Multiproxy cretaceous-paleogene boundary event stratigraphy: An Umbria-marche basinwide perspective

Abstract

The complete and well-studied pelagic carbonate successions from the Umbria- Marche basin (Italy) permit the study of the event-rich stratigraphic interval around the Cretaceous-Paleogene boundary (e.g., Deccan volcanism, boundary impact, Paleocene recovery, and climate). To test the robustness of various proxy records (bulk carbonate δ13C, δ18O, 87Sr/86Sr, and Ca, Fe, Sr, and Mn concentrations) inside the Umbria-Marche basin, several stratigraphically equivalent sections were investigated (Bottaccione Gorge, Contessa Highway, Fornaci East quarry, Frontale, Morello, and Petriccio core). Besides the classical Gubbio sections of Bottaccione and Contessa, the new Morello section is put forward as an alternative location for this stratigraphic interval because it is less altered by burial diagenesis. Elemental profiles (Ca, Fe, Sr, Mn) acquired by handheld X-ray fluorescence (pXRF) efficiently provide regional chemostratigraphic and paleoenvironmental information. The Deccan volcanism, the Cretaceous-Paleogene boundary, the characteristic pattern of the Sr/Ca profile across the boundary driven by the extinction and recovery of coccolithophores, and the Dan- C2 hyperthermal event are examples of such recorded paleoenvironmental events. Moreover, cyclostratigraphic analyses of proxies of detrital input (magnetic susceptibility and Fe concentrations) show the imprint in the sedimentary record of a 2.4 m.y. eccentricity minimum around 66.45-66.25 Ma, and suggest that the occurrence of the Dan-C2 hyperthermal event was astronomically paced.