Shear wave structure in the Grenville Province beneath the lower Great Lakes region from Rayleigh wave tomography
Bibliographic record
Abstract
We have constructed a high resolution 3‐D shear wave velocity model of the upper mantle beneath the Grenville Province in the lower Great Lakes region. A two‐plane wave tomography method was applied to fundamental mode Rayleigh wave data recorded at 35 broadband seismic stations. Rayleigh wave phase velocities were obtained at 15 periods from 20 s to 143 s and then inverted for shear wave velocity variation. A high velocity lid to ~150 km depth is imaged beneath most of the studied Grenville Province. One low velocity anomaly of −4% appears at a failed rift in the northeast above 100 km depth, coinciding with the Great Meteor hot spot track and the high seismicity band, which can be interpreted as high temperature and high iron and/or volatile content related to the hot spot activity. Low velocity anomaly of ~2% at the depths of 100–200 km are found beneath the east of Lake Ontario and Lake Huron where the lithosphere is relatively thin. These anomalies follow the NW‐SE trend of the slow indentation imaged on the continental‐scale models. We conclude that the location of low velocity anomalies is not only related to the hot spot track but also controlled by the pre‐existing lithosphere morphology and strength. A high velocity column appears between southern Lake Ontario and the Appalachian front centered at ~100 km depth. It is likely caused by high Mg content at the formation of the lithosphere or the presence of ecologite or garnet phases generated during the opening and closure of the Iapetus Ocean.
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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 | 0.000 | 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) | 0.001 | 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".