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Lithology and origin of Tertiary Jelar Breccia within the framework of tectogenesis of Dinarides

Jelar deposit are represented by massive, unbedded calcareous breccia (rarely breccio-conglomerate), composed of variable, angular (rarely subangular to rounded), weakly sorted fragments in grey to reddish carbonate matrix. Clasts belong to different stratigraphic units: the most common are fragments of Cretaceous limestones and dolomites and Jurassic and Paleogene limestones, although clastic of Triassic carbonates, small bauxite grains and clasts of Peleogene flysh deposits and Promina conglomerates and chert can also be found. The thickness of Jelar deposits are very variable, ranging from several meter to more than 300 m. Stratigraphic position of Jelar deposits estimated between the upper Lutetian and Bartonian in the Drniš area and Hercegovina, Eocene in the area of Ćićaria (hinterland of Istria) an Middle Eocene - Oligocene in the area of Omiš (SE of Split). The origin of the Jelar breccia is a consequence of tectonic disturbances during the Tertiary tectonic cycle, which resulted in the uplift of Dinarides. This process resulted in production of huge amounts of tectogenetic materials (fine grains, pebbles, cobbles and blocks) which was transported down steep slopes, forming abundant rockfall breccia fans. Part of this unsorded material was imported into water-filled sedimentary basins and part of the rockfall breccia represented the source material for braided-river systems and alluvial fans of the Promina formation.

Carbonate breccia,Jelar-breccia, Tectogenesis, Velebit Mt., Hrvatsko Primorje, Croatia

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