Current geoscientific knowledge on the High Arctic submarine Alpha-Mendeleev complex
Notice bibliographique
Résumé
Today Alpha-Mendeleev Ridge is the largest single submarine feature in the Arctic Ocean, which geological origin is still unknown. A better understanding of the evolution of the ridge complex in relation to the opening of the Canada Basin would have profound consequences for Arctic geodynamic models. Currently models in which Alpha Ridge represents a former spreading centre or "hot spot" trail are favoured. In this contribution the state of knowledge will be reviewed.The ridge was discovered by the US ice station Alpha during its drift in the years 1957-1958, which acquired the first information on the ridges topography and sedimentary thickness. The largest single-channel seismic data set was gathered during the drift of the US ice station T-3 from February 1967 to June 1970. The width of Alpha Ridge ranges from 250 to 800 km. In bathymetric cross sections it is roughly symmetrical with greatest elevation at the centre. The existing single channel seismic reflection lines acquired from ice stations Alpha, T-3 and CESAR and ship based seismic experiments show that Alpha-Mendeleev Ridge is mainly covered by a sedimentary sequence, which can reach up to 1000 m in thickness. Along most of the profiles the sediments lie conformably on the basement. Deep seismic experiments of Canadian and Russian researchers indicate that the crust beneath the ridge has a thickness well above 30 km, and high seismic velocities above 7.0 km/s are present at lower crustal levels.The most important and complete geophysical data sets in that area are aeromagnetic and aerogravity data acquired by US and Russian researchers. The magnetic data across the Alpha Ridge indicate the presence of mostly irregular magnetic anomalies up to 2000 nT. No clear evidence of magnetic seafloor spreading anomalies has been obtained. Based on the existing geophysical data various researchers suggested that the ridge must have been formed during the Cretaceous positive polarity chron from 124 to 83 Ma, if the irregular magnetic anomalies are due to oceanic basalts. At three locations Cretaceous and Early Cenozoic sediments were recovered from western part of Alpha-Mendeleev Ridge. Two volcanic rock samples were dredged from the Alpha-Mendeleev Ridge. One of them could be dated to 83 Ma. So far, all existing geoscientific data support a formation of this complex in Cretaceous times. However, details on the responsible processes and the plate movements during this period are rather hypothetical.
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 distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,003 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,004 |
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; les deux têtes enseignantes s’accordent sur ce qui est montré ici.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».