DOI: 10.1038/ngeo2075
论文题名: Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography
作者: Valley J.W. ; Cavosie A.J. ; Ushikubo T. ; Reinhard D.A. ; Lawrence D.F. ; Larson D.J. ; Clifton P.H. ; Kelly T.F. ; Wilde S.A. ; Moser D.E. ; Spicuzza M.J.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2014
卷: 7, 期: 3 起始页码: 219
结束页码: 223
语种: 英语
Scopus关键词: accuracy assessment
; crust
; data acquisition
; dating method
; Hadean
; high temperature
; magma
; tomography
; zircon
英文摘要: The only physical evidence from the earliest phases of Earth's evolution comes from zircons, ancient mineral grains that can be dated using the U-Th-Pb geochronometer. Oxygen isotope ratios from such zircons have been used to infer when the hydrosphere and conditions habitable to life were established. Chemical homogenization of Earth's crust and the existence of a magma ocean have not been dated directly, but must have occurred earlier. However, the accuracy of the U-Pb zircon ages can plausibly be biased by poorly understood processes of intracrystalline Pb mobility. Here we use atom-probe tomography to identify and map individual atoms in the oldest concordant grain from Earth, a 4.4-Gyr-old Hadean zircon with a high-temperature overgrowth that formed about 1 Gyr after the mineral's core. Isolated nanoclusters, measuring about 10 nm and spaced 10-50 nm apart, are enriched in incompatible elements including radiogenic Pb with unusually high 207 Pb/ 206 Pb ratios. We demonstrate that the length scales of these clusters make U-Pb age biasing impossible, and that they formed during the later reheating event. Our tomography data thereby confirm that any mixing event of the silicate Earth must have occurred before 4.4 Gyr ago, consistent with magma ocean formation by an early moon-forming impact about 4.5 Gyr ago. © 2014 Macmillan Publishers Limited. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/106539
Appears in Collections: 气候减缓与适应 科学计划与规划
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作者单位: NASA Astrobiology Institute, Department of Geoscience, University of Wisconsin, Madison, WI 53706, United States; University of Puerto Rico, Mayaguez 00681, Puerto Rico; CAMECA, Madison, WI 53711, United States; Curtin University, GPO Box U1987, Perth 6845, WA, Australia; University of Western Ontario, London, ON N6A 5B7, Canada
Recommended Citation:
Valley J.W.,Cavosie A.J.,Ushikubo T.,et al. Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography[J]. Nature Geoscience,2014-01-01,7(3)