Geological map and stratigraphic evolution of the central sector of the Carnic Alps (Austria-Italy)

The central sector of the Carnic Alps spans the border between Austria and Italy and consists of a succession ranging from the Upper Ordovician to the lowermost part of the upper Carboniferous that has been recently revised in order to formalize the stratigraphic units. Although this area was mapped both on the Austrian and Italian side, the presence of different units with different stratigraphic boundaries prevented from a complete representation of the stratigraphic relationships and the lateral geometrical variability within the basin. We focused mainly on the Devonian ‘transitional facies’ that indirectly reflect the establishment and the demise of a platform. The basin shows a transition from a ramp-type to a rimmed shelf- type profile that occurred between the upper part of the Pragian to the lower Emsian that is constrained by the increasing abundance of reef-derived gravity-driven rudstone deposits. The platform system reached its maximum expansion around the end of the Eifelian and the beginning of the Givetian when the largest debris deposits have been shown to accumulate. Although less productive, the platform system appears to persist until roughly the lower part of the upper Frasnian when the rudstone deposits become depleted of platform- derived clasts and interbedded with microbial limestone. This evolution might have been caused by a sea-level drop event.