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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 >Freeboard revisited: continental growth, crustal thickness change and Earth's thermal efficiency
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Freeboard revisited: continental growth, crustal thickness change and Earth's thermal efficiency

机译：再谈干舷：大陆增长，地壳厚度变化和地球热效率

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The rate of growth of Earth's continental crust is commonly estimated from the age distribution of present continental crust and from the geochemistry of ancient mantle-derived lavas. In this paper, I assess the rate of growth from relationships between the volume and thickness of continental crust. The thickness of the continental crust is governed by its total volume and by the relative buoyancy of the continental and oceanic lithospheres. The buoyancy of the oceanic lithosphere is governed by the amount of melting at mid-oceanic ridges and the mean age of the ocean floor, which are functions of the mantle temperature and its relationship to global heat loss. Thus, the relationship between continental crustal thickness, continental crustal volume and mantle temperature may be specified provided the functional dependence of global heat loss on mantle temperature is known. Using this relationship, I investigate the implications of crustal growth models for changes in continental crustal thickness over time. If Archean continental crustal volumes had been the same as or similar to modern ones, continental crustal thicknesses would have been significantly greater than today. This would be reflected in subsequently deeply eroded Archean terrains and is inconsistent with the geological record. Sigmoidal growth models, in which significant crustal growth occurred during the Proterozoic, also require several kilometers of erosion for strong dependence of heat loss on mantle temperature, but permit nearly constant continental crustal thicknesses through time if the dependence is weak. With more precise information on the erosion of Archean terrains, it will be possible to constrain both crustal growth models and the nature of the functional dependence of heat loss on mantle temperature.
机译：通常根据目前大陆壳的年龄分布和古代地幔衍生的熔岩的地球化学来估算地球大陆壳的生长速率。在本文中，我从大陆壳的体积和厚度之间的关系评估了增长率。大陆壳的厚度取决于其总体积以及大陆和海洋岩石圈的相对浮力。海洋岩石圈的浮力取决于洋中脊的融化量和海床的平均年龄，这是地幔温度及其与全球热量散失的关系的函数。因此，只要已知全球热量损失对地幔温度的函数依赖性，就可以规定大陆地壳厚度，大陆地壳体积与地幔温度之间的关系。利用这种关系，我研究了地壳生长模型对大陆地壳厚度随时间变化的影响。如果太古宙大陆壳的体积与现代相同或相似，大陆壳的厚度将比今天大得多。这将反映在后来深度侵蚀的太古宙地形中，并且与地质记录不一致。在元古代期间发生显着地壳生长的S形增长模型，也需要几千米的侵蚀，以使热量损失对地幔温度的强烈依赖关系，但是如果这种依赖关系较弱，则整个时间段内大陆壳的厚度将保持恒定。利用有关太古代地形侵蚀的更精确的信息，将有可能同时约束地壳生长模型和热量损失对地幔温度的函数依赖性。

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