Drilling in the Geoscience Australia Exploring for the Future East Tennant project was conducted as part of the MinEx CRC National Drilling Initiative. Ten stratigraphic boreholes were drilled for scientific purposes in the region around the Barkly Roadhouse in the Northern Territory. Where possible, the boreholes were comprehensively wireline logged to obtain petrophysical data on the cover and basement rocks to help improve knowledge and geophysical models of the region. Formation density data obtained by wireline logging were validated using laboratory-based bulk density data obtained by Archimedes method on diamond drill core samples at Geoscience Australia. Results of the validation show that wireline-logged formation density data and Archimedes wet bulk density data are in good general agreement in the first five boreholes drilled (NDIBK01, NDIBK02, NDIBK03, NDIBK04 and NDIBK05). Difficult drilling and some lost drilling equipment meant that boreholes NDIBK06, NDIBK07 and NDIBK09 could not be cased properly, or could not be re-entered, and thus formation density wireline logs could not be obtained in these holes. Boreholes NDIBK08 and NDIBK10 were wireline logged, however formation density results from these last two holes were problematic. Wireline formation density results for borehole NDIBK08 are shown to be too high due to miscalibration of the wireline formation density tool, and results from borehole NDIBK10 cannot be robustly assessed because of a lack of sufficient Archimedes bulk density data needed to provide statistical relevance and validate the wireline formation density data.

The Geoscience Australia Rock Properties database stores the result measurements of scalar and vector petrophysical properties of rock and regolith specimens and hydrogeological data. Oracle database and Open Geospatial Consortium (OGC) web services. Links to Samples, Field Sites, Boreholes. <b>Value:</b> Essential for relating geophysical measurements to geology and hydrogeology and thereby constraining geological, geophysical and groundwater models of the Earth <b>Scope:</b> Data are sourced from all states and territories of Australia

Data in the GEOCHEM database comprises inorganic geochemical analytical data and associated metadata. Geochemical data comprises concentration data (value, error, unit of measure) measured on a range of analytical instruments, for a range of elements of the periodic table. Associated metadata includes information on analytical techniques, analytical methodology, laboratory, analysts, date of analysis, detection limits, accuracy, and precision. The GEOCHEM database also records results for reference standards. Data is specifically for rocks, soils and other unconsolidated geological material and does not include oils, gases or water analyses. Geochemical data may be total rock (i.e., whole rock analysed) or for a variety of fractions of the total rock, e.g., various non-total acid digests, mineral separates, differing size fractions. It also includes quantitative to semi-quantitative data from field measurements, such as portable x-ray fluorescence (XRF). It does not include geochemical data for individual minerals. <b>Value: </b>Geochemical data underpins much geoscientific study, and is used directly to classify, characterise and understand geological material and its formation. It has direct relevance to understanding the formation of the earth, the continents, and the processes that create and shape the surface we live on. For example, this information is used within: both discovering and the understanding of mineral deposits we depend on; the nature, health and sustainability of the soils we live and farm on; as well as providing input into a range of potential geohazards. <b>Scope: </b>The collection includes data from over 60 years of Geoscience Australia (GA) and state/territory partner regional geological projects within Australia, as well as continental-scale and regional geochemical surveys like National Geochemical Survey of Australia (NGSA) and Northern Australia Geochemical Survey (NAGS) (Exploring for the Future- EFTF). It also includes data from other countries that GA has worked with, e.g., Papua New Guinea, Antarctica, Solomon Islands and New Zealand. Explore the <b>Geoscience Australia portal - <a href="https://portal.ga.gov.au/">https://portal.ga.gov.au/</a></b>

A `weighted geometric median’ approach has been used to estimate the median surface reflectance of the barest state (i.e., least vegetation) observed through Landsat-8 OLI observations from 2013 to September 2018 to generate a six-band Landsat-8 Barest Earth pixel composite mosaic over the Australian continent. The bands include BLUE (0.452 - 0.512), GREEN (0.533 - 0.590), RED, (0.636 - 0.673) NIR (0.851 - 0.879), SWIR1 (1.566 - 1.651) and SWIR2 (2.107 - 2.294) wavelength regions. The weighted median approach is robust to outliers (such as cloud, shadows, saturation, corrupted pixels) and also maintains the relationship between all the spectral wavelengths in the spectra observed through time. The product reduces the influence of vegetation and allows for more direct mapping of soil and rock mineralogy. Reference: Dale Roberts, John Wilford, and Omar Ghattas (2018). Revealing the Australian Continent at its Barest, submitted.

