Crustal evolution and architecture of the Wawa Subprovince, Superior Province: Insights from zircon U-Pb-Hf-O isotopes and geochemistry
Bibliographic record
Abstract
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 machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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 source (direct Gemma or distilled Codex), 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".