High-resolution planktic stable isotope and trace element record of ODP Hole 161-976

Multi-decadal to centennial planktic d18O and Mg/Ca records were generated at ODP976 in the Alboran Sea. The site is in the flow path of Atlantic inflow waters entering the Mediterranean and captured North Atlantic signals through the surface inflow and the atmosphere. The records reveal similar climatic oscillations during the last two glacial-to-interglacial transitions, albeit with a different temporal pacing. Glacial termination 1 (T1) was marked by Heinrich event 1 (H1), post-H1 Bolling/Allerod (B/A) warming and Younger Dryas (YD) cooling. During T2 the H11 d18O anomaly was twice as high and lasted 30% longer than during H1. The post-H11 warming marked the start of MIS5e while the subsequent YD-style cooling occurred during early MIS5e. The post-H11 temperature increase at ODP976 matched the sudden Asian Monsoon Termination II at 129 ka BP. Extending the 230Th-dated speleothem timescale to ODP976 suggests glacial conditions in the Northeast Atlantic region were terminated abruptly and interglacial warmth was reached in less than a millennium. The early-MIS5e cooling and freshening at ODP976 coincided with similar changes at North Atlantic sites suggesting this was a basin-wide event. By analogy with T1 we argue that this was a YD-type event that was shifted into the early stages of the last interglacial period. This scenario is consistent with evidence from northern North Atlantic and Nordic Sea sites that the continuing disintegration of the large Saalian Stage (MIS6) ice sheet in Eurasia delayed the advection of warm North Atlantic waters and full-strength convective overturn until later stages of MIS5e.在阿尔沃兰海的大洋钻探计划976站位（Ocean Drilling Program Site 976，ODP976），获取了年代跨度为数十年至百年尺度的浮游有孔虫δ¹⁸O（planktic δ¹⁸O）与镁钙比（Mg/Ca）记录。该站位位于流入地中海的大西洋水流路径之上，通过表层洋流与大气过程记录了北大西洋的气候信号。这些记录揭示了末次两次冰期-间冰期转型期存在相似的气候振荡，尽管二者的时间演化节奏存在差异。冰期终止I（T1）以海因里希事件1（Heinrich event 1，H1）、H1后的博林-阿勒罗德（Bolling/Allerod，B/A）升温以及新仙女木（Younger Dryas，YD）降温为标志性特征。冰期终止II（T2）期间，H11对应的δ¹⁸O异常幅度是H1的两倍，持续时间也比H1长30%。H11后的升温标志着海洋同位素阶段5e（Marine Isotope Stage 5e，MIS5e）的起始，而随后出现的新仙女木型降温则发生在MIS5e早期。ODP976站位记录的H11后升温过程，与129 ka BP的亚洲季风终止II（Asian Monsoon Termination II）突变事件高度吻合。将经钍-230（²³⁰Th）定年的石笋时间标尺拓展应用至ODP976站位的结果表明，东北大西洋区域的冰期环境曾发生突发性终止，并在不到千年的时间内便进入了间冰期温暖状态。ODP976站位记录的MIS5e早期降温与淡化事件，与北大西洋其他站位的同类变化相一致，说明这是一次全盆地尺度的气候事件。通过类比T1时期的过程，我们认为这是一次新仙女木型事件，但其发生时段被提前至末次间冰期的早期阶段。该情景与北大西洋北部及挪威海区域的研究证据相符：欧亚大陆萨利安阶（Saalian Stage）对应的海洋同位素阶段6（Marine Isotope Stage 6，MIS6）巨型冰盖的持续解体，延缓了北大西洋暖水团的平流输送以及强对流翻转环流的形成，直至MIS5e晚期才得以完成。