Seismic refraction profiles in the Gulf of Saint Lawrence and implications for extent of continuous Grenville lower crust
Bibliographic record
Abstract
Near the exposed Grenville craton, a two-layer crust with velocities of 6.2 km s1 and 6.65 km s1 and low gradient is measured. The 6.65 km s1 velocity is observed at the shallow depth of 15 km and the Moho at greater than 40 km depth. Towards the Appalachian orogen, a southwards dipping ramp is developed in the mid crust on the top of the 6.65 km s1 layer. A collinear reflection profile confirms the southwards dipping ramp, the shallowing Moho and the lateral changes in the lower crust. A published refraction profile that crosses this reflection profile near the southern end confirms the termination of the 6.65 km s1 layer and its replacement by a slower velocity. With the publishing of wide angle reflectionrefraction (WAR) profile 88-2, two pairs of lines are now available in the gulf that cross the craton into the orogen with both WAR and deep seismic reflection coverage. The combined data sets are used to distinguish the Grenville lower crustal block based on patterns of reflectivity and associated velocities. Near the Gaspé, the Grenville lower crustal block extends southwestward and, by extrapolation of the tectonostratigraphic zones offshore, underlies the Humber zone. In contrast, profiles in the gulf to the west of Newfoundland imply the continuous Grenville lower crustal block terminates seaward of the Humber surface terrane. Along-strike variations in the extent of Grenville lower crustal block beneath the northern Appalachians are suggested as an important factor in determining the style of crustal deformation.
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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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".