A preliminary biogeochemistry-based quantification of primary productivity of end-Permian deep-water basin in Dongpan Section ,Guangxi ,South China

In this paper, the mean primary productivity of the Talung Formation in the deep-water basin (50–500 m depth) of Dongpan, Guangxi, South China, was calculated, roughly ranging from 0.1 to 0.6 g C·m⁻²·day⁻¹ on the basis of the content of the trace element Cu. Results showed that the primary productivity obtained was comparable with the previously-reported data for the black shale of the Phosphoria Formation, a Permian phosphate deposit in the northwest United States, and also similar to that of the modern deposit in the Cariaco basin, Venezuela. It was observed that the primary productivity increased with the enhanced abundance of algae and photosynthetic bacteria, and with the decrease in both the radiolarian individuals and the body size of brachiopods during the faunal mass extinction. This ecological coupling indicates that the changes of primary productivity are closely related to the propagation and the decline of producers (algae and bacteria), and that consumers (radiolarians and brachiopods) probably have little influence on the changes of primary productivity.