Benthic foraminiferal bioevents through the Italian geological sheet N. 377 "Trasacco" (CARG Project)

Geological mapping represents a valuable tool to understand the past settings and future evolution of the Earthsystem. Through the several activities involved for the final release of an official geological survey, biostratigraphy mayhave a pivotal role. This is true in particular when fossil-rich rock succession crops out into the studied area, and evenmore when shallow-water carbonate units have to be characterized and mapped in detail. The lithostratigraphy of theMesozoic and Cenozoic units of carbonate platform is, usually, intimately related with the fossil content, benthicforaminifera among others, and to the relative stratigraphic extension for each taxon or assemblages. We present anexample coming from the succession cropping out into the Apennines (Central Italy), included into the geological sheetn. 377 "Trasacco" (CARG Project), that has been characterized by applying a micropaleontological analysis based onbenthic foraminifera and algae. Even not completely calibrated against the chronostratigraphic scale, the shallow-waterzones here used help to define the relative position of taxa through time, supporting the characterization of thelithostratigraphic units and the recognition of stratigraphic gaps. The observation of foraminifera by hand lens has firstpermitted to establish some unit boundaries in the field, whereas refined biostratigraphy by using thin sections helped tosolve problems at the mesoscale.The shallow-water succession encompasses great part of the Jurassic and Cretaceous with 'Bahamian-type' facies,overlain by Lower Miocene succession made of heterozoan carbonates. This has helped to broadly resume the bioeventsrecorded through the platform, especially during the Mesozoic. Through the Lower Jurassic only oligotypicforaminiferal associations developed, constrained by the environmental conditions of supratidal and near-emersionsettings. The Middle to Upper Jurassic succession records a recovery of larger foraminiferal species included into thefamily Pfenderinidae, among others. Through the Lower Cretaceous some larger agglutinated and porcelaneousforaminifera typify the benthic association, among representative of the genera Akcaya, Mesorbitolina,Praechrysalidina, Cribellopsis and Archaeoalveolina, associated with green algae and the bivalve Chondrodonta. TheCenomanian records high diversity with Cisalveolina, Sellialveolina, Rotorbinella, several soritids and nezzazatids,among others, which underwent mostly extinguished soon after at the Cenomanian-Turonian boundary (related to theOceanic Anoxic Event 2). The following Upper Cretaceous succession records a post OAE2 diversification of severalgroups of larger benthic foraminifera such as the lamellar perforated rotaloideans whose evolution started by smallrepresentatives that likely survived to the Cenomanian-Turonian boundary extinction. The Lower Miocene benthiccoenosis was inhabited by the foraminiferal genera Neorotalia,