Formation and evolution of the Asian landscape during the Cenozoic

Abstract

<p>Asia has a unique set of landscapes, notably characterized by the highest plateau in the world, the strongest monsoon circulation, and an immense arid region. When and how this landscape was formed have long been investigated, but explanations remain elusive. In this paper, through a synthesis of both terrestrial and marginal marine sedimentary records and numerical simulation analyses, we propose that tectonic uplift/deformation and global cooling during the Cenozoic have controlled the evolution of Asian topography and climate, respectively, and, the Asian landscape. The Asian landscape has undergone three main stages of evolution, <i>viz</i>: development of low-relief topography and warm-dry climate during the Eocene (~50-34 Ma); emergence of high relief topography in the southwest, along with a diverse range of landforms elsewhere, associated with a warm monsoon-arid climate coupling system during the Oligocene to early Pliocene (34-3.0 Ma); and development of the typical Asian summer and winter monsoon circulation and present landscape since the late Pliocene, accompanied by significant global cooling. Our analyses reveal that the distribution of river catchments, flora, fauna and soils are controlled by tectonic uplift/deformation and palaeoclimate changes. Stepwise evolution of the Asian landscape since ~50 Ma was driven by tectonic deformation and global temperature changes, each of which may play different role(s) in landscape evolution. For instance, the India-Asia collision played a vital role in the formation of the Asian topographic configuration in the middle Eocene, which generated regional atmospheric circulation. On the other hand, global cooling during the late Pliocene played an important role in generating the modern-like Asian landscape including the rapid accumulation of loess deposits, strengthening of the Asian monsoon circulation, and the evolution of modern topography. To summarize, we broadly propose a three-stage history of landscape evolution in Asia during the Cenozoic. The detailed processes of Asian landscape evolution and the specific roles of tectonism and global temperature in controlling Asian landscapes and palaeoclimate evolution need to be further investigated.</p>