The timing and mechanisms of Cenozoic deformation and landscape evolution in the eastern Tibetan Plateau remain contentious, particularly the roles of crustal shortening, strike-slip faulting, and fluvial erosion. Here we integrate low-temperature thermochronological data, including apatite fission-track, apatite (U-Th)/He, and zircon (U-Th)/He ages, from the northern Jinsha region of eastern Tibet, between the low-relief plateau interior and the deeply incised eastern margin. Our results reveal two broad phases of rapid cooling/exhumation: an early phase at ca. 68-45 Ma, with cooling rates of 4-10 degrees C/Myr, broadly compatible with early Cenozoic crustal shortening and thickening; and a later phase at ca. 20-0 Ma, with cooling rates of >= 5 degrees C/Myr. The three profiles record similar late Cenozoic cooling histories; therefore, the post-20 Ma signal cannot be uniquely attributed to local activity on the Jinsha Fault or to simple local river incision. Combined with published thermochronological data from the Jinsha River corridor, the results suggest a segmented regional cooling/exhumation pattern more compatible with fault-influenced drainage organization and focused incision than with a single upstream-propagating river-incision wave. Between the two cooling/exhumation phases, the study area experienced prolonged thermal stability, or near-isothermal holding, from 45 to 20 Ma, with cooling rates of <1 degrees C/Myr. This interval is consistent with development and/or preservation of a high-elevation, low-relief landscape by the late Eocene to Oligocene. Overall, our results provide new constraints on the multi-stage Cenozoic cooling/exhumation history of the northern Jinsha region and offer insight into the coupled tectonic and surface-process evolution of eastern Tibet.

The Tibetan Plateau developed through either stepwise or continuous outward expansion during the Cenozoic. However, its evolution prior to the Cenozoic remains poorly constrained. Understanding this earlier phase is crucial for reconstructing the complete orogenic evolution of the Tibetan Plateau. In this study, we present new insights from low-temperature thermochronometric analyses along an elevational transect in the Basu region of the eastern Tibet, combining Apatite/Zircon (U-Th)/He (AHe, ZHe). Our dataset reveals AHe ages ranging from 17.85 +/- 0.19 to 69.30 +/- 1.50 Ma and ZHe ages ranging between 126.17 +/- 3.21 and 187.59 +/- 5.0 Ma. Furthermore, QTQt thermal modeling identifies a pronounced Late Cretaceous-Early Eocene cooling phase (similar to 80-55 Ma), which we interpret as rapid exhumation and potential surface uplift in response to the northward subduction of the Neo-Tethyan oceanic lithosphere and convergence compression between India and Eurasia. This tectonic pulse was followed by markedly slower exhumation rates post- similar to 55 Ma. Our findings indicate that the proto-Tibetan Plateau, encompassing the central Tibetan Plateau's northern Lhasa and southern Qiangtang terranes, had already expanded to the Basu region by similar to 55 Ma. Regional evidence indicates that areas northwest of Basu had formed elevated topography prior to similar to 60 Ma, and regions to the southeast (including Markam, Gonjo and Weixi basins) had nearly reached their current elevations at similar to 40-35 Ma. This temporal-spatial pattern of cooling ages indicates the southeastward progression of regional exhumation and uplift from the Late Cretaceous through the Eocene, supporting the plateau stepwise expansion from the proto-Tibetan Plateau.

