The Pleistocene clastic sediments in the Divje babe I cave, Slovenia. Geochemical characterisation and provenance (Part 2)

Different grain size fractions of clastic sediments (40-65, 0.5-3, and < 0.5 mm) 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.