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

Abstract. The complex tectonic evolution in the Tibetan region has impacted climate, the Asian monsoon system, and the development of major biodiversity hotspots, especially since the onset of the India-Eurasia continental collision during the early Paleogene. Untangling the links between the geologic, climatic, and ecological history of the broader region can provide insights into these Earth system mechanisms, relevant for the future of our rapidly changing planet. To better understand environmental conditions across this critical time and place, we reconstruct the climatic and environmental history from a key sedimentary repository within the Lühe Basin, Yunnan, China, uniquely located between high elevation Tibet and low elevation coastal China. We investigate a 340-m long section using a multi-proxy organic geochemistry approach, complemented with sedimentological interpretations and climate model simulations. The complementary organic geochemical proxies, including n-alkanes, terpenoids, and hopanes, suggest that these thermally immature sediments were deposited in a dynamic environment that fluctuated between low energy floodplains and high energy fluvial systems. Our branched glycerol diakyl glycerol tetraether-based proxies indicate terrestrial temperatures of around 17 °C ± 3 SD and our model-based temperatures indicate terrestrial temperatures for Chattian of around 19 °C, consistent with the literature palaeobotany-based temperatures from the nearby Lühe town section. These combined palaeotemperatures match present-day values, suggesting that this area has not undergone significant temperature change since the late Paleogene.