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Hf-Nd isotopes of Archean komatiites A Hadean component in the Neoarchean mantle

Created 17/10/2025

Updated 17/10/2025

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Komatiites are extinct volcanic rocks that formed by partial melting of 20-50% of their mantle source – a unique feature that allows us to understand the composition of the mantle in the early Earth. Due to their high temperature, komatiites incorporate proximal rock types on their way to, and on, the Earth’s surface. In this craton-scale study, we looked to use this property of komatiite magmas to track their interaction with the crust of the Yilgarn Craton. The results yielded Hf and Nd isotope arrays (Figure 1), that potentially have three components. The first likely represents the depleted mantle source of the magmas, and most plot in the region between +2 and +6 εHfi and 0 to +3.3 εNdi. The second source represents a more unradiogenic component, most likely 3.5-3.3 Ga continental crust (minimum). This component is more notable in the 2.8 and 2.9 Ga events with values trending to CHUR and negative εNd. The 2.8 Ga dataset, and particularly the komatiitic basalts from the Marda region, appear to show the most contamination with old crust. This is likely due to this area representing the old nucleus of the craton, as shown in Hf-isotope mapping. The final component represents an ultra-depleted source. Data from Ravensthorpe, Mt Clifford, and Wiluna show trends towards this source referred to as the Early Refractory Reservoir (ERR)(Nebel et al. 2014). We suggest that the 2.7 and 2.9 Ga plumes interacted with refractory Hadean plume residues, which constitute the ERR, within the Yilgarn lithosphere. Isotopic data on crustal rocks suggests the Yilgarn may have formed in the Hadean to Eoarchean, and hence the ERR could represent the residue of the Hadean crust generation process that formed the low Lu/Hf Jack Hills zircons. If correct, this suggests that the ERR survived for much longer than previously thought, as a rare component within the Earth’s oldest cratons. This Abstract was submitted/presented to the 2023 6th International Archean Symposium (6IAS) 25 - 27 July (https://6ias.org/)

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Title Hf-Nd isotopes of Archean komatiites A Hadean component in the Neoarchean mantle
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/en/dataset/c7db3fc8-8032-4e4d-9dfd-5d52788b6916
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 11/09/2023
Geospatial Coverage
Map data © OpenStreetMap contributors
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This dataset was originally found on Geoscience Australia "Hf-Nd isotopes of Archean komatiites A Hadean component in the Neoarchean mantle". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/hf-nd-isotopes-of-archean-komatiites-a-hadean-component-in-the-neoarchean-mantle