Epilithic organisms in Priabonian marls with pillow lavas of Euganean Hills (NE Italy)

In the Castelnuovo area of the Euganean Hills, upper Priabonian marls (referred to as Brendola Marl) are associated with products of submarine basaltic eruptions, including pillow lavas and lava flows, pertaining to the first, late Eocene magmatic phase in the district. A biostratigraphical revision of the marl by means of calcareous nannofossils allowed to ascribe the succession to the Priabonian Zone CNE19 (Agnini et al., 2014) and to the upper part of planktonic foraminiferal Zone E15, with an estimated age of 35.3-34.3 Ma (Berggren and Pearson, 2005). The benthic foraminiferal assemblage provided a palaeodepth estimation suggesting a deep neritic environment. A reconstruction of the late Priabonian events in the study area indicates various episodes of submarine eruptive activity with formation of pillows and associated hyaloclastic material, alternating with phases of colonization of the upper parts of the pillows and larger hyaloclasts by epilithic and vagile organisms such as crinoids, cirripeds, brachiopods and cidarid echinoids, followed by their post-mortem disaggregation, dispersal and eventual burial due to the uninterrupted marly sedimentation. These episodes ceased with the emplacement of a lava flow, whose flat top was colonized only by sparse cirripeds.