Evolution of Labrador Sea–Baffin Bay: Plate or Plume Processes?
Bibliographic record
Abstract
Breakup between Greenland and Canada resulted in oceanic spreading in the Labrador Sea and Baffin Bay. These ocean basins are connected through the Davis Strait, a bathymetric high comprising primarily continental lithosphere, and the focus of the West Greenland Tertiary volcanic province. It has been suggested that a mantle plume facilitated this breakup and generated the associated magmatism. Plume-driven breakup predicts that the earliest, most extensive rifting, magmatism and initial seafloor spreading starts in the same locality, where the postulated plume impinged. Observations from the Labrador Sea–Baffin Bay area do not accord with these predictions. Thus, the plume hypothesis is not confirmed at this locality unless major ad hoc variants are accepted. A model that fits the observations better involves a thick continental lithospheric keel of orogenic origin beneath the Davis Strait that blocked the northward-propagating Labrador Sea rift resulting in locally enhanced magmatism. The Davis Strait lithosphere was thicker and more resilient to rifting because the adjacent Paleoproterozoic Nagssugtoqidian and Torngat orogenic belts contain structures unfavourably orientated with respect to the extensional stress field at the time.RÉSUMÉLa cassure entre le Groenland et le Canada a entraîné une expansion océanique de la mer du Labrador et de la baie de Baffin. Ces bassins océaniques sont reliés par le détroit de Davis, un haut bathymétrique constitué principalement de lithosphère continentale et de la province volcanique tertiaire de l'ouest du Groenland. Il a été suggéré qu'un panache du manteau a facilité cette cassure et généré le magmatisme associé. L’hypothèse d’une cassure produite par panache du manteau prédit que la première distension océanique, la plus importante, le magmatisme et l'expansion océanique initial se produisent là où le panache mantélique touche la croûte continentale. Or les observations dans la région de la mer du Labrador–baie de Baffin ne correspondent pas à ces prédictions. Et donc l'hypothèse du panache ne fonctionne pas dans cette région à moins que des facteurs ad hoc déterminants ne soient présents. Un modèle qui correspond mieux aux observations présuppose la présence d’une épaisse quille lithosphérique continentale d'origine orogénique sous le détroit de Davis qui aurait bloqué l’expansion océanique de la mer du Labrador vers le nord, ce qui aurait provoqué une augmentation du magmatisme localement. La lithosphère du détroit de Davis était plus épaisse et plus résistante à l’expansion océanique parce que les bandes orogéniques paléoprotérozoïques du Nagssugtoqidian et de Torngat renferment des structures défavorablement orientées par rapport au champ de contraintes d’extensions de l'époque.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".