Fault-Block Platform Evolution between Late Cretaceous and Early Miocene along the Margin of the Latium-Abruzzi Carbonate Platform (Southern Prenestini Mountains, Central Apennines, Italy)

Abstract

Since the origin of the carbonate platform concept, the reconstruction of the geometry and the evolution of the margin has been an intriguing topic. The Latium-Abruzzi platform is one of the largest shallow water domains of the Central Apennines, however, the reconstruction of the geometry and evolution of its margin has been classically problematic because the latter has been erased by the out-of-sequence Olevano-Antrodoco thrust system. The investigated area is placed in the Prenestini Mountains, the southernmost portion of the Sabina Domain, where a Cretaceous to Neogene carbonate succession, ascribed the Latium-Abruzzi platform margin, crops out. Stratigraphic and facies analyses showed a Late Cretaceous extensional stage that produced two main fault-block platforms, respectively, South Eastern Prenestini and South Western Prenestini platforms, developed westward of the large Latium-Abruzzi Platform domain. In these platforms, during the Paleocene–Eocene interval, pelagite deposition coincides with the main relative sea-level rise. Instead, during the following falling stage, the seafloor, consisting of the Cretaceous carbonate, was in the wave abrasion zone and the pelagic carbonate mud was swept away or trapped in local depressions or fractures (neptunian dykes), whereas the coarse sediment produced by the erosion of indented and fractured substrate formed polygenic conglomerate accumulation on the Cretaceuos carbonate platform substrate. Successively, an isolated homoclinal ramp, the Guadagnolo Fm, Aquitanian to Serravallian in age, developed on the drowned fault-block platforms, suggesting that during Neogene the articulation of the substrate of the two fault-block platforms had to be limited to host the bioclastic sedimentation of the Guadagnolo Fm and to allow the development of a carbonate ramp depositional profile.