Snowball Earth glaciations are the most extreme climate perturbations recorded in Earth’s history. It has been argued that the termination of these events was characterized by a single rapid transition from near-global ice coverage to an ice-free greenhouse climate state. Notably, this deviates with more extended transition periods of ice sheet waxing and waning typical of Phanerozoic glaciations. Using a coupled mineralogical and Mg and Li isotopic approach, we explore the role that authigenic clay formation within the seafloor may have played on Earth’s climate during deglaciation of the Marinoan Snowball Earth event. Marine authigenic clay formation—a process referred to as reverse weathering—recycles carbon within the ocean–atmosphere system and acts to elevate atmospheric CO₂ levels. The results indicate a shift towards more extensive reverse weathering within the uppermost portion of the glaciogenic Nantuo Formation in South China. Carbon cycle modeling indicates that widespread reverse weathering could have driven a protracted (millions of years) carbon dioxide drawdown following high carbon dioxide levels expected during deglaciation.

雪球地球冰川是地球历史上记录的最极端的气候扰动。有人认为，这些事件终止的特点是从近乎全球的冰覆盖到无冰温室气候状态的单一快速过渡。值得注意的是，这与显生宙冰期典型的冰盖增减过渡期更长。使用耦合矿物学和镁和锂同位素方法，我们探索了在马里诺斯雪球地球事件冰消期期间海底内自生粘土形成可能对地球气候所起的作用。海洋自生粘土的形成——一个被称为逆风化的过程——在海洋 - 大气系统内循环碳并起到提升大气 CO _{2 的作用}水平。结果表明，华南冰川成因南沱组最上部发生了更广泛的逆风化作用。碳循环模型表明，在冰川消退期间预期的高二氧化碳水平之后，广泛的逆风化可能会导致长期（数百万年）的二氧化碳下降。