This data set comprises elemental data obtained from 57 sediment samples. The sediments originate from a wide range of lacustrine and marine settings and were selected to fingerprint the depositional environment (marine or lacustrine) based on the elemental composition. Geochemical analyses were performed on freeze-dried and ground material. Total organic carbon (TOC) and total inorganic carbon (TIC) were analyzed with a DIMATOC 200 analyzer (DIMATEC Corp.). Nitrogen (N wt%) and sulphur (S wt%) were measured with a Vario Mircrocube (Elementar). Other elements reported here were measured by energy-dispersive X-ray fluorescence spectrometry using a SPECTRO XEPOS (SPECTRO Analytical Instruments Ltd.). The data set is a supplement to the manuscript "Rapid relative sea-level fall during the mid-Holocene in the Windmill Islands, East Antarctica" in preparation for submission and targeted for publication in the journal Quaternary Science Reviews by Small et al.