Accessory Minerals in the Xihuashan Y-Enriched Granitic Complex, Southern China: A Record of Magmatic and Hydrothermal Stages of Evolution

Abstract

The Xihuashan granitic complex (southern China) is mainly composed of coarse-grained porphyritic biotite granite (G-a), medium-grained porphyritic biotite granite (G-b), and medium-to fine-grained porphyritic biotite granite (G-c). The G-a granite is characterized by monazite-(Ce) and xenotime-(Y), in addition to commonly observed zircon and uranoan thorite. In the G-b and G-c intrusive units, monazite-(Ce) becomes very scarce, whereas Y-bearing minerals, including Y-bearing spessartine, xenotime-(Y), gadolinite-(Y), fergusonite-(Y), and yttrian fluorite (up to 15 wt% Y 2 O 3 ), are concentrated to various extents. Spessartine exhibits chemical zoning, which is displayed, in the core, by elevated contents of Y and heavy REE (HREE) (up to 2.32 wt% Y 2 O 3 and 1.51% HREE 2 O 3 ) and micrometric inclusions of Y-bearing minerals. Similarly, zircon from the G-b and Gc granites contains polymineralic micro-inclusions in the core. Overall, the accessory minerals point to a magmatic environment of crystallization for the G-a granite. In contrast, the crystallization of the G-b and G-c granites involved magmatic and hydrothermal stages. The late-to postmagmatic fluid is enriched in F and CO 2 , and appeared as a result of the final oversaturation of the granitic melt in a fluid phase.Keywords: yttrian fluorite, yttrium-bearing spessartine-almandine, xenotime-(Y), zircon, electron-microprobe data, granite, Xihuashan, China. in the endo-and exocontact zones of the Xihuashan granitic complex (Hsu 1943). Mining of quartz-ferberitetype ores started in 1935. The metallogeny of the deposits and the petrology of associated granites were described by Hsu

In situ U-Pb dating of xenotime by laser ablation (LA)-ICP-MS

“…Xenotime is observed throughout the Xihuasan complex. Wang et al [37] suggested that xenotime crystallized at the magmatic stage and experienced further evolution at the late-magmatic and hydrothermal stage. Xenotimes from G-1, G-2, G-3 and G-5 granites were separated for U-Pb dating in this study.…”

Genesis of kasolite associated with aplite-pegmatite at Jabal Sayid, Hijaz region, Kingdom of Saudi Arabia

“…Furthermore, the association of Y-poor fluorite and synchysite-(Y) in the aplite-pegmatite of Jabal Sayid may suggest a genetic relationship between the two minerals. Wang et al (2003) reported alteration of yttrian fluorite in fluid rich environment to fluorite and synchysite-(Y) according to the following reaction:…”

Tveitite-(Y) and REE-enriched fluorite from amazonite pegmatites of the Western Keivy, Kola Peninsula, Russia: Genetic crystal chemistry of natural Ca,REE-fluorides

“…Such late hydrothermal variety was described as fluorite III at Mt. Ploskaya (Voloshin and Pakhomovsky, 1986) and noted at the Kutessai (Zuev and Kosterin, 1960), Katugin (Arkhangel'skaya, 1970), and Xihuashan (Wang et al, 2003) deposits. These findings coupled with data on the synthesis conditions show that incorporation of substantial amounts of REE into fluorite at the late, low-temperature stage of natural hydrothermal process is hampered.…”

“…The best-known occurrences of the mineral are known from Norway, including Tysfjord, Nordland; Iveland, Aust-Agder; and Tørdal, Telemark (Vogt, 1911;Sverdrup, 1968;Neumann, 1985). Yttrofluorite was described from alkaline metasomatized granitic rocks at the Kutessai and Aktyuz deposits in Kyrgyzstan (Zuev and Kosterin, 1960); alkali granitic pegmatite in Pikes Peak, Colorado, United States (Haynes, 1965); Suishoyama and Fukushima, Japan (Uetani et al, 1968); and Y-enriched granite in Xihuashan, Jiangxi, China (Wang et al, 2003). Yttrofluorite is known in Russia as well.…”