Testing modes of exhumation in collisional orogens: Synconvergent channel flow in the southeastern Canadian Cordillera
Bibliographic record
Abstract
This study investigates exhumation processes in collisional orogens.A critical test between three modes of exhumation is presented based on a review of quantitative numerical and analogue modeling studies.The test is applied to the large tract of migmatites surrounding the Monashee Complex in the southeastern Canadian Cordillera.It reveals that the extensive and multidisciplinary database of this region is entirely compatible with the synconvergent channel-fl ow mode but not with critical wedge and gravitational collapse modes.We propose that a partially molten channel decoupled from its lid and base and started to fl ow in the middle crust toward the foreland at 100-90 Ma.A steady-state channel-fl ow system was established for the following ~30 m.y., during which rocks at the front of the channel were exhumed to upper-crustal levels as they fl owed above an underthrusting basement ramp.Flow was accommodated by oppositely verging shear zones bounding the channel, by internal ductile deformation, and by shortening in the foreland belt.The locus of fl ow migrated downward to exhume rocks of the Monashee Complex between 60 and 50 Ma by a similar process.The southeastern Canadian Cordillera thus constitutes an excellent natural analogue for the channel-fl ow model.In contrast to the commonly held view of large-magnitude extension and core complex formation, the role of extension was limited to the fi nal ~10-15 km of exhumation after 50 Ma.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 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".