英国牛津大学Fendley, Isabel M.团队在研究沉积汞限制下的早侏罗世大火成岩省碳排放中取得新进展。该项研究成果发表在2024年2月26日出版的《自然—地球科学》上。

研究人员使用了来自Llanbedr (Mochras Farm)钻孔的高分辨率(约5 -200kyr)沉积汞数据，以得出2000万年的早侏罗世间隔(1.95-1.75亿年前)的定量大火成岩省脱气估计值。沉积汞含量相对升高的间隔与碳循环变化相一致，包括北极洋海洋缺氧事件(1.83-1.82亿年前)。研究使用过量的汞负荷来估计与大火成岩省相关的碳排放，揭示了数千年的活动事件似乎推动了公认的PCO₂和温度升高。

然而，先前基于碳循环模型的碳排放情景需要比其研究提出的排放更快和更大的碳输入。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反应，而这一过程在当前模型中可能被低估。研究人员对早侏罗世大火成岩省活动的长期和近乎连续的记录表明，汞有可能成为解决过去碳通量的工具。

据研究人员介绍，大火成岩省的喷发及其碳排放通常与地质历史时期的严重环境扰动相一致，并被假设为是其驱动因素。然而，巨大的火成岩省的规模和岩浆挥发物含量和放射性同位素日期的不确定性，限制了研究人员详细分析气体排放随时间变化的能力。

附：英文原文

Title: Early Jurassic large igneous province carbon emissions constrained by sedimentary mercury

Author: Fendley, Isabel M., Frieling, Joost, Mather, Tamsin A., Ruhl, Micha, Hesselbo, Stephen P., Jenkyns, Hugh C.

Issue&Volume: 2024-02-26

Abstract: 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 (~5–200kyr) 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 PCO₂ 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.

DOI: 10.1038/s41561-024-01378-5

Source: https://www.nature.com/articles/s41561-024-01378-5