气候变化领域集成服务门户(CCPortal): Formation of the Ce-Nd mantle array: Crustal extraction vs. recycling by subduction

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DOI	10.1016/j.epsl.2019.115941
	Formation of the Ce-Nd mantle array: Crustal extraction vs. recycling by subduction
	Israel C.; Boyet M.; Doucelance R.; Bonnand P.; Frossard P.; Auclair D.; Bouvier A.
发表日期	2020
ISSN	0012821X
卷号	530
英文摘要	We present new measurements of 138Ce/142Ce and 143Nd/144Nd isotopic ratios in terrestrial and extra-terrestrial samples. The mean value obtained from nine chondrites defines the 138Ce/142Ce ratio of the chondritic uniform reservoir (CHUR) as 0.02256577±66 (2sd). MORBs and OIBs define the mantle array in the εNd vs. εCe diagram to be εNd=−7.3(±0.5)×εCe+0.4(±0.3). From MORB measurements, we derive the isotopic composition of the depleted MORB mantle (DMM) to be εCe=−1.1±0.6 (2sd). Both CHUR and a modelled early-depleted mantle reservoir plot on the mantle array. Thus, the precise determination of the mantle array does not further constrain the La/Ce and Sm/Nd ratios of the bulk silicate Earth (BSE; i.e., primitive mantle). The composition of 1.8 Ga upper continental crust obtained from aeolian sediments is εCe=1.8±0.3 (2sd; εNd=−11.2), and that of its 2.2 Ga equivalent is εCe=2.3±0.3 (2sd; εNd=−17). Binary mixing models between depleted (DMM) and enriched (upper crust or mafic crust composition) components do not reproduce the linear Ce-Nd mantle array but plots close to the island arc basalt data. When the bulk Ce isotopic composition of the continental crust is calculated from the range of accepted Nd isotope values and a mass-balance budget of the BSE, the mixing curves are closer to the mantle array. However the calculated Ce isotopic composition for the bulk crust is always less radiogenic than measurements. Adjusting the Ce-Nd isotopic composition or the Ce/Nd ratio of the end-members to fully linearise the mixing curve leads to unrealistic values never measured in terrestrial samples. We propose a recycling model to reconstruct the mantle array with the participation of both oceanic crust and sediments in the mantle through time. Cerium is a redox sensitive element, making the La-Ce and Sm-Nd systematics an ideal combination to investigate sediment recycling through time. In this recycling model, the most extreme EM-like signatures require the involvement of oceanic sediments that formed under reduced conditions before the Great Oxygenation Event at 2.4 Ga, and which are devoid of Ce elemental anomalies. © 2019 Elsevier B.V.
关键词	138Ce/142Ce chondritic bulk silicate Earth mantle array ocean island basalts rare earth elements silicate reservoirs
英文关键词	Basalt; Binary alloys; Budget control; Cerium; Gallium; Isotopes; Lanthanum alloys; Mixing; Neodymium alloys; Rare earth elements; Rare earths; Recycling; Samarium alloys; Sediments; Silicates; Bulk silicate earth; Depleted MORB mantles; mantle array; Nd isotopic compositions; Ocean island basalts; Precise determinations; Upper continental crust; ^138Ce/^142Ce; Cerium alloys; cerium; chondrite; crustal recycling; crustal structure; isotopic composition; isotopic ratio; neodymium isotope; ocean island basalt; rare earth element; silicate; subduction
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202672
作者单位	Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, Clermont-Ferrand, F-63000, France; Department of Earth Sciences, University of Western Ontario, Canada; Bayerisches Geoinstitut, Universität Bayreuth, Germany
推荐引用方式 GB/T 7714	Israel C.,Boyet M.,Doucelance R.,et al. Formation of the Ce-Nd mantle array: Crustal extraction vs. recycling by subduction[J],2020,530.
APA	Israel C..,Boyet M..,Doucelance R..,Bonnand P..,Frossard P..,...&Bouvier A..(2020).Formation of the Ce-Nd mantle array: Crustal extraction vs. recycling by subduction.Earth and Planetary Science Letters,530.
MLA	Israel C.,et al."Formation of the Ce-Nd mantle array: Crustal extraction vs. recycling by subduction".Earth and Planetary Science Letters 530(2020).