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

Abstract

The timing of crustal shortening and strike-slip faulting along the East Kunlun Shan provides insight into the history of surface uplift and may constrain the time at which the Tibetan Plateau reached high elevations. We investigate a series of extensional basins and restraining bends along the Xidatan strand of the Kunlun strike-slip fault, which provide an ideal setting to unravel the tectonic history of the northern plateau margin. We present new apatite (U-Th)/He, apatite fission track, and zircon (U-Th)/He ages and QTQt thermal modeling, 40 Ar/ 39 Ar fault gouge dating, and structural mapping from the central East Kunlun Shan. Our data suggest that the East Kunlun Shan experienced slow to negligible exhumation until late Cretaceous time, followed by an increase in rate by 65-50 Ma. Along with a~47 Ma fault gouge age, we posit that the Paleocene-early Eocene was a time of crustal shortening along the northern plateau. Rapid exhumation along transpressional portions of the Xidatan fault initiated by 23-20 Ma, which we interpret as the local onset of strike-slip faulting. An early Miocene transition from north-south crustal shortening to left-lateral shear along the East Kunlun Shan, the onset of normal and strike-slip faulting in central and southern Tibet by 18 Ma, and lower crustal flow in eastern Tibet by 13 Ma suggest the establishment of orogen-wide east-west oriented extension and extrusion by the middle Miocene. The plateau-wide shift in stress accommodation implies that high gravitational potential energy, and likely high elevation, was attained by the middle Miocene.

Late Oligocene Tectonic Uplift of the East Kunlun Shan: Expansion of the Northeastern Tibetan Plateau

“…Previous studies emphasize the Paleocene to Eocene rapid exhumation in the EKLS and argue for an early Cenozoic shortening event in the northern Tibetan Plateau (Clark et al, 2010;Staisch et al, 2020;Tian et al, 2020;Wang et al, 2016aWang et al, , 2017aYuan et al, 2006). However, reanalysis of existing low-temperature thermochronologic data and sedimentary records provides an alternative scenario.…”

“…(2013); (6) Staisch et al. (2020); (7) Tian et al. (2020); (8) Wang et al.…”

Topographic growth of the northeastern Tibetan Plateau during the middle‐late Miocene: Insights from integrated provenance analysis in the NE Qaidam Basin

“…13-8 Ma. Third, the intensification of precipitation (Nie et al, 2017) Staisch et al (2020). "Debated events" represents the evidence for Cenozoic deformation in the Qilian Shan, which are highly debated.…”

“…Fine fraction (<75 μm) of modern river sediments originating from the East Kunlun Shan yield ε Nd values between −9.9 and −7.9 (Figure 1b; Wu et al., 2010), which may be controlled by widespread early Paleozoic and Permo‐Triassic granites with ε Nd values ranging from −9.2 to 3.6 (Mo et al., 2007). Studies along the East Kunlun Shan suggest the Eocene to late Oligocene thrust faulting (Clark et al., 2010; Li, Zheng, et al., 2020; Wang, Feng, et al., 2016; Wang, Shi, et al., 2017; Yin et al., 2007), followed by an early Miocene left‐lateral shear along the Kunlun Fault (Duvall et al., 2013; Staisch et al., 2020).…”

Population genetic structure and evolutionary history of Psammochloa villosa (Trin.) Bor (Poaceae) revealed by AFLP marker

“…The process of desert formation in Northern China was once understood to be a result of sustained orogenesis of the Qinghai-Tibetan Plateau and surrounding areas during the Quaternary (Meng & Zhang, 2011;Wu, 2002). However, new data showed that the plateau reached its height earlier than originally thought in the Miocene (Hu et al, 2020;Staisch et al, 2020) and suggested that the deserts might have originated during glacial periods, when global ice volume was high and, thus, liquid water was more limited (Sun et al, 2018). The same climatic processes that gave rise to the deserts also appear to have profoundly shaped regional plant diversity and yielded highly complex demographic histories of native species (Ge et al, 2005).…”