A Cretaceous carbonate escarpment from Western Sicily (Italy): biostratigraphy and tectono-sedimentary evolution

Abstract

The presence of a huge carbonate slope of Cretaceous age is recorded in some imbricated thrust sheets from the Maghrebian fold-and-thrust belt cropping out in northwesternmost Sicily (southern Italy). The sedimentological features of this escarpment, named as the Western Sicily Cretaceous Escarpment (WSCE), have been recently described. The present paper aims to provide a detailed bio- chronostratigraphic characterization of the different facies types that occur in the four lithostrati- graphic units spanning the whole slope depositional system. The detailed biostratigraphic analysis and correlation of a number of well-exposed sections allowed to differentiate eight informal biozones and to place the different studied sections, either from a single tectonic unit or from different ones, in a reliable chronostratigraphic frame. The integration of sedimentological and biostratigraphic data allowed in turn to time-constrain the main tectono-sedimentary events along the WSCE. In particular: i) the abrupt transformation from a carbonate ramp to a tectonically-controlled escarpment during the Berriasian- Valanginian; ii) the peak of tectonic instability leading to the emplacement of thick megabreccia bodies and repeated submarine volcanic emissions during the Aptian- Cenomanian; iii) the almost coeval increase in the skeletal supply in response to highstand shedding occurred during the Albian- Cenomanian; iv) the tectonic backstepping of the carbonate depositional system during the Senonian ending with the definitive shutdown of the carbonate factory in the late Maastrichtian. The acquired biostratigraphic dataset is in large part new for the Cretaceous of Sicily and provides information on the associations that populated a southwestern Tethyan carbonate platform during the Cretaceous.