Origin of unusual HREE-Mo-rich carbonatites in the Qinling orogen, China
| Autor: | Cheng Xu, Chunwan Wei, Qihai Shu, Kangjun Huang, Martin Smith, Li Zhou, Wenlei Song, Jindrich Kynicky |
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| Rok vydání: | 2016 |
| Předmět: |
Multidisciplinary
010504 meteorology & atmospheric sciences Subduction Rare-earth element Geochemistry Crust 010502 geochemistry & geophysics 01 natural sciences Article Mantle (geology) 13. Climate action Molybdenite Carbonatite Fluid inclusions Sedimentary rock Geology 0105 earth and related environmental sciences |
| Zdroj: | Scientific Reports |
| ISSN: | 2045-2322 |
| DOI: | 10.1038/srep37377 |
| Popis: | Carbonatites, usually occurring within intra-continental rift-related settings, have strong light rare earth element (LREE) enrichment; they rarely contain economic heavy REE (HREE). Here, we report the identification of Late Triassic HREE-Mo-rich carbonatites in the northernmost Qinling orogen. The rocks contain abundant primary HREE minerals and molybdenite. Calcite-hosted fluid inclusions, inferred to represent a magmatic-derived aqueous fluid phase, contain significant concentrations of Mo (~17 ppm), reinforcing the inference that these carbonatitic magmas had high Mo concentrations. By contrast, Late Triassic carbonatites in southernmost Qinling have economic LREE concentrations, but are depleted in HREE and Mo. Both of these carbonatite types have low δ26Mg values (−1.89 to −1.07‰), similar to sedimentary carbonates, suggesting a recycled sediment contribution for REE enrichment in their mantle sources. We propose that the carbonatites in the Qinling orogen were formed, at least in part, by the melting of a subducted carbonate-bearing slab, and that 10 Ma younger carbonatite magmas in the northernmost Qinling metasomatized the thickened eclogitic lower crust to produce high levels of HREE and Mo. |
| Databáze: | OpenAIRE |
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