Discontinuities in the Icebox Formation (Ordovician), Williston Basin, North Dakota and Montana
Notice bibliographique
Résumé
The Ordovician Winnipeg Group is composed of three formations; in ascending order, the Black Island Formation, the Icebox Formation, and the Roughlock Formation. The Icebox Formation is largely composed of shale. This work shows that discontinuities and coarser facies exist within the Icebox Formation and that they are traceable throughout the subsurface of North Dakota and eastern Montana. This work also illustrates possible sea-level changes during the deposition of the Icebox Formation along with probable source areas providing detrital sediments into the study area. Gamma-ray wireline logs were used to distinguish the formations of the Winnipeg Group from each other, and isopach maps were constructed for each formation to ensure consistency and uniformity in the stratigraphic data. Most gamma-ray curves within the Icebox Formation interval tend to extend off-scale. A total of 365 gamma-ray curves were extracted from a LogSleuthTM program and converted into a digital format using Surfer™ for Windows. The individual log segments were traced and adjusted to eliminate the off-scale effect. The digitized well logs were then converted into a numerical format using UN-SCAN-IT™ for Windows and the x-y coordinates were imported into Petra™ for Windows. Nine west-east and nine north-south cross-sections were constructed across the study area. Traceable discontinuities were established by correlating digitized wireline log curves using similar gamma-ray signatures within the same stratigraphic interval. These discontinuities and coarser facies were arbitrarily labeled D1 through D40 and classified as extensive or isolated discontinuities. The extensive discontinuities were separated into three groups: major, intermediate, and minor discontinuities. Attribute and isopach maps were then constructed to display thicknesses and distributions of the discontinuities. Traceable discontinuities exist within the Icebox Formation of the Winnipeg Group throughout the subsurface of North Dakota and eastern Montana and these discontinuities probably consist of bioturbated silt and sand. The discontinuities are mappable on both large and small scales as illustrated by the isopach and attribute maps such as major, intermediate, and minor discontinuities. During the deposition of the Icebox Formation, the study area was covered by a warm, shallow, epicontinental sea. The Icebox Formation probably represents an offshore marine environment that was below normal wave base adjacent to a nearshore marine environment in the northwestern part of the study area. The extensive discontinuities could represent detrital sediments, probably from Deadwood deposits or reworked Precambrian rocks; which were deposited from distal sources such as the Canadian Shield and a southern deltaic source. Major, intermediate, and minor discontinuities indicate that the rate of sediment input varied throughout Icebox Formation time. The thick extensive discontinuities in the northwestern part of the study area could be sediment deposits from a paleoshoreline along which sea-level fluctuated throughout the deposition of the Icebox Formation. The isolated discontinuities were probably deposited on topographically high areas such as the Nesson Anticline, the Burleigh High, and the Stutsman High. The Ordovician sea was deeper relative to sea-level during the deposition of the extensive discontinuities, but still shallow enough for sediments to be deposited.
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 | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,003 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 ».