Late Triassic flora of the northern part of the Fore-Caspian depression(Kazakhstan)as exemplified by data from the S.Nurzhanov-509 borehole

The Late Triassic Nurzhanov flora is characterized on the basis of the material originated from the S.Nurzhanov-509 borehole disposed in the northern part of the Fore-Caspian depression,near the City of Atyrau,Republic of Kazakhstan.Taxonomic composition of the Nurzhanov flora includes equisetophytes Neocalamites sp.,ferns Phlebopteris hazarensis Naugolnykh et Pronin,Todites sp.,Cladophlebis sp.,ginkgophytes Ginkgoites spp.,conifers Podozamites sp.Palaeophytogeographic status of the Nurzhanov flora is discussed.According to the data obtained,this flora belongs to a transitional zone(an ecotonous belt),which existed between the Euro-Sinian and the Siberian-Canadian palaeofloristic realms during most of the Mesozoic time.