Crustal and Upper-Mantle Anisotropy Related to Fossilized Transpression Fabric along the Denali Fault, Northern Canadian Cordillera
Bibliographic record
Abstract
We analyze crustal and upper‐mantle structure near the Denali fault (northern Canadian Cordillera) using 11 broadband seismic stations. Receiver functions at five stations within 5–30 km of the fault trace display a strong P‐to‐S conversion within the midcrust (10–25 km depth) that systematically varies with back azimuth. Stacking and velocity inversion along complementary northwest–southeast and northeast–southwest back‐azimuth ranges yield a strong anisotropy (>10%) in the midcrust, with complex crustal anisotropic behavior (at least two layers) close to the Denali and Duke River faults junction. Anisotropy occurs in a low‐velocity zone with the fast axis parallel to the Denali fault trend. Three additional stations close to the Denali fault (15–30 km), as well as two stations further away (>100 km) show no significant crustal anisotropy. Shear‐wave (SKS) splitting analysis indicates similar upper‐mantle anisotropy, with a fast axis parallel to the trend of the Denali fault for all stations, except for station WHY located 125 km away. We relate this crustal and upper‐mantle anisotropy to fossilized structural and mineral fabrics due to Eocene transpression on the Denali fault. These results suggest the main transpression phase (∼400 km displacement) was accommodated in a shear zone at least 50–60 km (less than 125 km) wide in the midcrust and upper mantle. Lack of clear anisotropy in the lowermost crust may relate to complex deformation within a detachment layer (orogenic float model).
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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 | 0.002 | 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) | 0.003 | 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".