The Monterey event within the Central Mediterranean area: The shallow-water record

The middle Miocene is an important time to understand modern global climate evolution and its consequences on marine systems. The Mid-Miocene Climatic Optimum (between 17·0 Ma and 13·5 Ma) was the warmest time interval of the past 35 million years during which atmospheric CO2 concentrations were lower than today. In the Mid-Miocene Climatic Optimum, a significant carbon cycle perturbation occurred, expressed as a last long-term positive carbon isotope shift, known in literature as the Monterey Carbon Isotope Excursion and recorded in open-ocean settings. In this work, the lower to middle Miocene carbon isotope records from three different domains of the Central Mediterranean are analysed with the aim of identifying the local carbonate platform response to the major global carbon cycle perturbation of the Monterey Event. Carbon and oxygen isotope ratios have been measured on samples belonging to three different stratigraphic sections, two of them are representative of shallow-water settings (Latium-Abruzzi and Apula platforms), and the latter of a hemipelagic setting (Umbria-Marche Basin). A well-defined Monterey Carbon Isotope Excursion is recorded also in these shallow-water sections. Despite their expected problematic stratigraphic constraints, a reliable age model is provided by calcareous nannofossil biostratigraphy and strontium isotope stratigraphy. In both of the carbonate platform successions examined, the Monterey Carbon Isotope Excursion coincides with a spread of bryozoans over other carbonate-producing biota. The high productivity of the bryozoan-dominated factory in the aphotic zone had an important control on the platform depositional profile. The high rates of sediment production in the deeper aphotic and oligophotic zones produced a depositional profile of a low-angle ramp.