Palynological assemblages and their implications for paleoclimate of the Middle Jurassic Wanbao Formation in Suolun region, Hinggan League, the western margin of Songliao Basin

In recent years, Jurassic strata have become a new layer for oil and gas exploration in Songliao Basin and its periphery. To determine the paleoclimate environment in the Middle Jurassic, we systematic analysized palynological fossils collected from the Middle Jurassic Wanbao Formation in Suolun region, the western margin of Songliao Basin.Totally 48 species of 32 genera, including 46.01% in pteridophyte spores and 53.99% in gymnosperm pollen, were recognized from the Wanbao Formation.The palynological assemblage is represented by Cyclogranisporites-Protopinus-Pristinuspollenites, indicating that the age of the Wanbao Formation in the Suolun region should be assigned to the Middle Jurassic.Combined with the features of the ecological environment, the Middle Jurassic Wanbao palynoflora mainly composed of coniferous forests and shrubs, could indicate a subhumid to humid warm temperate climate, providing new evidence for the recovery of the paleoclimate and paleovegetation of the Suolun region in the Middle Jurassic.