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The modern high topography of the eastern Tibetan Plateau is drained by several of the largest rivers on Earth, and exerts a prominent influence on the Asian monsoon pattern. However, when the high terrain was formed remains highly debated. Here, we present detrital zircon U‐Pb ages that indicate a south‐flowing drainage system with distal headwaters passed through the Ninglang Basin at ca. 45 Ma. We advocate for early–middle Eocene surface uplift in the Gonjo Basin and areas to the west creating a southeast tilted topography across eastern Tibet. The termination of sedimentation at ca. 40 Ma implies that the river system had deviated from the Ninglang Basin, which we interpret as a result of rise of the Yalong‐Yulong thrust belt. Combined with other lines of evidence from previous studies, we support the establishment of moderate‐high elevation topography of eastern Tibet by late Eocene time. Plain Language Summary: The eastern Tibetan Plateau has been a hotspot for studying the interactions between tectonic uplift, monsoon evolution, Asian biodiversity, and topographic development during continental collision. However, the timing of high‐elevation topography formation in eastern Tibet is a matter of debate, with age estimates ranging from middle Eocene to late Miocene. This directly leads to contradictory understanding of uplift processes and plateau growth mechanisms. Sedimentary basins are excellent recorders of past drainage pattern and tectonic process, while many Cenozoic basins in eastern Tibet have been understudied. Here we focus on the Ninglang Basin and carry out comprehensive research including stratigraphy, sedimentology, chronology, and provenance analysis. We indicate that the Ninglang Basin was mainly supplied by a south‐flowing exterior drainage system during the middle Eocene, implying the existence of a regional, low‐gradient landscape beveling to the southeast at that time. The extinction of this drainage system in late Eocene time likely means the initiation of the Yalong‐Yulong thrust belt, a major boundary fault system in eastern Tibet. Our study thus support that the topography of eastern Tibet has been elevated in the late Eocene. Key Points: A large‐scale, south‐flowing fluvial system drained through the Ninglang Basin during the middle EoceneThe demise of the Ninglang Basin in the late Eocene resulted from the uplift of the Yalong‐Yulong thrust beltThe elevated terrain of eastern Tibet was initially formed in the late Eocene [ABSTRACT FROM AUTHOR]

The uplift and deformation styles of the Tibetan Plateau have been long debated on stepwise growth and crustal channel flow. Here, we offer new insight into this issue by constraining the pulsed exhumation history of the Yalong thrust belt in eastern Tibet, using apatite and zircon (U–Th)/He data from three ∼1 km vertical transects. The results revealed two rapid cooling pulses in the Late Oligocene (∼24 Ma, 50°C/m.y.) and the Middle Miocene (17–14 Ma, 35 °C/m.y.), respectively, which we ascribe to the staged‐thrusting faulting of this belt. These thrust faulting events indicated upward and eastward growth of the Tibetan Plateau, further suggested that the high topographic relief across the Yalong thrust belt mainly formed (at least) since the Late Oligocene. The available documents from paleoaltimetry, basin sediment accumulation, and thermochronometers and our new results reveal a regional‐scale stepwise propagation pattern of tectonic deformation during the Middle–Late Cenozoic in eastern Tibet. Plain Language Summary: The role of faulting in crust thickening has been one of the main controversies in the formation and evolution of the Tibetan Plateau. The Yalong thrust belt in eastern Tibet is a major Cenozoic structure with a 1.8–2.4 km topographic step, and its deformation processes are closely associated with the Cenozoic eastward plateau growth. In this study, we report 79 apatite and 78 zircon (U–Th)/He (AHe and ZHe) ages of 26 granitoid samples from three ∼1 km vertical transects. We suggest that the Yalong thrust belt underwent two rapid cooling (exhumation) pulses in the Late Oligocene (∼24 Ma, 50°C/m.y.) and the Middle Miocene (17–14 Ma, 35°C/m.y.), respectively. These pulses of exhumation and uplift along the Yalong thrust belt contributed to the development of the current morphology across eastern Tibet. Integrating previous findings and those reported in our study allow us to propose a regional‐scale stepwise propagation pattern of tectonic deformation during the Middle–Late Cenozoic in eastern Tibet. We suggest that the dynamic development of the deformation pattern may have been driven by the northward indentation of the Eastern Himalayan Syntaxis and the consequent lower crustal flow into southeastern Tibet. Key Points: The Yalong thrust belt underwent two rapid cooling pulses in the Late Oligocene (∼24 Ma) and Middle Miocene (17–14 Ma)The topographic relief across the Yalong thrust belt is mainly the result of pulsed thrusting at least since 24 MaA regional‐scale stepwise propagation pattern was proposed for the Middle–Late Cenozoic tectonic deformation in eastern Tibet [ABSTRACT FROM AUTHOR]

