Abundances of Ordinary Chondrites in Thermally Evolving Planetesimals
Abundances of Ordinary Chondrites in Thermally Evolving Planetesimals
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DOI：
10.3847/1538-4357/aad0a2
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发表时间：
2018-06
期刊：
影响因子：
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通讯作者：
S. Wakita;Y. Hasegawa;T. Nozawa
中科院分区：
文献类型：
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作者：
S. Wakita;Y. Hasegawa;T. Nozawa
球粒陨石是太阳系中最原始的天体之一，它们保存着其母体经历的热变质程度的记录。这种热历史可以根据岩石学类型进行分类。我们调查了星子的热演化，以解释目前的丰度（称为秋季统计）的岩石学类型3-6的普通陨石。我们进行了一些数值计算，其中的形成时间和大小的星子作为参数。我们发现，在2.0万年内形成的星子形成后，富钙铝包体（CAIs）可以包含所有的岩石学类型的普通方解石。我们的研究结果还表明，合理的情况下的星子形成，这是一致的秋天的统计数据，是半径大于60公里的星子开始形成约2.0万年后，CAIs和/或半径小于50公里的应该在1.5万年后，CAIs。因此，星子的热模拟是重要的，以揭示发生和数量的变质陨石，并提供宝贵的见解星子的形成。
Chondrites are some of the most primitive objects in the solar system, and they maintain a record of the degree of thermal metamorphism experienced in their parent bodies. This thermal history can be classified by the petrologic type. We investigate the thermal evolution of planetesimals to account for the current abundances (known as the fall statistics) of petrologic types 3–6 of ordinary chondrites. We carry out a number of numerical calculations in which formation times and sizes of planetesimals are taken as parameters. We find that planetesimals that form within 2.0 Myr after the formation of Ca-Al-rich inclusions (CAIs) can contain all petrologic types of ordinary chondrites. Our results also indicate that plausible scenarios of planetesimal formation, which are consistent with the fall statistics, are that planetesimals with radii larger than 60 km start to form around 2.0 Myr after CAIs and/or that ones with radii less than 50 km should be formed within 1.5 Myr after CAIs. Thus, thermal modeling of planetesimals is important for revealing the occurrence and amount of metamorphosed chondrites and for providing invaluable insights into planetesimal formation.