Biogeochemical responses to global warming during the Paleocene–Eocene Thermal Maximum in the eastern Tethys

The Paleocene–Eocene Thermal Maximum (PETM; ~56 Ma) represents a rapid climatic perturbation, during which global average temperature rose by 5 to 10 °C and was likely triggered by a rapid emission of 13C–depleted CO2 evidenced by the large negative carbon isotope excursions observed globally. Numerous sites from deep oceans have been studied for the paleoclimatic changes during the PETM. However, subtropical shallow–marine eastern Tethys remains poorly understood despite its importance in regulating heat and moisture transport. A prior study on nannofossil biostratigraphy and carbon isotopes confirmed the occurrence of the PETM in the Tarim Basin of eastern Tethys. Here we present new high–resolution geochemistry data at the Kuzigongsu section in the Tarim Basin to assess environmental responses of eastern Tethys to climatic forcing during the PETM. Chemical weathering proxies (Chemical Index of Weathering, Plagioclase Index of Alteration, and Rb/Sr) support an enhanced terrestrial input shortly after the PETM onset, possibly due to intensified silicate chemical weathering. The PETM at the Kuzigongsu section is also characterized by increased nutrients such as P, Ni, and Cu, suggesting an intensification of marine primary productivity. Meanwhile, the Tarim Basin may have encountered bottom water anoxia supported by increased enrichment of redox–sensitive elements such as U and V. The ecosystem stress imposed by elevated nutrient fluxes and expansion of anoxic water is likely amplified by intensified chemical weathering, highlighting the importance of integrating multiple geochemical proxies in tracking environmental responses to rapid climate change.