Hafnium-neodymium isotopic evidence for latitudinal heterogeneity in continental silicate weathering during the Paleocene-Eocene thermal maximum

The Paleocene-Eocene Thermal Maximum (PETM) was a geologically transient global warming event accompanied by substantial carbon injection into the ocean-atmosphere system and profound changes to Earth surface environments. Enhanced continental silicate weathering provides a key potential mechanism to sequester carbon during recovery from “hyperthermal” conditions; however, evidence for this process and its spatial variability during the PETM remains limited. Here, we use coupled hafnium‑neodymium (Hf Nd) isotopes in fine-grained marine sediments (△ε Hfclay ) from three sites spanning low to high latitudes to reconstruct spatial variability in chemical weathering intensity during the PETM. Rare earth element abundances and Nd isotopic compositions of detrital fractions indicate dominantly fluvial inputs from surrounding continents at all studied sites. During the PETM, both low- and high-latitude sites exhibit pronounced increases in △ε Hfclay values, indicative of enhanced terrestrial weathering intensity under warm and humid regional climate. By contrast, the mid-latitude site shows minimal variability in △ε Hfclay , suggesting latitudinal heterogeneity in silicate weathering. We infer that enhanced annual aridity superimposed by intensified hydrological seasonality likely explains the muted weathering response at mid-latitudes, which effectively reduced the water availability of the source regions. By integrating physical erosion rates with chemical weathering intensity, we further estimate an approximately 2–10-fold increase in silicate weathering rate during the PETM, indicating enhanced capacity for atmospheric CO 2 drawdown across latitudes. Overall, our results emphasize the role of regional hydroclimate variability in modulating the continental silicate weathering, thereby contributing to the global carbon cycle during the PETM recovery.