Cadmium isotopic evidence for the evolution of marine primary productivity and the biological extinction event during the Permian-Triassic crisis from the Meishan section, South China

• Published in: Chemical geology Vol. 481; pp. 110 - 118
• Main Authors: Zhang, Yuxu, Wen, Hanjie, Zhu, Chuanwei, Fan, Haifeng, Cloquet, Christophe
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.03.2018; Elsevier
• Subjects: Cd isotope; Earth Sciences; Geochemistry; Mass extinction; Meishan section; Permian-Triassic Boundary; Primary productivity; Sciences of the Universe; Cd isotope; Primary productivity; Meishan section; Permian-Triassic Boundary; Mass extinction
• ISSN: 0009-2541; 1872-6836
• DOI: 10.1016/j.chemgeo.2018.02.005

Cadmium (Cd) isotopic compositions in seawater are important parameters for tracing the biogeochemical cycling of Cd in modern oceans and may be used as a direct proxy for nutrient utilization by phytoplankton and an indirect proxy for primary productivity. In this study, we measured the stable Cd isotope ratios (δ114Cd) of marine sedimentary carbonates from the Meishan section in Changxing County of Zhejiang Province, South China, the Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary (PTB). The results suggest that the inferred marine primary productivity recorded in the marine carbonates from the Late Permian (i.e., before the mass extinction) was high and relatively stable (the δ114/110Cd values of carbonates range from +0.31‰ to +0.60‰; after correction for salinity-controlled fractionation into inorganic calcite, the δ114/110Cd values of palaeo-seawater range from +0.47‰ to +0.79‰). During the mass extinctions, the δ114/110Cd values of carbonates abruptly decreased at the beginning of each episode of mass extinction, suggesting that the primary productivity of the palaeo-ocean declined before each episode of extinction events at the PTB. We suggest that the mass extinction events at the PTB in the Meishan section could be a ripple effect due to the destruction of primary producers at the base of the food chain in the palaeo-ocean ecosystem. •Cd isotopic variations from the Meishan GSSP section were investigated.•Shift of Cd isotopes correspond with each episode of mass extinction during the PTB.•Decline of marine primary productivity may result in mass extinction as revealed by Cd isotopes.•Cd isotopes can be as a proxy to reconstruct past ocean circulation and nutrient utilization.