The role of oceanographic conditions on Cenozoic carbonate platform drowning. Insights from Alpine and Apennine foreland basins

The drowning of carbonate platforms is a fascinating topic because it may be induced by several concomitant factors. A key setting to investigate carbonate platform drowning is a foreland basin. The Nummulitic Limestone ramp developed in the foreland of the western Alps during the Bartonian, while the Lithothamnion and Bryozoan Limestone ramp deposited in the foreland of the central Apennines between the Burdigalian and Serravallian. The drowning of Nummulitic Limestone is related to the reduction in light for the photo-dependent biota according to the progressively increasing depth and poor efficiency of aphotic carbonate factory. The drowning of the Lithothamnion and Bryozoan Limestone ramp is attributed to the deterioration of the environmental conditions that predate tectonic subsidence related to the Apennine orogenesis. Eutrophication triggered by upwelling events induced a crisis in the shallow-water carbonate production, while during the following tectonic subsidence the shallow-water carbonate factory was definitively inactive.