Different grain size fractions of clastic sediments (40–65, 0.5–3, and <0.5mm) from the Divje babe I cave were chemically analysed. In the chemical composition of the medium and fine fractions, four groups of variables were revealed: 1) MgO, LOI, TOT/C — dolomite, autochthonous terrigenous component; 2) P2O5, TOT/S, Mo, Sr, Cu, CaO, and so on — bones/apatite cement, biochemical chemical components; 3) SiO2, Al2O3, REE, Rb, Zr, K2O, Th, TiO2, Fe2O3, and so on — non-carbonate, allochthonous terrigenous components; and 4) U (Cd, MnO) — more mobile chemical components. Vertical distributions of P2O5, SiO2, and U in the fine fraction suggest five geochemical boundaries. The origin of P2O5 is attributed mainly to the cave bear. A negative correlation between the content of SiO2 and cavernously corroded clasts (indicating a humidity), indicates a dominant aeolian transport of non-carbonate material into the cave. Vertical distribution of U indicates the migration of U and its enrichment in the deeper parts of the sedimentary sequence. The mobilization of U was influenced by the duration of exposure of the sediments on the cave floor. The chemical characteristics of non-carbonate material indicate that source rocks probably belong to the Triassic volcanic, volcanogenic and terrigenous sedimentary rocks. •Chemical composition is used to interpret the provenance of the cave sediment components.•The origin of P2O5 is attributed to the cave bear.•Maximum of SiO2 is explained by the increase of aeolian activity.•Vertical distribution of U indicates the migration of U and its enrichment in the deeper parts.