The Miocene beds in the northern part of central Slovenia, part of the sedimentary succession of the former Paratethys Sea, have been poorly researched to date, particularly from sedimentological perspectives. This study presents the first detailed analysis of a 97-meter-thick section of Miocene sediments outcropping in the Kokra River canyon near Milje.
The objective of the research was to determine the lithological characteristics, age, and depositional conditions, and to establish a correlation with the nearby Tunjice Hills. The methods included sedimentological logging of the section, petrographic analysis, and biostratigraphic dating using calcareous nannoplankton. Based on the biostratigraphic analysis, the succession was assigned to the late Eggenburgian and Ottnangian time interval (calcareous nannoplankton biozones NN2–NN3), enabling a reliable correlation with the Govce Formation. The sedimentological analysis revealed a clear transgressive succession: the lower part of the section consists of coarse-grained sandstones and conglomerates deposited in a high-energy, shallow-marine nearshore environment. Upsection, these transition into fine-grained siltstones and marlstones, indicating a deepening of the basin and a shift to a calmer, deeper marine environment. A rich fossil assemblage, including bivalves, gastropods, shark teeth, and cirriped crustaceans, confirms a fully marine, normal-salinity environment under a subtropical climate. The findings confirm that the Milje section represents a proximal equivalent of the Govče Formation, deposited on the western margin of the Pannonian Basin System. The sedimentation was syn-orogenic in nature, controlled by the tectonic subsidence of the basin and the coeval uplift of the Alps, which served as the primary source of clastic material. This research thus provides a significant contribution to the paleogeographic and tectonic reconstruction of the westernmost part of the Central Paratethys during the Early Miocene.
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