The influence of crustal recycling on the molybdenum isotope composition of the Earth's mantle

doi:10.1016/j.epsl.2022.117760

IOCAS-IR > 海洋地质与环境重点实验室

	The influence of crustal recycling on the molybdenum isotope composition of the Earth's mantle
	Hin, Remco C.1,7; Hibbert, Kate E. J.1; Chen, Shuo 1,2,3; Willbold, Matthias 1,8; Andersen, Morten B.1,9; Kiseeva, Ekaterina S.4,10; Wood, Bernard J.4; Niu, Yaoling 5; Sims, Kenneth W. W.6; Elliott, Tim 1
	2022-10-01
发表期刊	EARTH AND PLANETARY SCIENCE LETTERS
ISSN	0012-821X
卷号	595 页码:11
通讯作者	Hin, Remco C.([email protected])
摘要	Several studies have suggested that the Earth's upper mantle is slightly enriched in light molybdenum isotopes relative to bulk Earth, defined by chondrites, but there is no consensus on the presence of this subtle but potentially notable signature. To establish better whether or not the Mo-98/Mo-95 of Earth's upper mantle is indeed sub-chondritic, we have analysed hand-picked glasses of depleted (i.e. chondrite normalised La/Sm<1) mid-ocean ridge basalts (MORE) from the Pacific, Atlantic and Indian ocean basins. The mean Mo isotope composition of our depleted MORE relative to reference NIST SRM 3134 (delta(98)/Mo-95(NIST SRM) (3134)) is -0.22 +/- 0.03 parts per thousand (95% confidence interval, c.i.) compared to a value of -0.15 +/- 0.01 parts per thousand (95% c.i.) for bulk Earth. Our high precision analyses of the U-234/U-238 activity ratios of these samples are within uncertainty of unity, which rules out the effect of possible secondary, sea-floor processes as the dominant cause of their low delta(98)/Mo-95(NIST SRM) (3134). We further report experimental data showing that sulphide liquid has delta(98)/Mo-95(NIST SRM) (3134) 0.25 +/- 0.01 parts per thousand lower than basaltic silicate liquid at 1400 degrees C. This fractionation is too small to significantly alter the Mo isotope composition of basalts relative to their sources during melting or differentiation. Our MORE data show that resolvably sub-chondritic Mo isotope compositions are common in the upper mantle. Moreover, an appropriately weighted average delta(98)/Mo-95(NIST SRM) (3134) of depleted and enriched MORE, taken from this study and the literature, yields an estimated mantle value of -0.20 +/- 0.01 parts per thousand, indicating that the upper mantle as a whole is sub-chondritic. Since prior work demonstrates that core formation will not create a residual silicate reservoir with a sub-chondritic delta(98)/Mo-95(NIST SRM) (3134), we propose that this feature is a result of recycling oceanic crust with low delta(98)/Mo-95(NIST SRM) (3134) because of Mo isotope fractionation during subduction dehydration. Such an origin is in keeping with the subchondritic Th/U and low Ce/Pb of the depleted mantle, features which cannot be explained by simple melt extraction. We present mass balance models of the plate tectonic cycle that quantitatively illustrate that the delta(98)/Mo-95(NIST SRM) (3134) of the Earth's mantle can be suitably lowered by such oceanic crustal recycling. Our Mo isotope study adds to the notion that the depleted mantle has been substantially modified by geodynamic cycling of subduction-processed oceanic crust. (C) 2022 Published by Elsevier B.V.
关键词	Mo isotope fractionation mantle geochemistry
DOI	10.1016/j.epsl.2022.117760
收录类别	SCI
语种	英语
资助项目	NERC[NE/L007428/1]; NERC[NE/H023933/1]; NERC studentship[NE/I528250/1]
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000877976300005
出版者	ELSEVIER
引用统计	被引频次：19[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/337002/180471
专题	海洋地质与环境重点实验室
通讯作者	Hin, Remco C.
作者单位	1.Univ Bristol, Sch Earth Sci, Bristol BS8 1RJ, England 2.Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, Qingdao 266071, Peoples R China 3.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Geol, Qingdao 266061, Peoples R China 4.Univ Oxford, Dept Earth Sci, Oxford OX1 3AN, England 5.Univ Durham, Dept Earth Sci, Durham DH1 3LE, England 6.Univ Wyoming, Dept Geol & Geophys, Laramie, WY 82071 USA 7.Univ Bayreuth, Bayer Geoinst, D-95447 Bayreuth, Germany 8.Georg August Univ Gottingen, Geowissenschaftl Zent, D-37077 Gottingen, Germany 9.Cardiff Univ, Sch Earth & Environm Sci, Cardiff CF10 3AT, Wales 10.Univ Coll Cork, Sch Biol Earth & Environm Sci, Cork T23 N73K, Ireland
推荐引用方式 GB/T 7714	Hin, Remco C.,Hibbert, Kate E. J.,Chen, Shuo,et al. The influence of crustal recycling on the molybdenum isotope composition of the Earth's mantle[J]. EARTH AND PLANETARY SCIENCE LETTERS,2022,595:11.
APA	Hin, Remco C..,Hibbert, Kate E. J..,Chen, Shuo.,Willbold, Matthias.,Andersen, Morten B..,...&Elliott, Tim.(2022).The influence of crustal recycling on the molybdenum isotope composition of the Earth's mantle.EARTH AND PLANETARY SCIENCE LETTERS,595,11.
MLA	Hin, Remco C.,et al."The influence of crustal recycling on the molybdenum isotope composition of the Earth's mantle".EARTH AND PLANETARY SCIENCE LETTERS 595(2022):11.