Miocene carbonates of the Eratosthenes Seamount

The Miocene is a key epoch in the climatic history of our planet since it witnessed the transition from the Green House Earth to the modern Ice House condition. Although the beginning of this fundamental climatic shift dates back to the Eocene, with the opening of the Drake Passage, it is only after the Middle Miocene Climatic Optimum that the Antarctic Ice-sheets experienced a major expansion and the North Hemisphere Ice-sheets began to form. While Earth’s climate was cooling, the Mediterranean basin was facing a major revolution: turning from a large seaway connecting the Indo-Pacific with the Atlantic to anenclosed basin. During the early Miocene, the eastern deep-water connection was severed. During the late Miocene, the sealing of the western passage determined the Messinian Salinity Crisis. Since the Eastern Mediterranean basin was for a long time the only gateway to the Indopacific Ocean, it plays a crucial role in the understanding of the environmental evolution of the Mediterranean.In order to understand the environmental dynamics of Mediterranean during the Miocene, the carbonates of the Eratosthenes Seamount, located offshore Cyprus in the Eastern Mediterranean (ODP Leg 160, Site 966), have been reanalysed. The use of SEDEX sequential extraction for evaluating the nutrient concentrations and of CT-Scan for the identification of large benthic foraminifera resulted in a detailed palaeoenvironmental reconstruction and an improved stratigraphic framework.The succession formed in an oligotrophic tropical environment and it is possible to recognize three major intervals within it. The lower interval, dated to the early Miocene, is characterised by a large benthic foraminifera and echinoid skeletal assemblage deposited in a water depth of 30-60 m. The central interval, which likely represents the middle Miocene, is dominated in its basal part by coralline algae and corals, probably related to a moderately shallow setting (20-30 m). Upward, epiphytic foraminifera, hooked coralline-algal crusts and thin and flat specimens of Heterostegina become dominant, pointing to a seagrass/seaweed meadow paleoenvironment (30-60 m). The uppermost part of the central interval is again dominated by coralline algae and corals. The last interval has been dated to the late Miocene, its base presents a typical modern reef assemblage with abundant corals compatible with a shallow-water depositional environment (10-20 m). A lagoonal facies with small miliolids and mollusks characterizes the top of the interval testifying to a further shallowing (less than 10 m). Marine carbonates are overlain by an ostracod-dominated brackish limestone and a limestone breccia, both related to the Messinian Salinity Crisis. The Eratosthenes succession, with large benthic foraminifera in the lower Miocene, coralline algae in the middle Miocene and corals in the uppermost part of the Miocene, presents a trend typical of Mediterranean Miocene carbonates. As the Seamount has been an isolated platform protected from continental influx for the entire Miocene, this succession represents a fundamental reference point for the Eastern Mediterranean.