Nd isotope mapping of the Lac Dumoine thrust sheet: implications for large‐scale crustal structure in the SW Grenville Province
Bibliographic record
Abstract
Terra Nova, 24, 363–372, 2012 Abstract Over 100 new Nd model ages are presented for orthogneisses from the Lac Dumoine region, western Quebec, interpreted as a thrust sheet of the Grenvillian Allochthonous Polycyclic Belt. The thrust sheet has an isotope signature consistent with other terranes of the allochthonous belt, with TDM ages <1.8 Ga in the main allochthon, but ages of 1.8–2.0 Ga in an underlying tectonic unit, itself thrust over parautochthonous Archean crust. However, the new data also reveal a half‐window of Palaeoproterozoic crust that divides the allochthon into two lobes, showing them to be relatively thin‐skinned nappes originating from the Baskatong crustal‐scale ramp. When combined with new Nd isotope mapping for Algonquin Park, Ontario, these results suggest that the main ramp of the Allochthon Boundary Thrust is located further to the SE than previously thought, with a strong SW‐NE linear trend that coincides with dipping reflectors imaged on Lithoprobe seismic line 32 south of Algonquin Park.
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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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".