Lower Maastrichtian dinoflagellates from the Viano Clay Formation at Viano, northern Apennines, Italy

Abstract

The Viano Clay Formation, exposed in the northern Apennines, Italy, is a 360-m-thick, calcareous to siliciclastic turbidite that was deposited in a deep, open-marine environment. This paper focuses on the organic-walled dinoflagellate assemblages in the basal 253.3m of the Viano Clay Formation in the type locality at Viano, Reggio Emilia. Key events are the highest occurrence datums of Cannosphaeropsis utinensis, Hystrichodinium pulchrum,Isabelidinium cooksoniae and Odontochitina operculata, and the lowest occurrence datums of Cerodinium diebelii and Palaeocystodinium golzowense, which correlate with the lower Maastrichtian dinoflagellate Cerodinium diebelii Interval Zone. Upper Cretaceous foraminifera and nannoplankton occur in the Viano Clay Formation at Viano, together with rare Lower Paleocene species. Reworking of Upper Cretaceous nannofossils and foraminifera has been suggested in the literature but could not be confirmed in the present study. At Viano, the Viano Clay Formation is of early Maastrichtian age and conformably overlies the upper Campanian–lower Maastrichtian Monte Cassio Formation.