Understanding the geologic evolution of Northern Tibetan Plateau with multiple thermochronometers

Miocene Range Growth Along the Altyn Tagh Fault: Insights From Apatite Fission Track and (U‐Th)/He Thermochronometry in the Western Danghenan Shan, China

“…The proposed rapid exhumation commencing in the middle Miocene coincides with the onset of a suite of significant phenomena along the Altyn Tagh fault: (1) thermochronology on basement rocks along the Altyn Tagh fault (e.g., Jolivet et al, , ; Ritts et al, ; Shi et al, ; Sobel et al, ; Zhuang et al, ); (2) acceleration in sedimentation rate, provenance change and growth strata recorded by paleomagnetic studies in the western Qaidam Basin and along the Altyn Tagh fault (e.g., Chang et al, ; Gilder et al, ; B. Li et al, ; Lu et al, ; Wang, Zhang, Pang, et al, ; W. Zhang et al, ); (3) provenance analyses based on lithofacies variations and detrital zircon U–Pb ages along the Altyn Tagh fault (e.g., F. Cheng et al, , ; Wu, Xiao, Wang, et al, ; Wu, Xiao, Yang, et al, ; Yue et al, ; Zhu et al, ; T. Zhang et al, ); and (4) initiation of growth strata in the basins along the Altyn Tagh fault and western Qaidam Basin revealed by seismic data (e.g., F. Cheng et al, , , ; B. Li et al, ; R. Liu, Allen, et al, ; Yin et al, ).…”

“…Our new thermochronological data combined with published data in the western Danghenan Shan indicate a period of accelerated deformation since the middle Miocene in the southwestern portion of the Qilian Shan. The accelerated deformation in the middle Miocene is observed not only in the southwestern portion of the Qilian Shan but also throughout the rest of the Qilian Shan: (1) Thermochronological data indicate that the northern margin of the Qilian Shan has undergone accelerated exhumation since ~10 Ma (George et al, ; B. Li et al, ; Zheng et al, , ; Zhuang et al, ); (2) a shift in provenance in the Hexi Corridor from the Bei Shan to the north to the northern Qilian Shan to the south, and facies change in the Hexi Corridor suggest that the deformation that created the high topography of the northern Qilian Shan began at the middle Miocene (Bovet et al, ; Wang, Zhang, Pang, et al, ); (3) rapid exhumation of the central Qilian Shan is reported to have occurred since the middle Miocene (Duvall et al, ; D. Yuan et al, , ; Yu et al, ; Zheng et al, ); (4) accelerated exhumation and depositional rates, sediment coarsening, development of growth strata, and climate change attributed to mountain building in the middle Miocene are widespread across the eastern portion of the Qilian Shan east of the Qinghai Lake, such as the Linxia, Xunhua, Guide, and Gonghe basins (see a review in Lease, ); and (5) new thermochronological data and magnetostratigraphy in the southern margin of the Qilian Shan and northern Qaidam Basin suggest that the region has experienced rapid exhumation since the middle Miocene (Fang et al, ; Pang et al, ; W. Wang, Zheng, Zhang, et al, ; Zhuang et al, ; Figure a).…”

“…Competing models include progressive northward deformation, synchronously deformation, and rigid block tectonics (e.g., Burchfiel et al, ; Clark, ; Meyer et al, ; Molnar & Stock, ). Although a large body of evidence has been accumulated on the timing of deformation in north Tibet (Lease, ; Molnar & Stock, ; Zhuang et al, ) and along the Altyn Tagh fault (e.g., Yin et al, ; F. Cheng et al, , ), the kinematics and dynamics of north Tibet remain highly debated. For example, whether the northern Tibetan Plateau has undergone gradual northward propagation in the Cenozoic (e.g., Bovet et al, ; Burchfiel et al, ; Meyer et al, ; Zheng et al, ) and whether the entire Qilian Shan has experienced a synchronous deformation in the early Cenozoic (Clark, ; Clark et al, ) or middle Miocene (Lease, ; Molnar & Stock, ).…”

“…The onset of its left‐lateral slip and how it was accommodated are two prominent issues for understanding the geodynamics of uplift of the Tibetan Plateau (Yin et al, ; Yin & Harrison, ; Yue & Liou, ). A large number of studies have investigated the geology along the Altyn Tagh fault (e.g., Chang et al, ; F. Cheng et al, , ; Cowgill et al, ; Dupont‐Nivet et al, ; Gilder et al, ; Jolivet et al, ; Lin et al, ; B. Li et al, ; Lu et al, ; Ritts et al, ; Shi et al, ; Sobel et al, ; Sun et al, ; Wang, ; Wu, Xiao, Wang, et al, ; Wu, Xiao, Yang, et al, ; Yin et al, ; Yue et al, , ; Zhuang et al, , ). But despite this large body of data, there is no consensus about its temporal–spatial evolution due to a lack of ideally dated geological or geomorphological records on the Cenozoic slip.…”

“…Estimates for the onset of movement along the Altyn Tagh fault range from the Eocene, not long after the India‐Eurasia collision (e.g., Yin et al, ; Jolivet et al, ; F. Cheng et al, , ), to the Miocene (e.g., Chang et al, ; Lin et al, ; B. Li et al, ; Meyer et al, ; Ritts et al, ; Shi et al, ; Sun et al, ; Wu, Xiao, Yang, et al, ; Yue et al, ). Others have proposed a model with multiple stages of accelerated faulting to reconcile all available data along the Altyn Tagh fault (Yue et al, ; Yue & Liou, ; Zhuang et al, , ). Nevertheless, the initiation and slip history of the Altyn Tagh fault remain the subject of much debate.…”