Changing Alluvial Style in Response to Changing Accommodation Rate in a Proximal Foreland Basin Setting: Upper Cretaceous Dunvegan Formation, North‐East British Columbia, Canada
Notice bibliographique
Résumé
The early–mid-Cenomanian Dunvegan Formation represents a major deltaic complex that prograded > 400 km from the north-west to the south-east, parallel to the rising Rocky Mountain Cordillera, over about 2 Myr. The formation comprises at least ten regressive–transgressive allomembers, separated by regional marine transgressive surfaces and, further up-dip, by lacustrine flooding surfaces. The lower five allomembers (J–F) have a sigmoidal geometry, thinning up-dip towards the north-west. Allomember E differs in showing in the north-west a pronounced isopach ‘moat’, into which strata thicken from 35 to 80 m over 120 km, suggestive of renewed subsidence along the basin margin. Collectively, allomembers D–A show an even more pronounced thickening towards the active basin margin, from 30 to 100 m over 250 km, and this geometry persists in the lower units of the overlying Kaskapau Formation. Outcrop sections of the Dunvegan Formation in the Chetwynd–Pine River area are located within the thickened isopach ‘moats’ of allomembers E–A, and are dominated by alluvial deposits about 160 m thick. Non-channelized alluvial facies represent lake, mouth-bar, levee and crevasse splay environments, and organic histosol (coal), poorly drained, intermediate redox and better drained palaeosols. Siderite, organic debris and dinosaur tracks are ubiquitous elements of these facies. Channelized facies are dominated by non-migrating (probably anastomosed) sandstone channel-fills. Non-channelized facies form two associations: A, which is dominated by crevasse splays, levees, intermediate redox and better drained palaeosols; B, which is dominated by lakes, mouth-bars, organic and poorly drained palaeosols. Facies association A, indicating relatively well-drained conditions, dominates allomembers G to the lower part of E. From near the middle to near the top, allomember E is progressively dominated by facies association B, but the uppermost 5 m shows an abrupt return to better drained palaeosols. Allomembers D to A show alternations between associations A and B, although overall, association B predominates upward. The basal units of the overlying Kaskapau Formation comprise a transitional succession 40–50 m thick dominated by facies of association B, but including brackish-water lagoonal deposits, overlain by marine deposits. The thinning of allomembers H–F towards the north-west suggests minimal accommodation in that direction, and this is reflected in their constituent alluvial facies (association A), dominated by relatively well-drained environments. The upward change within allomember E, from association A to relatively poorly drained association B, is interpreted to record an upward increase in accommodation rate. This change is independently suggested by the isopach ‘moat’ in allomember E, attributed to renewed flexural subsidence. A pedocomplex 5 m thick at the top of allomember E suggests a final phase of very low accommodation rate. Allomembers D–A are again dominated by poorly drained freshwater environments, which pass upward into rocks of the basal Kaskapau Formation which show progressively increasing marine influence. This facies succession reflects an increasing accommodation rate, also suggested by regional isopach patterns.
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) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,013 | 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 tête enseignante, 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 ».