The role of ocean anoxia as a cause of the end-Triassic marine mass extinction is widely debated. Here, we present carbonate-associated sulfate δ³⁴S data from sections spanning the Late Triassic–Early Jurassic transition, which document synchronous large positive excursions on a global scale occurring in ~50 thousand years. Biogeochemical modeling demonstrates that this S isotope perturbation is best explained by a fivefold increase in global pyrite burial, consistent with large-scale development of marine anoxia on the Panthalassa margin and northwest European shelf. This pyrite burial event coincides with the loss of Triassic taxa seen in the studied sections. Modeling results also indicate that the pre-event ocean sulfate concentration was low (<1 millimolar), a common feature of many Phanerozoic deoxygenation events. We propose that sulfate scarcity preconditions oceans for the development of anoxia during rapid warming events by increasing the benthic methane flux and the resulting bottom-water oxygen demand.

海洋缺氧作为三叠纪末海洋大规模灭绝的原因之一受到广泛争论。在这里，我们提供了来自晚三叠世-早侏罗世过渡剖面的与碳酸盐相关的硫酸盐 δ ³⁴ S 数据，这些数据记录了大约 5 万年中发生的全球范围内的同步大型正偏移。生物地球化学模型表明，这种硫同位素扰动最好的解释是全球黄铁矿埋藏量增加了五倍，这与泛海带边缘和西北欧陆架海洋缺氧的大规模发展相一致。这次黄铁矿埋藏事件与研究剖面中看到的三叠纪类群的消失同时发生。模拟结果还表明，事件前海洋硫酸盐浓度较低（<1毫摩尔），这是许多显生宙脱氧事件的共同特征。我们认为，硫酸盐稀缺通过增加底栖甲烷通量和由此产生的底层水需氧量，为快速变暖事件期间海洋缺氧的发展奠定了先决条件。