The origin of Earth's first continents and the onset of plate tectonics
The origin of Earth's first continents and the onset of plate tectonics
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DOI：
10.1130/g38226.1
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发表时间：
2016-10-01
期刊：
影响因子：
5.8
通讯作者：
Odling, Nicholas W. A.
中科院分区：
文献类型：
--
作者：
Hastie, Alan R.;Fitton, J. Godfrey;Odling, Nicholas W. A.
大陆地壳的生长和再循环导致了地幔、水圈、大气层和生物圈的化学和热变化，持续了大约 4.0 年的时间。然而，关于形成第一批大陆的原岩以及形成环境是否是俯冲带的知识仍然未知。在这里，英云闪长岩熔体是在高 P-T 实验中形成的，其中原始海洋高原起始材料被用作早期扩张中心产生的太太古代 (3.6-4.0 Ga) 洋壳的类似物。英英闪长岩在 1.6-2.2 GPa 和 900-950 摄氏度下产生，并与板片衍生的水性流体混合，产生成分与始太古代大陆地壳相同的熔体。我们的数据支持这样的观点：第一块大陆形成于大约。 4 Ga之后，通过俯冲和类似30-45公里厚的始太古代洋壳的部分熔化，改变了地幔和始太古代的环境和生态系统。
The growth and recycling of continental crust has resulted in the chemical and thermal modification of Earth's mantle, hydrosphere, atmosphere, and biosphere for similar to 4.0 b.y. However, knowledge of the protolith that gave rise to the first continents and whether the environment of formation was a subduction zone still remains unknown. Here, tonalite melts are formed in high P-T experiments in which primitive oceanic plateau starting material is used as an analogue for Eoarchean (3.6-4.0 Ga) oceanic crust generated at early spreading centers. The tonalites are produced at 1.6-2.2 GPa and 900-950 degrees C and are mixed with slab-derived aqueous fluids to generate melts that have compositions identical to that of Eoarchean continental crust. Our data support the idea that the first continents formed at ca. 4 Ga and subsequently, through the subduction and partial melting of similar to 30-45-km-thick Eoarchean oceanic crust, modified Earth's mantle and Eoarchean environments and ecosystems.