Abstract
The Tibetan Plateau was built through a succession of Gondwanan terranes colliding with Asia during the Mesozoic. These accretions produced a complex Paleogene topography of several predominantly east–west trending mountain ranges separated by deep valleys. Despite this piecemeal assembly and resultant complex relief, Tibet has traditionally been thought of as a coherent entity rising as one unit. This has led to the widely used phrase ‘the uplift of the Tibetan Plateau’, which is a false concept borne of simplistic modelling and confounds understanding the complex interactions between topography climate and biodiversity. Here, using the rich palaeontological record of the Tibetan region, we review what is known about the past topography of the Tibetan region using a combination of quantitative isotope and fossil palaeoaltimetric proxies, and present a new synthesis of the orography of Tibet throughout the Paleogene. We show why ‘the uplift of the Tibetan Plateau’ never occurred, and quantify a new pattern of topographic and landscape evolution that contributed to the development of today’s extraordinary Asian biodiversity.
Highlights
The modern Tibetan Plateau (Fig. 1) is the highest and most extensive elevated surface on Earth covering an area of 2,500,000 km2at an average elevation above 4500 m
Westwards the plateau boundary is marked by the Karakoram strike–slip fault, while 2000 km to the east the plateau morphs into the Hengduan Mountains and down into Yunnan and Sichuan
There are several depositional basins preserved along the Bangong– Nujiang Suture Zone (BNSZ) and two, the Nima and Lunpola (Fig. 1), are of particular importance because they yield surface height estimates based on both isotopes and fossils
Summary
The modern Tibetan Plateau (Fig. 1) is the highest and most extensive elevated surface on Earth covering an area of 2,500,000 km2at an average elevation above 4500 m. There are several depositional basins preserved along the BNSZ and two, the Nima and Lunpola (Fig. 1), are of particular importance because they yield surface height estimates based on both isotopes and fossils The successions within these basins are divisible into a predominantly fluvial Paleocene–Eocene Niubao Formation and an overlying 1000-m-thick, predominantly lacustrine, Oligocene–Miocene (25.5–20 Ma) Dingqing Formation (Du et al 2004; Ma et al 2015, 2017; Han et al 2019), with limited age control constrained by radiometrics (He et al 2012), magnetostratigraphy (Sun et al 2014a, b), cyclostratigraphy (Ma et al 2017) and palynology (Wang et al 1975; Sun et al 2014a, b). Even if we ignore avian propagule dispersal, just a few narrow mountain passes would have been sufficient to afford biotic exchange
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