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Facies characteristics of the Upper Jurassic limestones along the road Banska vrata-Breze (Karst Dinarides, Croatia)

The facies succession exposed along the road Banska Vrata-Breze suggests that after deposition of the Early Upper Jurassic shallow subtidal deposits of Facies A, synsedimentary tectonics caused the formation of a regional sedimentary trough connected with the open basin. On the margin of such a deeper-water sedimentary environment below the fair-weather wave-base, deposits of facies B slowly accumulated simultaneously influenced by pelagic material brought from the open sea area. By periodic shedding of the shallow-water carbonate material from the reefal/perireefal margin of the intraplatform trough by mechanisms of the gravity flows, triggered by periodical storms and/or, more likely, smaller earthquakes, the deeper-water marginal part of the trough was progressively filled up when normaly graded bioclastic intervals of facies C were deposited. When this shallowing reached the shallow subtidal the shallow-water allochems and bioota of facies D was developed. Therefore, once, the shallow subtidal environment was re-established, the rate of carbonate accumulation was rather high capping the thick bioclastic unit of facies C, resulting in further shallowing which reached the low tide and even intertidal levels with sporadic subaeral exposure.

Upper Jurassic; facies; limestones; Karst Dinarides; Croatia

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