Sedimentary Processes and Carbon Isotope Records Across the Devonian-Carboniferous Boundary in South China

The Hangenberg mass extinction across the Devonian–Carboniferous transition exerted a profound impact on ecosystem evolution and was accompanied by intense perturbations in the global carbon cycle. However, global correlation of Devonian–Carboniferous boundary (DCB) remains challenging due to eustatic sea-level fluctuations, stratigraphic condensation or hiatuses, and faunal provincialism, which collectively pose difficulties in determining the precise position of the DCB. Currently, the International Working Group is actively seeking a new Global Boundary Stratotype Section and Point (GSSP) for the DCB, although the previous GSSP was established in 1990 at La Serre section, France. This study presents a high-resolution carbon isotope (δ13Ccarb) chemostratigraphic and sedimentological investigation of three sections across different sedimentary facies in South China (the Malanbian, Xiasi, and Bangshangtun sections). Within the biostratigraphic framework, our results reveal that the DCB is consistently located near the “trough” between two distinct positive carbon isotope excursions, a pattern that is consistent with global chemostratigraphic records. We therefore propose that high-resolution carbon isotope stratigraphy, when integrated with biostratigraphy, can offer robust support in sections where biostratigraphic markers are discontinuous. This study not only establishes a high-precision chemostratigraphic framework for DCB correlation in South China but also provides a valuable basis for evaluating the selection of an ideal GSSP.