Geodynamic and palaeobathymetric reconstruction between Greenland and Canada
Notice bibliographique
Résumé
The Baffin Bay and the Labrador Sea are located between Greenland and Canada. Both basins evolved from Cretaceous to Eocene times. They are linked by the bathymetric high of Davis Strait, which limits the water transport between both basins. The Labrador Sea is an extinct rift system of the early North Atlantic. Oceanic crust has been identified from magnetic spreading anomalies. It is also proposed that the crust of Baffin Bay is oceanic. But no clear magnetic spreading anomalies are detected and therefore the presence of stretched continental crust is also possible. A similar controversy exists on the nature of the Davis Strait crust. Thick oceanic crust as well as continental fragments are debated. The tectonic evolution of the area is an important factor for the role of Davis Strait as a polar gateway in palaeocean models. \nIn 2008 and 2010 research expeditions to the Davis Strait and Baffin Bay were undertaken to collect geophysical data on the tectonic evolution of this area. Here, I present P-wave velocity and density models of a 710-km-long line in southern Baffin Bay and of a 315-km-long line in the central Davis Strait. The models are supported and complemented by seismic reflection and magnetic anomaly data. \nThe models support results of previous studies: southern Baffin Bay is underlain by oceanic crust of 7.5 km thickness on average. The crust is covered by sediments of up to 6 km thickness. Conjugate to breakup volcanics off Baffin Island, we find seaward dipping reflector sequences in the seismic reflection data of the Greenland margin. We conclude, that the opening of southern Baffin Bay was accompanied by volcanism. The Davis Strait is also characterized by volcanism - along most of the profile basalt flows are imaged. The models reveal that the Davis Strait consists mainly of sections of continental crust. These are saparated by a 45-km-wide unit of new igneous or highly intruded, stretched, continental crust. We account this feature to an influence of the early North Atlantic mantle plume. \nWith the new information of our crustal models, I developed a plate kinematic model. Although southern Baffin Bay is underlain by oceanic crust, magnetic spreading anomalies are probably missing due to many fractures. These lead to small scale crustal sections which are shifted to each other. Due to the reorientation of the Greenland plate in the Late Paleocene, compressional forces were compensated in the Davis Strait. These probably resulted first in a deformation within the Ungava Fault Complex (the pre-Eocene plate boundary) and then caused the evolution of a new transform fault, the Hudson Fracture Zone. \nTo estimate at what time a water transport was possible via the Davis Strait and how the Labrador Sea basin evolved, I calculated palaeobathymetry grids. I compiled published and new seismic data with information from drill sites. In a backstripping routine, I calculated the effects of flexual unloading for the lithosphere, of sedimentdecompaction, of global sea-level changes, and of thermal subsidence of the lithosphere. \nPalaeolocations of the profiles and the age structure of the crust are derived from our recent plate kinematic model. Although the grids are characterized by great uncertainties, we can conclude that the Davis Strait separated the Labrador Sea from the Baffin Bay in pre-Eocene times. We propose that, similar to today, an early West Greenland Current formed a cyclonic circulation in the early Labrador Sea basin since the Paleocene. Our palaeobathymetric reconstruction can be used in palaeocean models and improve palaeoclimate reconstructions.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,002 | 0,004 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,002 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,004 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».