The Palaeocene-Eocene Thermal Maximum (PETM) was a period of intense global warming that began ∼55.9 million years ago and lasted about 170,000 yrs. Various mechanisms have been proposed to cause this warming, including the emplacement of the North Atlantic Igneous Province (NAIP). Equally, many mechanisms have been invoked to explain sequestration of carbon from the ocean-atmosphere system necessary to promote the recovery to more temperate conditions. Here we propose that an important path for carbon sequestration was tied to NAIP volcanism through the precipitation of calcium carbonate (CaCO₃) cements within the tephra layers. These cements formed after the deposition and burial of tephra over a wide area of the North Atlantic Ocean during the late Palaeocene and early Eocene. We find strong evidence that authigenic CaCO₃ cements formed shortly after tephra deposition. Monte Carlo simulations suggest that this process may have been responsible for a quarter of the carbon sequestered during the PETM recovery phase, providing a major, but previously unconsidered sink of isotopically-light carbon, and one which may have persisted into the Eocene.

古新世-始新世热极期 (PETM) 是一段全球剧烈变暖的时期，始于约 5590 万年前，持续了约 170,000 年。已经提出了导致这种变暖的各种机制，包括北大西洋火成岩省（NAIP）的进驻。同样，许多机制被用来解释从海洋-大气系统中固存碳是促进恢复到更温和的条件所必需的。在这里，我们提出碳封存的一条重要途径与 NAIP 火山作用通过碳酸钙 (CaCO ₃) 火山灰层内的水泥。这些胶结物是在古新世晚期和始新世早期火山灰在北大西洋大片区域沉积和掩埋后形成的。我们发现强有力的证据表明自生 CaCO ₃胶结物在火山灰沉积后不久形成。蒙特卡罗模拟表明，在 PETM 回收阶段，这一过程可能导致四分之一的碳被封存，提供了一个主要的但以前未被考虑的同位素轻碳汇，并且可能一直持续到始新世。