海洋地质与第四纪地质2024，Vol.44Issue(4)：1-15,15.DOI:10.16562/j.cnki.0256-1492.2024011702
晚更新世冰期旋回成因的南大洋机制及其对北极冰盖形成的启示
The Southern Ocean mechanism of the Late Pleistocene glacial cycling and its implications for the formation of the northern hemisphere ice sheet
摘要
Abstract
It has been generally believed that the Southern Ocean has played an important role in modulating glacial/interglacial changes of the atmospheric partial pressure of carbon dioxide(pCO2)during the Late Pleistocene.In the late Pleistocene,the atmospheric pCO2 during the glacial periods was about 90×10-6 lower than that during the interglacial periods.Furthermore,in around 2.7 Ma,with the intensification of the Northern Hemisphere Glaciation(iNHG),the amplitude of glacial cycles increased,while the atmospheric pCO2 greatly decreased.Exploring the reasons for the decline in atmospheric pCO2 during the Late Pleistocene glaciation and the iNHG period is of great significance for constructing a complete theory of the Ice Ages.We combined the records of ocean currents,sea ice,and productivity in the Subantarctic Antarctic Zone(SAZ)in the northern part of the Southern Ocean and the Antarctic Zone(AZ)in the southern part of the Southern Ocean during the Late Pleistocene glaciation,investigated the possible carbon storage mechanisms in these two regions during this period,and discussed the changes in the Southern Ocean currents and carbon reservoirs during the iNHG period by integrating geological records.We proposed that SAZ and AZ had different carbon storage mechanisms during ice ages.The enhancement of iron fertilization increased the biological pump efficiency in the SAZ,thus increasing ocean carbon sequestration.Meanwhile,in the AZ,weakened deep-water ventilation,sea ice expansion,and enhanced deep-sea stratification were the key mechanisms for enhancing deep-sea carbon sequestration.Additionally,records of ocean currents and carbon reservoirs during the iNHG period indicate that southern ocean sourced waters expanded significantly towards the deep North Atlantic and North Pacific,with an expansion of sea ice in the Southern Ocean,enhancement in iron fertilization,and the increase in the Pacific carbon reservoir.We infer that the Southern Ocean mechanisms of the Late Pleistocene ice glacial cycling had probably contributed greatly to the decrease in the atmosphericpCO2 during the period of the iNHG,which triggered the final formation of the northern hemisphere glaciation.关键词
北极冰盖/冰期旋回/深部洋流/碳储库/南大洋Key words
northern hemisphere ice sheet/glacial cycling/deep ocean circulation/carbon reservoir/Southern Ocean分类
海洋科学引用本文复制引用
马悦,田军,李杨..晚更新世冰期旋回成因的南大洋机制及其对北极冰盖形成的启示[J].海洋地质与第四纪地质,2024,44(4):1-15,15.基金项目
国家重点研发计划项目"新近纪晚期印太暖池区海道闭合与高纬冰盖演变的耦合机制研究"(2023YFF0803900) （2023YFF0803900）
国家自然科学基金重点项目"探索晚新生代太平洋中深层经向翻转流与气候演变冰期旋回的关系"(42030403) （42030403）
