Palaeogeographic Variability and Depositional Environments of the Upper Jurassic Carbonate Rocks of Velika Kapela Mt. (Gorski Kotar Area, Adriatic Carbonate Platform, Croatia)

• Published in: Geologia Croatica
• Main Authors: Ivo Velić, Josip Tišljar, Igor Vlahović, Josipa Velić, Georg Koch, Dubravko Matičec
• Format: Article in Journal/Newspaper
• Language: English
• Published: Croatian Geological Survey 2002
• Subjects: Palaeogeography; Synsedimentary tectonics; Facies variability; Platform carbonates; Intra-platform trough; Limestones with chert; Hydrozoan– coral reefs and peri-reefal area; Kimmeridgian; Velika Kapela Mt; Croatia; Geology; QE1-996.5; Planktonic foraminifera
• Online Access: https://doi.org/10.4154/GC.2002.13; https://doaj.org/article/c2e70147d05b4a519748094700009bcf

Synsedimentary tectonics caused significant differentiation of sedimentaryenvironments of the Adriatic Carbonate Platform during the Kimmeridgian. The most important changes have been recorded in W and central Croatia: along the NW part in present day W Istria there was an emergence with bauxite deposits, while along the NE margin of the platform, in the Karlovac area, a former emerged area was submerged. Penecontemporaneously between these areas, in the wider area of Velika Kapela Mt., a shallow intraplatform trough was formed, characterised by deposition of dark mudstones with nodules and thin layers of cherts and thin interbeds of tuffs in the upper part of the succession. Occurrences of planktonic foraminifera, radiolarians, calcisphaeresand rare ammonites indicate the sporadic influence of the open sea. Along the margins of the trough, peri-reefal environments were established, with flourishing developments of different reef-building organisms – hydrozoans, stromatoporoids, corals and bryozoans. Reefs were continuously destroyed, and in this way derived material was reworked and transported towards the trough slopes. An enormous quantity of this material caused progradation towards the deeper central part of the area, which was gradually infilled andnarrowed. In the final phase, the trough was completely infilled, and peri-reefal environments gradually disappeared, since they were covered by ooid bars, culminating in the establishment of shallow environments over the entire area. A similar situation was recorded in another contemporaneous, also tectonically formed environment – the Lemeš trough, stretching from the vicinity of Bihać in NW Bosnia towards the south into Croatia, into E Lika and N Dalmatia. This trough had direct communication with the open Tethys realm, and thin-bedded and platy limestones with chert and pelagic organisms, including common ammonites, were deposited within it. The Lemeš trough was also surrounded by coral–hydrozoan reefs, and it was infilled by the same depositional processes ...