DOI: 10.1016/j.epsl.2021.117086
论文题名: Zirconium isotopic composition of the upper continental crust through time
作者: Tian S. ; Moynier F. ; Inglis E.C. ; Rudnick R.L. ; Huang F. ; Chauvel C. ; Creech J.B. ; Gaschnig R.M. ; Wang Z. ; Guo J.-L.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 572 语种: 英语
中文关键词: BSE
; glacial diamictites
; loess
; oceanic sediments
; upper continental crust
; zirconium isotopes
英文关键词: Alumina
; Aluminum oxide
; Deposition
; Gallium
; Geochemistry
; Glacial geology
; Hematite
; Isotopes
; Rivers
; Sedimentary rocks
; Sedimentology
; Weathering
; Zircon
; Zirconium
; BSE
; Glacial diamictites
; Isotope compositions
; Isotopic composition
; Oceanic sediments
; Sedimentary samples
; Stable isotopic compositions
; Upper continental crust
; Zirconium isotope
; Sediments
; age determination
; continental crust
; depositional environment
; diagenesis
; isotopic composition
; loess
; magmatic differentiation
; zircon
英文摘要: The stable isotopic composition of insoluble, refractory elements such as titanium (Ti) or zirconium (Zr), which are modified by magmatic differentiation but, a priori, are poorly affected by weathering or diagenesis, serve as powerful potential proxies to reconstruct the compositional evolution of the continental crust. Here we present the evolution of the Zr stable isotopic compositions (δ94/90ZrIPGP-Zr, per mille deviation of 94Zr/90Zr from IPGP-Zr standard) of the continental crust through time, using 38 sedimentary samples from the upper continental crust (UCC), including 12 Holocene loesses from the Chinese Loess Plateau and Xinjiang, three oceanic sediments from the sea floor outboard of the Lesser Antilles island arc and 23 glacial diamictite composites with depositional ages ranging from ∼ 2.9 Ga to 0.3 Ga from South Africa, South America, Canada, USA and China. The samples show limited Zr isotopic variations with δ94/90ZrIPGP-Zr values of 0.043‰ - 0.109‰ for loess; 0.069‰ - 0.083‰ for oceanic sediments and 0.031‰ - 0.118‰ for glacial diamictites; their Zr-weighted average values are, 0.081 ± 0.044‰ (2SD, n = 12), 0.073 ± 0.015‰ (2SD, n = 3) and 0.078 ± 0.047‰ (2SD, n = 23), respectively. The isotopic similarity among loess, oceanic sediments and glacial diamictites, suggests that zircon enrichment effects previously documented in some sedimentary samples have not biased the Zr isotope compositions of these sedimentary rocks from their source rocks. Two groups with or without Zr enrichment have similar average δ94/90ZrIPGP-Zr values (0.075 ± 0.040‰ and 0.080 ± 0.046‰). There is no correlation between Zr isotope compositions and any proxy of chemical weathering (e.g., Al2O3/SiO2, Fe2O3/SiO2, CIA, K2O/Al2O3 and δ7Li). The δ94/90ZrIPGP-Zr values are quite constant for these sedimentary samples regardless of their depositional ages and locations. Therefore, the UCC appears to have had a constant Zr isotopic composition between 3 Ga and present, and is homogeneous at a large scale. Combining data for sedimentary reference materials from the literature and the sedimentary rocks in this study, we suggest a Zr-weighted δ94/90ZrIPGP-Zr value of 0.077 ± 0.058‰ (2SD, n = 44) for the UCC, which is statistically distinct (t test, p value = 2.88 × 10−10) and higher than that of the mantle (0.040 ± 0.044‰, n = 72). Combining the δ94/90ZrIPGP-Zr values of different terrestrial reservoirs, the δ94/90ZrIPGP-Zr of the BSE and bulk Earth is constrained to be 0.041 ± 0.041‰. © 2021 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165690
Appears in Collections: 气候变化与战略
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作者单位: Université de Paris, Institut de Physique du Globe de Paris, CNRS, Paris cedex 05, France; Department of Earth Science, University of California-Santa Barbara, Santa Barbara, CA 93106, United States; CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China; Department of Earth and Planetary Sciences, Macquarie UniversityNSW 2109, Australia; University of Massachusetts – Lowell, Department of Environmental, Earth, and Atmospheric Science, Lowell, MA 01854, United States; State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China
Recommended Citation:
Tian S.,Moynier F.,Inglis E.C.,et al. Zirconium isotopic composition of the upper continental crust through time[J]. Earth and Planetary Science Letters,2021-01-01,572