Palaeo-altimetry of the late Eocene to Miocene Lunpola basin, central Tibet

Abstract

The elevation history of the Tibetan plateau provides direct insight into the tectonic processes associated with continent-continent collisions. Here we present oxygen-isotope-based estimates of the palaeo-altimetry of late Eocene and younger deposits of the Lunpola basin in the centre of the plateau, which indicate that the surface of Tibet has been at an elevation of more than 4 kilometres for at least the past 35 million years. We conclude that crustal, but not mantle, thickening models, combined with plate-kinematic solutions of India-Asia convergence, are compatible with palaeo-elevation estimates across the Tibetan plateau.

A late Eocene palynological record of climate change and Tibetan Plateau uplift (Xining Basin, China)

“…The onset of the Indo-Asia collision is generally assumed to have occurred during Eocene times with a large range of ages (Tapponnier et al, 1986;Qinghai et al, 2012) including recent paleomagnetic estimates at 49 ± 6 Ma (Dupont-Nivet et al, 2010;van Hinsbergen et al, 2012). After the onset of the collision, there is growing evidence for accelerated intracontinental convergence, deformation and uplift during the Early Cenozoic (Horton et al, 2002;Spurlin et al, 2005;Rowley and Currie, 2006;DeCelles et al, 2007; C. Q. Wang et al, 2008;van der Beek et al, 2009;Song et al, 2010).…”

The altitude effect of δ 18O in precipitation and river water in the Southern Himalayas

“…According to the Rayleigh isotopic fractionation model [15], the relationship between precipitation δ 18 O and altitude is not linear, especially at extremely high elevation. At high elevation, the δ 18 O lapse rate decreases.…”

“…Thus, it is likely that isotope signals from the paleo-sediment record may preserve information about plateau uplift. Oxygen isotope signals from paleosoil have been used to reconstruct the uplift history of the plateau [11][12][13][14][15][16][17][18][19][20]. The stable isotope lapse rate is also used to calculate the contribution of tributaries from different elevations [21].…”

“…A crucial issue is calculating the precise isotopic lapse rate [15]. This can be achieved by a few approaches, such as isotopes in precipitation, river water, snow and ice, as well as modeling based on Rayleigh fractionation [21][22][23][24][25][26][27][28][29].…”

China: The third pole

“…Thus, the 18 O/ 16 O ratio can be used to deduce past elevation. Studies of sediments at various sites on the plateau show that those areas were at elevations of over 4,000 metres between 11 million and 35 million years ago [11][12][13] .…”