Crustal growth/reworking and stabilization of the western Superior Province: Insights from a Neoarchean gneiss complex of the Winnipeg River terrane
Bibliographic record
Abstract
Abstract Long-term stability of the continental lithosphere is attained through a cumulative increase in net buoyancy and rigidity due to progressive compositional differentiation (i.e., cratonization). As stable cratons provided the nucleus for the subsequent accretionary growth and tectono-magmatic reworking that produced modern continental crust, the geodynamic processes that facilitated the stabilization of cratons are critical for understanding the evolution of Earth’s lithosphere. This study uses a portion of the Winnipeg River terrane, one of the oldest terranes of the western Superior Province, as a natural laboratory to investigate Archean crustal growth (partial melting of mantle) and reworking (partial melting of crust) and provides insights into the geodynamic processes driving mantle depletion and crustal remelting. Zircon U-Pb data obtained by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) from an extensive Winnipeg River terrane gneiss complex reveal six major magmatic events at ca. 3060 Ma, 2930–2920 Ma, ca. 2910 Ma, 2830–2800 Ma, 2735–2730 Ma, and ca. 2700 Ma and regional metamorphism at ca. 2900 Ma. Whole-rock geochemistry and zircon Lu-Hf and trace element data indicate that (1) the magmatism at ca. 3060 Ma and ca. 2930–2920 Ma represents reworking of the isotopically evolved components of the incipient Winnipeg River terrane at shallow depths, (2) the ca. 2910 Ma magmatism features a step-change of Hf isotopic compositions from subchondritic to suprachondritic and records the formation of new juvenile magmas and the first reworking of existing juvenile crust, and (3) the magmatism after ca. 2830 Ma largely reflects reworking of the juvenile components of the incipient Winnipeg River terrane at medium to shallow depths prior to the ca. 2700 Ma trans-crustal magmatism associated with the convergence of the Winnipeg River terrane and western Wabigoon terrane. Juvenile magmatism and crustal growth in the Winnipeg River terrane at ca. 2910 Ma are inferred to correspond with significant mantle depletion below the Winnipeg River terrane, which led to a more stable lithospheric mantle in this part of the western Superior Province. Zircon trace element data support a mantle upwelling model rather than lithosphere recycling models for the depletion of mantle at ca. 2910 Ma. This study suggests that crustal growth and mantle depletion bracketed by prolonged, episodic crustal reworking may be a fundamental characteristic of the cratonization process.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".