07177c9f-bb3a-468e-b066-5f1dfa50fc11 urn:uuid eng UTF-8 nonGeographicDataset nonGeographicDataset 2025-10-16T22:41:31 creation ISO 19115 2016 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 07177c9f-bb3a-468e-b066-5f1dfa50fc11 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. {"type": "Polygon", "coordinates": [[[128.0, -32.0], [131.0, -32.0], [131.0, -30.5], [128.0, -30.5], [128.0, -32.0]]]} 128.0 131.0 -32.0 -30.5 EARTH SCIENCES Geochronology Igneous and Metamorphic Petrology Isotope Geochemistry Published_External Link to the Article documentDigital Link to the Article HTML Download Appendix A (pdf) [4.2 MB] documentDigital Download Appendix A (pdf) [4.2 MB] PDF Download the Supplementary Data Tables (xlsx) [336.7 KB] documentDigital Download the Supplementary Data Tables (xlsx) [336.7 KB] XLSX Download Supplementary Figures S1-S2 UPb-Hf Standards (pdf) [1.9 MB] documentDigital Download Supplementary Figures S1-S2 UPb-Hf Standards (pdf) [1.9 MB] PDF Download Supplementary Figures S3-S11 Zircon Images (pdf) [390.4 MB] documentDigital Download Supplementary Figures S3-S11 Zircon Images (pdf) [390.4 MB] PDF