Palynostratigraphical characterization of the Marne a Fucoidi Formation from the Umbria-Marche Basin (Northern Apennines, Italy)

The Early Cretaceous of the Umbria-Marche Basin is marked by three Oceanic Anoxic Events (OAEs) within the Marne a Fucoidi Formation, which is composed of multicolour marlstones and marly limestones interbedded with organic-rich black shale layers. These events are associated to the development of anoxic conditions at the sea floor. Some of these occurred on a global scale—such as the early Aptian OAE1a—while others were regional, such as the early Albian OAE1b. In the present study, the microfloristic content from the Fiume Bosso, Roccaccia, and Bottaccione sections was analysed for the first time, along with data from the Poggio le Guaine section. The palynological assemblage of OAE1b is characterized by sporomorphs as Cyathidites spp. and Afropollis spp., and dinocysts as Florentinia mantellii. The dinoflagellate cyst species Litosphaeridium conispinum was recorded in all studied sections. Its first occurrence marks the late Albian in the Tethyan domain. The occurrence of Elaterosporites klaszii and E. verrucatus—typical of the Albian to Cenomanian—was also recorded. These taxa were found in association with L. conispinum in the Fiume Bosso section, and below its first occurrence in the Bottaccione section. The distribution of dinoflagellate cysts provides valuable insights into the palaeobiogeographic dynamics of the Tethyan realm during the Early Cretaceous, highlighting patterns of ecological response to regional and global anoxic events and reinforcing their utility as biostratigraphical and palaeoenvironmental markers.