The central-western Getic Carbonate Platform: Upper Jurassic to Lower Cretaceous biostratigraphy and sedimentary evolution of the Cioclovina-Bnia sector (Southern Carpathians, Romania)

Detailed sedimentological and micropaleontological investigations have been carried out on nine sections from the central-western part of the Southern Carpathians (Cioclovina-Bnia sector) that provide new insights into the Upper Jurassic-Lower Cretaceous biostratigraphy and sedimentary successions of the Getic Carbonate Platform. Based on themicrofossil assemblages, three biostratigraphic intervals are recognized: upper Kimmeridgian-lower Tithonian, upper Berriasian-lower Valanginian and upper Barremian-lower Aptian, the third being recognized only in elements of an Upper Cretaceous (Cenomanian) breccia/conglomerate sequence. Eight main microfacies have been identified based on different structural/textural traits, bioclasts, and sedimentary paleoenvironments. The microfacies associations of the Upper Jurassic succession mainly describe platform margin domains (fore-reef, small bioconstructions, bioclastic sands) and partly inner-platform peritidal carbonates and lagoonal deposits. The lowermost Cretaceous main microfacies types reflect tidal action in shallow-water sedimentary settings of the platform interior (lagoons and ponds). The sedimentary evolution of the carbonate succession commenced with Upper Jurassic pelagic and shallow-water carbonates, the last characterizing also the lowermost Cretaceous. The presence of Lower Cretaceous (Barremian-Aptian) limestone elements within the Upper Cretaceous breccia/conglomerates suggest that platform margin sedimentation might have existed during this stratigraphic interval in several parts of the studied region. Last, but not least, this study significantly contributes to knowledge of the Upper Jurassic-Lower Cretaceous microfossil assemblages from this part of the Getic Carbonate Platform.