This study reveals how rare earth elements and yttrium (REY) cycle through an ocean margin system, clarifying the mechanisms that govern benthic REY fluxes and the preservation of Nd isotope compositions (εNd) in authigenic sediment phases. This dataset contains rare earth element and yttrium (REY), aluminum (Al), calcium (Ca), iron (Fe), and manganese (Mn) concentrations of bulk, authigenic and detrital sedimentary phases from the Mauritanian margin. Samples were collected during cruise M182 in 2022. Bulk sediment samples were freeze-dried and ground prior to leaching and bulk digestion.Authigenic phases were extracted through a 10s leaching procedure using 0.005 M hydroxylammonium hydrochloride, 1.5% acetic acid, and 0.03 M Na-EDTA buffered to ca. pH 4 with NaOH solution (Huang et al., 2021). For selected samples, data is also provided for a "strong" leach using 0.05 M hydroxylammonium hydrochloride, 15% acetic acid and 0.03 M Na-EDTA buffered to ca. pH 4 with NaOH, that followed after a decarbonation step using 40% acetic acid buffered to pH 4 using Na acetate. The leftover detrital sediment fraction was processed using alkaline fusion based on Bayon et al. (2009).The homogenized bulk sediments were digested in nitric acid, hydrofluoric acid and perchloric acid. Al, Ca, Fe, and Mn concentrations were subsequently determined by ICP-OES Agilent 5800 (GEOMAR, Kiel).REY in all samples and Al, Ca, Fe, and Mn in the authigenic phase were analyzed using a quadrupole ICP-MS Agilent Technologies 7500 Series (GEOMAR, Kiel). Europium data for the bulk and detrital phases were corrected for Ba oxide interferences.