Five Million Years of North Atlantic Deep Water Flow Variability from IODP Site U1564, Gardar Drift

Authors: Halima Ibrahim, Molly Patterson

Field of Study: Geological Sciences

Faculty Mentors: Molly Patterson

Easel: 2

Timeslot: Afternoon

Abstract: North Atlantic Deep Water (NADW) is a key component of the Atlantic Meridional Overturning Circulation (AMOC), and its variability influences the distribution of heat and tracers in the North Atlantic. A major pathway of NADW export is the Iceland–Scotland Overflow Water (ISOW), which flows along the Gardar Drift on the eastern flank of the Reykjanes Ridge. Despite its climatic importance, the long-term behavior of ISOW remains incompletely constrained. A ~5 Ma reconstruction of ISOW variability is presented here using sediment cores from IODP Expedition 395, Site U1564 on the Gardar Drift. The multi-proxy approach integrates discrete wavelength-dispersive XRF (WDXRF) measurements and sortable silt (SS) grain-size data with high-resolution XRF core-scanner measurements. WDXRF data calibrate the scanner record via multivariate log-ratio transformation, and SS measurements are used to convert ln(Zr/Rb) ratios to relative bottom-current velocities. This high-resolution, near-continuous record reveals coherent shifts in ISOW strength across major Plio-Pleistocene climate transitions, including intervals of both enhanced and reduced bottom-current flow.