Benthic ecosystem variations along the middle Eocene Provençal drowning ramp

High-resolution lithology, fossil content, ichnofabrics, and spectral gamma-ray emissions are studied in the Capo Mortola section in the Liguria region (NW Italy), correlating it with other middle Eocene (Bartonian) sections in the same region. The succession unconformably overlies Upper Cretaceous open-marine deposits and records a deepening trend on a carbonate ramp during the middle Eocene. Six different microfacies have been recognized, recording the variation in fossil content, especially in the larger benthic foraminiferal assemblages, and lithology, which indicate a deepening trend in the succession. The variation in Th/U ratios, measured by gamma ray emissions along the section, allows for differentiation of oxidizing, normal, and reducing conditions throughout the succession. The increase in the concentration of Th and K suggests periods of increased terrigenous material, which was supplied by a fluvial system close to the studied section. In turn, the Th/K ratio shows an alternation between smectite and kaolinite, which are respectively associated with warm-humid and seasonal humid/dry climates. The upper part of this section shows the incipient drowning of the ramp, which correlates with nearby studied sections; nonetheless, biotic components, lithology, and depositional depth differ in all localities due to the specific paleogeographic portion of the ramp. We were able to identify sectors more prone to seafloor instabilities due to their proximity to the shoreline and the deltaic influence, whereas others were located considerably deeper or farther out with respect to the input of deltaic sediments.