Chemostratigraphy And Geochemical Constraints On The Deposition Of The Bakken Formation, Williston Basin, Eastern Montana And Western North Dakota
Notice bibliographique
Résumé
The late Devonian-early Mississippian Bakken Formation was deposited in a structural-sedimentary intracratonic basin that extends across a large part of modern day North Dakota, eastern Montana, and the southern portion of Canada's Saskatchewan Province. The deposition of the Bakken Formation occurred during a fascinating period of geologic time that is linked to one of the five major mass extinctions. The occurrences of these mass extinctions are recorded worldwide as organic rich mud rocks similar to the ones found in the Bakken Formation. Collectively, the Bakken Formation consists of a middle dolomitic siltstone that is representative of a transgressive deposit and is bound by regressive organic rich mud rocks deposits that were influenced by rapid flooding events induced by the late Devonian-early Mississippian seaway. Geochemical proxies, total organic carbon and stable isotopic results that were recovered from four cores provide insight into the paleoenvironmental conditions during the deposition of the Bakken Formation. Geochemical analysis and interpretation of sample suites exhibit aggregate mineralogical composition from related shifts in elemental concentrations in weight percent (wt. %) consisting of magnesium (Mg), calcium (Ca), silicon (Si), aluminum (Al) and iron (Fe). The occurrence of chemostratigraphic shifts from concentrations of the Bakken Formation's bulk rock mineralogical composition represent facies changes of sedimentary packages within the middle Bakken and are linked to dolomite, calcite, quartz, pyrite, and clay (mainly illite) content. Furthermore, geochemical proxies of redox sensitive elements expressed as enrichment factors (EF) brought insight into the redox conditions during deposition of the upper and lower Bakken shales across the Williston Basin (e.g., Mo, U, V, Zn, Ni, and Cu). Molybdenum-total organic carbon (Mo-TOC) relationships, established two separate anoxic episodes that are represented by the Bakken shales and also provided insight into the degree of basin restriction the Williston Basin experienced during late-Devonian-early Mississippian time. Observed geochemical Mo-TOC relationships from the Bakken shales display similar trends of basin restriction comparable to modern silled basin analogues, specifically the Cariaco Basin (Algeo et al. 2006). The elemental shifts from Mo-TOC vs. depth profiles, demonstrate that the Bakken shales were deposited under semi-restricted conditions. Furthermore, Mo-TOC relationships also inferred water mass residence times and variable hydrographic mixing from deep basin waters from the Williston Basin. TOC and stable isotopic composition of TOC (δ¹³C) from the Bakken shales were utilized as geochemical proxies to examine the change and distribution of organic matter across the Williston Basin. Lastly, stable isotopic composition of TOC results potentially demonstrate a blend of kerogen source formed from marine organic matter (plankton) and land-plant lipids based on previous studies.
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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 | 0,000 | 0,001 |
| 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) | 0,000 | 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.
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