The Early Zanclean succession of Piedmont (Northwestern Italy): new data and perspectives about the paleogeographical setting of the region

• Main Authors: VIOLANTI, Donata, DELA PIERRE, Francesco, LOZAR, Francesca, CLARI, Pierangelo, Trenkwalder S., Irace A., Bernardi E., Lasagna N.
• Other Authors: Violanti D., Dela Pierre F., Lozar F., Clari P.
• Format: Conference Object
• Language: English
• Published: Geoitalia Federazione Italiana di Scienze della Terra 2009
• Subjects: Early Zanclean; Biostratigraphy; Paleobathymetry Paleogeography; Northwestern Italy; NADW; North Atlantic Deep Water; North Atlantic
• Online Access: http://hdl.handle.net/2318/66026

Recent researches, still in progress, are adding a great amount of data about the Messinian/Zanclean succession of the central part of Piedmont (Northwestern Italy). Until few years ago, the Messinian/Zanclean boundary and the Early Zanclean basal interval were very poorly documented in the region. The M/Z boundary was only briefly described by Sturani (1978) in the Narzole (Alba, CN) borehole. The lowermost Zanclean deposits seemed missing in the Pliocene succession, that was widely studied in many other sections, allowing the identification of a marine sedimentation that spans the MPl2 - MPl4 foraminiferal zones. New micropaleontological and stratigraphical analyses have documented the M/Z boundary in the central Piedmont, from the Turin Hill (Moncucco T.) to the Astigiano. The M/Z boundary, marked by a black decimetric arenitic layer intercalated between the Upper Messinian Lago-Mare sediments and the Zanclean Argille Azzurre Formation, was recently recovered also in the succession cropping out along the Tanaro river (Albese). In the Moncucco quarry outcrop and borehole, as well as in the Narzole borehole, quantitative micropaleontological analyses were carried out on foraminifers, calcareous nannofossils and ostracods. In both these sites, many bioevents recognized at the Mediterranean scale were progressively recorded in the Piedmont Early Zanclean succession at stratigraphic distances from the M/Z boundary similar to the ones recorded in Sicily, Western and Eastern Mediterranean basins: a basal abundance peak of Globigerina nepenthes, one sinistral coiling shift of Neogloboquadrina acostaensis, the Globorotalia scitula common occurrence (CO), the re-immigration of Siphonina reticulata, the first influx of NADW (North Atlantic Deep Water) forms as Cibicidoides robertsonianus and the Globorotalia margaritae first common occurrence (FCO). Rare specimens of Ceratholithus acutus have been recorded at the very base of the Zanclean, whereas no specimens of Triquetrorhabdulus rugosus are recorded. Assemblages were ...