6533b7d1fe1ef96bd125cada

RESEARCH PRODUCT

Pliocene-lower Pleistocene chronostratigraphy: A re-evaluation of Mediterranean type sections

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The Pliocene-Pleistocene stages defined for the Mediterranean region are generally used as the standard chronostratigraphic units for the upper Neogene and Quaternary. The recently developed calcareous plankton bio-chronology based on results from Ocean Drilling Program Leg 107 and numerous outcrop sections provides the necessary time control for evaluating the ages and stratigraphic relationships for the various Pliocene-Pleistocene stages and their associated stratotypes. Our results indicate that the currently accepted stratotypes do not provide a continuous stratigraphic representation for all of Pliocene-early Pleistocene time. On the basis of these findings, we propose a revised chronostratigraphic scheme for this time period. A tripartite subdivision is proposed for the Pliocene Series. The Zanclean Stage is retained for the lower Pliocene, representing the interval from the Miocene/Pliocene boundary (ca. 4.93 Ma) to ca. 3.5 Ma. The middle Pliocene is represented by the Piacenzian Stage, and it incorporates strata deposited from ca. 3.5 to 2.5 Ma. None of the currently used Pliocene stages fully represents the upper Pliocene (ca. 2.5 to 1.6 Ma). As a result, late Pliocene time lacks an adequately defined chronostratigraphic unit. The Selinuntian Stage appears to be the most appropriate stage for the lower Pleistocene (ca. 1.6 to 0.8 Ma). It can be divided into three stratigraphically continuous substages (Santernian, Emilian, and Sicilian). The Calabrian Stage, which is commonly used to designate the lowest part of the Pleistocene, should be abandoned because its stratotype does not include a record of the first 500,000 yr of Pleistocene time.