engleski

GEOLOGICAL SURVEY OF MILJACKA 1-5 CAVE SYSTEM

Miljacka 1-5 cave system is located within the borders of the Krka National Park whose entrance is situated at the right bank of the Krka river, 115 m above sea level. Relatively well-known cave system Miljacka 1-5 is predominantly horizontal with significant hydrogeological function. The most recent explored length of the cave system is 1530 m. However, geological data from the cave are scarce, because no detailed geological surveys have been carried out through the whole length of the cave so far. The cave is developed in the lower part of syncline striking NW-SE in Eocene-Oligocene Promina beds (GRIMANI et al., 1972). According to previous geological data from the surrounding surface area, it is most likely that Miljacka 1-5 cave system is developed between two informal lithostratigraphic units, Miljacka Fm. and underlying Modrino Fm. (MRINJEK, 2008). The aim of this research was reconstruction of geological relations, and their interconnection with morphology of the cave channels. In that order, ten detailed morphological cross sections were recorded together with detailed sedimentological columns. Morphological cross sections of the cave channels were recorded using the Disto X310 laser distance measure modified for cave measurements, coupled with the PDA device and the PocketTopo software to store and manage measured data and to draw sketches (HEEB, 2008). Sedimentological columns were measured according to standard field procedure (TUCKER, 2011), and sampled for further micropetrographic analyses. First results indicating, that most of cave channels were developed in the contact zones between two main lithofacies units: clast- supported conglomerates and laminated fine- grained calcarenites with calcilutites and conglomerates (Fig. 1). Contact zone between these two units is marked with a thin layer of coal and clay with high content of organic matter, thus representing zone most prone to dissolution and erosion. This research is founded through project “Istraživanje sedimentoloških, mineraloških i geokemijskih značajki recentnih sedimenata u speleološkom objektu Miljacka 1” by Krka National Park. Authors are grateful for the help provided by speleological and expert team within our project, namely D. Grozić, B. Jalžić, A. Kirin, N. Kuharić, N. Sudar, A. Jarić, D. Japundžić & I. Sondi.

Cave Miljacka 1-5, lithofacies, cave morphology

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