Geochemistry and petrology of nephrite from Alamas, Xinjiang, NW China

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	Geochemistry and petrology of nephrite from Alamas, Xinjiang, NW China
	Liu, Y (Liu, Yan); Deng, J (Deng, Jun); Shi, GH (Shi, Guanghai); Yui, TF (Yui, Tzen-Fu); Zhang, GB (Zhang, Guibin); Abuduwayiti, M (Abuduwayiti, Maituohuti); Yang, LQ (Yang, Liqiang); Sun, X (Sun, Xiang)
刊名	JOURNAL OF ASIAN EARTH SCIENCES
	2011
卷号	42 期号:3 页码:440-451
关键词	Nephrite Tremolite Geochemistry Petrology Metasomatism Xinjiang NW China
ISSN号	1367-9120
英文摘要	The Hetian nephrite deposit is one of the largest nephrite deposits worldwide. Located within the Hetian deposit, Xinjiang, Northwest China, the Alamas ore body occurs as veins on the contact between the Late Variscan granodiorite and Precambrian dolomitic marble. Petrographic studies and electronic microprobe analyses reveal two possible nephrite formation processes (1) dolomitic marble -> tremolite and (2) dolomitic marble -> diopside -> tremolite. Nephrite veins show continuous coloration zones, ranging from white and white-green zones to a green zone towards the granodiorite, with increasing concentrations of Cr, FeO and TFe(2)O(3). All these nephrite samples have quite low Cr and Ni contents (8.95-178.7 ppm and 0.05-3.95 ppm, respectively) relative to serpentinite-related nephrite (Cr(2)O(3), 0.07-0.43 wt.%; NiO, 0.08-0.36 wt.%). Their bulk-rock REE patterns exhibit strong negative Eu anomalies (0.03-0.21) with declined LREE, flat HREE and low Sigma REE concentration (2.84-84.81 ppm), similar to those of host dolomitic marble samples with negative Eu anomalies (0.15-0.23), declined LREE, flat HREE and lower Sigma REE concentration (8.48-11.1 ppm), indicating a close genetic relationship between them. Homogenization temperatures analyses on the fluid inclusions in tremolite yield a minimum temperature 293 degrees C for the nephrite formation. Nephrites have oxygen and hydrogen isotope compositions in the range from +3.2 to +6.2 per mil and -83.0 to -94.7 per mil, respectively. The corresponding equilibrated fluids have isotope compositions of delta(18)O = +3.1 to +6.1 (293 degrees C). Combined with field observation, there are at least three possible fluid sources meteoric water, magmatic water and CO(2) derived from decarbonation of dolomite, and a metasomatic and dolomite-related origin is suggested for the Alamas ore body in the Hetian nephrite deposit, Xinjiang, NW China. (C) 2011 Elsevier Ltd. All rights reserved.
学科主题	结晶学与矿物学
WOS关键词	OXYGEN-ISOTOPE FRACTIONATION ; MYANMAR JADEITITE ; FLUID EVOLUTION ; STABLE-ISOTOPE ; NEW-ZEALAND ; JADE ; MINERALS ; ORIGIN ; CARBON ; SILICATES
WOS研究方向	Geology
语种	英语
出版者	PERGAMON-ELSEVIER SCIENCE LTD
WOS记录号	WOS:000296078100022
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39420]
专题	中国地质调查局
作者单位	Hetian Bur Qual & Tech Supervis, Hetian 848000, Xinjiang, Peoples R China
推荐引用方式 GB/T 7714	Liu, Y ,Deng, J ,Shi, GH ,et al. Geochemistry and petrology of nephrite from Alamas, Xinjiang, NW China[J]. JOURNAL OF ASIAN EARTH SCIENCES,2011,42(3):440-451.
APA	Liu, Y .,Deng, J .,Shi, GH .,Yui, TF .,Zhang, GB .,...&Sun, X .(2011).Geochemistry and petrology of nephrite from Alamas, Xinjiang, NW China.JOURNAL OF ASIAN EARTH SCIENCES,42(3),440-451.
MLA	Liu, Y ,et al."Geochemistry and petrology of nephrite from Alamas, Xinjiang, NW China".JOURNAL OF ASIAN EARTH SCIENCES 42.3(2011):440-451.