Geochemical evidence for Late Eocene to Oligocene climate change in the Lühe Basin of the southeastern Tibetan Plateau

Abstract

The transition from the Eocene to the Oligocene marks a critical phase in Earth’s history, characterized by a shift from greenhouse to icehouse conditions. While global climate changes during this period have been extensively studied, continental geological evidence particularly from landmasses such as the Tibetan Plateau (TP) and its surrounding regions remained limited. Addressing this research gap, our study employs high-resolution trace element geochemical records from the Lühe Basin at the southeastern margin of the Tibetan Plateau (SEMTP) to systematically investiate sediment provenance and weathering processes from the Late Eocene to the Oligocene (35.5–25.5 Ma). The results indicate that the sediment provenance in the Lühe Basin shows limited variation across different scales of provenance analysis, and lithological have little effect on the reconstruction of chemical weathering records. Based on various geochemical proxies, three distinct phases in the evolution of weathering are identified: (1) a phase of progressively intensified weathering during the Late Eocene, (2) a marked decline in weathering intensity during the Eocene-Oligocene Transition (EOT), and (3) a phase of recovery followed by sustained fluctuations in the Oligocene. Furthermore, we discuss the potential global climatic and regional environmental drivers underlying each phase.