Revised stratigraphy of the Serra Palazzo Formation, a Miocene foredeep turbidite succession of the Southern Apennines (Italy)

This paper illustrates a new structural and stratigraphic framework of the Serra Palazzo Formation, a Miocene turbidite succession cropping out at the outer border of the Southern Apennines. The study was performed in the type area of the Serra Palazzo Formation, in the neighbourhood of Stigliano village (Basilicata, Southern Italy). Structural data indicate that in the area under study the Serra Palazzo Formation has been split into different east-verging thrust sheets, whose decollement level is localized in the upper part of the Flysch Rosso Formation. The stratigraphy of the formation is shown in two sections (S1 and S2), which belong to two superimposed thrust sheets. Quantitative biostratigraphic analyses were performed on the calcareous nannofossil assemblages. The study shows that the Serra Palazzo Formation is about 500 m thick in the type area and from bottom to top consists of: a) a lower, coarse-grained siliciclastic turbidite unit (Tempa Cisterna Member), which lies stratigraphically on the Flysch Numidico Formation and is Burdigalian-Langhian in age; b) an upper siliciclastic and calciclastic, fine-grained turbidite unit (Jazzo Porcellini Member) that is Serravallian in age. The Jazzo Porcellini Member passes upward into the Marne argillose del Toppo Capuana Formation, of Serravallian-Tortonian age. The Tempa Cisterna Member, which has a northwestern feeding area, reaches its maximun thickness (350 in) in the inner thrust sheet; on the contrary, the Jazzo Porcellini Member shows evidence of a consistent eastern supply and has its maximum thickness (250 m) in the outer thrust sheet. Preliminary studies suggest that the stratigraphic framework of the Serra Palazzo Formation as reconstructed in the study area can be recognised also in other areas of the Southern Apennines; these observations provide new data on the evolution of the Southern Apennines Miocene foredeep.