Paleoceanography and Paleoclimate Group, Arctic Research Centre, and iCLIMATE Aarhus University Interdisciplinary Centre for Climate Change, Department for Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, 8000, Aarhus C, Denmark.
Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, 1350, Copenhagen K, Denmark.
Sci Rep. 2021 Mar 24;11(1):6788. doi: 10.1038/s41598-021-86224-z.
The Last Glacial Maximum (LGM, 23-19,000 year BP) designates a period of extensive glacial extent and very cold conditions on the Northern Hemisphere. The strength of ocean circulation during this period has been highly debated. Based on investigations of two marine sediment cores from the Davis Strait (1033 m water depth) and the northern Labrador Sea (2381 m), we demonstrate a significant influx of Atlantic-sourced water at both subsurface and intermediate depths during the LGM. Although surface-water conditions were cold and sea-ice loaded, the lower strata of the (proto) West Greenland Current carried a significant Atlantic (Irminger Sea-derived) Water signal, while at the deeper site the sea floor was swept by a water mass comparable with present Northeast Atlantic Deep Water. The persistent influx of these Atlantic-sourced waters entrained by boundary currents off SW Greenland demonstrates an active Atlantic Meridional Overturning Circulation during the LGM. Immediately after the LGM, deglaciation was characterized by a prominent deep-water ventilation event and potentially Labrador Sea Water formation, presumably related to brine formation and/or hyperpycnal meltwater flows. This was followed by a major re-arrangement of deep-water masses most likely linked to increased overflow at the Greenland-Scotland Ridge after ca 15 kyr BP.
末次冰盛期（LGM，23-19000 年前）指的是北半球冰川广泛扩张和非常寒冷的时期。在此期间，海洋环流的强度一直存在争议。基于对戴维斯海峡（水深 1033 米）和拉布拉多海北部（水深 2381 米）的两个海洋沉积物岩芯的调查，我们证明了在 LGM 期间，次表层和中层都有大量的大西洋源水涌入。尽管表层水条件寒冷且海冰负载，但（原）西格林兰流的较低层携带了显著的大西洋（伊尔敏格尔海来源）水信号，而在较深的站位，海底被与现今东北大西洋深水相当的水团所冲刷。这些由边界流夹带的大西洋源水的持续涌入表明，在 LGM 期间，大西洋经向翻转环流是活跃的。在 LGM 之后，冰川消退的特征是一次显著的深水通风事件和潜在的拉布拉多海形成，这可能与卤水形成和/或高浓度融水流动有关。随后，在大约 15000 年前，北大西洋深层水团发生了重大重组，这很可能与格陵兰-苏格兰海脊的溢流量增加有关。
