Radiogenic chromium isotope evidence for the earliest planetary volcanism and crust formation in the solar system
Radiogenic chromium isotope evidence for the earliest planetary volcanism and crust formation in the solar system
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DOI：
10.1093/mnrasl/slac061
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发表时间：
2022-07
影响因子：
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通讯作者：
K. Zhu;H. Becker;Shijin Li;Yan Fan;Xiao-Ning Liu;T. Elliott
中科院分区：
文献类型：
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作者：
K. Zhu;H. Becker;Shijin Li;Yan Fan;Xiao-Ning Liu;T. Elliott
Erg Chech (EC) 002 是一颗具有安山岩成分的陨石，可能记录了其母体的熔岩结晶和地壳形成。 EC 002 的核合成 Cr 同位素组成 (ε54Cr = -0.35 ± 0.06) 表明太阳系存在非碳质区域，并且可能代表了粗碳岩母体的地壳组成。 53Mn-to-53Cr 衰变系统显示它在 4566.6 ± 0.6 Ma 结晶，即太阳系形成后 0.7 ± 0.6 Ma（仅考虑具有相似 ε54Cr 值的同生基质分数）。这个时代代表了太阳系中行星融化和火山活动的最早记录证据，表明行星地壳的形成发生得很早，仅在太阳系历史的最初几十万年之内。然而，53Mn-53Cr年龄与26Al-26Mg定年结果并不重叠，这可能表明非碳质无球粒陨石的初始26Al/27Al低于由碳质球粒陨石中的难熔包裹体定义的标准值。
Erg Chech (EC) 002 is a meteorite with andesitic composition, potentially recording the lava crystallization and crust formation of its parent body. Nucleosynthetic Cr isotope composition (ε54Cr = −0.35 ± 0.06) for EC 002 suggests a non-carbonaceous region of the solar system, and possibly represents the crustal composition of the brachinite parent body. The 53Mn-to-53Cr decay system shows it crystallized at 4566.6 ± 0.6 Ma, i.e. 0.7 ± 0.6 Ma after solar system formation (only considering the cogenetic matrix fractions with similar ε54Cr values). This age represents the earliest recorded evidence for planetary melting and volcanism in the solar system, suggesting that the planetary crust formation occurred very early, only within the first few hundred thousand years of solar system history. However, the 53Mn-53Cr age does not overlap with 26Al-26Mg dating results, which might indicate that non-carbonaceous achondrites have lower initial 26Al/27Al than the canonical value defined by refractory inclusions in carbonaceous chondrites.