Here we present the total organic carbon to total nitrogen (TOC/TN) ratio from the mid-Cretaceous layer in drill core 9R and 10R at MARUM-MeBo70 Site PS104_20-2 (73.57°S, 107.09°W; 946 m water depth) for reconstructing past wildfire activity and vegetation near the South Pole. The site is located within the Pine Island cross-shelf trough in the Amundsen Sea Embayment (ASE), West Antarctica and was drilled during RV Polarstern Expedition PS104 in 2017. The TOC/TN ratio was calculated on a molar basis and used to distinguish between land-based and aquatic organic matter input. Total carbon (TC) and total nitrogen (TN) contents were analysed with an Elementar Vario EL III elemental analyser. The TOC content was determined after removal of the total inorganic carbon (TIC) with 20% HCl using an ELTRA CS-2000.