One of the most severe extinctions of complex marine life in Earth’s history occurred at the end of the Triassic period (~201.4 million years ago). The marine extinction was initiated by large igneous province volcanism and has tentatively been linked to the spread of anoxic conditions. However, the global-scale pattern of anoxic conditions across the end-Triassic event is not well constrained. Here we use the sedimentary enrichment and isotopic composition of the redox-sensitive element molybdenum to reconstruct global–local marine redox conditions through the extinction interval. Peak δ⁹⁸Mo values indicate that the global distribution of sulfidic marine conditions was similar to the modern ocean during the extinction interval. Meanwhile, Tethyan shelf sediments record pulsed, positive δ⁹⁸Mo excursions indicative of locally oxygen-poor, sulfidic conditions. We suggest that pulses of severe marine de-oxygenation were restricted largely to marginal marine environments during the latest Triassic and played a substantial role in shallow-marine extinction phases at that time. Importantly, these results show that global marine biodiversity, and possibly ecosystem stability, were vulnerable to geographically localized anoxic conditions. Expanding present-day marine anoxia in response to anthropogenic marine nutrient supply and climate forcing may therefore have substantial consequences for global biodiversity and wider ecosystem stability.

地球历史上最严重的复杂海洋生物灭绝之一发生在三叠纪末期（约 2.014 亿年前）。海洋灭绝是由大型火成岩省火山活动引发的，初步认为与缺氧条件的蔓延有关。然而，三叠纪末期全球范围内的缺氧条件模式并没有得到很好的限制。在这里，我们利用氧化还原敏感元素钼的沉积富集和同位素组成来重建灭绝区间的全球-局部海洋氧化还原条件。峰值 δ ⁹⁸ Mo 值表明硫化物海洋条件的全球分布与灭绝期间的现代海洋相似。与此同时，特提斯陆架沉积物记录了脉冲式、正 δ ⁹⁸ Mo 偏移，表明局部缺氧、含硫条件。我们认为，严重的海洋脱氧脉冲主要局限于三叠纪末期的边缘海洋环境，并在当时的浅层海洋灭绝阶段发挥了重要作用。重要的是，这些结果表明，全球海洋生物多样性以及可能的生态系统稳定性容易受到地理局部缺氧条件的影响。因此，由于人为海洋养分供应和气候强迫而导致的当今海洋缺氧的扩大可能会对全球生物多样性和更广泛的生态系统稳定性产生重大影响。