Author: YIN Feng-Juan and HOU Hong-Wei
J Integr Plant Biol 1999, 41 (3): -.
Abundant spores and pollen grains including 60 genera and 83 species were collected from the Yan'an Formation in Binxian County, Shaanxi Province. In this assemblage gymnospermous pollen grains amounted to 51.2%, among which Cycadopites made up 27.2% and Quadraeculina 7.2%, also including a certain amount of other genera such as Monosulcites, Eucommiidites, Cerebropollenites, Chasmatosporites, Pinuspollenites , Piceaepoltenites , Piceites Podocarpidites , Psophosphaera , Araucaracites , Classopollis , Callialasporites, etc. Pteridophyte spores amounted to 48.8%, among which Cyathidites made up 21.4%; Deltoidospora 9.1% and Duplexisporites 3.1%. Osmundaciclites , Granulatisporites , Lycopodiumsporites , Neoraistrickia, Densoisporites, Microreticulatisporites, Undulatisporites, Cibotiumsporites, Gleicheniidites, Concavissimisporites, Cyclogranisporites, etc, each constituted less than 3%. Based on stratigraphical ranges of certain important known species and comparison with those from other regions in China and Western Canada, the sporopollen assemblage of the Yan' an Formation under study may be assigned to Middle Jurassic in age. Its palaeovegetation and palaeoclimatic conditions are also discussed.