The origin of glimmerite and its significance to rare earth element mineralization: Insights from the Longbaoshan deposit in North China Craton
Notice bibliographique
Résumé
• The geochemistry of phlogopite suggests that glimmerite is metasomatic origin. • The glimmerite at Longbaoshan has undergone three stages of REE mineralization. • The combination of mineralogy, image processing, and mass balance calculations estimate the contribution of fluids to REE mineralization. Glimmerite is often associated with critical metal mineralization; however, its origin remains controversial, and the significance of glimmerite in rare earth mineralization is unclear. At Longbaoshan, glimmerite exhibits significant rare earth mineralization. We conducted mineralogical, morphological, and mineral geochemical analysis on the glimmerite REE orebodies in the Longbaoshan deposit in the Luxi Block of China. Micro X-Ray Fluorescence Spectrometry (μ-XRF) elemental mapping combined with an ImageJ image analysis was used to evaluate the mineralization of the glimmerite. We identified that the glimmerite experienced three stages of hydrothermal metasomatism, all of which led to REE enrichment in the glimmerite. The stage-Ⅰ metasomatism formed the glimmerite, during which phlogopite (∼80 %) and chevkinite-(Ce) crystals (1–2 % in volume) were formed. Titanite was replaced and enclosed by chevkinite-(Ce), suggesting a metasomatic origin of the latter. Because the phlogopite and chevkinite-(Ce) crystals share equilibrium contacts with each other, indicating their common, metasomatic origin. This is also supported by the lower Fe/Mg value and higher concentrations of Na, Ba, and Sr of unaltered phlogopite compared to the alteration halos surrounding unaltered phlogopite. This alteration halo is interpreted as alteration by a stage-II metasomatism, which is, in nature, a siliceous alteration that added Si and F in phlogopite and formed quartz veins and fluorbritholite-(Ce) which occupied 15 vol% and 24 vol% of glimmerite, respectively. The fluorbritholite-(Ce) crystals are formed through the replacement of fluorapatite in the glimmerite. The halogen fugacity during stage-II metasomatism is lower than that during the formation of glimmerite, with the rate of decrease in F fugacity faster than that of Cl fugacity. We use this to conclude that the primary factor driving the precipitation of rare earth minerals is the dominant decrease of F relative to Cl fugacity. The stage-III metasomatism was brought about by a carbonate fluid that altered fluorbritholite-(Ce) into aggregates of parisite-(Ce) and synchysite-(Ce) (these two together occupy 29 % of the volume of glimmerite). Mass balance calculations reveal that the second stage of siliceous metasomatism resulted in 15 times of REE enrichment in the glimmerite compared to the initial mineralogy of glimmerite, while the contribution of carbonate fluid metasomatism (Stage III) to REE enrichment was minimal.
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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 | 0,001 |
| 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) | 0,000 | 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 ».