Late Mesozoic–Cenozoic cooling history of the northeastern Tibetan Plateau and its foreland derived from low-temperature thermochronology

Abstract

The growth history and formation mechanisms of the Cenozoic Tibetan Plateau are the subject of an intense debate with important implications for understanding the kinematics and dynamics of large-scale intracontinental deformation. Better constraints on the uplift and deformation history across the northern plateau are necessary to address how the Tibetan Plateau was constructed. To this end, we present updated field observations coupled with low-temperature thermochronology from the Qaidam basin in the south to the Qilian Shan foreland in the north. Our results show that the region experienced a late Mesozoic cooling event that is interpreted as a result of tectonic deformation prior to the India-Asia collision. Our results also reveal the onset of renewed cooling in the Eocene in the Qilian Shan region along the northern margin of the Tibetan Plateau, which we interpret to indicate the timing of initial thrusting and plateau formation along the plateau margin. The interpreted Eocene thrusting in the Qilian Shan predates Cenozoic thrust belts to the south (e.g., the Eastern Kunlun Range), which supports out-of-sequence rather than northward-migrating thrust belt development. The early Cenozoic deformation exploited the south-dipping early Paleozoic Qilian suture zone as indicated by our field mapping and the existing geophysical data. In the Miocene, strike-slip faulting was initiated along segments of the older Paleozoic suture zones in northern Tibet, which led to the development of the Kunlun and Haiyuan left-slip transpressional systems. Late Miocene deformation and uplift of the Hexi corridor and Longshou Shan directly north of the Qilian Shan thrust belt represent the most recent phase of outward plateau growth.

The Formation of the North Qilian Shan through Time: Clues from Detrital Zircon Fission-Track Data from Modern River Sediments

“…To the south, the thick conglomerate beds of the early Eocene Lulehe Formation are widely found along the margins of the North Qaidam Basin [13,139]. Bedrock apatite FT ages from the North Qilian Shan largely cluster at 52-47 Ma [22,138,140]. This is consistent with the few ZFT data around 50 Ma observed in this study.…”

“…A growing set of data points toward an early Eocene onset of deformation and exhumation as a first likely response to far-field effects of the India-Asia collision [14,31,48,81,87,138] (Figure 9F). In the Yumen and Jiuquan basins, late Lutetian to early Bartonian coarse clastic sediments deposited in alluvial fan and braided river environments are separated from the underlying Upper Cretaceous strata by an angular unconformity indicating tectonic movement around or prior to 40 Ma ([48,87], Figure 10B).…”

Quantifying the long‐term slip rate of Liupan Shan thrust fault through the low‐temperature thermochronology

“…As shown in Figure 8a, the Early Cenozoic deformation has been documented in many localities along the NE Tibetan Plateau and adjacent areas, such as the East Kunlun Shan (e.g., Clark et al, 2010; Duvall et al, 2013; Li et al, 2021; Wang et al, 2017), North Qaidam thrust system (e.g., Cheng et al, 2016; He et al, 2018, 2022; Jolivet et al, 2001); Qian Shan (e.g., An et al, 2020; He et al, 2017; Li et al, 2020; Qi et al, 2016; Wu, Li, & Ding, 2021; Wu, Zuza, et al, 2021), the West Qinling Fault (e.g., Clark et al, 2010; Duvall et al, 2011), and some areas without our study (e.g., Liu et al, 2017; Wu et al, 2020). Furthermore, the enhanced sedimentation rates and clockwise rotation of the Xining‐Lanzhou Basin also imply deformation not long after collision (e.g., Dai et al, 2006; Dupont‐Nivet et al, 2004).…”

Evolution of drainage patterns in active fold-thrust belts: A case study in the Qilian Mountains

“…The Cenozoic tectonics of the Qilian Mountains are characterized by folds, thrust faults and crustal thickening and shortening (Tapponnier et al, 2001;Zheng et al, 2017). The Qilian Mountains initiated there in the Eocene immediately in response to the Indian-Eurasian plate convergence (Yin et al, 2008;Wu et al, 2021). However, significant exhumation tracked via low-temperature thermochronology, indicates that the Qilian Mountains experienced accelerated uplift in the Miocene (Duvall et al, 2013;Zheng et al, 2017;Yu et al, 2019;Wang et al, 2020;Wu et al, 2021).…”

“…The Qilian Mountains initiated there in the Eocene immediately in response to the Indian-Eurasian plate convergence (Yin et al, 2008;Wu et al, 2021). However, significant exhumation tracked via low-temperature thermochronology, indicates that the Qilian Mountains experienced accelerated uplift in the Miocene (Duvall et al, 2013;Zheng et al, 2017;Yu et al, 2019;Wang et al, 2020;Wu et al, 2021). In the late Miocene, the uplift and deformation of the Qilian Mountains expend to the Hexi Corridor Basin resulted from outward intracontinental growth of the Tibetan Plateau (Zheng et al, 2017;Wang et al, 2020).…”