The Early Cretaceous (133-109 Ma) Bomi-Chayu batholith in the easternmost Lhasa terrane provides key insights into crustal growth and tectonic evolution, yet its petrogenesis and geodynamic setting remain contentious. Integrated petrographic, geochronological, geochemical, and isotopic analyses of three granitic suites identify crystallization ages of 134.3 Ma, 116.7-118.0 Ma, and 102.6-102.8 Ma, extending the known duration of regional magmatism. The -134 Ma and -103 Ma granites are classified as A2-type, formed under hightemperature, low-pressure settings. The -134 Ma biotite monzogranites show enriched isotopic compositions, suggesting derivation from ancient crustal sources. In contrast, the -103 Ma monzogranites exhibit decoupled epsilon Nd(t)-epsilon Hf(t) values, consistent with dehydration remelting of ancient crust. The -117 Ma granitoid suit is synchronous with a regional magmatic flare-up. The granodiorites in this stage display I-type affinities, with enriched Sr-Nd but relatively depleted zircon Hf isotopes. Geochemical and isotopic trends indicate hybridization between mantle-derived melts (represented by coeval gabbrodiorites and basalts) and crustal components (represented by coeval biotite monzogranites), followed by fractional crystallization and minor upper-crustal contamination. Magmatic types and isotopic compositions correlate the Bomi-Chayu batholith with the magmatic belt in the central Lhasa terrane. The two-stage A-type granites, together with synchronous I-S-type granitoids and bimodal volcanism, provide robust evidence for prolonged crustal extension in the eastern Lhasa terrane (at least the Bomi-Chayu area) during -134-103 Ma. We interpret this extensional regime as the result of slab rollback of the northward subducted Neo-Tethyan oceanic lithosphere.

[Objective]Coseismic surface ruptures provide key evidence for identifying the seismogenic structures of earthquakes,elucidating crustal deformation mechanisms,and assessing seismic hazards.To understand the surface deformation and disaster development characteristics associated with different types of fault activity on the Tibetan Plateau,and to reveal the current crustal deformation patterns reflected by a series of strong earthquakes in recent years,we systematically compiled and analyzed the surface rupture characteristics of five M>6.5 earthquakes that have occurred on the Tibetan Plateau and surrounding areas since 2021,based on field surveys.[Methods]We used the 2021 MW 7.4 Maduo,2022 MW 6.6 Menyuan,2022 MW 6.6 Luding,2024 MW 7.0 Wushi,and 2025 MW 7.1 Dingri earthquakes as representative cases.We integrated results from remote sensing interpretation,field surveys,and UAV photogrammetry,as well as seismological and geodetic data,to conduct a detailed analysis of the surface rupture and coseismic displacement distribution characteristics of these events.[Results]The strike-slip Maduo and Menyuan earthquakes formed coseismic surface rupture zones approximately 150～160 km and 22～31 km long,respectively,with maximum coseismic surface displacements of～3.6 m and～3.7 m.Contrastingly,the Luding earthquake,also a strike-slip event,exhibited a surface rupture only～450 m long at Ertaizi.The strong,MW 5.7 aftershock of the thrust-type Wushi earthquake generated a coseismic surface rupture zone～5 km long with a maximum vertical displacement of～1.7 m,while the normal-fault-type Dingri earthquake formed a coseismic surface rupture zone 25～36.5 km long with a maximum vertical displacement of～2.7 m.[Conclusions]A comprehensive analysis of the spatiotemporal distribution characteristics of major regional earthquakes indicates that,prior to the 2022 Luding earthquake,major earthquakes on the Tibetan Plateau were primarily clustered around the periphery of the active Bayan Har block.The subsequent Wushi and Dingri earthquakes both occurred far from the Bayan Har block,suggesting that the clustering period of major earthquakes in this active block may have ended.Further analysis of focal mechanism solutions indicates that strike-slip earthquakes have dominated recent moderate-to-strong seismic events on the Tibetan Plateau and its periphery.This may be related to the fact that current crustal deformation on the Tibetan Plateau is primarily regulated and absorbed through the lateral extrusion of active blocks along large strike-slip fault zones.[Significance]The above research findings provide fundamental data and references for earthquake early warning,disaster prevention and mitigation,as well as the planning,construction,and seismic design of major regional engineering projects in the Tibetan Plateau region.

