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Palaeoclimatic implications of palaeontological and geochemical data from the Upper Permian and Lower Triassic carbonates of the Velebit Mt. (Croatia)

Permian deposits in the Velebit Mt. area (Croatia) derive from the epeiric platform which existed in equatorial area along northern Gondwana. Late Permian is characterized by dolomites encompassing three relatively thin zones of dark limestones (together named as Velebit Fm., Flügel, 1977). Late Permian dolomites in the Velebit Mt. area are mostly early-diagenetic. The deposition took place in subtidal, intertidal and supratidal environments, as a result of global trends in sea level oscillations. Latest Permian Transitional Dolomite (TD) includes complete remains and bioclasts of algae (dasycladales, solenoporaceans, gymnocodiaceans), foraminifera (Earlandia, Ammodiscus, Glomospira, Tuberitina, Pachyphloia, Globivalvulina, Permodiscus, Staffela, Hemigordius, Lagenidae), with fragments of sponges, ostracods, gastropods, echinoderms and brachiopods. Conodont remains have not been found. The lithologic boundary between Transitional Dolomite and overlying Sandy Dolomite (SD) is marked by a sudden occurence of ooids and siliciclastic grains. Even though it was previously considered as the chronostratigraphic PTB, it represents latest Permian regressive phase marked by an enrichment in concentrations of most major, trace and rare earth elements, followed by the Last occurence of the Permian fossils (LPE) in the lower part of the SD unit (Fio et al., 2010). Chemostratigraphic Permian–Triassic Boundary (PTB) is set within the SD unit marked by the parallel negative carbon isotope excursions in carbonate and organic carbon and changes in element concentrations. First fossil remains after the PTB belong to foraminifera Earlandia sp., which is found together with the pyrite framboids just above the chemostratigraphic boundary, pointing to suboxic and anoxic conditions (Fio et al., 2010). Up in the column, only probable cyanobacterial mats and juvenile mollusc remains have been found within the SD.

Permian; Triassic; Velebit Mt.; Croatia

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