Structural evolution of the southern Swayze greenstone belt, Superior Craton: Implications for the Neoarchean crustal dynamics
Notice bibliographique
Résumé
Numerous studies suggest that the Neoarchean may have been a transitional period from vertical tectonism to horizontal tectonism in crustal dynamics. The former is characterized by spontaneous gravitational redistribution of crustal materials, while the latter is characterized by partitioning of far-field tectonic stress into localized high shear zones and regional-scale strike-slip motion. However, how these combined crustal dynamics are manifested in the geological record remains poorly understood. In this study, a deformation analysis was carried out in the southern part of the Neoarchean Swayze greenstone belt, southeastern Superior Craton, as well as in the enclosing Ridout deformation zone. Our structural analysis reveals four generations (G 1 – G 4 ) of ductile deformation. G 1 deformation is preserved only in the pre-tectonic granitoid intrusion. G 2 deformation established the dome-and-keel architecture of the Swayze greenstone belt and is associated with regional F 2 folding, the S 2 foliation subparallel to the granitoid-greenstone boundary and the L 2 stretching lineation which exhibits a reversal in the plunge direction on the opposing granitoid-greenstone boundaries. The G 2 deformation zones show a granitoid-up/greenstone-down sense of shear. G 3 deformation is associated with oblique sinistral movement on the Ridout deformation zone possibly due to regional sinistral transpression. G 4 deformation is a reactivation event of pre-existing weak planes in the form of transcurrent dextral shearing. The kinematics of G 2 structures is interpreted to be the result of combined sagduction/diapirism and regional dextral shearing, thus implying a crustal condition that is “weak” enough to allow spontaneous crustal-scale gravitational readjustments while at the same time “strong” enough to transfer regional tectonic stress. In this sense, both styles of tectonism may have operated simultaneously in the Swayze greenstone belt. Our results support the hypothesis that the Neoarchean era is a transitional period during which the crustal dynamics evolved from being mainly vertical to horizontal and that the Swayze greenstone belt preserves evidence for the co-operation of both processes. Furthermore, our analysis, including temporal constraints, recognizes a comparable structural history between the Ridout deformation zone in the Swayze greenstone belt and the Cadillac-Larder Lake deformation zone in the Abitibi greenstone belt. However, discrepancies exist in terms of the vertical kinematics and the position of the deformation zone with respect to the syntectonic Timiskaming-type sedimentary assemblage. Therefore, we propose that the two deformation zones may have been initiated as separate entities rather than a coherent crustal-scale deformation corridor. • Four generations of ductile deformation (G 1 –G 4 ) are identified in the southern Swayze greenstone belt. • Deformation zones in the Swayze and the Abitibi greenstone belts likely initiated as separate entities under similar tectonic settings. • The G 2 deformation, which established the dome-and-keel architecture, is interpreted to be the result combined sagduction/diapirism and regional dextral shearing. • The Neoarchean may represent a transitional period when both vertical and horizontal crustal dynamics coexisted and operated simultaneously.
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 machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| 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 | 0,002 | 0,002 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 source (Gemma direct ou Codex distillé), 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 ».