Samples of river sediments around Ljubljana were sedimentologically, petrologically and quantitatively characterized using optical microscopy, scanning electron microscopy with an energy-dispersive spectrometer, and X-ray powder diffraction. Samples were, based on the quantitative petrological composition, classified into three main groups and five subgroups.
The group of carbonate sediments reflects the predominantly carbonate hinterland. Based on the type of non-carbonate grains, we divided the group into three subgroups: predominantly carbonate, carbonate with clastites, and carbonate-mixed sediments. The subgroup of predominantly carbonate sediments includes samples from the Krim Highlands (Borovniščica and Iška), with carbonate hinterland. The subgroup of carbonate sediments with clastites includes sediments from Podlipščica, lower course of Gradaščica and some samples of Sava. These rivers' hinterland is mostly made of carbonates with minor clastic presence. The sediments from the rivers of the Mokrško Highlands (Ižica and Želimeljščica), and most of the Sava samples, are classified under the carbonate-mixed sediments, where carbonate hinterland is associated with minimal and diverse non-carbonate rocks.
The group of carbonate-clastic sediments includes samples with equal amounts of carbonates and clastites, directly reflecting the mixed geological composition of the hinterland. Sediments from the Mali Graben, Ljubljanica, Gradaščica near Polhov Gradec, and one sample from the Sava River were classified into this group.
The clastic sediment group reflects a predominantly clastic hinterland with intermittent carbonates. Based on the type and quantity of clastic grains, we divided this group into two subgroups: quartz-sandstone and mudstone-sandstone sediments. The quartz-sandstone sediment subgroup includes samples from the Horjulščica and Gradaščica near Stranska vas, with predominantly sandy hinterland. The mudstone-sandstone sediment subgroup comprises samples from the Pržanec and Glinščica, where sandy and silty formations predominate.
The diverse composition of sediments from rivers around Ljubljana enables the identification of the source areas for used aggregates in Emona mortars, at least to the river system's precision.
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