Fenitized Wall Rock Geochemistry of the First Carbonatite Dyke at Bayan Obo, Inner Mongolia, China

doi:10.1111/1755-6724.13545

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	Fenitized Wall Rock Geochemistry of the First Carbonatite Dyke at Bayan Obo, Inner Mongolia, China
	Wang Kaiyi; Zhang Jien; Yu Liangjun; Fang Aimin; Dong Ce; Hu Fuyou
刊名	ACTA GEOLOGICA SINICA-ENGLISH EDITION
	2018-04-01
卷号	92 期号:2 页码:600-613
关键词	Bayan Obo first carbonatite dyke fenitization
ISSN号	1000-9515
DOI	10.1111/1755-6724.13545
英文摘要	The first carbonatite dyke at Bayan Obo is well exposed on the surface for a length and width of approximately 60 m and 1.1-1.5 m, respectively. Along its strike, the fenitized H1 (Qs) and H2 (Cs) quartzite is replaced by Na-amphiboles, aegirines, and alkali-feldspars, intermittently stretching as far away as 800 m in length. Based on petrographical characteristics, the dyke's fenitized wall rocks are divisible into different zones: (1) outer, (2) middle, and (3) inner. The outer zone is 5-17 m from the NW margin of the dyke. The middle zone is located at 3.5-5 m from the NW margin of the dyke. The inner contact zone is located between direct contact with the dyke and 3.5 m from the dyke. In the outer zone, upon visual examination, no evidence of outcrop fenitization was found and the major elemental rock composition is nearly identical to the unaltered H1 and H2 lithologies. In the thin sections, however, small amounts of Na-amphibole and phlogopite are present. Despite relatively poor development throughout the 5 m of fenitization, the wall rocks have retained at least a small geochemical signature comparable to the original sedimentary protolith. The fenites occurring in the inner zone exhibit distinct variations, not only for the sharp contact at the outcrop scale, but also for variations in major, rare earth elements (REE), and trace elements and Sm-Nd isotope composition. The wall rocks within 3.5 m have undergone strong fenitization, inheriting the geochemical signature derived from the carbonatite dyke. Fenitization in the middle zone was not as strong, at least compared to the inner zone, but was stronger than the outer zone. Compared to some trace elements and REEs, the major elements are relatively immobile during fenitization. The Sm-Nd isotope data for the carbonatite dyke and the adjacent fenitized wall rocks, where the Sm and Nd originate solely from the dyke, plots as a six-point isochron with an age of 1308 +/- 56 Ma. This age is identical to that of ore-bearing dolomite carbonatite and the related ore-forming events, indicating that there may be a petrogenetic link between the two. Based on Sr and Nd isotope compositional data, the first carbonatite dyke may be derived from an enriched mantle.
资助项目	National Nature Science Foundation of China[41372081]
WOS关键词	NORTH CHINA ; ORE-DEPOSIT ; NB DEPOSIT ; SM-ND ; REE ; MINERALIZATION ; CONSTRAINTS ; DOLOMITE ; MINERALS ; ELEMENTS
WOS研究方向	Geology
语种	英语
出版者	WILEY
WOS记录号	WOS:000437257000011
资助机构	National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China ; National Nature Science Foundation of China
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/94028]
专题	地质与地球物理研究所_离退休科研人员
通讯作者	Wang Kaiyi
作者单位	Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Wang Kaiyi,Zhang Jien,Yu Liangjun,et al. Fenitized Wall Rock Geochemistry of the First Carbonatite Dyke at Bayan Obo, Inner Mongolia, China[J]. ACTA GEOLOGICA SINICA-ENGLISH EDITION,2018,92(2):600-613.
APA	Wang Kaiyi,Zhang Jien,Yu Liangjun,Fang Aimin,Dong Ce,&Hu Fuyou.(2018).Fenitized Wall Rock Geochemistry of the First Carbonatite Dyke at Bayan Obo, Inner Mongolia, China.ACTA GEOLOGICA SINICA-ENGLISH EDITION,92(2),600-613.
MLA	Wang Kaiyi,et al."Fenitized Wall Rock Geochemistry of the First Carbonatite Dyke at Bayan Obo, Inner Mongolia, China".ACTA GEOLOGICA SINICA-ENGLISH EDITION 92.2(2018):600-613.