A hallmark of the rapid and massive release of carbon during the Palaeocene–Eocene Thermal Maximum is the global negative carbon isotope excursion. The delayed recovery of the carbon isotope excursion, however, indicates that CO₂ inputs continued well after the initial rapid onset, although there is no consensus about the source of this secondary carbon. Here we suggest this secondary input might have derived partly from the oxidation of remobilized sedimentary fossil carbon. We measured the biomarker indicators of thermal maturation in shelf records from the US Mid-Atlantic coast, constructed biomarker mixing models to constrain the amount of fossil carbon in US Mid-Atlantic and Tanzania coastal records, estimated the fossil carbon accumulation rate in coastal sediments and determined the range of global CO₂ release from fossil carbon reservoirs. This work provides evidence for an order of magnitude increase in fossil carbon delivery to the oceans that began ~10–20 kyr after the event onset and demonstrates that the oxidation of remobilized fossil carbon released between 10² and 10⁴ PgC as CO₂ during the body of the Palaeocene–Eocene Thermal Maximum. The estimated mass is sufficient to have sustained the elevated atmospheric CO₂ levels required by the prolonged global carbon isotope excursion. Even after considering uncertainties in the sedimentation rates, these results indicate that the enhanced erosion, mobilization and oxidation of ancient sedimentary carbon contributed to the delayed recovery of the climate system for many thousands of years.

在古新世—始新世热最大值期间，碳迅速大量释放的标志是全球负碳同位素偏移。但是，碳同位素偏移的恢复延迟表明，尽管最初的第二碳源尚未达成共识，但在最初的快速发作之后，CO _2的输入仍持续良好。在这里，我们建议该次要输入可能部分来自于固定化沉积化石碳的氧化。我们在美国中大西洋沿岸的陆架记录中测量了热成熟的生物标志物指标，构建了生物标志物混合模型以限制美国中大西洋和坦桑尼亚沿岸记录中化石碳的含量，估算了沿海沉积物中的化石碳积累率，并确定了全球CO的范围₂从化石碳库中释放出来。这项工作提供证据的化石碳递送幅度增加始于〜10-20 KYR事件发生后，并表明再活化化石碳的氧化释放10之间的海洋的顺序²和10 ⁴的CO PGC ₂期间古新世-始新世最大热体。估算的质量足以承受大气中CO ₂的升高延长的全球碳同位素偏移所需的水平。即使考虑了沉积速率的不确定性，这些结果也表明，古老沉积碳的侵蚀，动员和氧化作用的增强导致了数千年以来气候系统的延迟恢复。