Fluid Migration Regimes during the Formation of the Unconformity-Related Uranium Deposits of the Alligator Rivers Uranium Field, Australia
Notice bibliographique
Résumé
Abstract In world U production, the unconformity-related deposits currently yield ∼24%. The main unconformity-related deposits were found in the Athabasca U-bearing province in the southwestern part of the Canadian Shield and Alligator Rivers Uranium Field of the North Australian Shield. The deposits are localized close to the surfaces of structural-stratigraphic unconformity in the bottom of sedimentary basins: Athabasca in Canada and Kombolgie in Australia. According to a series of geological–structural parameters of formation, the Canadian and Australian unconformity-related deposits significantly differ allowing their classification as subtypes. In the Canadian deposits, the ore bodies occur both above and beneath the unconformity surface of the Athabasca basin, whereas the ores of the Australian deposits are localized exclusively beneath the unconformity surface in rocks of the basement of the Kombolgie basin. This paper is devoted to the reconstruction of paleohydrodynamic formation conditions of the Australian unconformity-related deposits. The computer models of fluid migration of following three scenarios were successively considered during the analysis of fluid mass transfer processes: (i) thermal fluid convection in a fault zone with periodic upward and downward free thermal fluid convection, (ii) forced convective fluid migration at subcritical permeability and therefore the absence of free thermal convection in the fault zone, and (iii) mixed convection with upward and downward fluid movement along the fault zone. We concluded that the processes of periodic thermal convective fluid circulation in the fault zone contradict the idea of infiltration mechanism of the formation of the Australian unconformity-related deposits in fault zones in the basement of the Kombolgie basin. We, therefore, considered possible influence of facies zoning of a combined aquifer in the basement of clastic sediments of the Kombolgie Supergroup on paleohydrodynamics of the ore-bearing system, which played the role of a main migration pass for U-transporting fluids. The analysis of zonal distribution of primary sedimentation environments and later diagenetic transformations of rocks of aquifers and aquitards of this basin allowed us to substantiate an idea on leading influence of zonal decrease in permeability of rocks of the combined aquifer on a circulation structure of U-transporting fluids with the change in their lateral migration in the basement of sedimentary deposits of the Kombolgie Supergroup on the downward infiltration along a transverse zone of the ore-controlling fault. This circulation of the structure of U-transporting fluids was accepted as a hypothesis of paleohydrodynamic formation conditions of Australian unconformity-related deposits exclusively in rocks of the basement of the Kombolgie basin. The additional computer calculations, however, showed that a trend of the directed change in the permeability of rocks along the lateral movement pass of U-transporting fluids is a trigger condition, which can be responsible both for the upward and downward fluid movement along the ore-bearing fault zone depending on the direction of the trend. In the Kombolgie basin in Australia, the direction of this trend depended on the change of facies conditions on the regional migration pass of diagenetic fluids, whereas the local topographic features of the unconformity surface could affect the Athabasca basin in Canada. At an alternative trend of variation in permeability along the lateral migration of U-transporting fluids, the proposed transport mechanism of the formation of the Australian unconformity-related deposits could probably contribute also to the formation both of infiltration and exfiltration Canadian unconformity-related deposits, which are described by a paleohydrodynamic interfault geothermal convection model.
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 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| 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 ».