The terrestrial late veneer from core disruption of a lunar-sized impactor
The terrestrial late veneer from core disruption of a lunar-sized impactor
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DOI：
10.1016/j.epsl.2017.09.041
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发表时间：
2017-12-05
影响因子：
5.3
通讯作者：
Mojzsis, S. J.
中科院分区：
文献类型：
--
作者：
Genda, H.;Brasser, R.;Mojzsis, S. J.
地球地幔中高亲铁元素 (HSE) 的过量可以通过在月球形成和地核闭合之后来自单个、巨大（D 大约 3000 公里）“晚饰面”球粒陨石撞击物的传送来解释。这种大约月球质量（类似于 00.01 M 圆以上）的岩石物体应该被区分，这样几乎所有的 HSE 有效载荷都是被隔离在铁芯中。在这里，我们分析了这种晚单板撞击器核心的机械和化学命运，并追踪其 HSE 是如何悬浮并因此污染地幔的。对于统计上最有可能的倾斜碰撞（类似于 45 度），撞击器的核心会拉长，然后分解成小颗粒的金属冰雹（类似于 10 m）。其中一些以次生撞击物的形式撞击绕月轨道运行的撞击物，但大多数会以二次撞击物的形式重新吸积到地球并进一步破碎。我们表明，单个倾斜冲击器通过氧化（
Overabundances in highly siderophile elements (HSEs) of Earth's mantle can be explained by conveyance from a singular, immense (D similar to 3000 km) "Late Veneer" impactor of chondritic composition, subsequent to lunar formation and terrestrial core-closure, Such rocky objects of approximately lunar mass (similar to 00.01 M-circle plus) ought to be differentiated, such that nearly all of their HSE payload is sequestered into iron cores. Here, we analyze the mechanical and chemical fate of the core of such a Late Veneer impactor, and trace how its HSEs are suspended - and thus pollute - the mantle. For the statistically most-likely oblique collision (similar to 45 degrees), the impactor's core elongates and thereafter disintegrates into a metallic hail of small particles (similar to 10 m). Some strike the orbiting Moon as sesquinary impactors, but most re-accrete to Earth as secondaries with further fragmentation. We show that a single oblique impactor provides an adequate amount of' HSEs to the primordial terrestrial silicate reservoirs via oxidation of (