Quantifying late Cenozoic extension in central Tibet is critical to models of the tectonic evolution of the Tibetan Plateau. A series of similar to NS-trending grabens in this region preserve important records of extensional deformation. Constraining their geometry and kinematics is essential for understanding the Cenozoic tectonic history of the plateau. In this study, we focus on the Yibug Caka graben (YCG), the most prominent graben system within the Qiangtang terrane, central Tibet. Using high-resolution satellite imagery, field investigations, and cosmogenic Be-10 dating (n = 16), we analyze the tectonic and geomorphic characteristics of the YCG to determine the late Quaternary throw rates of the normal faults bounding this graben. UAV surveys reveal vertical offsets of similar to 10 to 21 m on alluvial fans dated to similar to 100 and similar to 200 ka, yielding minimum throw and extension rates of similar to 0.08 and similar to 0.07 mm/yr, respectively. These rates are the first well-dated, late Quaternary constraints for the YCG, and indicate that extensional deformation in central Tibet is distributed on widespread normal and strike-slip faults, hence with significantly lower extension rates than those in southern Tibet. This difference is thus attributed to distinct extensional mechanisms between the two regions.

The existence of a Mesozoic proto-Tibetan Plateau remains a subject of ongoing debate due to the difficulty in constraining Tibet's paleotopographic evolution. The Longmen Mountains-Sichuan Basin system, located along the eastern margin of the Tibetan Plateau, was selected as the research object to investigate this issue. This study conducts systematic detrital zircon UPb and fission track double dating analyses on Cretaceous-Paleogene sandstone samples from the Shiyang section in the southwestern Sichuan Basin, aiming to: (1) reconstruct the Meso-Cenozoic exhumation history of the Longmen Mountains; and (2) explore the Mesozoic tectonic evolution patterns of the Tibetan Plateau through comparative studies with other systems, such as the West Kunlun-Tarim, Altun-Qaidam, and Qilian Mountains-Hexi Corridor. The Cretaceous strata within the Shiyang section of the western Sichuan Basin exhibit consistent detrital zircon UPb age distributions (n = 388), characterized by five prominent age peaks: late Paleozoic-early Mesozoic (similar to 252-217 Ma), early Paleozoic (similar to 467-432 Ma), Neoproterozoic (similar to 779-732 Ma), and Paleoproterozoic-Neoarchean (similar to 1812-1675 Ma and similar to 2540-2400 Ma). Moreover, the Paleogene strata contain five major age clusters (n = 290): similar to 275-247, similar to 430-407, similar to 807-622, similar to 1770-1675, and similar to 2430 Ma. These results indicate that the detrital zircons from both the Cretaceous and Paleogene successions in the Shiyang section were mainly sourced from the Longmen Mountains and the eastern Songpan-Ganze flysch fold belt. Analysis of 678 detrital zircon grains from Cretaceous to Paleogene strata in the Shiyang section reveals multiple magmatic age populations, with zircon fission track ages clustering in distinct intervals including the Neoproterozoic (658-595 Ma), Paleozoic (488-363 Ma), late Paleozoic (313-259 Ma), and Meso-Cenozoic (245-31 Ma). Zircon fission track age peaks spanning Neoproterozoic to Paleozoic (658-259 Ma) intervals document pre-Longmen Shan orogeny thermal events along the western Yangtze Craton margin. The Meso-Cenozoic zircon fission track age peaks (245-31 Ma) document episodic exhumation of the Longmen Mountains, with three principal phases identified. The earliest phase (245-223 Ma) corresponds to the Indosinian orogeny driven by Paleo-Tethys subduction, followed (187-86 Ma) by the Yanshanian orogeny associated with combined Paleo-Pacific back-arc compression and Neo-Tethys subduction. The youngest phase (64-31 Ma) reflects Himalayan orogenesis resulting from the India-Asia collision. When combined with published datasets, these results provide evidence for synchronous Mesozoic exhumation along the proto-Tibetan Plateau's northern, northeastern, and eastern margins. Integrated datasets reveal the development of an extensive Mesozoic proto-plateau system (>1000 km wide) characterized by thickened crust (>50 km) and elevated topography (>1000 m), which emerged following the early Cretaceous Qiangtang-Lhasa collision.