An estimate of the spectra of the barest state (i.e., least vegetation) observed from imagery of the Australian continent collected by the Landsat 5, 7, and 8 satellites over a period of more than 30 years (1983 – 2018). The bands include BLUE (0.452 - 0.512), GREEN (0.533 - 0.590), RED, (0.636 - 0.673) NIR (0.851 - 0.879), SWIR1 (1.566 - 1.651) and SWIR2 (2.107 - 2.294) wavelength regions. The approach is robust to outliers (such as cloud, shadows, saturation, corrupted pixels) and also maintains the relationship between all the spectral wavelengths in the spectra observed through time. The product reduces the influence of vegetation and allows for more direct mapping of soil and rock mineralogy. This product complements the Landsat-8 Barest Earth which is based on the same algorithm but just uses Landsat8 satellite imagery from 2013-2108. Landsat-8’s OLI sensor provides improved signal-to-noise radiometric (SNR) performance quantised over a 12-bit dynamic range compared to the 8-bit dynamic range of Landsat-5 and Landsat-7 data. However the Landsat 30+ Barest Earth has a greater capacity to find the barest ground due to the greater temporal depth. Reference: Exposed Soil and Mineral Map of the Australian Continent Revealing the Land at its Barest - Dale Roberts, John Wilford and Omar Ghattas Ghattas (2019). Nature Communications, DOI: 10.1038/s41467-019-13276-1. https://www.nature.com/articles/s41467-019-13276-1

A `weighted geometric median' approach has been used to estimate the median surface reflectance of the barest state (i.e., least vegetation) observed through Landsat-8 Operational Land Image (OLI) observations from 2013 to September 2018 to generate a six-band Landsat-8 Barest Earth pixel composite mosaic over the Australian continent. The bands include BLUE (0.452 - 0.512), GREEN (0.533 - 0.590), RED, (0.636 - 0.673) NIR (0.851 - 0.879), SWIR1 (1.566 - 1.651) and SWIR2 (2.107 - 2.294) wavelength regions. The weighted median approach is robust to outliers (such as cloud, shadows, saturation, corrupted pixels) and also maintains the relationship between all the spectral wavelengths in the spectra observed through time. The product reduces the influence of vegetation and allows for more direct mapping of soil and rock mineralogy. Reference: Dale Roberts, John Wilford, and Omar Ghattas (2018). Revealing the Australian Continent at its Barest, submitted. <b>Value: </b>Has broad application in mapping surface geochemistry and mineralogy of exposed soil and bedrock. Has applications in geological mapping and natural resource management including mapping of soil characteristics. <b>Scope: </b>Two enhanced bare earth products have been generated reflecting different Landsat satellites and acquisition periods. The first only uses Landsat 8 observations from 2013 to 2018. The second incorporates the full 30+ year archive combining Landsat 5, 7, and 8 from 1986 to 2018.

