Evidence for asthenospheric flow rotation in northwest Canada: insights from shear wave splitting
Bibliographic record
Abstract
SUMMARY The Mackenzie Mountains (MM) of northwest Canada are an actively uplifting, seismogenic salient of the northern Canadian Cordillera that lie 750 km NE of the main Pacific–North America plate boundary. We present new shear wave splitting measurements from a linear array transecting the region to characterize upper-mantle anisotropy and the relative role of the lithosphere and asthenosphere in MM uplift. A gradual rotation in anisotropy occurs across the Canadian Cordillera, with stations nearest to the craton yielding NE fast-axis orientations that are subparallel to North America absolute plate motion (∼230°). Moving SW from the craton, across the MM and towards the plate boundary, fast-axis orientations rotate to become aligned with major lithospheric fabrics (NW–SE). Previous work has shown that the Cordilleran lithosphere is thin (≈50 km) in this region. We therefore interpret these results to primarily reflect sublithospheric flow. Three possibilities for asthenospheric flow are presented, but none of them fit the data well. Therefore, we believe that flow in the SW is due to upwelling from the slab window that opened up around 45–25 Ma, although it is possible the lithosphere is more than 50 km in thickness, in which case these splits reflect the tectonic fabric of the region.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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 teacher head, 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".