Dynamic environment but no temperature change since the late Paleogene at Lühe Basin (Yunnan, China)

Abstract

The Eocene-Oligocene transition (EOT; ~34 million years ago) marks a critical shift from a greenhouse to an icehouse climate. Whereas temperatures derived from marine records show a consensus ~ 4°C cooling worldwide, there is an emerging picture that the terrestrial realm experienced a heterogenous response to rapid climate change. Here, we reconstruct an 8-million-year terrestrial temperature record across the EOT at a tectonically unresolved location at the margins of the Tibetan Plateau, Lühe Basin (Yunnan, China). Our multi-proxy organic geochemistry approach, complemented by sedimentological interpretations, shows that Lühe Basin was a dynamic fluvial environment that maintained relatively stable average temperatures from ~ 35 − 27 million years ago. These palaeotemperatures match our model-based estimates, as well as palaeobotany-based estimates at a nearby site; these stable palaeotemperature trends differ from the global marine cooling, supporting a heterogenous response of terrestrial sections. Furthermore, these palaeotemperature estimates match present-day values at this location, suggesting that this area has not undergone significant temperature change – and possibly no significant uplift – since the late Paleogene.