Evidence for Magma‐Rich and Magma‐Poor Characteristics Across the Continent‐Ocean Transition Offshore Central Nova Scotia as Deduced From <i>V</i><sub><i>p</i></sub>/<i>V</i><sub><i>s</i></sub> Ratios Using 4‐Component Seismic Data
Bibliographic record
Abstract
Abstract To improve identification of crustal rock types within the continent‐ocean transition (COT) offshore Nova Scotia based on the standard approach of analyzing P‐wave velocities (Vp), we incorporate S‐wave velocity (Vs) modeling and determine Vp/Vs ratios. In this work, we construct detailed layered Vp and Vs models using four component wide‐angle ocean bottom seismometer data from profiles SMART‐2 and ‐3 across the central and southwestern Scotian margin, respectively. Along profile SMART‐3, the lower continental crust displays low Vp/Vs ratios (1.7), akin to felsic granulite. Vp/Vs ratios (1.7–1.9) within the COT suggest that syn‐rift volcanism and magmatism resulted in a basalt‐dominated upper crust overlying a thick layer (4–10 km) of laterally heterogeneous gabbroic underplate that jointly cover an estimated profile area of 1,230 . On Profile SMART‐2, we observe upper continental crust (Vp/Vs 1.7) with highly felsic composition within the continental and the COT domains. Serpentinized mantle (Vp/Vs 1.9) is interpreted within the seaward‐most segment of the transitional lower crust, alongside gabbroic underplate, based on its Vp/Vs ratio of 1.7–1.8 and high Vp of 6.9–7.4 km/s, notably thickening beneath the East Coast Magnetic Anomaly near the landward COT limit. Syn‐rift volcanism and magmatism SMART‐2 profile area is estimated at 513 . Our results portray the southwestern Scotian margin as magma‐rich, the northeastern as magma‐poor, and the central margin as a hybrid zone amalgamating characteristics from both. Regardless of margin type, the thinnest transitional crust is consistently observed toward its seaward termination leading into the full‐scale seafloor spreading.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| 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".