Late Eocene–Oligocene High Relief Paleotopography in the North Central Tibetan Plateau: Insights From Detrital Zircon U–Pb Geochronology and Leaf Wax Hydrogen Isotope Studies

Abstract

The knowledge of provenance and paleoelevation of late Cretaceous-Cenozoic terrestrial basins is crucial in discriminating different topography growth models for Tibetan Plateau. The Hoh Xil Basin is located in the north central Tibetan Plateau, and its thick sediments provide an excellent record for investigating the growth history of Tibetan Plateau. Here we present an integrated study by applying detrital zircon U-Pb geochronology and leaf wax n-alkane hydrogen isotope analysis to the Yaxicuo Group in the Tuotuohe subbasin of the southern Hoh Xil Basin. Maximum depositional age from the youngest detrital zircon U-Pb ages, along with previous palynological data, indicates that the Yaxicuo Group was deposited during late Eocene-Oligocene. Provenance analysis shows that the Yaxicuo Group was mainly sourced from the northern Qiangtang and Songpan-Ganzi terranes. Detrital zircon age spectra of the Yaxicuo Group samples show 33-50 Ma age group in the Tuotuohe subbasin, which is distinctive from those in the Erdaogou subbasin to the north, suggestive of formation of watershed within the Hoh Xil Basin and the tectonic transition from foreland to hinterland basin. The most negative leaf wax hydrogen isotope value yields an estimate of paleoelevation of~4 km, which records the high elevation of the source regions in the northern Qiangtang. We argue that sedimentary record of the Yaxicuo Group with the interpreted transition from foreland to hinterland basin is the result of the northward propagation of the upper crustal shortening, which in combination with other deep processes caused the surface uplift of the Hoh Xil Basin.

The topographic evolution of the Tibetan Region as revealed by palaeontology

“…A new discovery of a cool temperate, predominantly deciduous, early Oligocene flora (Fig. 12) in the northern Qaidam Basin also supports that view (Song et al 2020), as well as some leaf wax hydrogen isotope results from the radiometrically dated sediments on the Hoh-Xil Basin (Lin et al 2020). However, until the Hoh-Xil Basin results are evaluated using isotope-enabled climate models, they must be regarded as speculative because of unknowns regarding the source waters, air parcel trajectories and the 'continental effect'.…”

The Cenozoic Evolution of Crustal Shortening and Left‐Lateral Shear in the Central East Kunlun Shan: Implications for the Uplift History of the Tibetan Plateau

“…Strong lithospheric blocks to the north of the East Kunlun Shan focused plateau growth to the south of the Qaidam Basin; thus, the majority of crustal shortening in northern Tibet from 50–35 Ma occurred between the Tanggula Shan and the Kunlun Shan (Figure 10a; Burg et al, 1983; Clark, 2012; Clark et al, 2010; DeCelles, Quade, et al, 2007; Ding et al, 2014; Duvall et al, 2011; England & Searle, 1986; Hetzel et al, 2011; Kapp, DeCelles, Gehrels, et al, 2007; Kapp, DeCelles, Leier, et al, 2007; Kapp et al, 2005; Lin et al, 2020; Murphy et al, 1997; Rohrmann et al, 2012; Yin et al, 2008). DeCelles et al (2011) postulate that the Greater Indian lithosphere underthrust the Lhasa terrane early in the collision history, which may explain the propagation of crustal shortening north of the Tanggula Shan after the Indo‐Asian collision, as well as a northward sweep in volcanism into the Qiangtang terrane (Figure 10a; Ding et al, 2003, 2007; Kapp et al, 2003, 2005; Lin et al, 2020; Miller et al, 1999; Nomade et al, 2004; Williams et al, 2001, 2004; Yakovlev et al, 2019).…”

Revised chronology of central Tibet uplift (Lunpola Basin)

“…With respect to the India-Asia collision, this Late Eocene-Early Miocene interval with little deformation and relatively slow subsidence in central Tibet may suggest Fig. 1A for locations) are revised from (19,25), and those of the Nangqian and Fenghuo Shan basins are revised from (45,76). The lithospheric and tectonic configurations are estimated on the basis of seismic and tectonic observations of lithospheric structure (26-28, 30, 77-81).…”