Global chemical weathering dominated by continental arcs since the mid-Palaeozoic
Global chemical weathering dominated by continental arcs since the mid-Palaeozoic
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DOI：
10.1038/s41561-021-00806-0
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发表时间：
2021-08-23
影响因子：
18.3
通讯作者：
Mueller, R. Dietmar
中科院分区：
文献类型：
--
作者：
Gernon, Thomas M.;Hincks, Thea K.;Mueller, R. Dietmar
大陆弧风化导致的二氧化碳减少使地球表面温度得以稳定，根据相互依赖性的概率分析，大陆弧的长度被证明是全球风化通量的主要控制因素。地球的板块构造活动通过火山放气和硅酸盐岩石风化调节碳循环，从而调节气候。造山、弧-大陆碰撞和热带大陆的聚集都被认为是控制风化通量的因素，弧也是大气中二氧化碳的主要贡献者。然而，这些过程在很大程度上被孤立地考虑，而实际上它们都是紧密耦合的。为了正确解释这些过程之间的相互作用，以及地球系统中固有的数百万年的时间滞后，我们需要描述它们复杂的相互依赖性。在这里，我们使用贝叶斯网络分析了过去 4 亿年来的相互依赖性，以确定全球化学风化信号的主要关系、时间滞后和驱动因素。我们发现，大陆火山弧（地球上侵蚀最快的表面特征）的长度对全球化学风化通量具有最强的控制作用。我们认为，与电弧风化有关的二氧化碳的快速下降可以在地质时期内稳定地表温度，这与人们普遍认为的这种稳定性主要是通过海底和大陆内部风化之间的微妙平衡来实现的观点相反。
Earth's surface temperature is stabilized by the drawdown of CO2 owing to weathering of continental arcs, whose length is shown to be a primary control on global weathering fluxes, according to a probabilistic analysis of interdependencies.Earth's plate-tectonic activity regulates the carbon cycle and, hence, climate, via volcanic outgassing and silicate-rock weathering. Mountain building, arc-continent collisions and clustering of continents in the tropics have all been invoked as controlling the weathering flux, with arcs also acting as a major contributor of carbon dioxide to the atmosphere. However, these processes have largely been considered in isolation when in reality they are all tightly coupled. To properly account for interactions among these processes, and the inherent multi-million-year time lags at play in the Earth system, we need to characterize their complex interdependencies. Here we analyse these interdependencies over the past 400 million years using a Bayesian network to identify primary relationships, time lags and drivers of the global chemical weathering signal. We find that the length of continental volcanic arcs-the fastest-eroding surface features on Earth-exerts the strongest control on global chemical weathering fluxes. We propose that the rapid drawdown of carbon dioxide tied to arc weathering stabilizes surface temperatures over geological time, contrary to the widely held view that this stability is achieved mainly by a delicate balance between weathering of the seafloor and the continental interiors.