Shallow Benthic and Calcareous Nannofossil Zones of the Eocene Monte Postale section, northern Italy

The Monte Postale, near Bolca (Lessini Mts., northern Italy), is one of the most famous localities of the Italian Eocene, especially because of the fish-bearing laminated limestones. Recently, a series of intensive fieldwork and studies focused on the non-laminated limestones and marls allowed to collect new data about the biostratigraphy of the Monte Postale section. The larger foraminifera, mainly Alveolina, are very common in the non-laminated limestones along the entire section, more than 90 m thick. Several marly layers were investigated for calcareous plankton analysis, but only in a few of them the calcareous nannofossil content was suitable for dating. The Alveolina assemblages are indeed quite homogeneous along the section, but the range of the index species is different from the one reported in the standard SB Zonation of Serra-Kiel et al. (1998). It seems that a mix of elements from the SBZ 11 and 12 is present throughout the section, whereas some species characteristic of SBZ 10 are scattered only in the lowermost part of the section itself. The latter species could reasonably be reworked, but as to the rest of the assemblages the abundance and the preservation state of the specimens rather suggest the coexistence of species since now regarded as belonging to separate SBZ. Amongst calcareous nannofossils, the presence of Nannotetrina cristata s.l. and the absence of Nannotetrina alata in the lowermost part of the Postale section suggest the CNE 8 Zone (=NP 14b; Agnini et al., 2014) or lowermost Lutetian, according to the recent GSSP formalization of the base of the Lutetian (Molina et al., 2011). The correlation with the SBZ needs therefore to be revised, because both SBZ 11 and 12 are currently regarded as belonging to the Cuisian (=upper part of the Ypresian). References AGNINI, C., FORNACIARI, E., RAFFI, I., CATANZARITI, R., PÄLIKE, H., BACKMAN, J., RIO, D., 2014. Biozonation and biochronology of Paleogene calcareous nannofossils from low and middle latitudes. Newsletters on Stratigraphy, 47/2, 131-181. MOLINA, E., ALEGRET, L., APELLANIZ, E., BERNAOLA, G., CABALLERO, F., DINARÈS-TURELL, J., HARDENBOL, J., HEILMANN-CLAUSEN, C., LARRASOAÑA, J.C., LUTERBACHER, H., MONECHI, S., ORTIZ, S., ORUE-ETXEBARRIAT, X., PAYROS, A., PUJALTE, V., RODRÍGUEZ-TOVAR, F.J., TORI, F., TOSQUELLA, F., UCHMAN, A., 2011. The Global Stratotype Section and Point (GSSP) for the base of the Lutetian Stage at the Gorrondatxe section, Spain. Episodes, 34, 86-108. SERRA-KIEL J., HOTTINGER L., CAUS, E., DROBNE, K., FERRÀNDEZ, C., JAUHRI, A. K., LESS, G., PAVLOVEC, R., PIGNATTI, J., SAMSÓ, J. M., SCHAUB, H., SIREL, E., STROUGO, A., TAMBAREAU, Y., TOSQUELLA, J., ZAKREVSKAYA, E., 1998. Larger foraminiferal biostratigraphy of the Tethyan Paleocene and Eocene. Bulletin de la Société géologique de France, 169 (2), 281-299.