Analiza facijesa srednjeg miocena jugoistočnog dijela Medvednice

This work presents all Karpatian-Badenian facies units of the SE flanks of the Medvednica Mt., between Markusevac and Zelina. Sixteen facies units have been separated on the basis of their lithological, geographical and stratigraphical characteristics; according to their genetical, stratigraphical and environmental similarities they were grouped into 4 mapped lithostratigraphic members (Cucerje, Trstenik, Vejalnica and Vrapce). Karpatian Cucerje member consists of massive silt facies, massive marls with sand layers and horizontally bedded sands with laminated marls and massive tuffs, deposited in the transitional zone and shelf environments. Trstenik member is composed of trough-bedded sandstones, horizontally bedded biocalcarenites and biocalcrudites, calcitic silts and basal breccio-conglomerates, deposited in the lower shoreface and foreshore environments during Karpatian and Early Badenian. Vejalnica member is characterised by tuff facies, bioclastic tuffites, sandy bioaccumulated limestones, fossiliferous marls, biocalcarenites and chaotic sediments, deposited in transitional zone and shelf with important storm influence. Vrapce member is composed of biocalcruditic facies of the Late Badenian age, deposited in near-shore environments. On the basis of the evolution of sedimentary environments it may be concluded that the Ottnangian-Karpatian transition was characterised by marine transgression. Therefore, in prodeltaic and littoral and basinal environments sedimentation continued, while former terrestrial or alluvial environments composed of Palaeozoic-Mesozoic or Otnangian rocks were covered by transgressive deposits. Deposits of the Cucerje member were deposited during the Karpatian in the marine environments (shelf, and rarely transitional zone), characterised by sporadic volcanic activity. By the end of Karpatian regressive trend led to the shallowing, indicated in the western part of the investigated area by predominant deposition in the transitional zone, while in other parts shelf deposition continued. During the Early Badenian regression led to the further shallowing, resulting in deposition of biocalcarenites and biocalcrudites of Trstenik member, formed in the lower shoreface and foreshore environments. Subsequent deposition of bioclastic tuffites, tuffs and marls of the Vejalnica member in the transitional zone and shelf environments commenced new deepening of the marine environment, accompanied by volcanic activity. This deepening, i.e. relative sea-level rise in the Early Badenian, resulted in marine transgression in the eastern part of the investigated area, with succession from foreshore(? ) deposits (Trstenik member) to shelf deposits (Vejalnica member). Lower Badenian, as well as a part of the Upper Badenian deposits of the Vejalnica member are composed of fossiliferous marls with layers and lenses of biocalcarenites. Marls were deposited on the shelf from suspension, while biocalcarenites represent shallow water material reworked by severe storms, and transported by turbulent currents to the shelf. By the end of the Early Badenian gravitational instability on the gently inclined shelf slope caused sliding of the material, manifested in the field by lenses of chaotic deposits. At the end of the Late Badenian regression caused deposition of near-shore biocalcrudites of the Vrapce member. Subsequent transgression was characterised by deposition of shelf marls, and, during Sarmatian, gradual transition into brackish-water environments characterised by clastic deposits in the basinal part of the newly formed lake. In general, correlation of the sea-level changes recorded in the investigated area with the palaeogeographic situation in the Paratethys area, and partially even with the Pannonian Basin, is possible, excluding some local influences. Transgressive and regressive trends are most conspicuous in the western and northeastern parts of the investigated area. During the Karpatian and Badenian those parts represented shallowest areas, where numerous oscillations of the sea-level were easily recorded, and shorelines are best defined.