Mesozoic stratigraphy of Dinaric successions at the Dinarides – Southern Alps boundary, Sava Folds region, Slovenia

In central Slovenia, on the border between Southern Alpine derived units and Dinaric units in the northern part of the Sava Folds, detailed field observations and reambulation-type mapping were conducted. The research aimed to clarify the distribution of Mesozoic formations and the palaeogeographical and tectonic position of the studied area. Based on field observations, lithofacies, microfacies, and biostratigraphic studies (including benthos and planktonic foraminifers, dinocysts, acritarchs, chitinoidellids, calpionellids, green algae, microproblematica, calcareous nannofossils and ascidians), the following successions characterize the northern limb of the Trojane Anticline and the Tuhinj–Motnik Syncline: upper Anisian to lowermost Ladinian platform carbonates (Mendole Formation) are overlain by Ladinian siliciclastic successions including volcanoclastic resediments (Pseudozilian Formation). These either interfinger or are overlain by the Ladinian to lower Carnian platform limestone (Schlern Formation); in the upper part of this formation, the deep–marine siliciclastics and/or carbonates are locally intercalated. Following a significant stratigraphic gap, the lower Tithonian to lower Valanginian pelagic limestone and carbonate resediments (Biancone Formation s.l.) were deposited. The Biancone limestone is covered by upper Aptian–upper Albian (Cenomanian?) marlstone with occasional calcarenite (calciturbidite) interlayers (Lower Flyschoid/Gora Formation). The succession ends with Upper Cretaceous pelagic and resedimented limestones (Volče/Krško Formation). The age and spatial distribution of these successions often differ from that depicted on the existing geological maps. This succession resembles the Transition Zone between the External and Internal Dinarides. Our study indicates the presence of similar transitional Mesozoic Dinaric successions north of the previously proposed Southern Alpine thrust front.