Lithium isotopic compositions of post-collisional mafic-ultramafic rocks from Dabieshan, China: Implications for recycling of deeply subducted continental crust

doi:10.1016/j.lithos.2019.105327

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	Lithium isotopic compositions of post-collisional mafic-ultramafic rocks from Dabieshan, China: Implications for recycling of deeply subducted continental crust
	Tan, Dong-Bo 4; Xiao, Yilin 3,4; Sun, He 2; Li, Wang-Ye 4; Dai, Li-Qun 4; Liu, Haiyang 1,4; Tong, Fengtai 4
刊名	LITHOS
	2020
卷号	352 页码:9
关键词	Lithium isotopes Post-collisional mafic-ultramafic rocks Recycled continental crust Subduction
ISSN号	0024-4937
DOI	10.1016/j.lithos.2019.105327
通讯作者	Xiao, Yilin(ylxiao@ustc.edu.cn)
英文摘要	Lithium (Li) isotopes are potential tracers of processes related to crust-mantle interaction and recycled crustal materials. Previous studies have reported that Li isotopic compositions of island arc lavas are similar to those of fresh mid-ocean-ridge basalts (MORBs), although the former are expected to record high slab-derived delta Li-7 values caused by fluid metasomatism. However, it is unclear whether Li isotopic signatures of subducted continental crust were transported to mantle depths and preserved there. For clarification, we determined wholerock major and trace element, and Li isotopic compositions of post-collisional mafic-uitramafic rocks from northem Dabieshan, China. The analyzed samples have high MgO (up to 20.67 wt%) and low SiO2 (41.06-56.20 wt%) contents, and arc-like trace element distribution patterns, suggesting derivation by partial melting of fertile mantle sources. The samples have delta Li-7 values of -2.9 to +72%. (average = +2.7 parts per thousand, n = 42) and Li concentrations of 2.50 to 28.1 mu g/g (average = 9.20 mu g/g), both of which are beyond the relatively limited ranges of mantle values (delta Li-7= +2.9 to +4.3 parts per thousand, average = +3.5 +/- 1.0 parts per thousand, and Li = 1.20 +/- 0.10 mu g/g). Excluding possible effects of wall-rock assimilation and contamination, magmatic crystallization, and Li isotopic fractionation during subductionexhumation processes, the observed U isotopic heterogeneity is most likely related to the recycling of crustal materials. Based on a comparison with Li isotopic compositions of ultrahigh-pressure (UHP) metamorphic rocks from the Dabie-Sulu orogenic belt and terrestrial sediments, we suggest that the recycled continental crustal materials likely comprised gneisses, sediments, eclogites, and/or minor carbonate rocks (i.e., marbles). Our study demonstrates that Li isotopes may provide a novel means of tracing deeply subducted continental materials. (C) 2019 Elsevier B.V. All rights reserved.
资助项目	Natural Science Foundation of China[41673031] ; Strategic Priority Research Program (B) of CAS[XDB18020000] ; State Key Laboratory of Ore Deposit Geochemistry open funds[201608]
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
语种	英语
出版者	ELSEVIER
WOS记录号	WOS:000515201500011
内容类型	期刊论文
源URL	[http://ir.qdio.ac.cn/handle/337002/165607]
专题	中国科学院海洋研究所
通讯作者	Xiao, Yilin
作者单位	1.Chinese Acad Sci, Inst Oceanol, Qingdao 266071, Peoples R China 2.Hefei Univ Technol, Sch Resources & Environm Engn, Hefei 230009, Peoples R China 3.CAS Ctr Excellence Comparat Planetol, Hefei, Peoples R China 4.Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Peoples R China
推荐引用方式 GB/T 7714	Tan, Dong-Bo,Xiao, Yilin,Sun, He,et al. Lithium isotopic compositions of post-collisional mafic-ultramafic rocks from Dabieshan, China: Implications for recycling of deeply subducted continental crust[J]. LITHOS,2020,352:9.
APA	Tan, Dong-Bo.,Xiao, Yilin.,Sun, He.,Li, Wang-Ye.,Dai, Li-Qun.,...&Tong, Fengtai.(2020).Lithium isotopic compositions of post-collisional mafic-ultramafic rocks from Dabieshan, China: Implications for recycling of deeply subducted continental crust.LITHOS,352,9.
MLA	Tan, Dong-Bo,et al."Lithium isotopic compositions of post-collisional mafic-ultramafic rocks from Dabieshan, China: Implications for recycling of deeply subducted continental crust".LITHOS 352(2020):9.