Mediterranean Neogene stratigraphy: development and evolution through the centuries



The Mediterranean area, in general, and Italy, in particular, played an important role in developing the principles of stratigraphy since the early days of geological thinking. In the middle of the 19th Century there was a rush to name all the intervals of the stratigraphic column. At that time, when invertebrate palaeontology was the principal source of information on the relative age of the rock units, dozens of stage names were created for the Neogene. Only a few of these stage names survive and are accepted worldwide as Langhian, Serravallian, Tortonian, Messinian, Zanclean and Piacenzian. In the later part of the 19th Century and in the first decades of the 20th Century, a wealth of new data was made available by extensive palaeontological studies but the correlation potential of the fossil faunas was constrained poorly, and understood less, leading to the development of a ‘floating’ stratigraphy. The situation improved after World War II, when micropalaeontology underwent a fast development. The creation of common stratigraphic guidelines, the introduction of the ‘stratotype’ concept followed by the ‘Golden Spike’ concept (global stratotype section and point), combined with the application of multiple stratigraphic methodologies (especially palaeomagnetic stratigraphy or magnetic polarity time scale, astrocyclostratigraphy or astronomical time scale) resulted in new scenarios. A turning point may be located around 1970, soon after the beginning of the Deep Sea Drilling Project, which greatly contributed to the development of a new approach to Neogene Stratigraphy. Now all the global stratotype sections and points for the Neogene stages are being defined by multiple criteria, with precise definitions in terms of magnetic polarity time scale and astronomical time scale. The Rossello composite section in Southern Sicily is the template for the Late Neogene stratigraphy, with the best time resolution provided by astronomical forcing. To complete the planned study, the same criteria have to be applied downwards and upwards.