The southeastern margin of the Tibetan Plateau lies within the oblique convergence zone of the India-Eurasia collision. Since the Cenozoic, this region has experienced intense crust-mantle interactions, active tectono-magmatic processes, and complex focal mechanisms, reflecting a crustal structure with pronounced vertical layering and lateral segmentation. To better understand the regional stress regime and fault activity, we compiled a comprehensive database of focal mechanism solutions for the southeastern Tibetan Plateau. We collected and integrated earthquake data from 1950 to 2023 across the Sichuan-Yunnan region and adjacent areas. After data cleaning and integration, a database of 9902 high-quality focal mechanism solutions was established. Using a damped stress inversion method, we derived regional stress field models on 1°×1° and 0.2°×0.2° grids. The results reveal that: (1) focal mechanism types exhibit significant spatial heterogeneity; strike-slip events dominate the region, thrust events concentrate along the Longmenshan fault zone, and normal faulting prevails along the western boundary of the Sichuan-Yunnan block. (2) The large-scale stress field shows a systematic clockwise rotation of the maximum compressive stress axis (σ1) from north to south, consistent with the far-field effect of the ongoing India-Eurasia collision. (3) The high-resolution results reveal multi-scale stress variations, with strong horizontal continuity of σ1 across the plateau, supporting a long-term stable compressional regime. In contrast, higher three-dimensional complexity occurs along the block boundaries and southern Yunnan, particularly across the Lijiang-Xiaojinhe fault, where a clear north-south stress gradient is observed. This study provides the first systematic stress field characterization based on a unified focal mechanism database for the southeastern Tibetan Plateau, offering refined constraints on crustal deformation and insights into the geodynamic processes governing continental earthquake generation.

The southeastern Tibetan Plateau, an intracontinental deformation archetype recording oblique Indian-Eurasian convergence, has long been used to test geodynamic models of plateau growth. Driven by India's northward indentation, it has undergone multiphase deformation with kinematic and structural transitions. To explore its evolutionary dynamics, we developed 3D visco-elasto-plastic thermomechanical models reconstructing three tectonic stages: (i) crustal shortening; (ii) block lateral extrusion; and (iii) kinematic reversal in the southeastern Tibetan Plateau. Simulations show that strain localization along large-scale shear zones is initially controlled by lithospheric heterogeneities enabling rigid block extrusion. Since the mid-late Miocene, vertically stratified crustal rheology has promoted decoupling, in which potential energy-driven ductile lower crustal flow affects upper crustal deformation and triggers kinematic reversal. This transition reconciles block extrusion and lower crustal flow, which operate sequentially rather than exclusively and are modulated by temporal variations in crustal rheology and boundary conditions, resolving the long-lasting debate of geodynamics during continental collision.

The southeastern Tibetan Plateau represents a critical transition zone between the high plateau interior and the surrounding region with moderate elevation. Its topographic uplift history provides key constraints on the geodynamic mechanisms driving plateau growth, serving as an ideal natural laboratory for exploring the coupled effects of tectonics, monsoon dynamics, and biodiversity. However, the spatiotemporal patterns of regional uplift across distinct tectonic domains remain debated, primarily due to the limited resolution and accuracy of existing geochronological and paleo-elevation proxies. To resolve these uncertainties, we synthesize sedimentary archives from 16 Cenozoic basins across the southeastern plateau. We integrate high-resolution paleoelevation proxies, including stable and clumped isotopes, with multi-proxy paleoclimate records derived from palynological assemblages and leaf physiognomy. This multi-basin comparison reveals that the southeastern Tibetan Plateau experienced a major phase of regional uplift during the Late Eocene to Early Oligocene, characterized by a systematic decrease in uplift magnitude from the plateau interior toward the outer margins. A second phase of localized uplift occurred along the southeastern margin during the Middle to Late Miocene, progressively establishing the modern topographic configuration. Throughout the Cenozoic, this surface uplift was accompanied by distinct stages of climatic evolution. The region was predominantly arid during the Early Eocene, followed by a transition toward more humid conditions in the Late Eocene that persisted throughout the Late Oligocene. From the Middle to Late Miocene onward, the southeastern margin generally experienced a warm and humid subtropical climate, with regional variability reflecting the episodic reorganization and strengthening of the monsoon system. During the Pliocene, intensified global cooling and the expansion of Northern Hemisphere glaciation drove a shift toward cooler climatic conditions across the southeastern Tibetan Plateau. These findings clarify the spatiotemporal uplift history of the southeastern plateau margin and highlight its fundamental role in regional climate reorganization.

