Deep abiotic weathering of pyrite
Deep abiotic weathering of pyrite
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DOI：
10.1126/science.abb8092
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发表时间：
2020-10-23
期刊：
影响因子：
56.9
通讯作者：
Brantley, Susan L.
中科院分区：
文献类型：
--
作者：
Gu, Xin;Heaney, Peter J.;Brantley, Susan L.
黄铁矿是一种普遍存在的铁硫化物矿物，可被微量氧氧化。自从地球早期大气中氧气浓度上升以来，这种矿物在全球沉积物中基本上不存在。我们用化学和显微分析方法分析了地球表面最常见的岩石页岩的风化作用。通过从10（-9）到10（2）米的尺度上观察，我们确定了控制黄铁矿氧化的因素。在今天的大气条件下，黄铁矿的氧化速率受到氧气向颗粒表面扩散的限制，并受到大规模侵蚀和碎屑规模破裂的调节。我们确定，无论是铁或硫氧化微生物控制全球黄铁矿风化通量，尽管他们有能力催化反应。这个多尺度的图片强调，在地球历史上，断裂和侵蚀在限制黄铁矿反应性方面与大气中的氧气一样重要。
Pyrite is a ubiquitous iron sulfide mineral that is oxidized by trace oxygen. The mineral has been largely absent from global sediments since the rise in oxygen concentration in Earth's early atmosphere. We analyzed weathering in shale, the most common rock exposed at Earth's surface, with chemical and microscopic analysis. By looking across scales from 10(-9) to 10(2) meters, we determined the factors that control pyrite oxidation. Under the atmosphere today, pyrite oxidation is rate-limited by diffusion of oxygen to the grain surface and regulated by large-scale erosion and clast-scale fracturing. We determined that neither iron-nor sulfur-oxidizing microorganisms control global pyrite weathering fluxes despite their ability to catalyze the reaction. This multiscale picture emphasizes that fracturing and erosion are as important as atmospheric oxygen in limiting pyrite reactivity over Earth's history.