Calcareous nannofossils and foraminifers herald the Messinian Salinity Crisis: The Pollenzo section (Alba, Cuneo; NW Italy)

The record of the Messinian salinity crisis in the Tertiary Piedmont Basin (NW Italy): The Alba section revisited

“…suggesting the establishment of restricted conditions, with the increase of surface water eutrophy (Lozar et al, 2010). Also the calcareous nannofossil assemblages record the same ecological signal, with the sharp abundance peak of Sphenolithus abies recorded at the base of cycle Pm5 (Fig.…”

“…This hypothesis is confirmed by biomagnetostratigraphic analyses performed on the upper part of the Pollenzo section (Lozar et al, 2009(Lozar et al, , 2010 that have shown that the onset of MSC should be placed at the base of cycle Pm5, few metres above the peak abundance of the calcareous nannofossil S. abies. This event can be correlated with other sections in the Mediterranean region (Wade and Bown, 2006;Manzi et al, 2007), where it approximates the onset of the MSC.…”

“…assemblage documents the progressive deterioration of normal marine conditions prior to the onset of MSC, with increasing density stratification, surface salinity and bottom disoxia (Lozar et al, 2010).…”

“…In the lower part of the Pollenzo section (below the slump) and in the Arnulfi one, Messinian planktonic biostratigraphic markers are represented by Globorotalia conomiozea, whose First Common Occurrence (FCO), dated at 7.24 Ma (Hilgen et al, 1995), slightly postdates the Tortonian/Messinian boundary, and by Globorotalia nicolae whose First Occurrence (FO) (6.83 Ma, Hilgen et al, 1995) was recognized at Pollenzo 10 m above the base of the section (Lozar et al, 2010) (Fig. 6), whereas its Last Occurrence (LO) (6.722 Ma;Hilgen and Krijgsman, 1999;Krijgsman et al, 1999a) has been found at Arnulfi at the base of cycle Am2 (Figs.…”

“…Field work, consisting of geologic mapping and description, measurement and sampling of six stratigraphic sections (Arnulfi, Rio Berri, Cascina Merlotti, Rocca del Campione, Pollenzo and Santa Vittoria d'Alba, Fig. 2), has been supported by semiquantitative micropaleontologic analyses on foraminifer and calcareous nannofossil assemblages from Arnulfi section, that have been integrated to previous data from the Pollenzo one (Lozar et al, 2009(Lozar et al, , 2010. Finally, preliminary petrographic studies of carbonate-rich beds and of gypsum lithofacies have been performed.…”