近日，英国南安普顿大学Gernon, T. M.及其团队成员在研究中生代海洋缺氧事件的固体地球作用力中取得新进展。2024年8月29日出版的《自然—地球科学》发表了这项成果。

在这里，研究人员结合板块重建、构造—地球化学分析和全球生物地球化学模拟相结合的方式来验证这一假设。结果表明，在大陆分裂和海底扩张期间，基性岩石风化作用的增强可能导致一系列缺氧事件的发生。

风化脉冲共同导致了营养物磷向海的洋大量释放，并刺激了生物初级生产。反过来又加强了有机碳的埋藏，并引发了广泛的海洋脱氧，其规模足以导致反复缺氧。该模型补充了以火山释放气体为中心的触发这些事件的假设，证明了在与气候变暖相关的强烈风化期间，磷释放的充分量化的玄武岩来源。研究结果强调了大陆重组期间固体地球和生物圈之间的紧密耦合。

据介绍，海洋缺氧事件是海洋中极端氧气消耗的地质突变阶段，破坏了海洋生态系统并带来了进化更替。这些事件通常持续约150万年，频繁发生在中生代(约1.83亿至8500万年前)，这一时期与大陆分裂和广泛的大火成岩省火山活动有关。一种假说认为，缺氧事件是由火山碳释放形成的温室世界中地球表面的化学风化作用增强造成的。

附：英文原文

Title: Solid Earth forcing of Mesozoic oceanic anoxic events

Author: Gernon, T. M., Mills, B. J. W., Hincks, T. K., Merdith, A. S., Alcott, L. J., Rohling, E. J., Palmer, M. R.

Issue&Volume: 2024-08-29

Abstract: Oceanic anoxic events are geologically abrupt phases of extreme oxygen depletion in the oceans that disrupted marine ecosystems and brought about evolutionary turnover. Typically lasting ~1.5 million years, these events occurred frequently during the Mesozoic era, from about 183 to 85 million years ago, an interval associated with continental breakup and widespread large igneous province volcanism. One hypothesis suggests that anoxic events resulted from enhanced chemical weathering of Earth’s surface in a greenhouse world shaped by high volcanic carbon outgassing. Here we test this hypothesis using a combination of plate reconstructions, tectonic–geochemical analysis and global biogeochemical modelling. We show that enhanced weathering of mafic lithologies during continental breakup and nascent seafloor spreading can plausibly drive a succession of anoxic events. Weathering pulses collectively gave rise to substantial releases of the nutrient phosphorus to the oceans, stimulating biological primary production. This, in turn, enhanced organic carbon burial and caused widespread ocean deoxygenation on a scale sufficient to drive recurrent anoxia. This model complements volcanic outgassing-centred hypotheses for triggering these events by demonstrating well-quantified basaltic sources of phosphorus release during periods of intense weathering related to climate warmth. Our study highlights a close coupling between the solid Earth and biosphere during continental reorganization.

DOI: 10.1038/s41561-024-01496-0

Source: https://www.nature.com/articles/s41561-024-01496-0