Cenozoic global temperature and regional humidity changes jointly drove the silicate weathering evolution: A record from the Weihe Basin in Central China

The mechanisms that enable the Earth system to maintain habitability are much debated. The influences of active tectonic uplift and the temperature feedback are proposed. The temperature negative feedback mechanism is considered one of the key processes preventing excessive CO₂ consumption. However, the specific mechanisms by which temperature variations during the Cenozoic influenced silicate weathering are still poorly understood. Regional weathering records during the Cenozoic are needed to elucidate these processes. Up till now, records of robust Cenozoic weathering intensity is still limited. Most records are based on marine deposits, which contain mixed signals from tectonics and temperature. As the weathering indicator for the terrestrial sediments could be affected by provenance of sediments, or transportation processes, few method can simultaneously distinguish these influences and accurately reconstruct the weathering intensity. In this study, we generated a record of chemical weathering intensity from the Weihe Basin in Central China, with deposition covering the late Eocene, early Oligocene, middle to late Miocene, Pliocene and Pleistocene. The record is based on mineral composition by Evaluation of Minerals by Scanning Electron Microscopy, which can reveal weathering intensity by feldspar assembalges, and provenance by heavy mineral compositions in the sediments simultaneously. Our results show that, despite the persistent decrease in the global temperature, the chemical weathering intensity increasd at boundary of Eocene and Oligocene, remained relatively high during Oligocene to Pliocene, and decreased at the Pliocene-Pleistocene boundary. This indicates that silicate weathering may not respond directly to global temperature changes. Instead, variations in regional precipitation and humidity are also the influencing factors on the intensity of silicate weathering. Our findings contribute to understanding the weathering-climate interactions, but further data integration and comparative analyses are still needed for a more comprehensive assessment.