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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Redox evolution of the Earth caused by a multi-stage formation of its core
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Redox evolution of the Earth caused by a multi-stage formation of its core

机译：地球核心的多阶段形成导致地球的氧化还原演化

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摘要

A model of multi-stage formation of the Earth's core is presented allowing consistent solution to the problem of deficiency of heat sources in the Earth's thermal balance and problem of redox evolution of the Earth's mantle. The additional heat yield and oxidative evolution of the mantle are coordinated with continued growth of the core. It is suggested that after early formation of the major part of the core (ca. 95%) - within the first 100 million years of Earth's life - the growth of the core slowly continued. Following the exhaustion of native metal and sulfide iron, the core build-up proceeded at the expense of the mantle FeO. As partial disproportionation of iron in Fe2+O to Fe-0 and Fe23+O3 may occur in the deep mantle and at the core-mantle boundary, this brought about the gradual oxidization of the mantle. This stage lasted the next 150-300 million years. By the end of this period the mantle redox potential transformed so that the state of oxidization of the upper mantle approached the level of QFM buffer. At the same period the composition of the atmosphere must have been changed from a reduced (containing CH4, CO, NH3) to a neutral one (containing CO2, N-2). The final and the longest stage of the core build-up did not involve significant changes in its redox potential and is still under way. The slow core growth is implemented due to the mantle resources in FeO. The process of dissolution of FeO, which is delivered to the core boundary by the mantle convective downflow, ensures generation of heat maintaining the super-adiabatic temperature gradient in the mantle and eliminating apparent deficiency of heat sources in the Earth's thermal balance. Some other geological consequences of the model are considered. (C) 2005 Elsevier B.V All rights reserved.
机译：提出了一种地球核心的多阶段形成模型，可以一致地解决地球热平衡中热源不足的问题以及地幔的氧化还原演化问题。地幔的额外热量产生和氧化演化与岩心的持续增长相协调。建议在核心生命的主要部分（约95％）的早期形成之后-在地球生命的前一亿年之内-核心的生长缓慢地继续。随着天然金属和硫化铁的耗尽，堆芯的形成以地幔中的FeO为代价。由于Fe2 + O中的铁部分歧化可能发生在深地幔中以及在核心-地幔边界处，Fe-0和Fe23 + O3导致了地幔的逐渐氧化。此阶段持续了下一个150-3亿年。到这一时期结束时，地幔的氧化还原电势发生了变化，因此上地幔的氧化状态达到了QFM缓冲液的水平。同时，大气的成分必须从还原（含CH4，CO，NH3）变为中性（含CO2，N-2）。核心建设的最后阶段和最长阶段并未涉及其氧化还原潜力的重大变化，并且仍在进行中。由于FeO中的地幔资源，导致核心增长缓慢。 FeO的溶解过程通过地幔对流向下流动传递到核心边界，可确保产生热量，从而维持地幔中的超绝热温度梯度，并消除了地球热平衡中明显的热源不足。考虑了该模型的其他一些地质后果。 （C）2005 Elsevier B.V保留所有权利。

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