A collisional origin to Earth's non-chondritic composition?
A collisional origin to Earth's non-chondritic composition?
复制标题
DOI：
10.1016/j.icarus.2014.10.019
复制
发表时间：
2015-02-01
期刊：
影响因子：
3.2
通讯作者：
Stewart, Sarah T.
中科院分区：
文献类型：
--
作者：
Bonsor, Amy;Leinhardt, Zoe M.;Stewart, Sarah T.
有几行证据表明，块状地球上存在一种非球粒陨石成分。如果地球是由球粒物质的聚积而成的，那么它的非球粒成分，特别是超球粒的ND-142/ND-144和低的镁/铁比值，可能是在其形成过程中分化面的碰撞侵蚀所致。在这项工作中，我们使用N体程序，其中包括最先进的碰撞模型，以跟踪类似于原始地球的原行星的形成，从分化的平面-被盖(>；100公里)到孤立质量(>；0.16M-圆点)。不同天体之间的碰撞有可能改变被吸积的原行星的核-地幔比。我们表明，在失控和寡头结构的增长过程中，可以从碰撞的天体中剥离足够的地幔物质，从而最终的原行星可以具有类似于块状地球的镁/铁和硅/铁的比率，但前提是地球是一个极端的情况，并且假定地核的质量含有10%的硅。这可能表明，如果地球是由软骨物质形成的，那么在巨型撞击阶段，碰撞分化可能起到重要作用。(C)2014年提交人。由Elsevier Inc.出版。这是CC许可下的一篇开放获取文章。
Several lines of evidence indicate a non-chondritic composition for bulk Earth. If Earth formed from the accretion of chondritic material, its non-chondritic composition, in particular the super-chondritic Nd-142/Nd-144 and low Mg/Fe ratios, might be explained by the collisional erosion of differentiated plane-tesimals during its formation. In this work we use an N-body code, that includes a state-of-the-art collision model, to follow the formation of protoplanets, similar to proto-Earth, from differentiated plane-tesimals (>100 km) up to isolation mass (>0.16 M-circle dot). Collisions between differentiated bodies have the potential to change the core-mantle ratio of the accreted protoplanets. We show that sufficient mantle material can be stripped from the colliding bodies during runaway and oligarchic growth, such that the final protoplanets could have Mg/Fe and Si/Fe ratios similar to that of bulk Earth, but only if Earth is an extreme case and the core is assumed to contain 10% silicon by mass. This may indicate an important role for collisional differentiation during the giant impact phase if Earth formed from chondritic material. (C) 2014 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license.