Mineralogical fingerprints of crustal silica contamination in the Bayan Obo carbonatite

doi:10.2138/am-2023-9297

	Xiao, Yulun 1; Yang, Wubin 2; Yang, Xiaoyong 1; Cao, Yonghua 2; Tian, Pengfei 3; Zhao, Zhuang 4
	Mineralogical fingerprints of crustal silica contamination in the Bayan Obo carbonatite
刊名	AMERICAN MINERALOGIST
ISSN号	0003-004X
	2025-03-26
卷号	110 期号:3 页码:452-466
DOI	10.2138/am-2023-9297
语种	英语
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
摘要	Carbonatites are carbonate-rich and silica-undersaturated igneous rocks. The presence of various silicates in carbonatites has sparked discussions about the source of silica. In this study, abundant fluorbritholite-(Ce) and humite group minerals are identified in the No. 1 carbonatite dike at the Bayan Obo REE-Nb-Fe deposit. These silicates are relatively rare and poorly understood in carbonatite systems. Mineral textures, in situ EPMA, and LA-ICP-MS analyses have been combined to constrain the mineral genesis in the carbonatite. Fluorbritholite-(Ce), a member of the apatite super-group, occurs as euhedral to subhedral crystals in the dike. They are characterized by remarkably high concentrations of REE2O3 (56.0-63.7 wt%), SiO2 (19.6-21.2 wt%), and F (2.47-3.47 wt%), along with relatively lower P2O5 (0.25-3.69 wt%) and CaO (10.3-14.2 wt%) contents compared to common fluorapatite species. Additionally, their high-Y (961-3435 ppm) and low-Sr/Y (0.59-2.70) values suggest a hydrothermal origin from a fluid rich in SiO2, REE, and F. Humite group minerals, mainly chondrodite and humite, display irregularmineral textures. They also exhibit elevated SiO2 (32.5-34.7 wt%) and F content (3.59-7.32 wt%) with notably low TiO2 content (0.02-0.08 wt%), indicating a hydrothermal origin induced by fenitization in the shallow crust. Our results favor a model of crustal silica contamination for the fenitization fluids enriched in F, LREE, and SiO2. More importantly, the fluid-assisted silica contamination from wall rocks within carbonatites is likely to be a critical trigger of REE deposition in the carbonatite ore-forming systems.
关键词	Bayan Obo REE deposit carbonatite dike crustal contamination britholite humite group minerals
WOS记录号	WOS:001437504800002
收录类别	SCI
引用统计	被引频次：1[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.gig.ac.cn/handle/344008/83002
专题	中国科学院矿物学与成矿学重点实验室
通讯作者	Yang, Wubin
作者单位	1.Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei, Peoples R China 2.Chinese Acad Sci, Key Lab Mineral & Metallogeny, Guangzhou Inst Geochem, Guangzhou, Peoples R China 3.Shanxi Inst Technol, Cultivat Base Shanxi Key Lab Min Area Ecol Restora, Yangquan, Peoples R China 4.Yancheng Teachers Univ, Sch Wetlands, Yancheng, Peoples R China
推荐引用方式 GB/T 7714	Xiao, Yulun,Yang, Wubin,Yang, Xiaoyong,et al. Mineralogical fingerprints of crustal silica contamination in the Bayan Obo carbonatite[J]. AMERICAN MINERALOGIST,2025,110(3):452-466.
APA	Xiao, Yulun,Yang, Wubin,Yang, Xiaoyong,Cao, Yonghua,Tian, Pengfei,&Zhao, Zhuang.(2025).Mineralogical fingerprints of crustal silica contamination in the Bayan Obo carbonatite.AMERICAN MINERALOGIST,110(3),452-466.
MLA	Xiao, Yulun,et al."Mineralogical fingerprints of crustal silica contamination in the Bayan Obo carbonatite".AMERICAN MINERALOGIST 110.3(2025):452-466.