DOI: 10.1038/ngeo2195
论文题名: Redox control of the fractionation of niobium and tantalum during planetary accretion and core formation
作者: Cartier C. ; Hammouda T. ; Boyet M. ; Bouhifd M.A. ; Devidal J.-L.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2014
卷: 7, 期: 8 起始页码: 573
结束页码: 576
语种: 英语
英文摘要: As the Earth accreted, metallic materials segregated from silicates to form the iron-rich core. The proportions of the refractory lithophile elements in the silicate part of the Earth are thought to have remained similar to that of chondrite meteorites throughout accretion. However, although niobium (Nb) and tantalum (Ta) are both classified as refractory lithophile elements and share a similar degree of incompatibility in mineral structures, the Nb/Ta ratio of the bulk silicate Earth is subchondritic. To explain this paradox, it has been proposed that Nb becomes siderophile at the high pressures of core formation, and was preferentially removed from the silicate Earth. Here we conduct metal/silicate partitioning experiments at a range of oxygen fugacities and show that Nb and Ta are both siderophile elements under reducing conditions, but become so at different oxygen fugacities, leading to fractionation. We find that pressure has a negligible influence on the Nb/Ta ratio. Applying our partitioning data to existing theoretical accretion models, we reproduce the Nb/Ta ratios of the bulk silicate Earth, Mars and the differentiated asteroid 4 Vesta, and discuss the implications for Moon formation. We conclude that planetary accretion of reduced materials played an important role in the chemical evolution of Earth and, more generally, that Nb and Ta can be used to trace prevailing oxygen fugacities during the segregation of planetary cores. © 2014 Macmillan Publishers Limited. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/106578
Appears in Collections: 气候减缓与适应 科学计划与规划
There are no files associated with this item.
作者单位: Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 Clermont-Ferrand, France; CNRS UMR 6524, LMV, F-63038 Clermont-Ferrand, France; IRD, R 163, LMV, F-63038 Clermont-Ferrand, France
Recommended Citation:
Cartier C.,Hammouda T.,Boyet M.,et al. Redox control of the fractionation of niobium and tantalum during planetary accretion and core formation[J]. Nature Geoscience,2014-01-01,7(8)