古生态研究组知识库

The uplift of eastern Tibet, Asian monsoon development and the evolution of globally significant Asian biodiversity are all linked, but in obscure ways. Sedimentology, geochronology, clumped isotope thermometry, and fossil leaf-derived numerical climate data from the Relu Basin, eastern Tibet, show at similar to 50-45 Ma the basin was a hot (mean annual air temperature, MAAT, similar to 27 degrees C) dry desert at a low-elevation of 0.6 +/- 0.6 km. Rapid basin rise to 2.0 +/- 0.9 km at 45-42 Ma and to 2.9 +/- 0.9 km at 42-40 Ma, with MAATs of similar to 20 and similar to 16 degrees C, respectively, accompanied seasonally varying increased annual precipitation to > 1500 mm. From similar to 39 to 34 Ma, the basin attained 3.5 +/- 1.0 km, near its present-day elevation (similar to 3.7 km), and MAAT cooled to similar to 6 degrees C. Numerically-modelled Asian monsoon strength increased significantly when this Eocene uplift of eastern Tibet was incorporated. The simulation/proxy congruence points to a distinctive Eocene Asian monsoon, quite unlike that seen today, in that it featured bimodal precipitation and a winter-wet regime, and this enhanced biodiversity modernisation across eastern Asia. The Paleogene biodiversity of Asia evolved under a continually modifying monsoon influence, with the modern Asian monsoon system being unique to the present and a product of a long gradual development in the context of an ever-changing Earth system. (c) 2022 Science China Press. Published by Elsevier B.V. and Science China Press.