Research Advances in Paleobotany and Stratigraphy of the Lower Cretaceous Binggou Formation in the Jianchang Basin, Western Liaoning

The Binggou Formation, located in the Lower Cretaceous of the Jianchang Basin in western Liaoning, is well-exposed and yields abundant coal and fossils. Chronologically, it corresponds to the famous Fuxin Formation and has produced rich plant fossils and palynofloras. In recent years, comprehensive research on the stratigraphy, plant fossils, palynology, and paleoenvironment of the Binggou Formation has been conducted, yielding a series of significant findings, including: (1) The U-Pb zircon dating was performed on the fossil horizon of the formation. The obtained zircon age of 106.5 ± 1.9 Ma confirms that the Binggou Formation and its palynoflora belong to the Albian stage of the Early Cretaceous. (2) The overall characteristics of the Binggou Formation flora are dominated by conifers, accompanied by pteridophytes, cycads, ginkgos, and Czekanowskiales. Analysis of the composition characteristics and representative elements of the plant groups indicates that the flora exhibits typical features of the Early Cretaceous Northern Hemisphere (Boreal) flora of Eurasia, suggesting a temperate to warm temperate climate with seasonal variations. (3) The spore-pollen assemblage from samples collected layer by layer is primarily composed of gymnospermous plants (mainly conifers involved in forest formation), supplemented by moisture- and warmth-loving ferns, which indicates a warm, humid climate with seasonal variations. (4) The fossil leaves of Ginkgoales and Czekanowskiales collected from the Binggou Formation were analyzed using the stomatal parameter method, and the results yielded the paleoatmospheric CO2 concentration for this period (mid-Albian). The calculated values are 1137 ppmv (Recent Standardization) and 1895 ppmv (Carboniferous Standardization). Comparison with global geochemical models for the Cretaceous and other paleo-CO2 reconstructions using the stomatal proxy method suggests that global CO2 concentrations during the Albian should have been relatively high, corresponding to the overall higher global temperatures of that period. Grant Number: NSFC (41902009), Liaoning Provincial Department of Education Scientific Research Platform Construction Project (LJ232510166001)