Today, with an official ceremony in Urbania, the Chiodo d'Oro (Golden Spike) was placed in the Monte Cagnero section of the Umbria-Marche Apennines (near Urbania), to officially mark the basis of the Global Stratotype Section and Point (GSSP) of the Cattiano plain, a time period that includes significant global climate and sea level variations. To attribute it, the International Commission of Stratigraphy (ICS) and the International Union of Geological Sciences (IUGS).
The GSSP represents the reference standard for the definition of a certain chronostratigraphic limit (physical limit between the two layers that bring rocks of different ages into contact), and is attributed to sites of geological interest of worldwide importance.
Recognized, accepted and used by the entire geosciences scientific community, following years of discussions and insights, the prestigious recognition is the result of a multidisciplinary study of integrated stratigraphy published in 2008 in the bulletin of the American Geological Society (http://gsabulletin.gsapubs.org/content/120/3-4/487.short). Leonardo Sagnotti, Director of the Environmental Structure of the National Institute of Geophysics and Volcanology (INGV), took part in the works, coordinated by the University of Urbino and the Coldigioco Geological Observatory, contributing to the definition of the magnetostratigraphy of the Monte Cagnero section.
The merit of the research team was to have defined, in the Monte Cagnero section, the chronostratigraphic limit between the Rupelian and Cattiano plains, the two stratigraphic planes into which the Oligocene era is divided. Hence the recognition of Global Stratotype Section and Point (GSSP).
The Global Stratotype Section is defined as the section of a stratigraphic sequence characterized by the greatest number of physical, chemical and paleontological information that mark the geological time and define a specific chronostratigraphic limit. The point that indicates the physical limit between the two layers that bring rocks of different ages into contact, on the other hand, is defined as GSSP and is marked by a "Golden Spike". At present, 69 GSSPs have been ratified throughout the world, 10 of which in Italy.
The separation between floors has also been identified through the observation of the planktonic foraminifer Chiloguembelina cubensis. The GSSP of the base of the Cattiano plain, in fact, was set at the level in which a significant decrease in abundance of this planktonic foraminifera is recorded. Furthermore, based on the accurate astrochronological calibration of the Monte Cagnero section, this level has been attributed an age of 27,82 million years.
The official ceremony for the Golden Nail of the global stratotype section and the base point of the Cattiano Plan was held in the presence of institutional and academic authorities and members of the International Commission of Stratigraphy and the International Union of Geological Sciences.
Monte Cagnero section of the Umbria-Marche Apennines (near Urbania): official ceremony of the Chiodo d'Oro (Golden Spike) to officially signal the basis of the Global Stratotype Section and Point (GSSP) of the Cattiano plan