engleski

Triassic pelagic limestones in pillow lavas in the Orešje Quarry near Gornja Bistra, Medvednica Mt. (Northwest Croatia)

Investigated outcrops in the Orešje quarry near Gornja Bistra on Medvednica Mt. contain pillow lavas and fragments of carbonate rocks between them. Effusive rocks were determined as high-Ti tholeiitic metabasalts, corresponding to those originated in MOR area, which today represent obducted, allochthonous parts of Triassic oceanic crust. Carbonate rocks fragments are characterised by micrite, biomicrosparite, fossiliferous microsparite, biosparite and sparite types, and all are more or less recrystallised. Concerning their appearance between pillows together with hyaloclasts they were determined as peperites. Micropalaeontological analysis of conodonts from limestone samples indicated Ladinian-Carnian age, what is also the age of the effusive rocks found in the quarry. Described Triassic magmatic rocks probably represent the highest level of the disintegrated ophiolite sequence, which could be stratigraphically correlated with similar sequences in Inke - Toalmas - Darno Hill - Szarvasko - Bodva Valley Zone in Hungary and southern Slovakia, which represent a part of the Gemer-B¸kk Structural Subunit.

peperites; basaltic pillow lavas; Triassic conodonts; Medvednica Mt.; Croatia

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