Importance de la différenciation crustale

Table des matières

CHAPITRE 1 – Introduction
1.1 Introduction
1.1.1 Importance de la différenciation crustale
1.1.2 L’influence du transfert de magma sur la différenciation crustale
1.1.3 Importance de la fusion partielle de la croûte et sa différenciation
1.1.4 Importance de la migration pervasive comme mécanisme de transfert des magmas d’anatexie
1.1.5 Les complexes d’injections: terrains formés par la migration pervasive de magmas d’anatexie
1.2 Problématique
1.3 Hypothèse
1.4 Objectifs
1.5 Zone d’étude
1.5.1 Contexte géologique – La Sous-province d’Opinaca dans la Province du Supérieur
1.5.2 Description de l’Opinaca
1.5.2.1 Description générale
1.5.2.2 Description structurale
1.5.3 Description des composantes du complexe d’injection
1.5.3.1 Unités métasédimentaires
1.5.3.2 Veines leucogranitiques
1.6 Méthodologie
1.6.1 Travail de terrain
1.6.2 Analyse pétrographique
1.6.3 Microsonde
1.6.4 Lithogéochimie
1.6.5 Isotopes d’oxygène
1.6.6 SHRIMP U/Pb
1.7 Format de la thèse
1.8 Références
CHAPITRE 2 – New geochronological constraints from SHRIMP U-Pb analysis in zircon from the Opinaca Subprovince, Superior Province, Quebec
2.1 Résumé
2.2 Abstract
2.3 Introduction
2.4 Geological context
2.4.1 The Opinaca Subprovince in the Superior Province
2.4.1.1 Part of a large scale series of metasedimentary basins
2.4.1.2 Opinaca Subprovince surroundings
2.4.2 Review of the Opinaca geochronology
2.5 SHRIMP methodology
2.6 Results
2.6.1 Sample MAN4C: granulite facies metapelite
2.6.1.1 Sample description
2.6.1.2 Zircon morphology
2.6.1.3 Results
2.6.2 Sample 6116A: granulite facies metapelite 64
2.6.2.1 Sample description
2.6.2.2 Zircon morphology
2.6.2.3 Results
2.6.3 Sample 6263A2: metagreywacke 66
2.6.3.1 Sample description
2.6.3.2 Zircon morphology
2.6.3.3 Results
2.6.4 Sample 6263A3: Opx-bearing metagreywacke
2.6.4.1 Sample description
2.6.4.2 Zircon morphology
2.6.4.3 Results
2.6.5 Sample 6263C1: injected leucogranite
2.6.5.1 Sample description
2.6.5.2 Zircon morphology
2.6.5.3 Results
2.7 Discussion
2.7.1 Transition from inherited zircon to those formed in the injection complex
2.7.2 Populations of inherited zircon
2.7.2.1 Provenance of the sediments
2.7.3 Timing of the injection complex
2.7.4 Significance of post-injection complex ages
2.7.5 Isotopic disturbance and Discordia intercepts
2.8 Conclusion
2.9 Acknowledgements
2.10 References
CHAPITRE 3 – Large volumes of anatectic melt retained in granulite facies migmatites: An injection complex in northern Quebec
3.1 Résumé
3.2 Abstract
3.3 Introduction
3.4 Opinaca Subprovince in the Superior Province
3.5 The Opinaca Subprovince
3.5.1 Structural characteristics
3.5.2 Migmatites
3.5.3 Thin leucocratic felsic veins in migmatites
3.5.4 Large leucocratic dykes and sills
3.6 U-Pb SHRIMP geochronology
3.6.1 Results
3.7 Petrology of the migmatites
3.7.1 Metagreywacke paleosome
3.7.2 Migmatites
3.7.3 Rehydration of high temperature mineral assemblages
3.7.4 Temperature and pressure during anatexis
3.8 Discussion
3.8.1 Timing of granulite facies metamorphism and injection of leucogranite
3.8.2 Percentage of melt produced by local anatexis
3.8.3 Accumulation of felsic melt in the Opinaca Subprovince
3.8.4 Potential source of the felsic magma
3.8.5 Why an injection complex?
3.8.6 Why thin veins and dykes?
3.8.7 Some consequences of an injection complex in the deep middle crust
3.8.7.1 Transfer of heat producing elements into the injection complex
3.8.7.2 Latent heat of crystallization
3.8.7.3 Addition of H2O
3.9 Conclusion
3.10 Acknowledgments
3.11 References
CHAPITRE 4 – The geochemical signature of a felsic injection complex in the continental crust: Opinaca Subprovince, Quebec 
4.1 Résumé
4.2 Abstract
4.3 Introduction
4.4 Geological context
4.4.1 Regional geology
4.4.2 Geochronology
4.4.3 Local geology
4.4.3.1. Metamorphic conditions
4.5.1 Macroscopic features
4.5.2 Petrology of the leucocratic veins
4.5.3 Microstructure of the leucogranite
4.6 Geochemistry of the leucogranites
4.6.1 Sampling and analytical methods
4.6.2 Major oxides 197
4.6.3 Trace elements
4.6.4 Oxygen isotopes
4.7 Discussion
4.7.1 Modelling major element compositions
4.7.1.1 Composition of the source material
4.7.1.2 Composition of the initial melt
4.7.1.3 Low TiO2, FeO and MgO
4.7.1.4 Evolution of leucogranites by fractional crystallisation
4.7.1.5 Trace elements
4.7.2 H2O released in the host
4.7.2.1 δ¹⁸ O reequilibration
4.7.2.2 H2O available
4.7.2.3 Importance of water fluxed partial melting
4.7.2.4 Implications of water release
4.8 Conclusion
4.9 Acknowledgments
4.10 References
CHAPITRE 5 – Synthèse et conclusion