Tectonic and Climatic Impacts on Environmental Evolution in East Asia During the Palaeogene.

Palaeogene environmental evolution in East Asia remains ambiguous. Here we present integrative work including magnetostratigraphy, grain‐size, geochemistry, and clay mineralalogy from a 1609 m‐thick fluviolacustrine sequence in eastern China. The results reveal two periods of tectonic control alternating with three periods of climatic control on the sedimentary evolution. Tectonic activity in the study area, as revealed by particle coarsening and reduced weathering, occurred during 65.6–59 Ma and strengthened in Asia during 55–54 Ma in response to the India‐Eurasia collision. Weathering gradually enhanced in East Asia during 59–55 Ma, probably caused by global warming. Continuous global warming during 54–50.5 Ma is responsible for enhanced aridification in East Asia. From 50.5 to 37.6 Ma, global cooling weakened evapotranspiration and increased westerlies‐derived moisture. Both aspects increased effective moisture and chemical weathering in East Asia. These results shed light on how alternating tectonism and climate change impacted environmental evolution in Asia during the Palaeogene. Plain Language Summary: Most investigations in sedimentary basins generally focus exclusively on climatic signals at the expense of tectonic inputs. In this study, we extract both climatic and tectonic signals from long fluviolacustrine sediment records in eastern China comprehensively and objectively. We find that environmental evolution during the Paleogene of East Asia was dominated by tectonism during 65.6–59 and 55–54 Ma, and by climatic changes during 59–55 and 54–37.6 Ma. This work not only constrains the India‐Asia collision to a short 55–54 Ma interval for the first time, but also offers a sound explanation for one of the most important but disputed issues of eolian sediments in the North Pacific Ocean. Key Points: Tectonic activity occurred during 65.6–59 Ma in East Asia and strengthened during 55–54 Ma in response to the India‐Eurasia collisionIn East Asia, global warming led to enhanced weathering during 59–55 Ma and aridification during 54–50.5 MaGlobal cooling between 50.5 and 37.6 Ma increased westerlies‐derived moisture and enhanced chemical weathering in East Asia [ABSTRACT FROM AUTHOR]