Geochemical and isotopic characteristics of Youanmi terrane volcanism: the role of mantle plumes and subduction tectonics in the western Yilgarn Craton
Bibliographic record
Abstract
Abstract New geochemical and isotopic data for volcanic and shallow-level intrusive rocks of the Murchison Domain in the Youanmi Terrane of the Yilgarn Craton help to clarify some of the stratigraphic ambiguities in the area and are consistent with the most recent lithostratigraphic model. The results reveal the presence of previously unrecognised examples of the boninite-depleted tholeiite suite that, based on εNdT > 4, were likely derived from refractory mantle following plume melting. These new findings support the conclusions of previous studies that magmatism in Archean volcanic successions, including mantle plume-associated and arc sequences, display geochemical evidence of refractory plume-related magma sources throughout their development. The presence of well-preserved boninites in the Polelle Group indicates a significant role for subduction tectonics during the 2825–2700 Ma evolution of the Youanmi Terrane. The subduction zone is tentatively linked to the accretionary processes proposed along the Youanmi Terrane–Narryer Terrane boundary. This model also implies that in the eastern Yilgarn Craton, the initial phases of craton re-assembly may have been driven by this subduction zone prior to the development of an arc off the eastern edge of the craton at ca 2715 Ma. KEY WORDS: ArcheanYilgarnMurchison Domainboninitegeodynamics. ACKNOWLEDGEMENTS We appreciate the invitation to contribute to this Special Volume of AJES, stemming from the 5IAS, by Kevin Cassidy and Steven Wyche. Ali Polat, an anonymous reviewer and Kevin Cassidy are thanked for genuinely helpful comments that significantly improved the paper. The authors would like to thank David Champion and Kevin Cassidy for permission to use Figure 10 and Tony Crawford for discussions on boninites and Figure 3d. Geoff Clarke is thanked for use of boninites samples from the Népoui ophiolite (Figure 3c). DW gratefully acknowledges the assistance provided by Bryan Krapež in the early stages of this study. This study was partially supported by ARC research funds. R.K. acknowledges research support from an NSERC Discovery Grant, and the George McLeod endowment to the Department of Geological Sciences, University of Saskatchewan.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".