Original scientific paper

https://doi.org/10.4154/gc.2021.06

Tidal deposits in the Early Miocene Central Paratethys: the Vučji Jarek and Čemernica members of the Macelj formation (NW Croatia)

Radovan Avanić ; Croatian Geological Survey, Zagreb, Croatia
Davor Pavelić orcid.org/0000-0003-2697-448X ; University of Zagreb, Faculty of Mining, Geology and Petroleum Engineering, Zagreb, Croatia
Zoltan Pécskay ; Institute for Nuclear Research, Isotope Climatology and Environmental Research Centre, Debrecen, Hungary
Mirjana Miknić
Darko Tibljaš orcid.org/0000-0003-1021-585X ; University of Zagreb, Faculty of Science, Zagreb, Croatia
Lara Wacha orcid.org/0000-0002-8773-7077 ; Croatian Geological Survey, Zagreb, Croatia

Abstract

The Macelj formation is an informal Eggenburgian-early Ottnangian lithostratigraphic unit that is established in the area of the Hrvatsko Zagorje Basin, which represented a marginal zone of the Early Miocene Central Paratethys Sea. Modern studies, as a part of the Geologic Map of the Republic of Croatia 1:50 000 project, yielded new data that improves the knowledge of the depositional and stratigraphic characteristics of the formation. The sedimentological research within this study was focused on the two older lithostratigraphic units of the Macelj formation: the Vučji Jarek member and the Čemernica member. The Vučji Jarek mb. is represented by three facies. The Facies of horizontally bedded sandstones is characterized by mostly medium-grained, moderately sorted sandstones that reflect deposition on the foreshore to the upper shoreface. The facies of horizontally and cross-bedded glauconitic sandstones is composed of fine- to coarsegrained, well-sorted sandstones that indicate foreshore to shoreface deposition under tidal influence. The Facies of horizontally and cross-bedded pyroclastics consists of tuff, pumice, lapilli and large blocks, showing a chaotic structure in places. Deposition occurred at the shoreface under tidal influence. The Čemernica mb. is represented by the Facies of structureless clayey-silty sands that are poorly sorted and bioturbated, and indicates deposition below the fairweather wavebase, in the offshore-transition zone. Deposits of the members include marine macro- and microfossil associations.K-Ar dating of separated glauconite mineral fractions yielded an early Eggenburgian age for the Vučji Jarek mb. glauconitic sandstones (19.2±0.64 Ma) which is in accordance with biostratigraphical analyses. Sedimentological characteristics of the Eggenburgian Macelj fm., especially those that reflect the tidal influence, fit the general characteristics of the Central Paratethys Sea in the Early Miocene.

Keywords

Macelj formation; Vučji Jarek member; Čemernica member; tidal deposits; K-Ar dating; Eggenburgian; Hrvatsko Zagorje Basin; Central Paratethys

Hrčak ID:

253473

URI

https://hrcak.srce.hr/253473

Publication date:

28.3.2021.

Visits: 1.643 *