Expansion of the Tibetan Plateau during the Neogene

Abstract

The appearance of detritus shed from mountain ranges along the northern margin of the Tibetan Plateau heralds the Cenozoic development of high topography. Current estimates of the age of the basal conglomerate in the Qaidam basin place this event in Paleocene-Eocene. Here we present new magnetostratigraphy and mammalian biostratigraphy that refine the onset of basin fill to ∼25.5 Myr and reveal that sediment accumulated continuously until ∼4.8 Myr. Sediment provenance implies a sustained source in the East Kunlun Shan throughout this time period. However, the appearance of detritus from the Qilian Shan at ∼12 Myr suggests emergence of topography north of the Qaidam occurred during the late Miocene. Our results imply that deformation and mountain building significantly post-date Indo-Asian collision and challenge the suggestion that the extent of the plateau has remained constant through time. Rather, our results require expansion of high topography during the past 25 Myr.

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

“…It is consistent with thermochronological data along the mountain ranges in the southern margin of the Qilian Shan, which has undergone a phase of accelerated exhumation since the early‐middle Miocene (Pang et al, ; Zhuang et al, ). It is also supported by provenance analyses for the Qaidam Basin, which indicate that early Cenozoic sediments in the northern Qaidam Basin were shed from the Kunlun Shan rather than the southern Qilian Shan, and provenance change occurred during early‐middle Miocene (Bush et al, ; W. Wang, Zheng, Zhang, et al, ). While Lu et al () suggest that Bush et al () may misidentify the underlying Cretaceous Quanyagou formation as the lower part of the Lulehe formation such that produce improper conclusions, they concluded that the Lulehe formation is characterized by proximal alluvial fan deposits that originated from the northern Qaidam Basin and the southern Qilian Shan based on evidence of sedimentology, facies analysis, and seismic reflection profiles (e.g., F. Cheng et al, ; Lu et al, ; Yin et al, ).…”

“…This is supported by thermochronological data in the Qimen Tagh (Jolivet et al, ; D. Liu, Li, et al, ; Y. Wang et al, ), eastern Kunlun Shan (Clark et al, ; Mock et al, ; F. Wang, Shi, et al, ), and northern margin of the Qaidam Basin (He et al, ; Jolivet et al, ), and estimation on the sediments preserved in the Qaidam Basin and materials eroded in the surrounding drainage area (Cheng et al, ). However, recent published magnetostratigraphy and mammalian biostratigraphy refine the onset of basin fill in the Qaidam Basin to ~25.5 Ma and reveal that the detritus shed from the southern Qilian Shan occurred at ~12 Ma, suggesting that the deformation in the southern Qilian Shan is significantly later than previously estimated (W. Wang, Zheng, Zhang, et al, ). It is consistent with thermochronological data along the mountain ranges in the southern margin of the Qilian Shan, which has undergone a phase of accelerated exhumation since the early‐middle Miocene (Pang et al, ; Zhuang 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).…”

“…Yuan et al (); 34—Fang et al (); 35—Pang et al (); 36—W. Wang, Zheng, Zhang, et al (); 37—Jolivet et al, ; 38—Yin et al (); 39—D. Liu, Li, et al (); 40—F.…”

A New Sediment Accumulation Model of Cenozoic Depositional Ages From the Qaidam Basin, Tibetan Plateau

“…This petroliferous basin is filled with as much as ~14 km of Cenozoic clastic sedimentary rocks, that preserves an exceptional record of the intraplate response to the India‐Asia collision and postcollision convergence (Meng & Fang, ; Métivier et al, ; Meyer et al, ; Molnar & Tapponnier, ; Rieser et al, ; Xia et al, ; Yin, Dang, Wang, et al, ; Yin, Dang, Zhang, et al, ; Yin et al, ). Investigating the nature of these strata provides constraints on the topographic evolution of northern Tibet and the overall pattern of the Cenozoic plateau growth (Bush et al, ; F. Cheng, Fu, et al, ; F Cheng, Guo, et al, ; F. Cheng, Jolivet, et al, ; Fang et al, ; Ji et al, ; W Wang, Zheng, et al, ; Zhuang et al, ). Nonetheless, the depositional age of these Cenozoic strata remains highly debated.…”