The establishment of continental-scale drainage systems on Earth is largely controlled by topography related to plate boundary deformation and buoyant mantle. Drainage patterns of the great rivers in Asia are thought to be highly dynamic during the Cenozoic collision of India and Eurasia, but the drainage pattern and landscape evolution prior to the development of high topography in eastern Tibet remain largely unknown. Here we report the results of petro-stratigraphy, heavy-mineral analysis, and detrital zircon U-Pb dating from late Cretaceous–early Palaeogene sedimentary basin strata along the present-day eastern margin of the Tibetan Plateau. Similarities in the provenance signatures among basins indicate that a continental-scale fluvial system once drained southward into the Neo-Tethyan Ocean. These results challenge existing models of drainage networks that flowed toward the East Asian marginal seas and require revisions to inference of palaeo-topography during the Late Cretaceous. The presence of a continent-scale river may have provided a stable long-term base level which, in turn, facilitated the development of an extensive low-relief landscape that is preserved atop interfluves above the deeply incised canyons of eastern Tibet. This study provides evidence for a continental-scale river system that existed in eastern Tibet before the India-Asia collision. The river system developed an extensive low-relief landscape, which was uplifted and dissected during the late Cenozoic. [ABSTRACT FROM AUTHOR]

The drainage evolution in eastern Tibet during the India‐Eurasia collision has attracted considerable attention because of its critical link to topographic development and plateau growth, but the discussion still persists. In the present study, new and published detrital zircon U‐Pb ages are integrated from Pliocene‐Early Pleistocene Xigeda Formation (XGD) and modern river sands to decipher the paleo‐drainage evolution in eastern Tibet. The results confirm the eastward flow of the Jinsha River before the Pliocene, but the drainage patterns of its major tributaries (Dadu, Yalong, and Anning) in the Pliocene, differ from the modern ones. In conjunction with the previously documented fluvial incision in eastern Tibet, we interpreted that the excavation of the Paleo‐Xigeda lake in Early Pleistocene time initiated and accentuated incision of the Jinsha River and its major tributaries. This led to drainage reorganization and the modern river pattern establishment in eastern Tibet. Plain Language Summary: The developmental history of the Jinsha River and its major tributaries (Dadu, Yalong, and Anning) in eastern Tibet are considered to be closely associated with the topographic evolution during the Cenozoic plateau growth. However, the formation timing and mechanism of the current configuration of these large rivers remains debated. Here, we used detrital zircon U‐Pb age as "provenance tracer" to identify source signatures of the Pliocene‐Early Pleistocene Xigeda Formation, a sequence of lacustrine deposits sporadically distributed along the Middle Jinsha River and its large tributaries. Our provenance results demonstrate that current east‐flowing Jinsha River has been established before Pliocene time, while the present‐day pattern of its major tributaries, including the Yalong, Dadu, and Aning rivers, was achieved in the late Early Pleistocene. Combined with previous thermochronological and provenance studies, we infer that the spillover of dammed lake initiated the fluvial incision that led to drainage reorganization and, consequently, the formation of the modern river system. This study not only challenge existing models of Plio‐Pleistocene drainage pattern of eastern Tibet that flowed southward to the South China Sea, but also illustrates how river reorganization alone can dramatically influence landscape development even in the absence of significant tectonic and climatic forces. Key Points: The Jinsha River has flowed eastward before Pliocene timeThe present pattern of the Dadu, Yalong, and Anning Rivers achieved in the Early PleistoceneThe spillover of the Paleo‐Xigeda lake during the Early Pleistocene triggered incision of the Jinsha River and its major tributaries [ABSTRACT FROM AUTHOR]

