This dataset comes from the marine sediment core, IN2023_V01_04_KC02, from Cape Darnley, East Antarctica (Post et al., 2024). Laser grainsize analyses were conducted on samples at 10 cm depth intervals. Aliquots of wet sample were pipetted for grain size analysis of the 0–2 mm size fraction using a calibrated Malvern dispersion unit and a Malvern Mastersizer 3000 laser particle sizer at Geoscience Australia. Chemical treatment for the removal of biogenic silica was not undertaken. Duplicates were run to ensure consistency in measured grain size, and each sample was analysed three times to determine measurement variance (<0.4% across clay, silt, and sand fractions). Glass bead standards were run every 20–25 analyses for instrument calibration.