Authors / CoAuthors
de Caritat, P. | Dosseto, A. | Dux, F.
Abstract
<div>Strontium isotopes (87Sr/86Sr) are useful to trace processes in the Earth sciences as well as in forensic, archaeological, palaeontological, and ecological sciences. As very few large-scale Sr isoscapes exist in Australia, we have identified an opportunity to determine 87Sr/86Sr ratios on archived fluvial sediment samples from the low-density National Geochemical Survey of Australia (www.ga.gov.au/ngsa; last access: 15 December 2022). The present study targeted the northern parts of Western Australia, the Northern Territory and Queensland, north of 21.5 °S. The samples were taken mostly from a depth of ~60-80 cm in floodplain deposits at or near the outlet of large catchments (drainage basins). A coarse (< 2 mm) grain-size fraction was air-dried, sieved, milled then digested (hydrofluoric acid + nitric acid followed by aqua regia) to release <em>total</em> Sr. The Sr was then separated by chromatography and the 87Sr/86Sr ratio determined by multicollector-inductively coupled plasma mass spectrometry. Results demonstrate a wide range of Sr isotopic values (0.7048 to 1.0330) over the survey area, reflecting a large diversity of source rock lithologies, geological processes and bedrock ages. Spatial distribution of 87Sr/86Sr shows coherent (multi-point anomalies and smooth gradients), large-scale (> 100 km) patterns that appear to be broadly consistent with surface geology, regolith/soil type, and/or nearby outcropping bedrock. For instance, the extensive black clay soils of the Barkly Tableland define a > 500 km-long northwest-southeast-trending unradiogenic anomaly (87Sr/86Sr < 0.7182). Where sedimentary carbonate or mafic/ultramafic igneous rocks dominate, low to moderate 87Sr/86Sr values are generally recorded (medians of 0.7387 and 0.7422, respectively). In proximity to the outcropping Proterozoic metamorphic basement of the Tennant, McArthur, Murphy and Mount Isa geological regions, conversely, radiogenic 87Sr/86Sr values (> 0.7655) are observed. A potential correlation between mineralisation and elevated 87Sr/86Sr values in these regions needs to be investigated in greater detail. Our results to-date indicate that incorporating soil/regolith Sr isotopes in regional, exploratory geoscience investigations can help identify basement rock types under (shallow) cover, constrain surface processes (e.g. weathering, dispersion), and, potentially, recognise components of mineral systems. Furthermore, the resulting Sr isoscape and future models derived therefrom can also be utilised in forensic, archaeological, paleontological and ecological studies that aim to investigate, e.g., past and modern animal (including humans) dietary habits and migrations. The new spatial Sr isotope dataset for the northern Australia region is publicly available (de Caritat et al., 2022a; https://dx.doi.org/10.26186/147473; last access: 15 December 2022).</div> <b>Citation:</b> de Caritat, P., Dosseto, A., and Dux, F.: A strontium isoscape of northern Australia, <i>Earth Syst. Sci. Data</i>, 15, 1655–1673, https://doi.org/10.5194/essd-15-1655-2023, <b>2023</b>.
Product Type
document
eCat Id
147598
Contact for the resource
Resource provider
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
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Keywords
- ( Project )
-
- EFTF – Exploring for the Future
- ( Project )
-
- Australia’s Resources Framework
-
- 87Sr/86Sr
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- strontium isotopes
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- regolith
- theme.ANZRC Fields of Research.rdf
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- Exploration geochemistrySoil chemistry and soil carbon sequestration (excl. carbon sequestration science)Isotope geochemistry
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- Published_External
Publication Date
2023-05-26T00:56:31
Creation Date
2022-12-17T20:00:00
Security Constraints
Legal Constraints
Status
completed
Purpose
Publish a peer-reviewed article to support Sr isotope data release for northern Australia (eCat 147473, https://dx.doi.org/10.26186/147473) and complement earlier data release for inland southeastern Australia (eCat 146397, https://dx.doi.org/10.26186/146397)
Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
Earth System Science Data (ESSD) Volume 15, Issue 4, 2023 1655 - 1673
Lineage
<div>National Geochemical Survey of Australia (doi: 10.11636/Record.2011.020)</div><div>Northern Australia Geochemical Survey (doi: 10.11636/Record.2019.002) </div>
Parent Information
Extents
[-21.50, -11.00, 116.00, 149.00]
Reference System
Spatial Resolution
Service Information
Associations
Association Type - wasDerivedFrom
A strontium isoscape of inland southeastern Australia
eCat Identifier - 146397,
UUID - 004c6972-4d53-4b8f-ba35-2d2469d644e9
Association Type - wasDerivedFrom
National Geochemical Survey of Australia: The Geochemical Atlas of Australia
eCat Identifier - 71973,
UUID - a4a1ac2e-0a2c-653b-e044-00144fdd4fa6
Association Type - wasDerivedFrom
Northern Australia Geochemical Survey: Data Release 2 – Total (coarse fraction), Aqua Regia (coarse and fine fraction), and Fire Assay (coarse and fine fraction) element contents
eCat Identifier - 126296,
UUID - 631937cb-d57f-45b1-9e39-a79961db391e
Source Information