Sortable silt and neodymium isotope data from DSDP Site 29-278, Southern Emerald Basin (Southwest Pacific) and ODP Site 119-744 Southern Kerguelen Plateau (South Indian)

The Antarctic Circumpolar Current (ACC) has a pivotal role in global climate through its strong influence on the global overturning circulation, ocean heat and CO~2~ uptake and storage. When and how the ACC reached its modern-like conditions (i.e., vigorous, and deep-reaching) after the opening and deepening of the Drake Passage and the Tasmanian Gateway remains highly controversial. We present mean sortable silt and neodymium isotope records from the Deep Sea Drilling Project (DSDP) Leg 29 Site 278 located in the southern Emerald Basin (56°33.42'S, 160°04.29'E, 3675 m water depth) and Ocean Drilling Program (ODP) Leg 119 located in the southern Kerguelen Plateau (61°34.66'S, 80°35.43'E, 2307 m water depth) spanning the last 31 million years. These records were used to determine the timing of the onset of diagnostic features of today's ACC: a modern-like deep-reaching strong flow, and homogenisation (i.e., common water mass signature) of Circumpolar Deep Water within the ACC. Grain size was measured using the laser microgranulometer Malvern mastersizer hydro 2000G. Neodymium isotopes from Site 29-278 were measured on a Nu Plasma multiple collector inductively coupled plasma mass spectrometer (MC-ICP-MS).Neodymium isotopes from Site 119-744 were measured on a Thermo Scientific Triton Plus Thermal Ionization Mass Spectrometer (TIMIS).