Lower Cretaceous palynoflora from the Binggou Formation of Jianchang Basin, western Liaoning, NE China and its U–Pb zircon age

The Jianchang Basin of western Liaoning, NE China is one of the important Mesozoic non-marine sedimentary basins in China. The Lower Cretaceous Binggou Formation is well exposed in this basin yielding abundant coal and fossils. Lately research on the invertebrate and plant fossils from this formation indicates this biota chronologically corresponding to the famous Fuxin biota. The present work uncovers a palynoflora in the Formation composed of 153 species of 59 genera which are represented by the assemblage of Cicatricosisporites-Osmundacidites-Concentrisporites. The assemblage is dominated by gymnospermous pollen and is evidenced of the upper Lower Cretaceous by the characters of its composition and the occurrence of such age-diagnostic elements as Cicatricosisporites, Appendicisporites, Erlianpollis and Jiaohepollis. New U–Pb zircon dating made by the authors from the middle of the coal seam of the formation, indicates a 106.5 ± 1.9 Ma age, and confirms the Binggou Formation and palynoflora belonging to the Albian of the Lower Cretaceous, for the first time. The paleoecological and paleoenvironmental characteristics based on the palynoflora are also reconstructed by using the Sporopollen EcoGroup (SEG) model and the Plant Ecological Model (Eco-plant model). It suggests that the flora flourished in an environment characterized by the coexistence of both highland and lowland river systems. During the period when this flora existed, humidity levels increased slightly, and the environment remained stable, showing no evidence of large-scale climatic disturbances.