Abstract The Late Ordovician mass extinction (LOME) was the second most severe Phanerozoic biodiversity crisis. While environmental deterioration and oceanographic changes associated with the Hirnantian glaciation have been frequently invoked as potential extinction drivers, recent evidence for a large igneous province eruption at that time has challenged this prevailing view. As such, the triggering and killing mechanisms of the LOME remain debated. Here we report mercury (Hg) concentrations, isotopic compositions, Hg/total sulfur (Hg/TS), and Hg/total organic carbon (Hg/TOC) in Late Ordovician limestone/black shale alternations from two successions in South China and Laurentia that straddled the paleoequator. Our results, in both areas, show multiple Hg enrichments before and during the LOME, suggesting a global, or at least a widespread increase in environmental Hg loading. The initial Hg enrichments occur in the mid-upper Katian units and are followed by additional Hg anomalies in the lower Hirnantian strata that coincide temporally with the first pulse of the LOME. Extremely high levels of Hg, Hg/TS, and Hg/TOC, with maximum values of 737 ng g−1, 633 ng g−1 Hg/wt% TS, and 167 ng g−1 Hg/wt% TOC, respectively, represent ~3–13 × background values, indicating increased Hg input to the ocean. The absence of mass-independent fractionation of Hg isotopes in the Hg-enriched intervals suggests a volcanic source for the observed Hg anomalies. The temporal coincidence of Hg anomalies with the extinction horizon in both continents suggests that extensive and widespread volcanism may have had global climatic and ecological impact, and was a primary trigger for prolonged and synergetic deterioration of Late Ordovician environment such as climate changes, ocean acidification, and anoxia, causing the LOME.

中文翻译：

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与晚奥陶世大灭绝有关的主要火山爆发：来自汞富集和汞同位素的证据

摘要 晚奥陶世大灭绝（LOME）是显生宙第二严重的生物多样性危机。虽然与 Hirnantian 冰川相关的环境恶化和海洋学变化经常被称为潜在的灭绝驱动因素，但最近有关当时大型火成岩省喷发的证据对这一普遍观点提出了挑战。因此，LOME 的触发和杀死机制仍然存在争议。在这里，我们报告了来自华南和 Laurentia 两个系列的晚奥陶世石灰岩/黑色页岩交替中的汞 (Hg) 浓度、同位素组成、Hg/总硫 (Hg/TS) 和 Hg/总有机碳 (Hg/TOC)横跨古赤道。我们在这两个领域的结果都显示了 LOME 之前和期间的多次 Hg 富集，这表明在全球范围内，或者至少是环境汞负荷的普遍增加。最初的 Hg 富集发生在中上部 Katian 单元，随后在下部 Hirnantian 地层中出现额外的 Hg 异常，与 LOME 的第一个脉冲在时间上重合。极高水平的 Hg、Hg/TS 和 Hg/TOC，最大值分别为 737 ng g-1、633 ng g-1 Hg/wt% TS 和 167 ng g-1 Hg/wt% TOC，代表 ~3–13 × 背景值，表明向海洋输入的汞增加。在富含 Hg 的层段中不存在与质量无关的 Hg 同位素分馏，这表明观察到的 Hg 异常是火山源。两个大陆汞异常与灭绝地平线的时间重合表明，广泛和广泛的火山活动可能对全球气候和生态产生了影响，