EVENT STRATIGRAPHY OF CRETACEOUS AND TERTIARY PELAGIC LIMESTONES FROM THE NORTHERN APENNINES, ITALY (CARBONATE SEDIMENTOLOGY)

This dissertation is a collection of eight individual papers having in common the study of geological events recorded in deep-water limestones. The sequence of Upper Cretaceous-Lower Tertiary pelagic carbonates in the Umbria-Marches Apennines of Italy has been successfully used for this kind of study because it has recorded, with remarkable continuity, the geological history of an epeiric sea on the eastern continental margin of the ancient Ligurian Ocean. These unmetamorphosed rocks have suffered relatively little tectonic deformation during the complex geologic evolution of the Tethyan domain.; The first part of the dissertation comprises three papers which analyze geological events in the context of regional basin analysis, and describes in a time sequence, the sedimentary and tectonic evolution of the paleobasin.; The second part of the dissertation deals with more specific geologic events which express the synsedimentary tectonic activity of the Late Cretaceous-Early Tertiary pelagic basin of the Northern Apennines. The two papers included in this part analyze, in detail, soft-sediment slumps, submarine slides, bedding formation in homogeneous deep-water sediments, synsedimentary faulting, and submarine hydrothermal activity related to syndepositional tectonism.; The last three papers of the dissertation are related to events of global extent, specifically the mass extinction at the end of the Cretaceous Period and the biological crisis across the Eocene-Oligocene boundary. The extensive exposure of continuous sections containing these important geological boundaries allowed me to carry out high resolution stratigraphic studies and provide strong evidence that the terminal Cretaceous mass extinction was caused by the impact of a large extraterrestrial bolide on the earth's surface. Radiometric dating of several volcanic ash layers near the Eocene-Oligocene boundary allowed me to date, with unprecedented precision, this chronostratigraphic boundary. The unexpectedly short duration of 1 m.y. for the Late Eocene, resulting from this work, provides a new constraint on the attempt to understand the possible cause and effect relationship of the so-called terminal-Eocene events, which include stepwise mass extinction of marine organisms, global climatic changes, and one or more extraterrestrial impacts.