Origins of two types of serpentinites from the Qinling orogenic belt, central China and associated fluid/melt-rock interactions

doi:10.1016/j.lithos.2017.12.019

	Origins of two types of serpentinites from the Qinling orogenic belt, central China and associated fluid/melt-rock interactions
	Wu, Kai 1,2; Ding, Xing 3,4; Ling, Ming-Xing 3,4; Sun, Wei-dong4,5,6 ; Zhang, Li-Peng 1,2; Hu, Yong-Bin 1; Huang, Rui-Fang 1
	2018-03-01
发表期刊	LITHOS
ISSN	0024-4937
卷号	302 页码:50-64
通讯作者	Ding, Xing(xding@gig.ac.cn) ; Ling, Ming-Xing(mxling@gig.ac.cn)
摘要	Serpentinites are important volatile and fluid mobile element repositories in oceanic lithosphere and subduction zones, and thus provide significant constraints on global geochemical cycles and tectonic evolution at convergent margins. In this contribution, two types of serpentinites from the Mianlue suture zone in the Qinling orogenic belt, central China, are identified on the basis of detailed mineralogical and geochemical study. Serpentinites from the Jianchaling region (Group 1) are composed of lizardite/chrysotile + magnesite + magnetite. Most of these serpentinites (Group la), consist of pseudomorphic orthopyroxene and olivine, and are characterized by low Al2O3/SiO2, high MgO/SiO2 and Ir-type PGEs to Pt ratios, suggesting a residual mantle origin. Meanwhile, the U-shape REE pattern and positive Eu, Sr and Ba anomalies of these serpentinites indicate that serpentinization fluids have interacted with gabbroic cumulates at moderately high temperatures or associate with the chlorinity and redox conditions of the fluid. Considering the limited mobility of U in the hydrating fluids for the Group la serpentinites, hydrating fluids for these serpentinites are most likely derived from the dehydrated slab, and have been in equilibrium with subducting sediments. There are also some serpentinites with low-grade metamorphic recrystallization from the Jianchaling region (Group 1b), represented by recrystallized serpentine minerals (antigorite). The trace element compositions of these Group 1b serpentinites suggest that partial dehydration of serpentinites associated with the transformation from lizardite to antigorite in subduction zone is also likely to affect the geochemistry of serpentinites. Serpentinites from the Liangyazi region (Group 2) are composed of antigorite + dolomite + spinel + magnetite. The high Cr number (0.65-0.80) and low Ti concentrations of spinels in Group 2 serpentinites indicate a refractory mantle wedge origin. Fertile major element compositions (e.g., high Al2O3 content and Al2O3/SiO2) and conjoint enrichment in light rare earth elements and high field strength elements, however, suggest melt-rock interactions before serpentinization. Combined with their geochemical affinity to "subducted serpentinites", we conclude that their protoliths (refractory mantle wedge peridotite) experienced melt-rock interactions and then were incorporated into the subduction channel before serpentinization. Studies on these two types of serpentinites indicate that serpentinites from the orogenic belt are most likely characterized by multi-source, multi-stage and multi-genesis, further providing important constraints on subduction channel processes. (C) 2017 Elsevier B.V. All rights reserved.
关键词	Serpentinites Qinling orogenic belt Mianlue ophiolite melange Subduction channel
DOI	10.1016/j.lithos.2017.12.019
收录类别	SCI
语种	英语
资助项目	Chinese Academy of Sciences[XDB06030101] ; Natural Science Foundation of China[41421062] ; Guangdong Natural Science Funds[2014A030306032] ; Guangdong Natural Science Funds[2015TQ01Z611] ; Youth Innovation Promotion Association CAS[2016315] ; Chinese Academy of Sciences[XDB06030101] ; Natural Science Foundation of China[41421062] ; Guangdong Natural Science Funds[2014A030306032] ; Guangdong Natural Science Funds[2015TQ01Z611] ; Youth Innovation Promotion Association CAS[2016315]
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
WOS类目	Geochemistry & Geophysics ; Mineralogy
WOS记录号	WOS:000428497500004
出版者	ELSEVIER SCIENCE BV
引用统计	被引频次：17[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/158475
专题	深海极端环境与生命过程研究中心
通讯作者	Ding, Xing; Ling, Ming-Xing
作者单位	1.Chinese Acad Sci, Guangzhou Inst Geochem, Key Lab Mineral & Metallogeny, Guangzhou 510640, Guangdong, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 3.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Guangdong, Peoples R China 4.Chinese Acad Sci, Ctr Excellence Tibetan Plateau Earth Sci, Beijing 100101, Peoples R China 5.Chinese Acad Sci, Inst Oceanog, Ctr Deep Sea Res, Qingdao 266071, Peoples R China 6.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Mineral Resources, Qingdao 266237, Peoples R China
推荐引用方式 GB/T 7714	Wu, Kai,Ding, Xing,Ling, Ming-Xing,et al. Origins of two types of serpentinites from the Qinling orogenic belt, central China and associated fluid/melt-rock interactions[J]. LITHOS,2018,302:50-64.
APA	Wu, Kai.,Ding, Xing.,Ling, Ming-Xing.,Sun, Wei-dong.,Zhang, Li-Peng.,...&Huang, Rui-Fang.(2018).Origins of two types of serpentinites from the Qinling orogenic belt, central China and associated fluid/melt-rock interactions.LITHOS,302,50-64.
MLA	Wu, Kai,et al."Origins of two types of serpentinites from the Qinling orogenic belt, central China and associated fluid/melt-rock interactions".LITHOS 302(2018):50-64.

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