Collection of mineral, gem, meteorite, fossil (including the Commonwealth Palaeontological Collection) and petrographic thin section specimens dating back to the early 1900s. The collection is of scientific, historic, aesthetic, and social significance. Geoscience Australia is responsible for the management and preservation of the collection, as well as facilitating access to the collection for research, and geoscience education and outreach. Over 700 specimens from the collection are displayed in our public gallery . The collection contains: • 15,000 gem, mineral and meteorite specimens from localities in Australia and across the globe. • 45,000 published palaeontological specimens contained in the Commonwealth Palaeontological Collection (CPC) mainly from Australia. • 1,000,000 unpublished fossils in a ‘Bulk Fossil’ collection. • 250,000 petrographic thin section slides. • 200 historical geoscience instruments including: cartography, geophysical, and laboratory equipment." <b>Value: </b>Specimens in the collection are derived from Geoscience Australia (GA) surveys, submissions by researchers, donations, purchases and bequests. A number of mineral specimens are held on behalf of the National Museum of Australia. <b>Scope: </b>This is a national collection that began in the early 1900s with early Commonwealth surveys collecting material across the country and British territories. The mineral specimens are mainly from across Australia, with a strong representation from major mineral deposits such as Broken Hill, and almost 40% from the rest of the world. The majority of fossils are from Australia, with a small proportion from lands historically or currently under Australian control, such as Papua New Guinea and the Australian Antarctic Territory.

Remotely sensed datasets provide fundamental information for understanding the chemical, physical and temporal dynamics of the atmosphere, lithosphere, biosphere and hydrosphere. Satellite remote sensing has been used extensively in mapping the nature and characteristics of the terrestrial land surface, including vegetation, rock, soil and landforms, across global to local-district scales. With the exception of hyper-arid regions, mapping rock and soil from space has been problematic because of vegetation that either masks the underlying substrate or confuses the spectral signatures of geological materials (i.e. diagnostic mineral spectral features), making them difficult to resolve. As part of the Exploring for the Future program, a new barest earth Landsat mosaic of the Australian continent using time-series analysis significantly reduces the influence of vegetation and enhances mapping of soil and exposed rock from space. Here, we provide a brief background on geological remote sensing and describe a suite of enhanced images using the barest earth Landsat mosaic for mapping surface mineralogy and geochemistry. These geological enhanced images provide improved inputs for predictive modelling of soil and rock properties over the Australian continent. In one case study, use of these products instead of existing Landsat TM band data to model chromium and sodium distribution using a random forest machine learning algorithm improved model performance by 28–46%. <b>Citation:</b> Wilford, J. and Roberts, D., 2020. Enhanced barest earth Landsat imagery for soil and lithological modelling. 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.

3D structural and geological models that provide insight and understanding of the continents subsurface. The models capture 3D stratigraphy and architecture, including the depth to bedrock and the locations of different major rock units, faults and geological structures. <b>Value: </b>These models are valuable for exploration and reconstructions of Australia's evolution <b>Scope: </b>Contains a variety of 3D volumetric models and surfaces that were produced for specific projects at regional to continental scale.

The Sentinel-2 Bare Earth thematic product provides the first national scale mosaic of the Australian continent to support improved mapping of soil and geology. The bare earth algorithm using all available Sentinel-2 A and Sentinel-2 B observations up to September 2020 preferentially weights bare pixels through time to significantly reduce the effect of seasonal vegetation in the imagery. The result are image pixels that are more likely to reflect the mineralogy and/or geochemistry of soil and bedrock. The algorithm uses a high-dimensional weighted geometric median approach that maintains the spectral relationships across all Sentinel-2 bands. A similar bare earth algorithm has been applied to Geoscience Australia’s deeper Landsat time series archive (please search for "Landsat barest Earth". Both bare earth products have spectral bands in the visible near infrared and shortwave infrared region of the electromagnetic spectrum. However, the main visible and near-infrared Sentinel-2 bands have a spatial resolution of 10 meters compared to 30m for the Landsat TM equivalents. The weighted median approach is robust to outliers (such as cloud, shadows, saturation, corrupted pixels) and also maintains the relationship between all the spectral wavelengths in the spectra observed through time. Not all the sentinel-2 bands have been processed - we have excluded atmospheric bands including 1, 9 and 10. The remaining bands have been re-number 1-10 and these bands correlate to the original bands in brackets below: 1 = blue (2) , 2 = green (3) , 3 = red (4), 4 = vegetation red edge (5), 5 = vegetation red edge (6), 6= vegetation red edge (7), 7 = NIR(8), 8 = Narrow NIR (8a), 9 = SWIR1 (11) and 10 = SWIR2(12). All 10 bands have been resampled to 10 meters to facilitate band integration and use in machine learning.