Stratigraphy of the Valanginian Buwaib Formation and recognition of the Weissert Event on the Arabian Plate.

Abstract

Summary This study aims to reconstructs the stratigraphic framework of the Valanginian/Hauterivian carbonate deposits of the Buwaib Formation in Saudi Arabia by integrating detailed sedimentology and biostratigraphy along with carbon isotope variations. The main observations suggest that most of the Valanginian encompasses a 3rd order sequence initiated by the karstified early Valanginian exposure, likely dated from the top of the pertransiens ammonite zone. The early/late Valanginian transition has been identified by changes in dynocyst assemblages correlated with carbon isotope variations. The main result of this study particularly highlights that proliferation of the Lithocodium/Bacinella facies in the southern Tethys during the late Valanginian is strongly associated with the general drowning of the platform, associated with major climatic changes during the Weissert Event and would therefore correspond to a 3rd order maximum flooding interval at the vicinity of the verrucosum ammonite biozone.