Terrane accretion vs. re-working: An evaluation based on geology of the Sudbury area
Bibliographic record
Abstract
Terrane accretion is becoming almost universally as the main mechanism by which continents have been formed. As applied to the Canadian Shield, the concept treats entire crustal provinces, such as the Grenville, as accreted terranes. An older view, however, is that continents have evolved by re-working, largely in situ. The Sudbury area is the junction of three provinces: Superior, Southern, and Grenville. This paper reviews the relationships of these to compare terrane accretion with re-working.Terrane accretion in this area is contradicted by the facts that the Grenville Front is demonstrably not a suture, nor has a suture been clearly identified in the Grenville Province to the southeast. In addition, imbricated Superior-age crust has been radiometrically identified 50 to 100 km southeast of the Front. This implies that the Southern Province was deposited on Archean continental crust, as in fact field relations show. Re-working, in contrast, is demonstrated by radiometrically dated tectonic and magmatic events of the Sudbury area, compiled by D. Rousell et al. Starting with the Levack Gneiss Complex, 2.7 Ga ago, there has been repeated magmatism and tectonism of crust within an area roughly 150 km on a side for at least 1.7 Ga, down to the Grenvillian Orogeny 1 Ga ago. It is concluded that in this area, crustal evolution has been dominantly a process of repeated reworking of a coherent block of crust, not a series of terrane suturing events.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.005 | 0.004 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".