A dense seismological profile with 45 stations at a spacing of 5-10 km across the Longmenshan fault zone was deployed from 2018 to 2020. It complemented an array of 80 stations deployed in the region from 2012 to 2013. Using data from both deployments, dispersion curves were obtained from ambient noise Green's functions. Subsequently, a 3D shear (S) velocity model was derived using tomographic methods. Combining this S-wave velocity model with an existing 3D compressional velocity model, a 3D Poisson's ratio model was derived. These models show that the Precambrian Pengguan complex, which cores this part of the Longmenshan, is approximately 20-km thick and displays high velocities and low Poisson's ratios. The result of this study is that, along the dense profile, the complex is underlain between 20 and 40 km depth by low S velocities, which likely extend out beneath the Sichuan Basin in a 10-km thick basal crustal layer. These low S velocity zones have high Poisson's ratios and are best explained as a result of the compressive forces and push exerted by the Tibetan Plateau, causing processes such as ductile shearing and fluid/melt infiltration to occur.

The Chem Co graben is located in the westernmost part of the Qiangtang block, central Tibet. It is adjacent to the Longmu Co Fault to the north and approximately 50 km away from the Karakoram Fault to the west. The formation of the graben resulted in the exposure of basement rocks in the footwalls of the graben bounding normal fault, which hold crucial information on the Mesozoic closure of the Meso-Tethys Ocean. Garnet-biotite schist crops out sporadically in the footwall of the graben-boundary normal fault, and is intruded by leucogranite dikes. Pseudosection modeling indicates peak metamorphic conditions for the schist of 590-670 degrees C and 4.5-7.5 kbar, similar to the conditions of mid-crustal rocks at the western end of the Qiangtang block. Field investigations and microstructural analysis suggest syn-kinematical left-lateral strike-slip in both the biotite schist and granitoid veins. Zircon U - Pb, monazite U - Th - Pb, and Ar-40/Ar-39 ages show that intense regional intensive tectonic deformation and contemporaneous magmatism began at similar to 120.6 Ma and ended with the peak metamorphism conditions at 105.3 +/- 6.0 Ma. These results indicate that the closure of the Meso-Tethys Ocean in the westernmost part of central Tibet occurred over this period (i.e., 121-105 Ma) with final closure during the late Early Cretaceous. The closure of the Meso-Tethys Ocean likely triggered widespread far-field responses, extending from the Altyn Tagh Fault to the Longmu Co Fault, and reaching the Pangong and Hunza regions around the Western Himalayan Syntaxes. Episodic crustal thickening and surface uplift since the closure of the Meso-Tethys Ocean caused the upper crust to be extruded along the westernmost part of central Tibet, leading to the formation of the Chem Co graben.

The spatial and temporal evolution of active fault structures within the eastern Tibetan Plateau (ETP) helps constrain the tectonic and topographic history of that region. In this study, we focus on the tectonic evolution of the Longriba fault (LRF), located similar to 170 km west of the Longmenshan thrust belt (LTB) in the interior of the plateau. Increasing geological and geophysical evidence indicates that the LRF, a prominent dextral strike-slip fault with minor thrust components, serves as a significant tectonic and topographic boundary within the ETP. The basement rocks deformed by the LRF experienced rapid cooling between similar to 156 and 136 Ma based on three pairs of muscovite/biotite Ar-40/Ar-39 ages, while four illite K-Ar ages (similar to 37.8-35.6 Ma) from fault gouges from the fault indicate mineral growth during fault reactivation. These results, combined with regional chronology, document several thermotectonic stages in the ETP since the closure of the Paleo-Tethys in the Late Triassic. An early Cretaceous cooling event was identified, reflecting boundary fault reactivation and crustal thickening, due to the Lhasa-Qiangtang collision to the south. The similar to 38 Ma illite K-Ar ages are coeval with the India-Asia 'hard' collision, indicating fault propagation into the interior of the ETP. This study concludes that far field effects of plate convergence may strongly control fault movement, reactivation and propagation within the ETP, as well as triggered several pulses of cooling. Therefore, episodic mountain building may be due to continued fault-induced crustal thickening and uplift in the ETP.

