Weathering of silicate rocks at a planetary surface can draw down CO₂ from the atmosphere for eventual burial and long-term storage in the planetary interior. This process is thought to provide essential negative feedback to the carbonate-silicate cycle (carbon cycle) to maintain clement climates on Earth and potentially similar temperate exoplanets. We implement thermodynamics to determine weathering rates as a function of surface lithology (rock type). These rates provide upper limits that allow the maximum rate of weathering in regulating climate to be estimated. This modeling shows that the weathering of mineral assemblages in a given rock, rather than individual minerals, is crucial to determine weathering rates at planetary surfaces. By implementing a fluid-transport-controlled approach, we further mimic chemical kinetics and thermodynamics to determine weathering rates for three types of rocks inspired by the lithologies of Earth's continental and oceanic crust, and its upper mantle. We find that thermodynamic weathering rates of a continental crust-like lithology are about one to two orders of magnitude lower than those of a lithology characteristic of the oceanic crust. We show that when the CO₂ partial pressure decreases or surface temperature increases, thermodynamics rather than kinetics exerts a strong control on weathering. The kinetically and thermodynamically limited regimes of weathering depend on lithology, whereas the supply-limited weathering is independent of lithology. Our results imply that the temperature sensitivity of thermodynamically limited silicate weathering may instigate a positive feedback to the carbon cycle, in which the weathering rate decreases as the surface temperature increases.

硅酸盐岩石在行星表面的风化可吸收CO ₂从大气中最终埋葬并长期保存在行星内部。人们认为该过程为碳酸盐-硅酸盐循环（碳循环）提供了必要的负反馈，以维持地球和潜在的类似温带系外行星的自然气候。我们采用热力学来确定风化率与表面岩性（岩石类型）的关系。这些速率提供了上限，可以估算调节气候的最大风化速率。该模型表明，给定岩石中矿物组合的风化而不是单个矿物的风化对于确定行星表面的风化速率至关重要。通过实施流体运输控制的方法，我们进一步模拟化学动力学和热力学来确定三种类型的岩石的风化速率，这些岩石的类型受地球大陆和大洋地壳及其上地幔的岩性启发。我们发现，大陆壳状岩性的热力学风化速率比洋壳状岩性的热力学风化速率低约一两个数量级。我们证明当CO₂分压降低或表面温度升高，热力学而不是动力学对风化有很强的控制作用。风化的动力学和热力学限制机制取决于岩性，而供应受限的风化则与岩性无关。我们的结果表明，热力学上受限制的硅酸盐风化的温度敏感性可能会激发对碳循环的正反馈，其中碳风化率随表面温度的升高而降低。