Upper Cretaceous Reef Models from Rocca Di Cave and Adjacent Areas in Latium, Central Italy
Deposition of Upper Cretaceous carbonate sequences in central Italy (westcentral Latium) appears to be directly related to the tectonic evolution of an epioceanic Central Apennine Platform. From early Cenomanian to late Senonian time organic buildups, along with skeletal shelf-edge deposits, were laid down along the present northwestern margin of the Lepini Mountains, and the southern portion of the Prenestini Mountains. These sediments overlie rocks of the Cretaceous (Aptian-Albian) restricted platform facies. Late Cretaceous shelf-edge deposits are characterized by sequences of rudistid and coral communities laid down within varied depositional settings.
The rapid development of these organic communities along a linear tectonically induced shelf-margin caused pronounced increases in the production of bioclastic debris, and the distribution of these sediments both on the marginal slope and in the back-reef areas. This bioclastic debris accumulated in offshore shoals and in tidal banks connecting patch-reefs and organic banks.
The continued presence during Cenomanian time of a linear shelf-edge organic buildup complex appears to have been the dominant controlling factor in regards to inner-platform sedimentation. Here, nerineids (gastropods), ostreids (pelecypods), and radiolitid rudistid pelecypod communities, occurring in muddy skeletal wackestones, suggests deposition within both open marine shelf-lagoons and back-reef environments. In addition, the presence of mudstones (some laminated), and peloidal grainstones containing benthonic microfossils, suggests somewhat sheltered shelf-lagoonal to tidal flat depositional settings.
Differential tectonism during Turonian time, causing regional sea level fluctuations, produced varied facies patterns due to changes in water circulation and sedimentation over the shelf area. An open marine shelf-lagoon facies with abundant microfossils was widespread during this time. Conditions of sea level fluctuations and influx of clean marine waters onto the platform led to the development of rudistid banks and winnowed skeletal sands along the platform-margin. The tectonism of early Turonian time caused subaerial exposure of the western portion of the Rocca di Cave area, followed by sedimentary progradation.
Various changes in overall regional bathymetry, with resultant restriction in water circulation, increased during Senonian time. Isolated platform areas became outer “highs” surrounded by deeper water, although these “highs” were partially covered by shoaling transgressive sediments (Rocca di Cave). In some instances the shelf area was drowned bringing shelf-margin facies into former platform areas, and forming organic shoals and barrier islands during repeated progradation (Lepini Mountains).