Widely developed in the crust, crystal mush systems represent a primary mode of magma storage, and their reactivation is critical to understanding magmatic differentiation, mineralization, and volcanic eruption precursors. However, the complex physicochemical coupling mechanisms and dynamics within crystal mushes remain poorly understood. This study investigates the Early Ecocene (55 similar to 45Ma) Caina comples in the Gangdese belt through detailed petrographic observations, microstructural analysis, mineral chemistry, and crystallization thermobarometry. We decipher the origin and tectonic significance of clinopyroxene-amphibole core-rim structures within magmatic microgranular enclaves (MMEs). Key results reveal: (1) Clinopyroxene cores exhibit sieve textures, resorbed boundaries, and high crystallization temperatures (1088 similar to 1096 degrees C), supporting their origin as xenocrysts entrained from pre-existing crystal mushes by replenished mafic magmas; (2) The rim amphiboles yield erystallization temperatures (794 similar to 837 degrees C) and pressures (0.27 similar to 0.34GPa) consistent with those of the host rock and MME matrix, indicating autogenic crystallization from hydrous rejuvenated magma; (3) A sharp, Mg-enriched zone (10 similar to 20 mu m wide) at the core-rim interface provides direct evidence of chemical disequilibrium during magma recharge. These structures record the reactivation of an initially damp crystal mush; partial melting of the mush triggered resorption of clinopyroxene boundaries, while the newly replenished hydrous melts crystallized amphibole rims. Our findings provide microscopic insights into mush reactivation in collisional orogens and shed light on the linkage between magmatic system evolution and regional tectonics.

Large, shallow earthquakes typically produce surface ruptures, whereas aftershocks rarely do. Here, we document a rare case in which the 2024 Mw 7.0 Wushi earthquake (western China) did not rupture the surface, but a Mw 5.7 aftershock did. Integrated field observations, satellite imagery, interferometric synthetic aperture radar (InSAR) data, and relocated seismicity reveal that the aftershock reactivated shallow back- and fore-thrusts, forming a pop-up structure with clear surface breaks. This event demonstrates that aftershocks can generate significant surface deformation by reactivating pre-existing shallow faults—a process not commonly accounted for in seismic hazard assessments. Our findings emphasize the need to incorporate secondary shallow faults into hazard models, especially in complex fold-and-thrust systems.

The tectonic and topographic evolution of the southeastern Tibetan Plateau based on low-temperature thermochronology data is controversial, especially whether it is tectonically- or climatically-controlled, especially along the Lancang fault (LCF) that links the flat central plateau to the west with the high relief southeastern Tibetan Plateau to the east. To explore the tectonic evolution of the LCF and its role in the tectonic and topographic evolution of the southeastern Tibetan Plateau, we carried out detailed field investigation and low-temperature thermochronology (AHe, AFT, and ZHe) analyses. Field evidence indicate that the northern LCF splits into two branches, the Yangda-Yaxu and Baqing-Leiwuqi faults, the latter striking N50 degrees W and dipping to the SW at similar to 55 degrees, exposing >100 m-wide fault rocks composed of a fault damage zone, breccia, and gouge. New thermochronology data and thermo-kinematic modeling results suggest rapid exhumation of the region located between these two fault branches during similar to 22-10 Ma at an exhumation rate of similar to 1.57 km/Ma, compared to slow cooling prior to 22 Ma and since 10 Ma. We propose that internal anti-clockwise block rotation triggered rapid local exhumation, and that the final merging of different parts of the LCF during the Early-Middle Miocene assisted the southeastward escape of Sundaland, which profoundly affected the evolution of the regional geomorphology. The southeastern Tibetan Plateau (SE-TP) has attracted considerable attention due to its unique topography and geomorphology. Despite numerous studies in various disciplines such as tectonics, geophysics, and thermochronology, many controversies and gaps remain, especially regarding the transitional zone that connects the flat interior of the plateau with the highly rugged southeastern part. The understanding of the tectonic and topographic evolution related to large faults in this region is still limited. We conducted systematic field investigations on the northwest side of the southeastern Tibetan Plateau and provided, for the first time, systematic low-temperature (low-T) thermochronology data closely related to the large fault. We analyzed the composition and structure of the Lancang fault (LCF), reconstructed its tectonic evolution history, and revealed its relationship with regional topographic and geomorphic evolution. Our study suggests that, against the backdrop of the gradual diffusion of Cenozoic faults in the southeastern Tibetan Plateau, large faults still play an important role in regional tectonic and topographic evolution.

