High-resolution XRF analysis of sediment cores (IZN19-05, IZN19-07, IZN19-09, IZN19-11, IZN19-13, IZN19-15, IZN19-20, IZN19-21, IZN19-22, IZN19-23, IZN19-24, IZN19-27, IZN19-28 and IZN19-29) from Lake Iznik, NW Turkey. The relative contents of major and trace elements were analysed with an X-Ray Fluorescence (XRF) Avaatech Core Scanner (EDYTEM Laboratory). The split-core surface was first covered with a 4-μm-thick Ultralene film to avoid contamination and desiccation of the sediment. All cores are registered in the French national cyber-core repository https://www.cybercarotheque.fr and the International Geo Sample Number (IGSN) service https://www.igsn.cnrs.fr/#/search. All cores were collected in April and July, 2019.