Transient fluctuation in paleoclimate at the end of Permian: New constraints from paleosol carbonates in the Erlongkou section, Chongqing, southwestern China

Abstract

Paleosol carbonates were found in the Erlongkou section at the top of the Changhsing Formation in Chongqing, southwestern China. Detailed petrology study suggested that these paleosol carbonates have typical pedogenic structures and fabrics. Conodont biostratigraphy, volcanic ash zircon dating, and stratigraphic carbon isotopes indicated that the paleosol carbonates formed at the end of Permian (252.3 ± 1.0 Ma). Geochemical results indicate two different provenances for the paleosol (i.e., the micrite of the Changhsing Formation and volcanic ash). The calcretes and carbonates in the paleosol are pedogenic calcites that precipitated under well-drained conditions, and they are free of carbonate debris from the bedrocks. Atmospheric CO2 concentrations (pCO2) estimated based on the model of Cerling (1999) suggested that there was greenhouse paleoclimates with a transient fluctuation in pCO2 at the end of the Permian.