Foraminiferal Mg/Ca and isotope ratios from ODP Hole 164-994C over the last 340ka

These data were generated to investigate changes in the North Atlantic Subtropical Gyre (NASTG) and its western boundary current, the Gulf Stream, over the past 340,000 years. Sediment samples for this study were collected from ODP Site 994C, located in the western part of the NASTG and Gulf Stream region. Planktonic foraminifera Globigerinoides ruber white and Globigerina inflata (250–355 μm) were selected, and their Mg/Ca ratios were measured using ICP-MS (Bruker Aurora M90). These Mg/Ca data were used to reconstruct temperature variations in both surface waters and the thermocline. Additionally, oxygen and carbon isotopes from G. ruber white (250–355 μm) and Cibicidoides spp. (>250 μm) were analyzed using a MAT253 mass spectrometer to establish an age model.