Origin of low delta(26) Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere

doi:10.1016/j.gca.2016.05.021

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 > 中国科学院地球与行星物理重点实验室

	Origin of low delta(26) Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere
	Tian, Heng-Ci 1,2; Yang, Wei 1; Li, Shu-Guang 3; Ke, Shan 3; Chu, Zhu-Yin 4
刊名	GEOCHIMICA ET COSMOCHIMICA ACTA
	2016-09-01
卷号	188 页码:93-105
关键词	Magnesium isotopes Continental basalts Asthenosphere-lithosphere interaction Recycled carbonates Pacific slab subduction
DOI	10.1016/j.gca.2016.05.021
文献子类	Article
英文摘要	This study presents stable Mg isotopic data for Cenozoic potassic basalts from Wudalianchi and Erkeshan in northeastern China to determine the interactions between upwelling carbonated asthenosphere and enriched lithospheric mantle. Although the Wudalianchi and Erkeshan basalts have variable MgO contents of 4.45 to 9.47 wt.%, they exhibit a homogeneous Mg isotopic composition with delta(26) Mg values ranging from -0.57% to -0.46% and averaging -0.51 +/- 0.06 parts per thousand (2SD, n = 18). This Mg isotopic composition is lighter than that of the average mantle (delta(26) Mg = -0.25 +/- 0.07 parts per thousand) but similar to late Cretaceous (< 110 Ma) and Cenozoic basalts from the North China Craton and the South China Block (delta(26) Mg = -0.60 to -0.35 parts per thousand). The high CaO/Al2O3 and Ba/Rb, and low Hf/Hf* ratios of the Wudalianchi and Erkeshan basalts are typical characteristics of carbonatitic metasomatism, suggesting that the light Mg isotopic composition could derive from involvement of recycled sedimentary carbonates in the mantle source. The high Dy/Er ratios (2.55 to 2.75) and excess of Th-230 (Th-230/U-238 = 1.24 to 1.33) suggest presence of garnet in a relatively deep mantle source. Additionally, the seismic tomographic observations show the existence of the stagnant Pacific slab in the mantle transition zone (410-660 km) under eastern China. This carbonated mantle source should be located in the asthenosphere. However, compared to other low delta(26) Mg basalts from eastern China with MORB-like Sr-Nd-Pb isotopic compositions and OIB-like trace element features, the Wudalianchi and Erkeshan basalts exhibit EM-I Sr-Nd-Pb isotopic compositions combined with high SiO2, Ba, K, Pb and LREE contents, high Ba/Th and low Ce/Pb ratios. These geochemical features require a contribution from another mantle source, most likely an EM-I lithospheric mantle. Therefore, an asthenosphere-lithosphere interaction model is proposed for determine the origin of the Wudalianchi and Erkeshan basalts. The original melt was derived from partial melting of the carbonated asthenospheric mantle that was metasomatized by carbonate melt from the stagnant Pacific slab in the mantle transition zone. This ascending melt with a low delta(26) Mg signature subsequently interacted with the EM-I lithospheric mantle. The interaction dissolved pyroxene and crystallized olivine, releasing LILE, REE, Sr and Pb from dissolved minerals into the melt. Simultaneously, Mg was inherited by newly formed olivine. Therefore, this interaction modified the trace elements and the Sr-Nd-Pb isotopic compositions of the melt toward EM-I geochemical features but preserved the light Mg isotope signatures. (C) 2016 Elsevier Ltd. All rights reserved.
WOS关键词	NORTH CHINA CRATON ; CENOZOIC VOLCANIC-ROCKS ; MANTLE TRANSITION ZONE ; OCEAN ISLAND BASALTS ; MID-ATLANTIC RIDGE ; EASTERN CHINA ; NE CHINA ; TRACE-ELEMENT ; ISOTOPE GEOCHEMISTRY ; MAJOR-ELEMENT
WOS研究方向	Geochemistry & Geophysics
语种	英语
WOS记录号	WOS:000380752700006
资助机构	National Science Foundation of China(41230209 ; National Science Foundation of China(41230209 ; National Science Foundation of China(41230209 ; National Science Foundation of China(41230209 ; Youth Innovation Promotion Association, Chinese Academy of Sciences ; Youth Innovation Promotion Association, Chinese Academy of Sciences ; Youth Innovation Promotion Association, Chinese Academy of Sciences ; Youth Innovation Promotion Association, Chinese Academy of Sciences ; 41322022 ; 41322022 ; 41322022 ; 41322022 ; 41328004 ; 41328004 ; 41328004 ; 41328004 ; 41221002 ; 41221002 ; 41221002 ; 41221002 ; 41173012) ; 41173012) ; 41173012) ; 41173012) ; National Science Foundation of China(41230209 ; National Science Foundation of China(41230209 ; National Science Foundation of China(41230209 ; National Science Foundation of China(41230209 ; Youth Innovation Promotion Association, Chinese Academy of Sciences ; Youth Innovation Promotion Association, Chinese Academy of Sciences ; Youth Innovation Promotion Association, Chinese Academy of Sciences ; Youth Innovation Promotion Association, Chinese Academy of Sciences ; 41322022 ; 41322022 ; 41322022 ; 41322022 ; 41328004 ; 41328004 ; 41328004 ; 41328004 ; 41221002 ; 41221002 ; 41221002 ; 41221002 ; 41173012) ; 41173012) ; 41173012) ; 41173012)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/53375]
专题	地质与地球物理研究所_中国科学院地球与行星物理重点实验室
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earth & Planetary Phys, Beijing 100029, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 3.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China 4.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Tian, Heng-Ci,Yang, Wei,Li, Shu-Guang,et al. Origin of low delta(26) Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2016,188:93-105.
APA	Tian, Heng-Ci,Yang, Wei,Li, Shu-Guang,Ke, Shan,&Chu, Zhu-Yin.(2016).Origin of low delta(26) Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere.GEOCHIMICA ET COSMOCHIMICA ACTA,188,93-105.
MLA	Tian, Heng-Ci,et al."Origin of low delta(26) Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere".GEOCHIMICA ET COSMOCHIMICA ACTA 188(2016):93-105.