Nb-Ta mobility and fractionation during exhumation of UHP eclogite from   southwestern Tianshan, China

doi:10.1016/j.jseaes.2016.03.013

CORC > 北京大学 > 地球与空间科学学院

	Nb-Ta mobility and fractionation during exhumation of UHP eclogite from southwestern Tianshan, China
	Zhang, Lijuan ; Zhang, Lifei ; Lu, Zeng ; Bader, Thomas ; Chen, Zhenyu
刊名	JOURNAL OF ASIAN EARTH SCIENCES
	2016
关键词	Nb-Ta fractionation Mobility Rutile UHP eclogite Tianshan SUBDUCTED CONTINENTAL-CRUST FLUID-ROCK INTERACTION NIOBIUM-TANTALUM FRACTIONATION TRACE-ELEMENT CHARACTERISTICS PRESSURE METAMORPHIC ROCKS COESITE-BEARING ECLOGITE WESTERN TIANSHAN NW-CHINA NB/TA FRACTIONATION EASTERN CHINA
DOI	10.1016/j.jseaes.2016.03.013
英文摘要	In order to study the behavior of high field strength elements (HFSE) during retrograde overprint of ultrahigh-pressure (UHP) eclogites, analysis of Nb and Ta concentrations was carried out on bulk rock, rutile (in both veins and host rocks) and titanite in the host eclogite. The studied samples were collected from the UHP metamorphic belt of southwestern Tianshan, China. Petrographic observation and phase equilibria modeling show that the host eclogites have experienced UHP metamorphism and the rutile-bearing veins are thought to be originated from an internal fluid source, probably by lawsonite dehydration during exhumation. The presence of vein rutile indicates HFSE could be mobilized from host eclogites to veins, which is probably facilitated by complexation with dissolved Na-Al silicates and fluorine-rich fluids. Changes in fluid composition (e.g., F-1, X-(CO2))) may trigger the precipitation of rutile. Rutile/fluid partitioning may be the key to fractionating Nb and Ta, with preference for Ta in the fluid, resulting in Nb/Ta ratio of rutile in the veins lower than that in the host eclogite. Besides, the transformation of rutile into titanite also might be an effective mechanism for fractionating Nb from Ta, resulting in the intra-grain Nb-Ta zonations in vein rutile. The Nb-Ta mobility and fractionation can happen during exhumation of the UHP eclogite, which should be very important for understanding the behavior of HFSE in subduction zone metamorphism. (C) 2016 Elsevier Ltd. All rights reserved.; Major State Basic Research Development Program [2015CB856105]; National Natural Science Foundation [41330210, 41090371, 41272069, 41372074]; SCI(E); ARTICLE; lfzhang@pku.edu.cn; 136-157; 122
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/492306]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Zhang, Lijuan,Zhang, Lifei,Lu, Zeng,et al. Nb-Ta mobility and fractionation during exhumation of UHP eclogite from southwestern Tianshan, China[J]. JOURNAL OF ASIAN EARTH SCIENCES,2016.
APA	Zhang, Lijuan,Zhang, Lifei,Lu, Zeng,Bader, Thomas,&Chen, Zhenyu.(2016).Nb-Ta mobility and fractionation during exhumation of UHP eclogite from southwestern Tianshan, China.JOURNAL OF ASIAN EARTH SCIENCES.
MLA	Zhang, Lijuan,et al."Nb-Ta mobility and fractionation during exhumation of UHP eclogite from southwestern Tianshan, China".JOURNAL OF ASIAN EARTH SCIENCES (2016).