A regolith lead isoscape of Australia  

Authors / CoAuthors

Desem, C.U. | de Caritat, P. | Woodhead, J. | Maas, R. | Carr, G. | de Caritat, P.

Abstract

<div>We present the first national-scale lead (Pb) isotope maps of Australia based on surface regolith for five isotope ratios, ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, ²⁰⁸Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁶Pb, and ²⁰⁸Pb/²⁰⁶Pb, determined by single collector Sector Field-Inductively Coupled Plasma-Mass Spectrometry after an Ammonium Acetate leach followed by Aqua Regia digestion. The dataset is underpinned principally by the National Geochemical Survey of Australia (NGSA) archived floodplain sediment samples. We analysed 1219 ‘top coarse’ (0-10 cm depth, &lt;2 mm grain size) samples, collected near the outlet of 1098 large catchments covering 5.647 million km2 (~75% of Australia). This paper focusses on the Aqua Regia dataset. The samples consist of mixtures of the dominant soils and rocks weathering in their respective catchments (and possibly those upstream) and are therefore assumed to form a reasonable representation of the average isotopic signature of those catchments. This assumption was tested in one of the NGSA catchments, within which 12 similar ‘top coarse’ samples were also taken; results show that the Pb isotope ratios of the NGSA catchment outlet sediment sample are close to the average of the 12 sub-catchment, upstream samples. National minimum, median and maximum values reported for ²⁰⁶Pb/²⁰⁴Pb were 15.558, 18.844, 30.635; for ²⁰⁷Pb/²⁰⁴Pb 14.358, 15.687, 18.012; for ²⁰⁸Pb/²⁰⁴Pb 33.558, 38.989, 48.873; for ²⁰⁷Pb/²⁰⁶Pb 0.5880, 0.8318, 0.9847; and for ²⁰⁸Pb/²⁰⁶Pb 1.4149, 2.0665, 2.3002, respectively. The new dataset was compared with published bedrock and ore Pb isotope data, and was found to dependably represent crustal elements of various ages from Archean to Phanerozoic. This suggests that floodplain sediment samples are a suitable proxy for basement and basin geology at this scale, despite various degrees of transport, mixing, and weathering experienced in the regolith environment, locally over protracted periods of time. An example of atmospheric Pb contamination around Port Pirie, South Australia, where a Pb smelter has operated since the 1890s, is shown to illustrate potential environmental applications of this new dataset. Other applications may include elucidating detail of Australian crustal evolution and mineralisation-related investigations.&nbsp;</div> <b>Citation:</b> Desem, C. U., de Caritat, P., Woodhead, J., Maas, R., and Carr, G.: A regolith lead isoscape of Australia, <o>Earth Syst. Sci. Data</i>, 16, 1383–1393, https://doi.org/10.5194/essd-16-1383-2024, 2024.

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document

eCat Id

148848

Contact for the resource

Keywords

( Project )

• EFTF – Exploring for the Future

( Project )

• Australia's Resources Framework - ARF

• Exploration geochemistry

• environmental management

• isotope geochemistry

theme.ANZRC Fields of Research.rdf

• SOIL SCIENCESExploration GeochemistryIsotope GeochemistryEARTH SCIENCESGEOCHEMISTRY

• Published_External

Publication Date

2024-07-31T06:30:50

Creation Date

2023-09-06T16:00:00

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Australian Government Security Classification System    

Classification - unclassified

Legal Constraints

Creative Commons Attribution 4.0 International Licence    

Use - license otherRestrictions

Status

completed

Purpose

Publish detailed description of methods, validation, isoscapes, and applications of the NGA Pb isotope dataset.

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asNeeded

Topic Category

geoscientificInformation

Series Information

Earth System Science Data Volume 16, 2024 1383-1393

Lineage

<div>National Geochemical Survey of Australia: Lead Isotopes Dataset (http://dx.doi.org/10.26186/5ea8f6fd3de64)</div><div>National Geochemical Survey of Australia (http://dx.doi.org/10.11636/Record.2011.020)</div><div>Northern Australia Geochemical Survey (http://dx.doi.org/10.11636/Record.2019.002)</div><div>Desem et al., 2020. Exploring for the Future Extended Abstracts (http://dx.doi.org/10.11636/134130)</div><div>Desem et al., 2023. Applied Geochemistry paper (https://doi.org/10.1016/j.apgeochem.2022.105361)</div><div><br></div>

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Extents

[-44.00, -9.00, 112.00, 154.00]

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Spatial Resolution

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Association Type - wasDerivedFrom

National Geochemical Survey of Australia: Lead Isotopes Dataset    

eCat Identifier - 135585,

UUID - 2145fe53-1898-4e0a-86d1-f6298daa5809

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