Understanding changes in the surface water masses in the mid-latitude North Atlantic is important due to its pivotal role in influencing the global climate. Detailed documentation of the past surface water masses by foraminiferal assemblages and ensuing other sea-surface disturbances from the subtropical gyre (STG) is lacking. Here, we report 2-cm intervals (~ 400 years) resolution ice-rafted detritus (IRD), detailed planktonic foraminiferal census, and δ¹⁸O in Globigerina bulloides data from the IODP Site U1313 during the last glacial cycle. Moreover, we combined published paleo-proxy data, namely dolomite/calcite and quartz/calcite ratios, alkenones (Uk’37)-SST from the same site to provide an integrated assessment of the paleoclimate changes in mid-latitude North Atlantic. Our results show that a cooling hydrological environment prevailed during Heinrich ice-rafting events as reflected by the high percent of polar planktonic foraminifera Neogloboquadrina pachyderma and subpolar species (Globigerina bulloides, Turborotalita quinqueloba). Despite the absence of H3 and H6 IRD layers at Site U1313, the southward migration of the subarctic front (SAF) impacted the STG by subpolar water masses. Peak % temperate/North Atlantic Current (NAC) transitional species and the presence of the polar front (PF)/IRD belt impedes poleward heat transport by the NAC during the last glacial maximum (LGM), resulting in the heat accumulation in the STG. In addition, the planktonic foraminiferal assemblage data at Site U1313 can be divided into three phases during MIS 3 (MIS 3a, 3b, and 3c), revealing a gradual cooling trend. The Holocene and MIS 5e were characterized by the influence of subtropical water masses, inferring northward expansion of the STG, northward migration of the Azores Front (AzF), and Azores Current. However, the percent of subtropical species decreased during the late MIS 5e (122-116 ka), most likely reflects that the AzF moved south and the North Atlantic Transitional Water invaded the STG.
 

planktonic foraminifera,last glacial cycle,North Atlantic,water masses,subtropical gyre,ice-rafting