Abstract:Through study on Paleozoic sporopollen fossil assemblage of No.223 Yan well of Yanchang oil field, and the restoration of ancient vegetation, the significance of stratigraphy and paleoclimate of late Paleozoic plants fossil of pollen assemblages has been studied. According to the longitudinal distribution of main species of pollen fossils and regular change of percentage contents in all samples, 3 assemblages have been set up from lower to upper part, they are Gulisporites cochlearius Laevigatosporites minimus, Sinulatisporites Florinites and Lueckeisporites permianus Platysaccus radialis. According to characteristics analysis on these pollen assemblages, through comparision with adjacent areas and North China, significance of the times of these pollen assemblages has been studied. Through the establishment of pollen assemblages, the ancient vegetation types of corresponding periods have been inferred, and compared with the plant fosills in the same geological period, the rise, development, thriving and recession extincti historical process of vegetation in various geological periods have been analyzed. The Permian flora in the study area is typical Cathaysia flora. It reflects a warm and humidtropical rain forest climate. Accompanying with the increase of pine and cypress plants in late Permian, climate became more drought.
