,892 line kilometres. The remaining data will be released as a separate package. Geoscience Australia and Western Australia (Department of Mines, Industry Regulation and Safety) commissioned the AusAEM 2020 survey as part of the national airborne electromagnetic acquisition program, to complete 20km line separation AEM coverage over WA. The program is designed to deliver freely available pre-competitive geophysical data to assist in the investigation and discovery of potential mineral, energy and groundwater resources within Australia. Funding for the survey came from the Western Australian government’s Exploration Incentive Scheme. GA managed the survey data acquisition, processing, contracts, quality control of the survey and generated the inversion products included in the data package. The data release package contains 1. A data release package summary PDF document. 2. The survey logistics and processing report and TEMPEST® system specification files 3. ESRI shapefiles 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 conductivity-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 conductivity-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)

  • This short film promotes Geoscience Australia's online and publicly accessible hydrogen data products. The film steps through the functionality of GA's Australian Hydrogen Opportunities Tool (AusH2), and describes the upcoming Hydrogen Economic Fairways Tool which has been created through a collaborative effort with Monash University.

  • Geoscience Australia’s Exploring for the Future Program is investigating the mineral, energy and groundwater resource potential of sedimentary basins and basement provinces in northern Australia and parts of South Australia. A key challenge in exploring Australian onshore sedimentary basins is that these are often areas with limited seismic data coverage to image the sub-surface structural and stratigraphic architecture. Consequently, well logs are often the main data sets that are used to understand the sub-surface geology. Where good seismic data coverage is available, a considerable amount of time is generally required to undertake an integrated interpretation of well and seismic data. The primary aim of this study is to develop a methodology for visualising the three-dimensional tectonostratigraphic architecture of sedimentary basins using just well data, which can then be used to quickly screen areas warranting more detailed studies of resource potential. A workflow is documented which generates three-dimensional well correlations using just well formation tops to visualise the regional structural and stratigraphic architecture of the Amadeus, Canning, Officer and Georgina basins in the Centralian Superbasin. A critical step in the workflow is defining regionally correlatable supersequences that show the spatial linkages and evolution through time of lithostratigraphic units from different basin areas. Thirteen supersequences are defined for the Centralian Superbasin, which were deposited during periods of regional subsidence associated with regional tectonic events. Regional three-dimensional correlation diagrams have been generated to show the spatial distribution of these supersequences, which can be used as a reconnaissance tool for visualising the distribution of key stratigraphic elements associated with petroleum, mineral and groundwater systems. Three-dimensional well correlations are used in this study to redefine the Centralian Superbasin as encompassing all western, northern and central Australian basins that had interconnected depositional systems driven by regional subsidence during one or more regional tectonic events between the Neoproterozoic and middle Carboniferous. The Centralian Superbasin began to form during a series of Neoproterozoic rift-sag events associated with the break-up of the Rodinia Supercontinent at about 830 Ma. Depositional systems in the Amadeus and Officer basins were partially disconnected by an emergent Musgrave Province during these early stages of superbasin evolution. Subsequent regional uplift and erosion of the superbasin occurred during the late Neoproterozoic–early Cambrian Petermann Orogeny. The Officer and Amadeus were permanently disconnected by the uplifted Musgrave Province following this major orogenic event. Rejuvenation of the Centralian Superbasin occurred during middle–late Cambrian extension and subsidence resulting in the generation of several new basins including the Canning Basin. Subsidence during the Ordovician Larapinta Event created an intracontinental seaway that episodically connected the Canning, Amadeus, Georgina and Officer basins to the proto-Pacific Ocean in the east. Fragmentation of the Centralian Superbasin began at the onset of the Alice Springs Orogeny during the Rodingan Event when the uplifted Arunta Region disconnected the Amadeus and Georgina basins. The Rodingan Movement initially disconnected depositional systems between the Canning and Amadeus basins, which promoted the development of a large evaporitic depocentre over the southern Canning Basin. However, these basins subsequently reconnected during the Early Devonian Prices Creek Movement. Complete fragmentation of the Centralian Superbasin occurred during the Late Devonian–middle Carboniferous Pillara Extension Event when the Canning and Amadeus basins became permanently disconnected. Widespread uplift and erosion at the culmination of the Alice Springs Orogeny in the middle Carboniferous resulted in final closure of the Centralian Superbasin.

  • The emerging global trend of satellite operators producing analysis ready data combined with open source tools for managing and exploiting this data are leading to more and more countries using Earth observation data to drive progress against key national and international development agendas. This paper provides examples from Australia, Mexico, Switzerland and Tanzania on how the Open Data Cube technology has been combined with analysis ready data to provide new insights and support better policy making across issues as diverse as water resource management through to urbanization and environmental-economic accounting.

  • 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.

  • Geoscience Australia is Australia’s Earth science public sector organisation, recognised for its expert data capabilities and high level of expertise. As the nation’s trusted advisor on geology and geography the organisation is the premium provider of data, science and analysis for decision makers. Internally, Geoscience Australia is currently targeting and refining its core capabilities in order to establish and clearly articulate our value proposition and service offering to stakeholders.