Rapid crustal growth and efficient crustal recycling in the early Earth: Implications for Hadean and Archean geodynamics
Rapid crustal growth and efficient crustal recycling in the early Earth: Implications for Hadean and Archean geodynamics
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DOI：
10.1016/j.epsl.2018.04.051
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发表时间：
2018-07
影响因子：
5.3
通讯作者：
J. Rosas;J. Korenaga
中科院分区：
文献类型：
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作者：
J. Rosas;J. Korenaga
早期地球的地球动力学机制仍然难以捉摸，迄今为止提出的假设从停滞的盖子对流到快速的板块构造。在地球历史的头20亿年里，现有的地质数据非常有限，而相关数据的稀缺往往因解释的不唯一性而加剧。在这里，我们建议，钐-钕同位素的演变，这已被建议与停滞盖对流在早期地球，可能会更好地理解为地壳快速增长和广泛的地壳再循环的结果。我们通过对模型参数空间进行蒙特卡罗抽样的地球化学箱模型描述了地壳演化的可能情景，我们的结果表明，在冥古宙末期，大陆地壳的净生长已经完成，当时地壳的再循环速率可能高达2− 4× 10 22 kg Gyr− 1，此后逐渐下降。这种地壳演化对当今地壳形成年龄的分布做出了具体的预测，这与最近基于全球锆石年龄数据汇编的估计非常一致。在假定的岩浆海洋之后的固态下地幔对流模式可能是板块构造，但其风格可能与当代板块构造有很大不同，其特征是更大的岩浆活动和更具破坏性的俯冲作用。
The geodynamic regime of the early Earth remains elusive, with so far proposed hypotheses ranging from stagnant lid convection to rapid plate tectonics. Available geological data are severely limited for the first two billion years of the Earth's history, and this scarcity of relevant data is often compounded by the nonuniqueness of interpretation. Here we propose that the samarium–neodymium isotope evolution, which has been suggested to be consistent with stagnant lid convection in the early Earth, may be better understood as the result of rapid crustal growth and extensive crustal recycling. We delineate the permissible scenario of crustal evolution through geochemical box modeling with a Monte Carlo sampling of the model parameter space, and our results suggest that the net growth of continental crust was complete by the end of the Hadean and that the rate of crustal recycling could have been as high as 2− 4× 10 22 kg Gyr− 1 at that time and has gradually decreased since then. Such crustal evolution yields a specific prediction for the present-day distribution of crustal formation ages, which is shown to be in remarkable agreement with a recent estimate based on the global compilation of zircon age data. The mode of subsolidus mantle convection after the putative magma ocean is probably plate tectonics, but its style could have been very different from that of contemporary plate tectonics, characterized by more voluminous magmatism and more destructive subduction.