Senonian rudist limestones in the Sorrento Peninsula sequences (Southern Italy)

Senonian carbonate sediments rich in rudists are widespread throughout central-southern Italy. The Coniacian-Santonian series, analyzed in the Lattari Mountains (Sorrento Peninsula), are almost completely composed of limestones, with very subordinate dolomitic beds. On a field scale we can distinguish rudist-rich beds rhythmically alternating with finer-grained foraminiferal beds. The studied series testify to a deposition in shallow-sea environments. In the lower part of the series periodical, more or less prolonged emersions (subaqueous with fresh/brackish waters or subaerial exposure) are documented. The upper part of the series lacks emersion evidence; submarine exposure surfaces are testified by firmgrounds or hardgrounds. Wave- and cross-laminations, HCS and the lack of fine sediments document an overall deposition under influence of occasional high-energy water regimes with some storm-related events. The sedimentology and taphonomic signature of the rudist shell beds have been described in order to get a better understanding of depositional environment and the physical processes that controlled the Senonian sedimentation. Monospecific tabular beds mainly characterize the lower part of the series; more complex rudist concentrations, characterized by moderate species diversity, increase up-section. The recognized lithofacies are organized in shallowing-upward depositional cycles that show a gradual change from peritidal/shallow-subtidal cycles to dominantly subtidal cycles up-section; this change records a general deepening-upward trend as a possible result of an increase of the accommodation space provided by a relative sea-level rise, according to what is suggested for other coeval Apennine and Sardinia series.