Biosedimentary and palaeoecological characterization of Norian bioconstructions (Western Tethys, North Calabria)

Abstract

In a Norian-Rhaetian carbonate system of the Western Tethys realm, cropping out in the Monte Cocuzzo tectonic window (North Calabria), a stratigraphic section through the margin setting of the early-middle Norian depositional unit was investigated. The section shows a trend of facies, starting with scattered small-scale isolated microbial and skeletal boundstones (corals, algae, sponges) interbedded with bioclastic/peloidal packstones and grainstones, evolving toward meter-scale, patch reefs and coarser breccias composed of reef-derived clasts. Globose clusters of sponges (Olangocoeliidae), encrusting red algae (Solenopora) and microbial crusts, all binding peloidal-bioclastic packstones, represent the starting-phase of the bioconstruction, followed by the progressive increasing of two genus of pennulate corals: Retiophyllia sp. (colonial) and Distichophyllia sp. (isolate). The oligotypic biota assemblage and the presence of pennulate corals, indicate a shallow water environment of deposition, underneath the fair-weather wave-base depth, characterized by stressed environmental conditions with disphotic and eutrophic waters.