Refining the depositional model of the lower Permian Carynginia Formation in the northern Perth Basin: anatomy of an ancient mouth bar
Notice bibliographique
Résumé
The late early Permian coincided with a short-lived cold episode in Western Australia, which occurred long after the demise of late Paleozoic ice sheets, and is manifested by conspicuous dropstones in corresponding marine strata. In the northern Perth Basin, this time interval is represented by the Carynginia Formation, which has long been regarded as a record of low-energy marginal-marine sedimentation. The low-diversity body-fossil content and impoverished trace-fossil assemblages in the formation were recognised as evidence of low salinities, low dissolved-oxygen levels and high suspended-sediment concentrations presumably related to freshwater influxes into a restricted basin. However, sedimentary facies indicative of river processes have yet to be documented to explain the sedimentological and paleontological character of the formation. This study examines an overlooked sandstone-rich interval of the Carynginia Formation in the Irwin Sub-basin, a marginal half graben faulted against crystalline basement of the Yilgarn Craton and forming part of a series of late Paleozoic intracratonic rift basins in Western Australia. Facies analysis indicates that the lower part of the interval is dominated by storm-generated deposits containing extraformational pebbles and boulders. These deposits are interpreted as recording lower-shoreface sedimentation under the influence of seasonal sea ice, and constitute a shallower, sandstone-rich equivalent of mudstone-prone strata that otherwise characterise the Carynginia Formation. The upper part of the interval consists of river-borne deposits representing friction-dominated deposition of a river-mouth bar, the first direct record of deltaic sedimentation in the Carynginia Formation. The stratal organisation of mouth-bar bedsets is likely the result of successive sediment-laden pulses related to seasonal floods in a shallow marine basin, and the autogenic evolution of the mouth-bar complex in response to fluctuating river discharge and compensational stacking. Formative runoff events were arguably responsible for reductions in salinity and the introduction of turbid buoyant plumes into the shallow sea that were adverse to faunal development. A fluvial influence may explain the sedimentary character and fossil content of coeval mudstone-prone formations in Western Australian rift basins, especially in the vicinity of cratonic margins.KEY POINTSThe lower Permian (late Artinskian–Kungurian) mudstone-prone Carynginia Formation in the northern Perth Basin has long been regarded as the record of low-energy, marginal-marine conditions in a cold-water seaway.The low-diversity fossil content in the lower part of the formation indicates stressed physico-chemical conditions influenced by freshwater, sediment-laden influxes.The described mouth-bar deposits are the first direct evidence of deltaic sedimentation in the Carynginia Formation, demonstrating that river outflows likely controlled water chemistry and impacted faunal development.
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 | 0,001 |
| 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 ».