AMMONITES AND INFRAZONAL STRATIGRAPHY OF THE KIMMERIDGIANAND VOLGIAN STAGES OF PANBOREAL SUPERREALM
Boreal and Subboreal ammonite taxa, belonging to the families Cardioceratidae, Aulacostephanidae, Oppeliidae, Aspidoceratidae,Ataxioceratidae, Virgatitidae, Dorsoplanitidae and Craspeditidae which are most characteristic for the Kimmerigian and Volgian stages were revised. Their phylogenetic relationship, geographic and stratigraphic distribution as well as peculiarities of evolution were specified. Key genera of Kimmeridgian and Volgian ammonites are described. Two new genera ( Michailoviceras and Arctocrendonites ), as well as10 new species ( Suboxydiscites birkelundae, Sutneria perplexa , Virgatites saratovensis , Dorsoplanites callomoni , D. laevis , Praechetaites schulginae , Kachpurites praefulgens , K. laevis , Laugeites mesezhnikowi , L. muravini ) are established. Infrazonal subdivision of the considered stratigraphic interval has been substantially specified (and for some regions it has been proposed for the first time). In the Kimmeridgian and Volgian Stages of the Panboreal Superrealm 42 inter-regionally correlated stratigraphic levels have been traced, allowing for a detailed correlation of zonal and infrazonal scales to be justified. On this basis, a new version of the ammonite scale of the Boreal zonal standard was developed. In the Kimmeridgian and Volgian Stages 31 stratigraphic levels have been identified that allow for detailed Boreal-Tethyan correlation. The lower boundaries of the Kimmeridgian and Volgian Stages are reliably traced in marine facies all over the world, while the upper boundary of the Volgian Stage is clearly fixed within the Panboreal Superrealm, but in the Tethys-Pantalassa Superrealm this level does not correspond to any zonal or subzonal boundary.The description of the key studied sections and the determination of ammonites from boreholes are given in the electronic supplement to the monograph: http://ginras.ru/library/pdf/627_2021_supplement.pdf