Eclogites in the high‐pressure (HP) and ultrahigh‐pressure (UHP) belt record important information about the subduction process and evolution history of the orogenic belt. The Luliangshan eclogites surrounded by granitic gneiss or paragneiss as lenses are exposed in the western segment of the North Qaidam UHP metamorphic belt, northwestern China. Petrology, mineral chemistry, and P–T pseudosection modelling show that the eclogites have experienced a multi‐stage metamorphic process. The peak eclogite‐facies metamorphic stage, is characterized by omphacite in matrix and as inclusion in garnet, with the peak mineral assemblages of garnet + omphacite + rutile + quartz at T > 790°C and P > 25.5 kbar. The initial HP granulite‐facies retrogression is characterized by the symplectite of diopside + plagioclase around omphacite, with P–T conditions of 911°C and 16.9 kbar. The subsequent amphibolite‐facies stage is characterized by amphibole + plagioclase symplectite around the clinopyroxene, with the metamorphic conditions of 674–686°C and 6.4–6.9 kbar. Zircon U–Pb analyses yielded two metamorphic age clusters: (a) HP granulite‐facies metamorphic age of 422–425 Ma, and (b) amphibolites‐facies retrograde age of 397–420 Ma. The protolith of eclogite have geochemical characteristics similar to those of normal mid‐ocean ridge basalt (N‐MORB); and the varying εNd(t) values (−6.3 to 2.1) indicate that the Luliangshan eclogites were derived from a mantle source with rare crustal contamination. Combining these data with previous studies, a multi‐stage tectonic model can be proposed: In the Early Neoproterozoic, the protolith of the Luliangshan eclogites were emplaced into ancient continental crust; during 460–430 Ma, following the oceanic subduction, the subduction of continental crust was dragged by the oceanic slab and continue to subduct towards the Qilian Block, and metamorphosed at the depth of at least 75 km. After a long and slow exhumation process, it returned to the shallow crust. [ABSTRACT FROM AUTHOR]

Rapid denudation and uplift of eastern Tibet have accelerated during the Late Miocene due to lateral lower crustal flow, without a significant contribution from upper crustal shortening. However, growing lines of evidence have revealed that Early Cenozoic faulting controlled enhanced denudation and shortening. Here, we report 51 new zircon and apatite (U Th)/He and apatite fission-track ages from seven granite samples along one primary branch fault (the Yunongxi fault) of the Yalong thrust belt in eastern Tibet. Cooling ages and inverse thermal modeling revealed two pulses of accelerated exhumation during the Late Cretaceous (70–65 Ma) and the Late Eocene–Early Oligocene (40–30 Ma). We suspect that the surface uplift of eastern Tibet, due to the convergence rate acceleration between India and Eurasia, triggered the first cooling stage. A synchronous out-of-pace Early Cenozoic cooling pattern across the Yunongxi fault was further identified and could be due to fault initiation at ca. 40–30 Ma. We argue that the Late Eocene–Early Oligocene rapid cooling and exhumation and the associated outward plateau growth were primarily accommodated through upper-crust faulting along the Yalong–Longmen Shan thrust belt. This deformation pulse was the first-stage response of fault activity to the India–Eurasia collision in eastern Tibet. More extensive Late Miocene deformation driven by lateral lower crustal flow consequently bypassed these early-stage fault systems and overwhelmed the Late Cretaceous and Late Eocene–Early Oligocene deformation in eastern Tibet. • The footwall of Yunongxi fault underwent accelerated exhumation during the Late Cretaceous and Late Eocene–Early Oligocene. • The striking differential cooling across the Yunongxi fault was most likely due to fault initiation ca. 40–30 Ma. • The second exhumation pulse was the first-stage response of fault activity to the India–Eurasia collision in eastern Tibet. [ABSTRACT FROM AUTHOR]

The Qilian Shan, located in the northeastern Tibetan Plateau, has been continuously extending to the foreland since the late Cenozoic, resulting in the deformation of the Hexi Corridor Basins. Five terraces of the Hongshui River are faulted in the southern Zhangye Basin, a sub-basin of the Hexi Corridor, documenting the tectonic history of the Minle Fault since the late Quaternary. In this study, a high precision digital elevation model (DEM) generated by unmanned aerial vehicle (UAV) photogrammetry is used to obtain the cumulative vertical offset of each terrace. And the abandonment ages of terraces are dated by AMS 14C dating. The results show that the Minle Fault has produced an almost constant shortening rate of 0.95 ± 0.30 mm/a since 42.3 ± 0.5 ka, and has been active throughout the Holocene. The shortening rate of the Minle Fault could represent the deformation rate in the south margin of the Zhangye Basin. Geological and geodetic data indicate the shortening rates of the Zhangye Basin are steady in 104 and 10-year timescales. The deformation rate of the north Qilian fault-fold system (NQF) has not changed significantly since the late Quaternary and may be consistent with that in the 106-year timescale, although further studies are needed. • Steady shortening rate of the Minle Fault since the late Pleistocene has been estimated to be 0.95 ± 0.30 mm/a. • Shortening rates of the Zhangye Basin are steady in 104 and 10-year timescales according to geological and geodetic data. • The deformation rate in the north Qilian Shan has not changed significantly since the late Quaternary. [ABSTRACT FROM AUTHOR]