Carbon isotopic variation in ureilites: Evidence for an early, volatile-rich Inner Solar System
Carbon isotopic variation in ureilites: Evidence for an early, volatile-rich Inner Solar System
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DOI：
10.1016/j.epsl.2017.08.039
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发表时间：
2017-11-15
影响因子：
5.3
通讯作者：
Gillet, Philippe
中科院分区：
文献类型：
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作者：
Barrat, Jean-Alix;Sansjofre, Pierre;Gillet, Philippe
我们分析了32个未角砾辉绿岩的碳同位素组成，它们代表了一个现已解体的、富碳的分化体的地幔碎片。其C组分的C-13值变化范围为-8.48~+0.11%o，C-13、O-18、O-17值与橄榄石岩心组成的相关性表明，两个储集层中的辉绿岩母体具有不同的氧、碳同位素组成。其地幔显示的Fe/Mg比值范围不是与C还原(熔融)有关的熔融过程的结果，而主要是由这两个组分的混合继承的。由于熔炼反应依赖于压力，这一结果对UPB的大小有很大的影响，并指向一个直径至少690公里的大型母体。这表明，在早期内太阳系的某些区域存在着与碳质球粒陨石不同的富碳原始物质，这可能对类地行星的生长起到了促进作用。我们推测，在包括地球在内的岩石行星的后期吸积阶段，分化的富碳天体或其分裂产生的碎片是挥发物的另一个来源。(C)2017爱思唯尔B.V.保留所有权利。
We analyzed the C isotopic compositions of 32 unbrecciated ureilites, which represent mantle debris from a now disrupted, C-rich, differentiated body. The delta C-13 values of their C fractions range from -8.48 to +0.11%o. The correlations obtained between delta C-13, delta O-18 and Delta O-17 values and the compositions of the olivine cores, indicate that the ureilite parent body (UPB) accreted from two reservoirs displaying distinct O and C isotopic compositions. The range of Fe/Mg ratios shown by its mantle was not the result of melting processes involving reduction with C ("smelting"), but was chiefly inherited from the mixing of these two components. Because smelting reactions are pressure-dependent, this result has strong implications for the size of the UPB, and points to a large parent body, at least 690 km in diameter. It demonstrates that C-rich primitive matter distinct from that represented by carbonaceous chondrites was present in some areas of the early inner Solar System, and could have contributed to the growth of the terrestrial planets. We speculate that differentiated, C-rich bodies, or debris produced by their disruption, were an additional source of volatiles during the later accretion stages of the rocky planets, including Earth. (C) 2017 Elsevier B.V. All rights reserved.