Microplate Solutions to Crustal Growth and Metal Endowment in Modern Back-Arc Basins and Ancient Greenstone Belts
Notice bibliographique
Résumé
Abstract Ore formation throughout Earth’s history has tracked major pulses of crustal growth. The spectacular endowment of some greenstone belts, in particular, has been linked to high heat flow and extensive Archean rifting. Three aspects were likely important: (1) greater numbers of plates required to dissipate the heat; (2) abundant crustal-scale transcurrent faults to accommodate plate growth; and (3) increased hydrothermal convection to cool the crust at the plate boundaries. Because the plates were smaller and more numerous than today, the total ridge length was greater, thus allowing for more efficient cooling of the newly formed crust. Mantle upwelling and rifting between microplate domains focused melts and fluids into well-mineralized corridors. This tectonic style is observed today at the Indo-Australian margin, providing clues to the crustal architecture of some well-endowed Archean terranes, such as the Abitibi greenstone belt in the Superior province of Canada. Hot, thickened oceanic crust, like that of the modern Lau basin and North Fiji basin, has strong similarities to mineral-rich greenstone belts like the Abitibi in terms of structure, kinematics, and magmatic evolution. The majority of this crust formed during a basin-wide microplate “breakout” that occurred in response to the collision of Australia with the Ontong Java and Melanesian Border plateaus in the Late Miocene. Today, the back-arc basins contain some of the fastest growing crust on Earth and an extraordinary concentration of magmatic and hydrothermal activity. In the northern Lau basin, at least seven distinct microplates formed within the last 5 m.y., with crustal growth partitioned across numerous simultaneously active plate boundaries in a complex microplate mosaic. The plates are bound by active spreading centers, ridges, and shear zones that are continuously deforming in response to plate rotation. Basin opening is dominated by many short, slow-spreading segments between large-scale transcurrent fault zones, with a combined strike length of spreading centers greater than in any other back-arc basin in the western Pacific. Seismic sections to depths of at least 20 km show that the plate boundaries are broad zones of deformation characterized by overlapping spreading centers, ridge jumps, and extensional transforms. Increased crustal permeability occurs where multiple spreading centers intersect (i.e., at triple junctions) with enhanced magmatic and hydrothermal activity at the plate boundaries. Seismic velocities and volcanic geochemistry also show large variations in crustal composition between the plates, indicating that the back-arc region is far more complex than supposed in earlier models. We suggest crustal growth and mineral endowment in some greenstone belts were similarly regulated by microplate formation. Because the microplates behave independently, often at great distances from the nearest subduction zone, their formation is akin to autochthonous growth in the Archean when subduction-zone processes were either absent or in their infancy. Compelling evidence of this architecture is now being revealed in the Abitibi greenstone belt by modeling of the Archean Moho topography.
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 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 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 ».