The youngest tectonic structures in Tibet are a series of grabens trending approximately north-south. However, the grabens in central Tibet are less prominent than those in southern Tibet, which suggests that there is spatial variability in deformation mechanisms. The Chem Co half-graben is situated in the westernmost segment of central Tibet and is characterized by boundary normal faulting that occurred during the late Quaternary. The bedrock exposure ages, as recorded by cosmogenic nuclides 10Be and 26Al, vary linearly with elevation along the normal fault plane, yielding an average extension rate of 2.2−2.4 mm/yr. This millennial extension rate is ten times higher than the long-term rate (i.e., 0.3−0.4 mm/yr over millions of years), suggesting an episode of accelerated extension. We performed lithospheric flexure modeling to simulate extension of the westernmost segment of central Tibet. The results reveal heterogeneous σ2 stress concentrations at depth, suggesting that the accelerated extension is most plausibly the result of localized stress concentrations associated with lateral variations in crustal rheology. By comparing the material loss calculated from the extensional rates and crustal thinning, it seems that the eastward spread of crustal material is decoupled from the middle−lower crust but is affected by its upwelling. Therefore, the direct effects of convergence between India and Eurasia are less prominent in central Tibet, except for its western part, where rapid uplift continues owing to oblique collision.

The Tibetan Plateau was formed by long-term terrane accretion and block collision, controlled by complicated Mesozoic-Cenozoic geodynamic mechanisms. However, its detail Cretaceous evolution history remains controversial. This study compiles available low-temperature thermochronology results and adakitic rocks data from the Qiangtang and Lhasa terranes to investigate its evolution. Two collected datasets synthetically demonstrate a deep-surface coupling relationship with rapid exhumation and crustal thickening during -120-80 Ma over the Qiangtang and Lhasa terranes. These terranes amalgamated before 120 Ma, resulting in rapid uplift and crustal thickening of southern Qiangtang during 120-80 Ma. Meanwhile, other sub-terranes outside of the southern Qiangtang terrane, including northern Qiangtang, northern Lhasa, and central Lhasa, also underwent stepwise surface uplift due to intense folding and thrusting. Instead of continuous crustal thickening, the northern and central Lhasa sub-terranes experienced intense erosion and delamination of early thickened crust during -90-80 Ma. Furthermore, the southern Lhasa sub-terrane rapidly uplifted during 70-60 Ma due to the Neo-Tethyan subduction. Eventually, the Cretaceous high geomorphic configuration across the Qiangtang and Lhasa terranes was shaped by terrane collision, lower crustal delamination, and Neo-Tethyan subduction prior to the India-Asia continental collision.

