RESPONSE OF TERRIGENOUS INPUT TO THE CLIMATIC CHANGES OF NORTHERN NORWEGIAN SEA SINCE THE LAST GLACIAL MAXIMUM

The North Atlantic has experienced climate changes on millennial scale since the Last Glacial Maximum (LGM). The core of ARC5-BB03, collected from the northern Norwegian Sea (NS), was analyzed for grain size composition, color reflectance and high-resolution XRF scanning and dated with AMS¹⁴C. The principal component analysis of the XRF measurements is adopted for sedimentary source identification. The grain size distribution and element contents of the core suggest that the sources of the sediments of the northern NS have changed dramaticaly since 26 cal. ka BP. Changes in terrigenous input in the north NS have close relationship with the variations in the North Atlantic Current (NAC), the melting of sea ice and ice sheet, the establishment of the thermohaline circulation (TC) and the formation of the North Atlantic Deep Water. The coarse sediments before 21.5 cal. ka BP implied different source from the younger sediments because the terrigenous input was dominant in this period and characterized by an ordered layered expandable minerals (OLEM). Strong sea ice expansion was deemed to be the main reason of the high terrigenous input in the NS before 21.5 ka BP. Between 21.5~16.5 cal. ka BP, biogenic substances increased as the terrigenous materials decreased. indicating the impact of northward intrusion of NAC and the acceleration of water ventilaiton in the NS. The phased decrease in biogenic substances and the increase in terrigenous inputs during 16.5~10 cal. ka BP were consistent with the fluctuation of ice sheet melting and intensification of the NAC during the last deglaciation. Compared with the early stages, the sediments after 10 cal. ka BP had high biogenic contribution and the magnitude of changes was relatively high, which reflects the controling influence of the NAC and TC changes on the sediment sources in the NS.