Stratigraphy and sedimentology of late Mesozoic platform carbonates, southern Italy
The aims of the study were to elucidate the stratigraphy, sedimentology and geochemistry of latest Jurassic - late Cretaceous Campania - Lucania platform carbonates in southern Italy. Eight formations and fifteen biozones have been proposed and described, representing platform carbonates and basin margin sediments. Most formations are isochronous, but the Lower Cretaceous Monte Faito Formation is diachronous, becoming younger and thinner from northwest to southeast across Campania, as a result of tectonically induced differential subsidence. The biostratigraphy indicates a late Cretaceous fauna/floral divergence between the Campania - Lucania and other Periadriatic platforms from a common late Jurassic biota. The sedimentary sequence reflects the development of a Bahamian type epioceanic platform. Restricted environments were characteristic of the late Jurassic and early Cretaceous while open marine, cyclic peritidal sediments were widespread during the late Cretaceous. Basin margin sediments include Jurassic pelagic radiolarian limestones, Cretaceous debris flows and Tertiary planktonic foraminiferal limestones. The western margin of the platform was probably a fault -bounded escarpment. Two large scale transgressive - regressive sequences (late Jurassic - mid Cretaceous) partly correspond to eustatic sea level fluctuations. The relatively simple diagenetic history has been locally complicated by dolomitisation and / or silicification. Early cements are uncommon, locally restricted and are non-luminescent. Late burial cements luminesce dull orange. Fabrics indicate several phases of dolomitisation; early syndepositional types occur but dolomitisation was largely the result of burial diagenesis. Magnesium was probably derived from pore fluids released by the compaction of shales in the Tyrrhenian Basin to the west. Geochemical trends reflect clay minerals and diagenetic history particularly dolomitisation. Palaeogeographically the Campania - Lucania and Latium - Abruzzi platforms were probably part of the same structure during the late Jurassic and early Cretaceous, becoming increasingly separated from each other through the late Cretaceous, during the closure of Tethys.