Late Maastrichtian-early Paleocene benthic stable carbon and oxygen isotope records from ODP Site 208-1262, South Atlantic

The late Maastrichtian warming event was defined by a global temperature increase of about 2.5-5°C, which occurred ~150-300 kyr before the K/Pg (Cretaceous/Paleogene) mass extinction. This transient warming event has traditionally been associated with a major pulse of Deccan Trap volcanism, however large uncertainties on radiogenic dating methods have long hampered a definitive correlation. Here we present a high-resolution, single-species benthic stable isotope record from the South Atlantic, calibrated to a new high resolution orbitally-tuned age model, to provide a revised chronology of the event, which we then correlate to the latest radiogenic dates of the main Deccan Trap eruption phases. The onset of deep-sea warming is synchronous with a 405-kyr eccentricity minimum, excluding a control by orbital forcing alone, although amplified carbon cycle sensitivity to orbital precession is evident during the greenhouse warming. Our data reveals that the initiation of deep-sea warming coincides, within uncertainty, with the onset of the main phase of Deccan volcanism, strongly suggesting a causal link.

晚马斯特里赫特期升温事件以全球气温升高2.5~5℃为典型特征，发生于白垩纪-古近纪（Cretaceous/Paleogene，简称K/Pg）集群灭绝事件前约15万~30万年。这一短暂升温事件传统上被归因于德干暗色岩火山活动（Deccan Trap volcanism）的一次主脉冲事件，但长期以来放射同位素测年（radiogenic dating）方法存在的较大不确定性，始终阻碍了二者间确定性关联的建立。本研究基于南大西洋区域的单物种底栖生物稳定同位素记录（single-species benthic stable isotope record），结合新建的高分辨率轨道调谐年龄模型（orbitally-tuned age model）进行校准，以此修订了该升温事件的年代学框架，并将其与德干暗色岩主要喷发阶段的最新放射同位素测年结果进行关联。深海升温的起始时间与40.5万年偏心率（eccentricity）极小值同步，排除了仅由轨道强迫（orbital forcing）驱动的可能性，尽管在此次温室升温过程中，碳循环（carbon cycle）对轨道岁差（orbital precession）的敏感性显著增强。本研究数据显示，深海升温的启动时间在测年误差范围内与德干暗色岩主喷发阶段的起始时间高度吻合，强烈暗示二者存在因果关联。