Magmatic periodicity is recognized in continental arcs worldwide, but the mechanism responsible for punctuated arc magmatism is controversial. Continental arcs in the Trans-Himalayan orogenic system display episodic magmatism and the most voluminous flare-up in this system was in early Eocene during the transition from subduction to collision. The close association of the flare-up with collision is intriguing. Our study employs zircon Lu-Hf and bulk rock Sr-Nd isotopes, along with mineral geochemistry, to track the melt sources of the Nymo intrusive complex and the role of mantle magma during the early Eocene flare-up of the Gangdese arc, Tibet. The Nymo intrusive complex is composed of gabbronorite, diorite, quartz diorite, and granodiorite which define an arc-related calc-alkaline suite. Zircon U-Pb ages reveal that the complex was emplaced between similar to 50-47 Ma. Zircon Hf isotopes yield epsilon(Hf)(t) values of 8.2-13.1, while whole-rock Sr and Nd isotopes yield epsilon(Nd)(t) values of 2.7-6.5 indicative of magmatism dominated by melting of a juvenile mantle source with only minor crustal assimilation (similar to 15%-25%) as indicated by assimilation and fractional crystallization modeling. Together with published data, the early Eocene magmatic flare-up was likely triggered by slab breakoff of subducted oceanic lithosphere at depths shallower than the overriding plate. The early Eocene magmatic flare-up may have contributed to crustal thickening of the Gangdese arc. This study provides important insights into the magmatic flare-up and its significant role in the generation of large batholiths during the transition from subduction to collision.

Present-day tectonic deformation in central Tibet is characterized by a series of -NS-trending grabens which accommodate EW extension. Quantifying the geometry and kinematics of these grabens is essential to understand Cenozoic tectonic deformation and Tibetan Plateau evolution. Here, we focus on the Norma Co graben (NCG), i. e., the southern segment of the Shuanghu-Norma Co graben (SH-NCG) system, which is the most prominent graben system within the Qiangtang terrane in central Tibet. We study its tectonic and geomorphologic characteristics to determine the late Quaternary throw rates of the normal faults bounding the graben, based on highresolution satellite images interpretation, field investigation, and cosmogenic 10 Be dating (n = 23). Using terrestrial LiDAR, UAV, and kinematic GPS, we precisely measure vertical offsets (up to 15 m) of -90 -120 ka-old alluvial surfaces, yielding a throw rate of 0.10( +0.04/-0.03) mm/yr. This rate is ten times lower than those published along other NS -trending grabens in southern Tibet, reflecting different deformation mechanisms, as previously suggested: grabens in eastern Qiangtang formed by rapid eastward block extrusion, those in western Qiangtang formed by distributed extension on numerous scattered normal faults, and those in southern Tibet result from divergent orthogonal thrusting along the curved Himalayan arc.

The Qinling Shan is located between the North China Craton and the South China Block. Not only is investigating the exhumation process of the Qinling Shan beneficial for comprehending the tectonic collision history of mainland China but also for enhancing our understanding of the development of the Yellow and Yangtze Rivers. Previous studies have predominantly focused on bedrock analysis in the Qinling Shan. However, modern fluvial detrital samples offer a more extensive range of thermal history information. Therefore, we gathered modern fluvial debris samples from the Hanjiang River, which is the largest river in the South Qinling Shan. Subsequently, we conducted apatite fission-track analysis using the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method. A total of 214 valid track ages were obtained, with an age distribution ranging from 9.5 to 334.0 Ma. The Density Plotter software was employed to decompose the data and generate four prominent age peaks: 185, 103, 69, 35, and 12 Ma. The exhumation events of the Early Jurassic (185 Ma) and Cretaceous (103–69 Ma) in the Southern Qinling Shan were strongly influenced by the collision between the South China Block and the North China Craton, as well as the subduction of the West Pacific Plate, respectively. The far-field effect of the collision between the Indian Plate and the southern Asian continent influenced the exhumation of the South Qinling Shan during the Late Eocene (35 Ma) and Middle Miocene (12 Ma), respectively. In conjunction with the reported findings, we comprehensively analyzed the geological implications of the Mesozoic and Cenozoic exhumations of the Qinling Shan. The Qinling Shan emerged as a watershed between the Ordos and Sichuan Basins in the early Mesozoic and Cenozoic, respectively. However, the exhumation and expansion of the Tibetan Plateau has forced the Yangtze River to flow eastward, resulting in its encounter with the South Qinling Shan in the late Cenozoic. The exhumation of the Qinling Shan has resulted in fault depression in the southern Ordos Basin. This geological process has also contributed to the widespread arid climatic conditions in the basin. During the Miocene, the Yellow River experienced limited connectivity due to a combination of structural and climatic factors. As a result, the Qinling Shan served as an obstacle, dividing the connected southern Yangtze River from the northern segment of the Yellow River during the late Cenozoic era.

