DOI: 10.1016/j.epsl.2018.06.029
Scopus记录号: 2-s2.0-85049555784
论文题名: Earth's chondritic Th/U: Negligible fractionation during accretion, core formation, and crust–mantle differentiation
作者: Wipperfurth S.A. ; Guo M. ; Šrámek O. ; McDonough W.F.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 498 起始页码: 196
结束页码: 202
语种: 英语
英文关键词: BSE composition
; core formation
; core heat production
; crust–mantle differentiation
; Th/U
Scopus关键词: Budget control
; Intelligent systems
; Monte Carlo methods
; Silicates
; Atmospheric oxidation
; Bulk silicate earth
; Continental crusts
; Core formation
; Heat production
; Mantle differentiation
; Planetary differentiation
; Radioactive decay
; Earth (planet)
; accretion
; chondrite
; concentration (composition)
; crust-mantle boundary
; differentiation
; fractionation
; Monte Carlo analysis
; thorium isotope
; uranium isotope
英文摘要: Radioactive decay of potassium (K), thorium (Th), and uranium (U) power the Earth's engine, with variations in 232Th/238U recording planetary differentiation, atmospheric oxidation, and biologically mediated processes. We report several thousand 232Th/238U (κ) and time-integrated Pb isotopic (κPb) values and assess their ratios for the Earth, core, and silicate Earth. Complementary bulk silicate Earth domains (i.e., continental crust κPb CC=3.95−0.13 +0.19 and modern mantle κPb MM=3.87−0.07 +0.15) tightly bracket the solar system initial κPb SS=3.890±0.015. These findings reveal the bulk silicate Earth's κPb BSE is 3.90−0.08 +0.13 (or Th/U = 3.77 for the mass ratio), which resolves a long-standing debate regarding the Earth's Th/U value. We performed a Monte Carlo simulation to calculate the κPb of the BSE and bulk Earth for a range of U concentrations in the core (from 0 to 10 ng/g). Comparison of our results with κPb SS constrains the available U and Th budget in the core. Negligible Th/U fractionation accompanied accretion, core formation, and crust–mantle differentiation, and trivial amounts of these elements (<0.2 ng/g U) were added to the core and do not significantly power (∼0.03 TW) the geodynamo. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109750
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Department of Geology, University of Maryland, College Park, MD 20742, United States; Institute of Crustal Dynamics, China Earthquake Administration, Beijing, 100085, China; Department of Geophysics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic; Research Center for Neutrino Science, Department of Earth Sciences, Tohoku University, Sendai, 980-8578, Japan
Recommended Citation:
Wipperfurth S.A.,Guo M.,Šrámek O.,et al. Earth's chondritic Th/U: Negligible fractionation during accretion, core formation, and crust–mantle differentiation[J]. Earth and Planetary Science Letters,2018-01-01,498