Triassic beds in the basement of the Adriatic-Dinaric carbonate platform of the Svilaja Mt. (Croatia)

Abstract

On the southwestern slope of Mt. Svilaja a Triassic sequence is exposed. It is composed of Lower Triassic carbonate siliciclastic shelf beds that are unconformably overlain by Anisian breccia. The overlying pelagic Anisian and Ladinian strata with pyroclastic rocks can be interpreted as a result of rift tectonics of Adria micro-plate. A 500 m thick sequence is capped by an emersion surface by karstification and terrigenous sediments including conglomerate as a result of Late Triassic transgression and marking the lower boundary of a new, Late Mesozoic, megasequence of the External Dinarides. By means of conodont study, in the lowermost part of the studied Mesozoic sequence, a Lower Triassic shallow-water conodont fauna yielding Pachycladina obliqua apparatus was recorded. Pelagic limestone beds overlying the »Otarnik breccia« are marked by conodont elements of the Anisian constricta Zone. The Ladinian interval is characterized (from bottom to top); trammeri A. Z., hungaricus A. Z. and mungoensis A. Z. The uppermost part of the section below the emersion surface is identified by Pseudofurnishius murchianus, indicating the Upper Ladinian-Lower Carnian murchianus Zone.