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Evaluating zircon initial Hf isotopic composition using a combined SIMS-MC-LASS-ICP-MS approach: a case study from the Coompana Province in South Australia

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Created 20/01/2025

Updated 20/01/2025

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The accessory mineral zircon is the most widely used geological timekeeper and tracer of crustal growth processes. Specifically, U-Pb isotopes in zircon offer a means to accurately determine the timing of magmatic events and their Hf isotopic composition provides a means to constrain magma source composition and potentially approximate source age. The high spatial resolution provided by in situ techniques such as secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled mass spectrometry (LA-ICP-MS) have the advantage of being able to target different growth zones within individual zircon crystals, and unravel complex magmatic histories. However, utilising this power effectively requires calculation of accurate initial Hf compositions, which are founded on the assumption that the information obtained via the U-Pb and Lu-Hf systems are correctly integrated. A typical Hf isotope LA-ICP-MS analysis ablates a sample volume that is two orders of magnitude greater than a typical SIMS analysis. Thus, when age determination has been carried out by SIMS it is necessary to demonstrate that each subsequent Hf isotope analysis has sampled a similar isotopically homogeneous volume. Here, we use a combined SIMS and laser ablation split stream (LASS)-ICP-MS approach, whereby U-Pb isotopic measurement concurrently on the same sample volume as the Hf isotope measurement is compared to prior lower volume SIMS measurements. Using a suite of new drill core magmatic rock samples from the comparatively unexplored Coompana Province in South Australia, we demonstrate how such an approach can be used to filter Hf isotope datasets by identifying LA-ICP-MS analyses that sampled mixtures of different zircon growth domains. The robust initial 176Hf/177Hf compositions obtained from the filtered Coompana data set indicate that the province represents part of a juvenile Paleoproterozoic-Mesoproterozoic arc system formed through hyperextension of the margin of the Archean Gawler Craton, which can be correlated to the Musgrave Province and Madura Province in central and western Australia respectively. This hyperextension process is temporally similar to that on the now-adjacent Archean Yilgarn Craton margin.

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Title Evaluating zircon initial Hf isotopic composition using a combined SIMS-MC-LASS-ICP-MS approach: a case study from the Coompana Province in South Australia
Language eng
Licence notspecified
Landing Page https://devweb.dga.links.com.au/data/dataset/4ca98caa-68a6-444b-8fe8-af220149a81d
Contact Point
Geoscience Australia
clientservices@ga.gov.au
Reference Period 01/01/2019 - 30/06/2020
Geospatial Coverage {"type": "Polygon", "coordinates": [[[128.0, -32.0], [131.0, -32.0], [131.0, -30.5], [128.0, -30.5], [128.0, -32.0]]]}
Data Portal data.gov.au

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This dataset was originally found on data.gov.au "Evaluating zircon initial Hf isotopic composition using a combined SIMS-MC-LASS-ICP-MS approach: a case study from the Coompana Province in South Australia". Please visit the source to access the original metadata of the dataset:
https://devweb.dga.links.com.au/data/dataset/evaluating-zircon-initial-hf-isotopic-composition-using-a-combined-sims-mc-lass-icp-ms-approach

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