Lead (Pb) isotope measurements are performed in the ferromanganese crust PS75/247-2, dredged on the southern flank of Haxby Seamount in the Pacific sector of the SO. We apply laser ablation coupled with multiple-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) and two-dimensional (2D) mapping techniques. This combined novel approach enables us to confidently resolve orbital Pb isotope variations for the past 800 ka.Pb isotope is a sensitive water mass tracer and our results reveal systematically higher 208Pb/206Pb ratios during lukewarm interglacials than during more recent interglacials while 206Pb/204Pb ratios remained similar, suggesting reduced vertical deep-water mixing in the Southern Ocean during lukewarm interglacials. By enhancing deep-sea carbon sequestration and thereby lowering atmospheric CO2, strengthened deep Southern Ocean stratification likely imposed critical impacts on the lukewarm interglacial climates.

Lead (Pb) isotope measurements are performed in the ferromanganese crust PS75/247-2, dredged from Haxby Seamount, Amundsen Sea, from a water depth of 1502-1734 m .