CALCAREOUS NANNOFOSSIL DATING OF THE SAN MARTINO FORMATION FROM THE BALAGNE OPHIOLITE SEQUENCE (ALPINE CORSICA): COMPARISON WITH THE PALOMBINI SHALE OF THE NORTHERN APENNINE

Abstract

In the Alpine Corsica, the ophiolitic sequences are regarded as remnants of the Ligure-Piemontese oceanic lithosphere. The best preserved ophiolitic sequences are represented by the succession from the Balagne nappe, northern Corsica. This succession consists of a Jurassic ophiolite sequence topped by a Jurassic - Late Cretaceous sedimentary cover. This sedimentary cover, affected by very-low grade metamorphism, consists of deep-sea deposits, represented by Chert, Calpionella Limestone, San Martino Fm., Lydienne Flysch and Novella Sandstone. The latters two formations are characterized by terrigenous turbidite deposits supplied by Europe/Iberia continental margin. In this paper the age of the San Martino Fm. and the lower part of the Lydienne Flysch has been determined by the study of the calcareous nannofossil assemblages. The collected data indicate for the San Martino Fm. an age spanning from Early Berriasian to Late Hauterivian - Early Barremian. Moreover, the lower part of the Lydienne Flysch is not older than Late Hauterivian and not younger than Early Barremian. By comparison with the data available from ophiolite sedimentary cover of Northern Apennine, the San Martino Fm. can be correlated with the lower part of the Palombini Shale. This correlation suggests that the upper part of the Palombini Shale can be considered as time equivalent to the Lydienne Flysch.