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