Terrigenous Input And Palaeoceanographic Evolution Research Of Northern Norwegian Sea Since 26ka

The North Atlantic experienced millennial climate change since the Last Glacial Maximum (LGM). In this paper, the sediments of core ARC5-BB03, which was collected from the northern Norwegian Sea (NS), has been analyzed for grain size composition, AMS14C dating, color reflectance and high-resolution XRF scanning, Planktic foraminiferal stable oxygen and carbon isotope analyses, total organic carbon and carbon isotope analyses and opal analyses.The principal component analysis of the XRF measurements is applied for the purpose of sedimentary source identification. The grain size variability and elemental counts for core ARC5-BB03 indicate that the sedimentary sources of the northern NS have undergone dramatic changes since the 26 cal. ka BP. One the other hand, using the data of planktic foraminiferal stable oxygen and carbon isotope analyses, total organic carbon and carbon isotope analyses and opal analyses, we reconstruct the palaeoceanographic evolution of the area since the Last Glacial Maximum on an millennial scale.Changes of terrigenous input in the north NS show close relationship with the variations of the North Atlantic Current (NAC), the melting of sea ice and ice sheet, the establishment of the Thermohaline Circulation (TC) and the forming of the North Atlantic Deep Water. The coarse grain size sediments before 21.5 cal. ka BP implies different source from those in the later period because the terrigenous input is dominant in this period and occupied by an orderly layer of expandable minerals (OLEM). Strang sea ice extension is deemed to the main reason for the high terrigenous input in the NS before 21.5 ka BP. Between 21.5-16.5 cal. ka BP, biogenic substances increase accompanied with the decrease of terrigenous material indicates the impact of northward intrusion of NAC and the strenghthen of water ventilaiton in NS, these condition resulted in a high biological productivity. Biogenic substance phased decrease and the increase of the terrigenous input during 16.5-10 cal. ka BP is consistent with the fluctuation in the melting of ice sheet and intensity of NAC during the last deglaciation, the freshwater event led to the decrease of ventilation and a stronger stratification of upper water layer result in a low biological productivity. Compare with the early stages, the sediments after 10 cal. ka BP have high biogenic contribution and the magnitude of changes is relatively high, which reflects the controling influence of NAC and TC changes on the sediment sources in the NS. The record indicates that the ventilation of upper water layers was more intense than at present result in a high biological productivity.