Calcium Isotopic Compositions of Normal Mid-Ocean Ridge Basalts From the Southern Juan de Fuca Ridge

doi:10.1002/2017JB014699

	Calcium Isotopic Compositions of Normal Mid-Ocean Ridge Basalts From the Southern Juan de Fuca Ridge
	Zhu, Hongli 1; Liu, Fang 1,2; Li, Xin 1; Wang, Guiqin 1; Zhang, Zhaofeng 1; Sun, Weidong 3,4,5
刊名	JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
	2018-02-01
卷号	123 期号:2 页码:1303-1313
关键词	Calcium Isotopes N-morb Fractional Crystallization Partial Melting Mantle Heterogeneity
ISSN号	2169-9313
DOI	10.1002/2017JB014699
文献子类	Article
英文摘要	Mantle peridotites show that Ca is isotopically heterogeneous in Earth's mantle, but the mechanism for such heterogeneity remains obscure. To investigate the effect of partial melting on Ca isotopic fractionation and the mechanism for Ca isotopic heterogeneity in the mantle, we report high-precision Ca isotopic compositions of the normal Mid-Ocean Ridge Basalts (N-MORB) from the southern Juan de Fuca Ridge. Ca-44/40 of these N-MORB samples display a small variation ranging from 0.750.05 to 0.860.03 (relative to NIST SRM 915a, a standard reference material produced by the National Institute of Standards and Technology), which are slightly lower than the estimated Upper Mantle value of 1.050.04 parts per thousand and the Bulk Silicate Earth (BSE) value of 0.94 +/- 0.05 parts per thousand. This phenomenon cannot be explained by fractional crystallization, because olivine and orthopyroxene fractional crystallization has limited influence on Ca-44/40 of N-MORB due to their low CaO contents, while plagioclase fractional crystallization cannot lead to light Ca isotopic compositions of the residue magma. Instead, the lower Ca-44/40 of N-MORB samples compared to their mantle source is most likely caused by partial melting. The offset in Ca-44/40 between N-MORB and BSE indicates that at least 0.1-0.2 parts per thousand fractionation would occur during partial melting and light Ca isotopes are preferred to be enriched in magma melt, which is in accordance with the fact that Ca-44/40 of melt-depleted peridotites are higher than fertile peridotites in literature. Therefore, partial melting is an important process that can decrease Ca-44/40 in basalts and induce Ca isotopic heterogeneity in Earth's mantle.
WOS关键词	IONIZATION MASS-SPECTROMETRY ; DING REFERENCE GLASSES ; MANTLE PERIDOTITES ; DEPLETED MANTLE ; ORTHO-PYROXENE ; FE ISOTOPES ; CA CYCLE ; ICP-MS ; FRACTIONATION ; MORB
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	AMER GEOPHYSICAL UNION
WOS记录号	WOS:000428437500022
资助机构	National Key R&D Program of China(2016YFC0600408) ; National Natural Science Foundation of China(41773009 ; 41773062 ; 41490632)
内容类型	期刊论文
源URL	[http://ir.qibebt.ac.cn/handle/337004/10739]
专题	中国科学院青岛生物能源与过程研究所
通讯作者	Zhang, Zhaofeng
作者单位	1.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou, Guangdong, Peoples R China 2.Univ Chinese Acad Sci, Beijing, Peoples R China 3.Chinese Acad Sci, Inst Oceanog, Ctr Deep Sea Res, Qingdao, Peoples R China 4.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Mineral Resources, Qingdao, Peoples R China 5.Chinese Acad Sci, CAS Ctr Excellence Tibetan Plateau Earth Sci, Beijing, Peoples R China
推荐引用方式 GB/T 7714	Zhu, Hongli,Liu, Fang,Li, Xin,et al. Calcium Isotopic Compositions of Normal Mid-Ocean Ridge Basalts From the Southern Juan de Fuca Ridge[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2018,123(2):1303-1313.
APA	Zhu, Hongli,Liu, Fang,Li, Xin,Wang, Guiqin,Zhang, Zhaofeng,&Sun, Weidong.(2018).Calcium Isotopic Compositions of Normal Mid-Ocean Ridge Basalts From the Southern Juan de Fuca Ridge.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,123(2),1303-1313.
MLA	Zhu, Hongli,et al."Calcium Isotopic Compositions of Normal Mid-Ocean Ridge Basalts From the Southern Juan de Fuca Ridge".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 123.2(2018):1303-1313.