Jurassic calcareous nannofossil biostratigraphy of western Europe. Compilation of recent studies and calibration of bioevents

Renewed interest in Jurassic nannofossils over the past decade has significantly advanced understanding of taxonomy, evolution, and biostratigraphy. The diverse amount of new biostratigraphic information integrated into the present version of the Jurassic chronostratigraphic chart is summarized in a stratigraphic context and organized into three palaeogeographic regions. The cosmopolitan nature of early to middle Jurassic a nannofossil assemblages and the wealth of new information allowed a single succession of nannofossil events to be developed for western Europe. Provincialism and the relative lack of well-constrained data prevented any such succession being developed for the late Jurassic. Jurassic calcareous nannofossil evolution are discussed relative to the major transgressive-regressive cycles and facies cycles. At present, available nannofossil records can be correlated indirectly to the sequences stratigraphy through the ammonite biostratigraphy and only inferences made about responses of assemblages within system tracts. Two new calcareous nannofossil combinations are introduced.