Late Eocene uplift and erosion of Eastern Tibet initiated long-term Cenozoic global cooling

It has long been hypothesized that the Cenozoic climate change in Asia was primary driven by uplift of the Tibetan Plateau through increased rock weathering, although it may also result from global cooling, yet deconvolving Tibet uplift versus global climate signals is notoriously challenging. Therefore, paleoenvironmental and paleoaltimetric records with precise age constraints are essential. The Mangkang Basin from Eastern Tibet preserves continuous sediments spanning the late Eocene-Oligocene and contains abundant plant fossils which show significant climate change, providing the best archive to test the interplay between Tibet uplift and global climate change, however, remains poorly dated. In this manuscript, we precisely dated the Mangkang Basin by radiometrically anchored magnetostratigraphy. With the new age, we recalculate the paleoelevation of the Mangkang area and reconstruct the paleoclimate via plant fossils and palynologic data. Our results show that the Eastern Tibet experienced rapid uplift and has attained its current elevation, associated with significant climate cooling prior to the Eocene-Oligocene climate transition (EOT), suggesting that this cooling is mainly driven by uplift. This uplift is also temporally coincident with increased regional rainfall, increased sediment flux to the marginal seas, and an uptick in oceanic strontium isotope signatures. We conclude that the late Eocene uplift and erosion of Eastern Tibet—rather than the later Miocene Himalaya uplift or plateau-wide rise—initiated the long-term decline in atmospheric CO₂ and global cooling that ultimately culminated in the EOT.