Pizzo Mondello is part of the Sicanian mountains formed by the Maghrebian orogeny fold-and-thrust belt. By comparison to the marly succession of the Carnian (see Cozzo Paparina), this succession shows the carbonate recovery from the Carnian Pluvial Event with the development of a very thick succession of carbonates. The sequence is composed of 430 meters of Cherty Limestones. Those limestones are carbonates of Upper Carnian to Upper Norian overlaid by 20 meters of calcilutites and marls from Lower to Middle Rhaetian. It shows a high-consistent sedimentation rate, 20 to 30 meters per million years. Because of its continuous record from Upper Carnian throughout Rhaetian and almost uniform facies, Pizzo Mondello has been recognized as the GSSP for the base of the Norian in 2021.
What is a GSSP? For a long time, stratigraphers used stage stratotypes to define stages, but there are really few localities where a stage is complete. In the late 70s they decided to define the boundaries between stages as GSSPs, short for Global Stratotype Section and Points. It’s a way more restricted interval of time, defined with as many criterias as possible, chemo/magneto/bio-stratigraphy etc. At Pizzo Mondello, the main criteria is the first occurence of Halobia austriaca, a 3 to 5 cm wide species of bivalve.
