第八届青年地学论坛

ast studies using planktonic foraminiferal assemblages in the North Atlantic were mainly focused on narrow regions. As a result, such data covering the wide areas are scarce, especially from the North Atlantic transition region (NATZ) and the western subpolar gyre (SPG). Here, we report planktonic foraminiferal assemblages, oxygen isotopes, and ice-rafted detritus (IRD) data from two sediment cores (i.e., Hu90-08 and Hu71-377) from the NATZ and western SPG. Our data suggest that the Polar front (PF) and Arctic front (AF) were located north of the cores Hu90-08 and Hu71-377 in Holocene. During the last glacial maximum (LGM), the PF migrated to 45°N, but the cores Hu90-08 and Hu71-377 were mainly affected by Arctic water, although the North Atlantic Current (NAC) transported heat influenced the mid-latitude. The abundance of N. pachyderma was higher (~90%) during the MIS 4 compared to the LGM, indicating polar water influence and a colder hydrological environment in core Hu90-08. During the MIS3, the increase in the transitional water mass species (i.e., Globigerina bulloides and Globigerinoides inflata) suggests that the core Hu71-377 was mainly affected by the NAC, and the SAF was located north of Hu71-377. Concurrently, core Hu90-08 recorded cold (40-27 ka) and warm (60-40 ka) periods. During the deglaciation periods (18-15 ka and 132-128 ka), the high abundance of polar species and lighter oxygen isotopes in both cores Hu90-08 and Hu71-377 reveal the freshwater impact at this time, with the PF migrated southward and cold polar water masses prevailed in the NATZ and SPG. The western SPG was generally warmer than the eastern SPG during the MIS 5. However, the abundance of planktonic foraminifers in core Hu90-08 shows that the western SPG was affected by seasonal subpolar water masses during the MIS 5e (~124-120 ka), indicating a transient southward movement of the PF and AF. This study presents the first large-scale water mass movements and frontal changes in the SPG and NATZ during the last glacial cycle to better understand the dynamics of the surface circulation in the North Atlantic.