1. Constraints of alkaline magmatic evolution on the enrichment and mineralisation of rare-earth elements in the eastern part of the northern margin of the North China Craton: a case study of the Baerzhe and Saima deposits.
- Author
-
Ju, N., Wu, Y., Zhang, G. B., Xin, H. T., Shi, L., Liu, X., and Feng, Y. H.
- Subjects
RARE earth metals ,URANIUM ,METALLOGENIC provinces ,GEOCHEMISTRY ,URANIUM-lead dating ,SYENITE - Abstract
The eastern part of the northern margin of the North China Craton is a key metal metallogenic province in China, hosting many important rare metal and rare earth element (REE) deposits and having great resource potential. This study investigated the Saima deposit, a niobium (Nb) and tantalum (Ta) deposit and the Baerzhe deposit hosting zirconium (Zr), Nb and REEs. Based on previous LA-ICP-MS zircon U–Pb dating results obtained by the authors' team, this study compared the whole-rock geochemistry and whole-rock Sr–Nd–Pb isotopes of an orebody with its surrounding rocks. The geochemical characteristics of both deposits are used to systematically review the evolution of the alkaline magma and the differences in the physical and chemical conditions for enrichment and mineralisation of late-stage rare elements and REEs such as Nb, Ta and Zr. Comparing the mineralisation of the Saima and Baerzhe deposits, the alkaline magmatic evolution plays a crucial role in the enrichment of rare-earth elements, which are generally formed in the late stage of alkaline magmatic evolution. The Saima deposit, which has a metallogenic age of 224.40 ± 6.10 Ma, formed in nepheline syenites with high alkali (Na
2 O + K2 O) and low MgO and CaO contents, with high TFeO/MgO ratios. The A-type granites formed in an extensional tectonic setting after the closure of the Paleo-Asian Ocean. The Baerzhe deposit, which has a metallogenic age of 125.2–122.15 Ma, formed in A-type alkali granites (orebody and surrounding rocks) that have high alkali (Na2 O + K2 O) and low MgO and CaO contents with high TFeO/MgO ratios, strong uranium (U) depletion and typical V-shaped distribution of REE. The mineralisation is controlled by melt–fluid interactions in the later stage of highly evolved magmas. The enrichment and mineralisation of rare elements and REEs in the eastern part of the north margin of the North China Craton are mainly associated with the high degree of evolution of alkaline magmas. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF