Testing for supply‐limited and kinetic‐limited chemical erosion in field measurements of regolith production and chemical depletion
Testing for supply‐limited and kinetic‐limited chemical erosion in field measurements of regolith production and chemical depletion
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DOI：
10.1002/2016gc006273
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发表时间：
2016-06
期刊：
影响因子：
3.7
通讯作者：
K. Ferrier;C. Riebe;W. Jesse Hahm
中科院分区：
文献类型：
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作者：
K. Ferrier;C. Riebe;W. Jesse Hahm
化学侵蚀向海洋提供溶质，通过温室效应影响大气中的二氧化碳，从而影响全球气候。因此，量化化学侵蚀速率如何随气候和构造变化，对于理解在地质时期将地球环境维持在可居住范围内的反馈至关重要。如果化学侵蚀速率受到可供溶解的新鲜矿物质的强烈影响，那么受化学侵蚀调节的气候与向地球表面提供新鲜矿物质的构造隆起之间应该有很强的联系。这种条件被称为供应有限的化学侵蚀，意味着化学侵蚀速率的强烈构造控制。它不同于动力学限制的化学侵蚀，其中溶解动力学和气候因素是化学侵蚀速率的主要调节剂。在这里，我们提出了一种统计方法，用于确定富含硅酸盐的基岩的化学侵蚀是供应有限还是动力有限，作为揭示构造和气候在地球硅酸盐风化恒温器中的相对重要性的方法。我们采用这种方法公布的数据集的矿物供应率和风化层化学消耗，并无法拒绝零假设，化学侵蚀是供应有限的16例中的8例。在剩下的8个案例中，我们发现了7个更接近于供应限制而不是动力限制的行为，这表明构造可能在调节化学侵蚀速率方面往往主导气候。然而，统计功效分析表明，需要在更广泛的供应率范围内进行新的测量，以帮助量化地球长期气候演变中气候和构造之间的反馈。
Chemical erosion contributes solutes to oceans, influencing atmospheric CO2 and thus global climate via the greenhouse effect. Quantifying how chemical erosion rates vary with climate and tectonics is therefore vital to understanding feedbacks that have maintained Earth's environment within a habitable range over geologic time. If chemical erosion rates are strongly influenced by the availability of fresh minerals for dissolution, then there should be strong connections between climate, which is modulated by chemical erosion, and tectonic uplift, which supplies fresh minerals to Earth's surface. This condition, referred to as supply‐limited chemical erosion, implies strong tectonic control of chemical erosion rates. It differs from kinetic‐limited chemical erosion, in which dissolution kinetics and thus climatic factors are the dominant regulators of chemical erosion rates. Here we present a statistical method for determining whether chemical erosion of silicate‐rich bedrock is supply limited or kinetic limited, as an approach for revealing the relative importance of tectonics and climate in Earth's silicate weathering thermostat. We applied this method to published data sets of mineral supply rates and regolith chemical depletion and were unable to reject the null hypothesis that chemical erosion is supply limited in 8 of 16 cases. In seven of the remaining eight cases, we found behavior that is closer to supply limited than kinetic limited, suggesting that tectonics may often dominate over climate in regulating chemical erosion rates. However, statistical power analysis shows that new measurements across a wider range of supply rates are needed to help quantify feedbacks between climate and tectonics in Earth's long‐term climatic evolution.