GRENVILLIAN METAMORPHISM OF MONOCYCLIC ROCKS, GEORGIAN BAY, ONTARIO, CANADA: IMPLICATIONS FOR CONVERGENCE HISTORY
Notice bibliographique
Résumé
The objective of this paper is to represent the main features inherent to Grenville-Sveconorwegian Orogen (GSNO) and to propose a model of tectonic and geodynamic evolution of this orogen based on the results of research concerning similar Precambrian tectonic units in the East European Craton.The studies of the conditions and settings related to origin and evolution of GSNO are of special interest, because it is located geographicaly and in a certain sense ideologically in the center of Rodinia, a supposed Neoproterozoic supercontinent.GSNO originated in the Mezo-Neoproterozoic in the inner region of the Lauroscandia continent.At present, the synformal tectonic structure of GSNO is divided into two portions: Grenville sector along the southeastern margin of the Canadian Shield, and Sveconorwegian sector in the southwestern Scandinavia.The integrity of Lauroscandia was twice disturbed in the Mezo-Neoproterozoic when oceanic structures resembling the Atlantic Ocean were formed.Later on, the continuity of the continent was restored with the involvement of oceanic lithosphere subduction and accretion and obduction of the island-arc and oceanic terranes.We distinguish two stages in the GSNO history: (1) 'preparatory' stage (from ~1.90 to ~1.16 Ga), and (2) formation of GSNO proper (from ~1.19 to ~0.90 Ga).The manifestations of granulite-facies metamorphism were repeatedly recorded before the Grenville Orogeny at 1.67-1.66,1.47-1.45,1.37-1.35,and 1.20-1.18Ga.The Ottawan stage of the Grenville metamorphism proper is dated between 1.16 and 1.05-1.03Ga.Metamorphism at the base of Allochthonous Belt corresponds to high-pressure granulite facies and, in a number of places, to hightemperature eclogite facies (800-900 °C at pressure in the range between 14 and 20 kbar).The age of metamorphism of rocks within Paraautochthonous Belt is 1.05-0.95Ga; metamorphic grade increases from the greenschist facies near the Grenville front to the high-pressure amphibolite facies near Allochthon Boundary Thrust showing an inverted metamorphic zoning.High-pressure granulite-facies metamorphism is characteristic of Sveconorwegian sector; and high-temperature eclogites are observed locally at the base of the allochthonous complexes and within the paraautochthonous complexes.A distinctive feature of GNSO is the abundant occurrence of specific intrusive magmatism.Massifs of anorthosite-mangerite-charnockite-granite (AMCG) and anorthosite-rapakivi granite (ARG) complexes formed 1.8-1.5 Ga ago frame the orogen as a wide arc.In the internal region of GSNO, these complexes were formed successively at 1.16-1.13,1.09-1.05,0.99-0.96,and 0.93-0.92Ga.Later on, after the intrusion, the massifs unevenly underwent granulite-facies metamorphism.The high-temperature magmatism and metamorphism, numerous repeated thermal pulses and enormous crustal body that underwent high-temperature transformation point to a mantle plume as the most adequate source of thermal energy.The model of intracontinental development of GSNO comes GEODYNAMICS & TECTONOPHYSICS
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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 | 0,000 | 0,001 |
| 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) | 0,023 | 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 ».