Estimates of Late Albian atmospheric CO2 based on stomata of Pseudofrenelopsis from Jilin Province, Northeast China

Abstract Stomata characteristics of two extinct conifer Cheirolepidiaceae species, Pseudofrenelopsis gansuensis and Pseudofrenelopsis dalatzensis were used to reconstruct the atmospheric carbon dioxide concentration levels during the late Albian of Cretaceous. A sequence of fossil samples was collected from 5 beds in the Dalazi Formation in Zhixin and Luozigou basins of Jilin Province, northeastern China. The stomatal index was used to estimate the palaeo- p CO 2 . The average stomatal index value of the two species was 4.1 and the atmospheric CO 2 content was ∼1200 ppmv by the average of Recent standardization and Carboniferous standardization. During the short interval of 104.8±0.5 Ma to 104.0±0.4 Ma in the late Albian, the atmospheric CO 2 contents present a deceasing tendency, and the highest value was ∼1300 ppmv in the Luozigou Basin. In addition, the higher atmospheric CO 2 values of late Albian likely linked to a “greenhouse climate” time of Oceanic anoxic event 1c (OAE1c).