Heating from Above or Below: Exploring Geodynamic Explanations for the Orogenic Thermal History of the Northern Canadian Cordillera
Bibliographic record
Abstract
An extensive new low-temperature thermochronometry dataset (zircon (U-Th)/He, apatite fission track and apatite (U-Th)/He) from the northern Canadian Cordillera spans much of the Paleozoic to present accretionary orogen, and reveals rapid cooling below 250 oC between ca. 70–50 Ma—seemingly at odds with inferences that the northern Canadian Cordillera has remained a relatively stable plateau with limited erosion since the Cretaceous. Several hypotheses could explain the inferred cooling: 1. Regional emplacement of the Carmacks volcanic suite at ca. 70 Ma inducing top-down heating of the underlying crust; 2. Crustal heating and uplift due to subduction of the Kula-Resurrection oceanic ridge below the orogen, leading to the formation of a slab window; 3. Removal of the continental lithospheric mantle, resulting in heating of the base of the crust and crustal uplift. Here we compare our regional thermochronometric dataset against 1D forward models of proposed geodynamic hypotheses developed in the thermal and thermochronometer age prediction software TC1D. Using TC1D we explore thermal signatures that characterize the geological scenarios listed above. The results indicate that lithospheric mantle removal, combined with ~4 km of post-Cretaceous crustal erosion, best explains the orogen-scale thermochronological patterns. Conversely, ~10 km of erosion is required to explain the cooling patterns for typical regional geotherms in the absence of transient heating events, which significantly exceeds geological constraints.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| 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".