Crustal evolution and architecture of the Wawa Subprovince, Superior Province: Insights from zircon U-Pb-Hf-O isotopes and geochemistry
Bibliographic record
Abstract
• Zircon U-Pb-Hf-O isotopes advance architectural knowledge of the Wawa subprovince. • The four stages of magmatism identified correlate with greenstone belt assemblages. • Hf isotopes identify two distinct sources with model-ages of 3.2 Ga and 2.9 Ga. • Geochemistry and trace element data shows increasing depth of TTG genesis from 2.9 − 2.65 Ga. • Wawa, Winnipeg River and Eastern Wabigoon crust share a common crustal evolution. The tectono-magmatic processes driving the evolution of Archean continental crust in the early-Earth are highly debated topics. To contribute to a better understanding of crustal evolution in the Meso- to Neoarchean, the Wawa subprovince of the Superior Province, comprising ∼ 2.9–2.6 Ga crustal rocks, represents an ideal location, located along-strike of the well-studied and mineralised Abitibi Subprovince. Here, we integrate whole-rock geochemistry and in-situ zircon U-Pb geochronology, Hf-O isotopes and trace element data from new and compiled magmatic samples across, and proximal to, the Wawa subprovince. Geochronology is used to identify four major volcano-magmatic stages at 2900–2750 Ma (I), 2750–2710 Ma (II), 2710–2680 Ma (III) and 2680–2670 Ma (IV), generally correlating with previous studies from the Michipicoten greenstone belt within the Wawa subprovince. Zircon Hf-isotopic data indicate TTG and felsic volcanic rocks follow two distinct crustal evolution lines from ∼ 3.2 Ga (mafic crust) and ∼ 2.9 Ga (felsic crust). We suggest at least two different sources are responsible for generating crust in the southwestern part of the SE Superior Province in the Archean; the older source is less juvenile and relatively dry, and the younger source is more juvenile and hydrous. Integration of isotopic data with whole-rock Sr/Y, La/Yb N and Nb, indicates that the depth of magma generation from Source 1 is shallower than that from Source 2, indicating an increase in crustal thickness from Stage I through Stage IV. The comparable Hf-isotopic signatures of the Wawa subprovince, Eastern Wabigoon subprovince and Winnipeg River Terrane samples suggest these areas may have a long-lived, shared crustal evolution.
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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 | 0.000 | 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) | 0.001 | 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".