Large igneous province eruptions and their carbon emissions often coincide with, and are hypothesized to have driven, severe environmental perturbations in the geological past. However, the vast scale of large igneous provinces and uncertainties in magmatic volatile contents and radioisotopic dates limit our ability to resolve gas emissions in detail over time. Here we employ high-resolution (~5–200 kyr) sedimentary mercury data from the Llanbedr (Mochras Farm) borehole, Wales, to derive quantitative large igneous province degassing estimates over a 20-million-year-long Early Jurassic interval (195–175 million years ago). Intervals of relatively elevated sedimentary mercury coincide with episodes of carbon-cycle change, including the Toarcian Oceanic Anoxic Event (183–182 million years ago). We use excess mercury loading to estimate large igneous province-associated carbon emissions, revealing that multi-millennial episodes of activity plausibly drove recognized \(p_{{\mathrm{CO}}_2}\) and temperature increases. However, previous carbon-cycle model-based carbon emission scenarios require faster and larger carbon inputs than our proposed emissions. Resolving this discrepancy may require climate–carbon-cycle feedbacks or co-emitted gases to substantially exacerbate the carbon-cycle response, processes potentially underestimated in current models. Our long and near-continuous record of Early Jurassic large igneous province activity demonstrates mercury’s potential as a tool to resolve past carbon fluxes.

大型火成岩省喷发及其碳排放通常与地质历史上严重的环境扰动同时发生，并被认为是其驱动因素。然而，大型火成岩省的规模庞大以及岩浆挥发物含量和放射性同位素日期的不确定性限制了我们详细解析随时间推移的气体排放的能力。在这里，我们利用来自威尔士 Llanbedr（莫克拉斯农场）钻孔的高分辨率（约 5–200 kyr）沉积汞数据，得出了 2000 万年早侏罗世间隔（195– 1.75 亿年前）。沉积汞相对升高的时期与碳循环变化的时期相一致，包括托阿尔纪海洋缺氧事件（183-1.82亿年前）。我们使用过量的汞负荷来估计与火成岩省相关的碳排放量，揭示了数千年的活动可能推动了公认的\(p_{{\mathrm{CO}}_2}\)和温度升高。然而，之前基于碳循环模型的碳排放情景需要比我们提出的排放更快、更大的碳输入。解决这一差异可能需要气候-碳循环反馈或共同排放的气体来大幅加剧碳循环响应，这一过程在当前模型中可能被低估。我们对早侏罗世大型火成岩省活动的长期且近乎连续的记录表明，汞具有作为解决过去碳通量的工具的潜力。