The fate of water within Earth and super-Earths and implications for plate tectonics.
The fate of water within Earth and super-Earths and implications for plate tectonics.
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DOI：
10.1098/rsta.2015.0394
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发表时间：
2017-05-28
期刊：
影响因子：
--
通讯作者：
Elkins-Tanton LT
中科院分区：
文献类型：
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作者：
Tikoo SM;Elkins-Tanton LT
地球很可能在吸积过程中获得了大部分的水。短寿命放射性同位素对微行星内部的热量会导致一些水分流失，但对微行星的撞击不足以产生进一步的干燥。水被认为对板块构造的发展至关重要，因为它降低了软流圈的粘度，使俯冲成为可能。以下问题仍然存在：如果水是板块构造所必需的，但俯冲作用本身使上地幔水合，那么上地幔最初是如何水合的呢？晚期吸积的巨大撞击产生了岩浆湖和海洋，这些岩浆在凝固过程中脱气，产生了沉重的大气。然而，一些水会留在地幔中，被困在名义上无水矿物的晶体缺陷中。在本文中，我们提出的模型表明，与岩浆海洋凝固和翻转的过程可能会隔离足够数量的水在上地幔引起部分熔融，并产生潮湿的软流圈，从而促进板块构造，反过来，类地太阳系外行星的可居住性。这篇文章是主题问题的一部分“起源，历史和水在内太阳系演化中的作用”。
The Earth is likely to have acquired most of its water during accretion. Internal heat of planetesimals by short-lived radioisotopes would have caused some water loss, but impacts into planetesimals were insufficiently energetic to produce further drying. Water is thought to be critical for the development of plate tectonics, because it lowers viscosities in the asthenosphere, enabling subduction. The following issue persists: if water is necessary for plate tectonics, but subduction itself hydrates the upper mantle, how is the upper mantle initially hydrated? The giant impacts of late accretion created magma lakes and oceans, which degassed during solidification to produce a heavy atmosphere. However, some water would have remained in the mantle, trapped within crystallographic defects in nominally anhydrous minerals. In this paper, we present models demonstrating that processes associated with magma ocean solidification and overturn may segregate sufficient quantities of water within the upper mantle to induce partial melting and produce a damp asthenosphere, thereby facilitating plate tectonics and, in turn, the habitability of Earth-like extrasolar planets. This article is part of the themed issue ‘The origin, history and role of water in the evolution of the inner Solar System’.