Valanginian Radiolarians of Ne Sardinia (Italy) in the Frame of the Weissert Event

Abstract

This article presents the very rich radiolarian fauna from the S’Ozzastru section of the Siniscola Marl crop-ping out in the northern part of Mt Albo massif (NE Sardinia, Italy). The formation was ascribed to the lower part of the upper Valanginian on the basis of the ammonite fauna indicating the Verrucosum Zone and the nannofossil con-tent suggesting the Zone NK3. Due to the scarcity of pantanelliids and especially of the absence of Cecrops septem-poratus, radiolarian marker of the upper Valanginian, radiolarians can only indicate a Valanginian age. Investigations for integrated litho-, bio-, and chemostratigraphy allowed the identification of the Valanginian Weissert Oceanic An-oxic Event (OAE), testified by a positive carbon isotope excursion (CIE) with values up to 2.98 ‰. Radiolarian study includes not only a determination of the species for biostratigraphic interpretations, but also a revision of the system-atics of the radiolarians occurring in the section. One new family (Crococapsidae), 3 new genera (Apiaromitra, Mi-crosandwichia and Ocellicapsa) and 43 new species are erected. The fauna has some elements in common with the Valanginian faunas from the Mediterranean area and many more with those from Japan, proving a wide circulation between the western and eastern Tethys.