Palaeoenvironmental reconstruction of the Mufara Formation (Upper Triassic, Sicily): High resolution sedimentology, biostratigraphy and sea-level changes

Abstract

This study contributes to the reconstruction of the geological and palaeoenvironmental settings of the Mufara Formation (Upper Triassic, Sicily), which consists of monotonous marly deposits intercalated with relatively thin limestones levels. Field study included description of sixteen sections corresponding to thirteen outcrops, from which ~ 500 samples were taken. Outcrops are mainly located in north-western to central Sicily (i.e., Monti di Palermo, Monti Sicani, Monti Madonie and Caltanisetta Basin). The stratigraphic contact of the Mufara Fm. with the underlying Anisian–Lower Carnian Lercara Formation, and the overlying Upper Triassic to Lower Jurassic formations (Panormide shallow carbonate platform, Fanusi slope deposits, Scillato and Calcari con selce basinal series) has not been observed. Investigations involved detailed facies and sedimentological descriptions, high resolution biostratigraphy, and genetic stratigraphy. Sedimentological data provide evidence for a new interpretation of the depositional setting of the Mufara Fm. The depositional framework extended from a shallow to deeper water offshore zone along a distally steepened shelf or ramp, on which sponge patch reefs developed. This ramp, which developed during Ladinian to Carnian, probably evolved into a rimmed carbonate platform during Late Triassic, due to changes in basin morphology and tectonic evolution. Biostratigraphy, mainly based on foraminifers and supported by conodonts and palynomorphs, indicates a Late Ladinian/Early Carnian ( Frankites regolenadus/ Trachyceras aon zones) to Late Carnian ( Tropites subbullatus/ Anatropites spinousus zones) age for the Mufara Fm. An Anisian–Early Carnian age for the underlying Lercara Formation implies that the transition between the Lercara and the Mufara formations took place during the late Middle Triassic to early Late Triassic interval, and was probably strongly diachronous.