Combined iron and magnesium isotope geochemistry of pyroxenite xenoliths from Hannuoba, North China Craton: implications for mantle metasomatism

doi:10.1007/s00410-017-1356-y

CORC > 地质与地球物理研究所 > 中国科学院地质与地球物理研究所 > 岩石圈演化国家重点实验室

	Combined iron and magnesium isotope geochemistry of pyroxenite xenoliths from Hannuoba, North China Craton: implications for mantle metasomatism
	Zhao, Xin Miao 1; Cao, Hui Hui 1; Mi, Xue 1,2; Evans, Noreen J.3; Qi, Yu Han 4; Huang, Fang 4; Zhang, Hong Fu 1,5
刊名	CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
	2017-06-01
卷号	172 期号:6
关键词	Iron and magnesium isotopes Pyroxenite xenoliths Melt-rock interaction Lithospheric mantle North China Craton
ISSN号	0010-7999
DOI	10.1007/s00410-017-1356-y
文献子类	Article
英文摘要	We present high-precision iron and magnesium isotopic data for diverse mantle pyroxenite xenoliths collected from Hannuoba, North China Craton and provide the first combined iron and magnesium isotopic study of such rocks. Compositionally, these xenoliths range from Crdiopside pyroxenites and Al-augite pyroxenites to garnet-bearing pyroxenites and are taken as physical evidence for different episodes of melt injection. Our results show that both Cr-diopside pyroxenites and Al-augite pyroxenites of cumulate origin display narrow ranges in iron and magnesium isotopic compositions (delta Fe-57 = -0.01 to 0.09 with an average of 0.03 +/- 0.08 (2SD, n = 6); delta Mg-26 = -0.28 to -0.25 with an average of -0.26 +/- 0.03 (2SD, n = 3), respectively). These values are identical to those in the normal upper mantle and show equilibrium inter-mineral iron and magnesium isotope fractionation between coexisting mantle minerals. In contrast, the garnet-bearing pyroxenites, which are products of reactions between peridotites and silicate melts from an ancient subducted oceanic slab, exhibit larger iron isotopic variations, with delta Fe-57 ranging from 0.12 to 0.30. The delta Fe-57 values of minerals in these garnet-bearing pyroxenites also vary widely (-0.25 to 0.08 in olivines, -0.04 to 0.25 in orthopyroxenes, -0.07 to 0.31 in clinopyroxenes, 0.07 to 0.48 in spinels and 0.31-0.42 in garnets). In addition, the garnet-bearing pyroxenite shows light delta Mg-26 (-0.43) relative to the mantle. The delta Mg-26 of minerals in the garnet-bearing pyroxenite range from -0.35 for olivine and orthopyroxene, to -0.34 for clinopyroxene, 0.04 for spinel and -0.68 for garnet. These measured values stand in marked contrast to calculated equilibrium iron and magnesium isotope fractionation between coexisting mantle minerals at mantle temperatures derived from theory, indicating disequilibrium isotope fractionation. Notably, one phlogopite clinopyroxenite with an apparent later metasomatic overprint has the heaviest delta Fe-57 (as high as 1.00) but the lightest delta Mg-26 (as low as -1.50) values of all investigated samples. Overall, there appears to be a negative co-variation between delta Fe-57 and delta Mg-26 in the Hannuoba garnet-bearing pyroxenite and in the phlogopite clinopyroxenite xenoliths and minerals therein. These features may reflect kinetic isotopic fractionation due to iron and magnesium inter-diffusion during melt-rock interaction. Such processes play an important role in producing inter-mineral iron and magnesium isotopic disequilibrium and local iron and magnesium isotopic heterogeneity in the subcontinental mantle.
WOS关键词	SINO-KOREAN CRATON ; MELT-PERIDOTITE INTERACTIONS ; EASTERN CHINA ; LITHOSPHERIC MANTLE ; MAJOR-ELEMENT ; MAGMATIC DIFFERENTIATION ; TRACE-ELEMENTS ; MAFIC ROCKS ; SUBCONTINENTAL LITHOSPHERE ; CONTINENTAL SUBDUCTION
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
语种	英语
出版者	SPRINGER
WOS记录号	WOS:000403544500003
资助机构	National Science Foundation of China(41373041 ; National Science Foundation of China(41373041 ; 41673021) ; 41673021) ; National Science Foundation of China(41373041 ; National Science Foundation of China(41373041 ; 41673021) ; 41673021) ; National Science Foundation of China(41373041 ; National Science Foundation of China(41373041 ; 41673021) ; 41673021) ; National Science Foundation of China(41373041 ; National Science Foundation of China(41373041 ; 41673021) ; 41673021)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/50670]
专题	地质与地球物理研究所_岩石圈演化国家重点实验室
通讯作者	Zhao, Xin Miao
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, POB 9825, Beijing 100029, Peoples R China 2.Univ Chinese Acad Sci, Beijing, Peoples R China 3.Curtin Univ, John de Laeter Ctr, TIGeR, Appl Geol, Perth, WA 6945, Australia 4.Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Peoples R China 5.Northwest Univ Xian, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Peoples R China
推荐引用方式 GB/T 7714	Zhao, Xin Miao,Cao, Hui Hui,Mi, Xue,et al. Combined iron and magnesium isotope geochemistry of pyroxenite xenoliths from Hannuoba, North China Craton: implications for mantle metasomatism[J]. CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,2017,172(6).
APA	Zhao, Xin Miao.,Cao, Hui Hui.,Mi, Xue.,Evans, Noreen J..,Qi, Yu Han.,...&Zhang, Hong Fu.(2017).Combined iron and magnesium isotope geochemistry of pyroxenite xenoliths from Hannuoba, North China Craton: implications for mantle metasomatism.CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,172(6).
MLA	Zhao, Xin Miao,et al."Combined iron and magnesium isotope geochemistry of pyroxenite xenoliths from Hannuoba, North China Craton: implications for mantle metasomatism".CONTRIBUTIONS TO MINERALOGY AND PETROLOGY 172.6(2017).