Downcore 40Ar/39Ar Thermochronology of Biotite and Hornblende Grains from Amundsen Sea Sediment Records during the Late Pleistocene

This dataset contains 40Ar/39Ar single-grain ages from two downcore sediment cores, PC493 and PS58/254, from the Amundsen Sea, used in support of the study “Reduced West Antarctic Ice Sheet size during prominent Quaternary interglacials constrained by iceberg-rafted debris provenance in the Amundsen Sea”. The data include biotite grains from PC493 and both biotite and hornblende grains from PS58/254. These age distributions are used to trace changes in sediment provenance linked to iceberg-rafted debris (IRD) delivery and variations in West Antarctic Ice Sheet behaviour during Quaternary interglacials. All grains were irradiated in 1.9 cm aluminium disks alongside Fish Canyon sanidine as a neutron flux monitor at the USGS reactor in Denver, Colorado. 40Ar/39Ar ages were obtained by single-step CO2 laser fusion at the AGES Laboratory (Lamont-Doherty Earth Observatory, USA) using a VG5400 mass spectrometer.