(Table 1) Age determination of ODP Hole 175-1084B

Mg/Ca analyses of G. bulloides and abundances of N. pachyderma (left coiling) from Ocean Drilling Program (ODP) Leg 175 Hole 1084B in the Benguela coastal upwelling system document lower sea surface temperatures during the Last Glacial Maximum (LGM), Younger Dryas, mid-Holocene, and Little Ice Age in the southeastern Atlantic. Taking into consideration the possible effects of differential carbonate dissolution, the Mg/Ca data indicate Younger Dryas temperatures 2°-3°C cooler than those of the early Holocene and LGM temperatures 4°-5°C cooler than those of the early Holocene. The cool interval during the deglacial period at Hole 1084B matches the timing of Younger Dryas shifts in Cariaco Basin and Greenland Ice Sheet records and that of a nearby alkenone record. Comparison of mid-Holocene cooling at Hole ODP1084B with other high-resolution records of Holocene and last deglacial sea surface temperatures from the tropical Atlantic implies consistent basin-wide changes in atmospheric circulation. A brief period of 1.5°-2°C cooling between 17.8 and 17.2 ka, if related to Heinrich event 1, is consistent with a previously hypothesized tropical origin of all Heinrich climate change events.

本格拉沿岸上升流系统内大洋钻探计划（Ocean Drilling Program, ODP）第175航次1084B孔的泡抱球虫（G. bulloides）Mg/Ca比值分析数据，以及左旋厚壁新方球虫（N. pachyderma (left coiling)）丰度数据，揭示了南大西洋东南部末次冰盛期（Last Glacial Maximum, LGM）、新仙女木事件、中全新世以及小冰期期间的较低海表温度。在考量差异性碳酸盐溶解作用的潜在影响后，Mg/Ca比值数据显示，新仙女木事件期间的海表温度较早全新世低2℃~3℃，而末次冰盛期温度较早全新世低4℃~5℃。1084B孔冰消期的冷期时段，与卡里亚科盆地、格陵兰冰盖记录中记录的新仙女木事件温度偏移时间，以及邻近区域的烯酮（alkenone）记录时间相吻合。将1084B孔记录的中全新世降温事件与热带大西洋其他高分辨率全新世及末次冰消期海表温度记录进行对比后可知，大气环流存在全盆地尺度的一致性变化。若将17.8~17.2 ka之间出现的1.5℃~2℃短期降温事件与海因里希事件1（Heinrich event 1）相关联，则该事件与此前提出的“所有海因里希气候事件均起源于热带区域”的假说相符。