DOI: 10.1038/ngeo1710
论文题名: Solid-state plastic deformation in the dynamic interior of a differentiated asteroid
作者: Tkalcec B.J. ; Golabek G.J. ; Brenker F.E.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2013
卷: 6, 期: 2 起始页码: 93
结束页码: 97
语种: 英语
Scopus关键词: aluminum
; asteroid
; backscatter
; calcium
; crystallography
; diogenite
; downwelling
; equilibrium
; harzburgite
; magma chamber
; meteorite
; microstructure
; olivine
; orthopyroxene
; plastic deformation
英文摘要: Diogenite meteorites are thought to represent mantle rocks that formed as cumulates in magma chambers on 4 Vesta or a similar differentiated asteroid. Northwest Africa 5480 is a harzburgitic diogenite, composed mainly of heterogeneously distributed olivine and orthopyroxene. Here we present a microstructural analysis of olivine grains from Northwest Africa 5480, using electron backscatter diffraction techniques to quantify any preferred orientation of crystallographic lattice. We find that the preferred orientation in the olivine-dominated zones can be explained neither by cumulate formation nor by impact reprocessing near the asteroid's surface. Rather, they represent high-temperature solid-state plastic deformation by the pencil-glide slip system. The detected type of preferred orientation is well known from dry ultramafic rocks on Earth, where it is typically formed by mantle shear at temperatures between 1,273 and 1,523 K. Numerical modelling indicates that our observations can be explained by large-scale downwelling inside the asteroid's mantle, within the first 50 million years after formation of calcium-aluminium-rich inclusions. The discovery of solid-state plastic deformation in an asteroidal ultramafic rock represents compelling evidence of dynamic planet-like processes in asteroids. We conclude that long-lasting enhanced mass exchange occurred in the dynamic interior of a differentiated asteroid such as Vesta, and enabled accelerated chemical, structural and thermal equilibration. © 2013 Macmillan Publishers Limited. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/106863
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: Geoscience Institute, Goethe University, Altenhöferallee 1, 60438 Frankfurt am Main, Germany; ENS Lyon, Laboratoire de Géologie, 46 Allée d'Italie, 69364 Lyon Cedex 07, France; ETH Zürich, Institute of Geophysics, Sonneggstrasse 5, 8092 Zürich, Switzerland
Recommended Citation:
Tkalcec B.J.,Golabek G.J.,Brenker F.E.. Solid-state plastic deformation in the dynamic interior of a differentiated asteroid[J]. Nature Geoscience,2013-01-01,6(2)