The Palaeoceanographic Account Of The Northeast Iceland Continental Shelf During The Last Glacial Cycle

The northeastern part of Iceland lies in the Norwegian Sea and is an important area that connects between the North Atlantic and the Arctic Ocean.The uniqueness of its location is mainly reflected by the seawater carrying warm water with high salinity from the North Atlantic where it meets with cold-water masses.Then these water masses gradually cool and sink,making it an integral part of the global temperature and salt circulation system,commonly known as the global thermohaline circulation.Therefore,the Norwegian Sea is very sensitive to the modern global climate change response,it has a significant amplification effect on climate change in the Northern Hemisphere.Any subtle changes in the sinking water masses will further affect global ocean and climate patterns through the global temperature and salt circulation system.Therefore,the palaeoceanographic study from this region would provide insights that may be used to guide the future direction.A sediment core IS1B was obtained from the northeastern Iceland of the Norwegian at 809 m water depth as part of the Fifth Arctic expedition of China.Comprehensive sedimentological data namely sediment color,magnetic susceptibility,foraminiferal assemblages,ice-rafted debris?IRD?,oxygen and carbon isotopes in planktonic foraminifera,and ¹⁴C-AMS dates were used to establish the stratigraphic framework of core IS1B.These data allowed to assess changes in the iceberg rafting and meltwater supply on the northeastern continental slope of Iceland during the last glacial cycle.Five IRD events were identified which may have derived from Iceland with potential contribution from NE Greenland.The IRD events reflect the collapse of the ice sheets and climate change in Greenland and Iceland.The low-temperature and high-salinity Arctic water invaded the core site resulting in a decrease in the injection of the North Atlantic warm water.The Norwegian Sea is affected by the strengthening of the Greenland-East Iceland cold current from the Arctic Ocean,and the increase in the degree of mixing of sea-water leads to the enhancement of the deep-water formation.At the onset of the last deglacial glacial to the B/A warm period,the seawater of the Arctic Ocean retreated and the North Atlantic warm current was restored,affecting the sedimentary environment.During the B/A warm period to the YD period,the Arctic Ocean cold current invaded again.At the onset of the Holocene period,the climate gradually warmed,the intensity of the North Atlantic warm current became stronger,the meridional circulation and surface ocean current system also gradually recovered,and the invading Arctic Ocean cold water gradually receded.From the late Heinrich 3 equivalent event to the last ice age,the ice sheet coverage in the Norwegian Sea gradually expanded and moved southward,eventually forming an annual ice sheet in northern Iceland.During the B/A warm period,although the ice sheet ablation began to retreat northward,rapid expansion occurred in the late B/A warm period and the YD period,but the duration was short.After the Holocene,the intensity of ice sheet ablation activity in the Norwegian Sea gradually decreased,and the impact on the study area gradually decreased,eventually maintaining a relatively stable state,and only slightly recovered until the late Holocene.