Dinoflagellate cyst biostratigraphy of the Bathonian, Callovian, and the Upper Jurassic in North Bulgaria

Forty-four selected organic-walled dinoflagellate cyst species have been used for biozonation of the Bathonian, Callovian, and Upper Jurassic in North Bulgaria. The dinocysts were collected from 49 borehole sections two exposures. following dinocyst zones are herein introduced described: Lithodinium valensii–Gongylodinium erymnoteichos Concurrent-range Zone (lower–middle Bathonian); Ellipsoidictyon reticulatum Assemblage (upper Bathonian–lower Callovian); Dingodinium harsveldtii Taxon-range (middle–upper Lambodinium absidatum (lower Oxfordian); Scriniodinium dictyotum papillatum–Caddasphaera halosa Rhyncodiniopsis gongylos Kimmeridgian); Systematophora varispinosa–Gonyaulacysta? crassicornuta Edmontodinium polyplacophorum Tithonian); Leptodinium? plagatum–Prolixosphaeridium perforospineum Tithonian). Some partly or completely subdivided subzones. subzones correlated with Bulgarian ammonite calpionellid