The Gangdese belt in southern Tibet is an excellent location for studying the growth and evolution of continental crust as it has undergone the Mesozoic subduction-accretionary orogeny and the Cenozoic collisional orogeny. The Early Eocene Quxu batholith, located at central part of the Gangdese belt, consists of granite, granodiorite, diorite, and gabbro, etc. Lots of chronologic and geochemical studies have been done for the Quxu batholith. However, there are still debates about whether the formation of the Quxu batholith is controlled by magma recharge. Besides, the detailed processes of magma recharge are unclear. The wide distribution of magmatic microgranular enclaves in the granodiorite such as enclave dikes and dispersed enclaves, indicates the important role of magma recharge during the formation of the Quxu batholith. Poikilitic texture, with amphibole embedded in plagioclase, is developed in enclaves. Here, we will focus on the poikilitic texture of plagioclase and the chadacrysts ( e. g., amphibole) and attempt to track the processes of magma recharge through backscattered-electron imaging, mineral energy spectrum scanning, and mineral electron probe analysis. Analytical results reveal that the crystallization temperature and pressure of the amphibole chadacrysts are the highest (783 similar to 853 degrees C, 0.23 similar to 0. 45GPa), followed by the amphiboles in the groundmass of enclaves (781 similar to 808 degrees C, 0.21 0. 31GPa), and then the amphiboles in the granodioritic host rocks (769 similar to 802 degrees C, 0. 18 similar to 0. 26GPa). In addition, plagioclase with poikilitic texture develops obvious discontinuous zoning, and the sodic core indicates the existence of crystal mush. Based on these observations, we establish a tentative model to explain the process of magma recharge and the formation of poikilitic texture. Mafic magma rises along the fractures in the lower part of felsic crystal mush and quenches, leading to the formation of numerous small grains of amphibole. Subsequently, as the mafic magma enters the upper part of crystal mush, it breaks up into small droplets and captures plagioclase crystals from the felsic crystal mush. The plagioclase xenocrysts enclose amphiboles crystallized at deep level and produces the poikilitic texture.

班公湖-怒江缝合带为青藏高原内部分隔羌塘和拉萨两地块的构造边界,是研究青藏高原构造演化的重要窗口之一.该缝合带自西向东分为西段(班公湖至改则)、中段(安多至东巧)和东段(丁青至怒江),其中东段的研究程度较低.本次以东段八宿县郭庆乡一条花岗岩高程剖面为研究对象,采用激光剥蚀电感耦合等离子体质谱仪(LA-ICPMS)法对锆石和磷灰石开展裂变径迹测试.花岗岩锆石U-Pb年龄为～180 Ma,指示其结晶时代为早侏罗世.锆石和磷灰石裂变径迹年龄分别为180～130 Ma、86～61 Ma,对应的年龄-海拔曲线分别为负斜率和正斜率.QTQt模拟显示花岗岩高程剖面顶部在130～60 Ma时剥蚀冷却速率快,中部在130～40 Ma时剥蚀冷却速率居中,而底部在～130 Ma之后一直保持最低的剥蚀冷却速率.这种差异性隆升源自班公湖-怒江缝合带东段的南向俯冲板片断离早于北向俯冲板片断离.