CORRELATING MEDITERRANEAN SHALLOW WATER DEPOSITS WITH GLOBAL OLIGOCENE–MIOCENE STRATIGRAPHY AND OCEANIC EVENTS

The Oligocene–Miocene transition is of particular interest for the development of the Mediterranean Sea. At this time, the convergence of Africa and Eurasia impacted the Circum-Mediterranean region by a complex pattern of changing seaways and landbridges and caused the reorganization of current patterns. These geodynamic changes were amplified by drastic climate changes in the course of the long-term, stepwise global cooling, which led from the Paleogene greenhouse to the modern icehouse earth. Shallow water sediment records have the strong potential to display sensitive environmental changes in sedimentary geometries and skeletal content. However, the time resolution of most shallow water carbonate records is not high enough to be compared with climatic events as recorded in the deep sea sediment archives. In order to resolve the paleoceanographic and -climatic changes during the Oligocene–Miocene transition in the Mediterranean shallow water carbonate systems with the best possible time resolution, we re-evaluated the Decontra section on the Maiella Platform (central Apennine, Italy), which acts as a reference for the correlation of Oligocene–Miocene shallow water deposits in the Mediterranean region. The widely continuous carbonate succession is composed of larger foraminiferan, bryozoan and corallinacean limestones interlayered with distinct planktonic foraminiferal carbonates representing a mostly outer neritic setting. Integrated multi-proxy and facies analyses indicate that CaCO₃ and total organic carbon contents as well as natural gamma radiation display only local to regional processes on the carbonate platform and are not suited for stratigraphic correlation on a wider scale. In contrast, new biostratigraphic data allow to correlate the Decontra stable carbon isotope record to the global deep sea carbon isotope record. This links relative sea level fluctuations, which are reflected by facies and magnetic susceptibility changes, to third-order eustatic cycles. The new integrated bio-, chemo-, and sequence stratigraphic framework enables a more precise timing of environmental changes within the studied time interval and identifies Decontra as a key locality for correlating not only shallow and deep water sediments of the Mediterranean region but also on a global scale.