The Paleocene Eocene Thermal Maximum (PETM) represents a major carbon cycle and climate perturbation that was associated with ocean de-oxygenation, in a qualitatively similar manner to the more extensive Mesozoic Oceanic Anoxic Events. Although indicators of ocean de-oxygenation are common for the PETM, and linked to biotic turnover, the global extent and temporal progression of de-oxygenation is poorly constrained. Here we present carbonate associated uranium isotope data for the PETM. A lack of resolvable perturbation to the U-cycle during the event suggests a limited expansion of seafloor anoxia on a global scale. We use this result, in conjunction with a biogeochemical model, to set an upper limit on the extent of global seafloor de-oxygenation. The model suggests that the new U isotope data, whilst also being consistent with plausible carbon emission scenarios and observations of carbon cycle recovery, permit a maximum ~10-fold expansion of anoxia, covering <2% of seafloor area.

古新世始新世最大热量（PETM）代表了与海洋脱氧有关的主要碳循环和气候扰动，在质量上与更广泛的中生代海洋缺氧事件相似。尽管海洋脱氧的指标在PETM中很常见，并且与生物更新有关，但脱氧的全球范围和时间进展受到的约束很有限。在这里，我们介绍了PETM的碳酸盐相关铀同位素数据。事件期间对U周期缺乏可解决的扰动，表明海底缺氧在全球范围内的扩展有限。我们将这一结果与生物地球化学模型结合起来，为全球海底脱氧程度设定上限。该模型表明，新的U同位素数据