[Objective]Tectonic vergence records the geometric asymmetry and kinematic directionality of shortening during orogenic thickening and provides a key link between surface deformation and lithospheric-scale geodynamics.Although vergence is widely used in structural geology,its expression at the scale of entire orogenic belts remains insufficiently clarified,especially in intracontinental settings where stable plate-boundary subduction is absent.This study aims to compare vergence patterns from plate-margin orogens to intracontinental mountain belts and to identify the mechanisms controlling their formation,maintenance,weakening,and transformation.[Methods]We synthesize five representative orogenic systems:the Central Andes,Taiwan,the Alps,the Qilian Shan,and the Tian Shan.Surface structural styles,fold-thrust belt geometry,orogen-foreland basin coupling,geomorphic evolution,modern crustal deformation,seismicity,and lithospheric architecture—constrained by Moho/LAB geometry and geophysical imaging—are integrated to evaluate vergence at multiple scales.[Results]Plate-margin convergent systems commonly develop stable one-sided tectonic vergence.In the Central Andes,long-lived subduction of the Nazca slab provides persistent asymmetric forcing,causing shortening to be localized above the subduction interface and transmitted eastward toward the retroarc and foreland.The Altiplano Plateau,with crustal thickness locally reaching 60-75 km,records progressive Cenozoic crustal thickening,uplift,and eastward propagation of deformation.Taiwan,as a young arc-continent collision system,locally records early-stage bidirectional deformation around the Central Range and arc-side backthrusting near the Longitudinal Valley-Coastal Range system.However,foreland basin evolution,westward migration of the frontal fold-thrust belt,and modern shortening concentrated along the western Taiwan thrust system indicate that its long-term,orogen-scale,dominant vergence remains west-directed.The Alps demonstrate that tectonic vergence is time-dependent.During early subduction and continental collision,deformation was localized along a single subduction interface,producing a north-vergent simple-shear-dominated architecture.After collision,slab break-off,eclogitization of the orogenic root,and thermomechanical reorganization weakened the earlier interface-controlled deformation and promoted strain redistribution across both flanks of the orogen,leading to paired north-and south-vergent thrust systems and a more symmetric collisional structure.In intracontinental orogens,stable one-sided vergence is not guaranteed.The Qilian Shan and Tian Shan lack compelling evidence for a continuous,long-lived,single-sided lithospheric subduction interface.Their deformation is mainly expressed by distributed crustal thickening,high-angle reverse faulting on opposing flanks,and near-symmetric shortening.Recent studies from the Qilian Shan further show that lithospheric-scale tectonic wedges may develop along basin-mountain transition zones,where relatively rigid basin lithosphere wedges into the weakened lower crust of a thickened orogen.Such wedge structures are best interpreted as local expressions within a pure-shear,vertically coherent deformation framework rather than as large-scale simple-shear intracontinental subduction.[Conclusions]Lithospheric-scale tectonic vergence is controlled by the coupling among boundary conditions,negative-buoyancy forcing,and lithospheric strength-buoyancy structure.Persistent single-sided slabs or effective negative-buoyancy sources favor stable simple-shear vergence,whereas slab break-off,loss of one-sided forcing,and mechanically strong opposing blocks favor distributed pure-shear thickening and weak or near-symmetric vergence.[Significance]This study provides a unified framework for interpreting tectonic vergence from plate margins to continental interiors.It highlights vergence as a geometrically testable indicator for linking surface deformation,basin-orogen coupling,and lithospheric-scale geodynamic processes.

The southeastern Tibetan Plateau (SETP) plays a pivotal role in accommodating intra-continental deformation driven by the ongoing India-Eurasia convergence. However, its contemporary surface vertical motions and the underlying geodynamic processes remain highly debated. Previous studies have proposed that spatial variations in lithospheric rheology govern intracontinental deformation and orogenesis. Here, based on a 2D viscoelastic model and geodetic observations, we infer the laterally varying lower crustal viscosity across the SETP, where is characterized by lithospheric heterogeneity, as indicated by seismic velocity and electrical resistivity anomalies. The optimal model reveals the lower crustal viscosities of 1020-21 and 1018-19 Pa s underneath the Songpan-Ganzi Block and the Xiaojiang region, respectively, and exceeding 1021 Pa s underneath the central Yunnan Block and South China. Such a heterogeneous lower crustal rheological structure can explain the geodetically observed regionally variable surface vertical motions. Particularly, it reconciles the apparent inconsistency related to surface uplift in the absence of upper crustal horizontal shortening across the SETP. Our findings highlight the role of lower crustal viscoelastic deformation in modulating surface vertical uplift in the absence of significant upper crustal shortening, and demonstrate that the rheologically weak lower crust complements existing models, including tectonic extrusion and gravitational collapse, to accommodate contemporary crustal motions in the SETP. Furthermore, we argue that lithospheric rheological heterogeneities play an essential role in controlling surface deformation within the context of continental extrusion.

The Lancangjiang tectonic belt along the southern margin of the Tibetan Plateau serves as a pivotal archive of the Late Palaeozoic to Cenozoic tectonic evolution, offering insights into Tethyan dynamics, the India-Eurasia collision, and plateau uplift. Despite extensive study, the tectonic history between the Indosinian orogeny and the Cenozoic collision remains poorly understood. In this study, we reconstructed the multi-stage tectonic history of the Lancangjiang tectonic belt by integrating structural analysis and petrology with zircon and apatite U-Pb geochronology and geochemistry. We identified four distinct tectono-thermal events with age ranges of 234-200 Ma, 80-69 Ma, 57-38 Ma, and 20-19 Ma. Geochronological data from granitoids reflect magmatic pulses related to the evolution of the Paleo-Tethys Ocean, while results from mylonites and gneisses constrain the timing of superimposed tectonic-metamorphic deformation. By considering the regional geological framework, the evolution of the Lancangjiang tectonic belt is divided into four stages: (1) a Triassic post-collisional period of tectonic quiescence following the closure of the Paleo-Tethys Ocean. (2) a Late Cretaceous metamorphic-thermal event induced by the far-field effects of the Neo-Tethys subduction-collision system. (3) a Paleogene phase of intracontinental convergence and crustal shortening triggered by the India-Eurasia collision. (4) an Early Miocene stage of large-scale sinistral ductile shearing developed under a regime of regional extension. Thus, a temporal framework for major tectonic events along the southeastern boundary of the Tibetan Plateau was established for deciphering the evolutionary history of the Tethyan realm and the underlying lithospheric deformation mechanisms.

The southeastern Tibetan Plateau lies in the eastern India-Eurasia oblique convergence zone, a region characterized by intense crustal shortening and continental-scale escape tectonics. Exposed rock assemblages along ductile shear zones and low seismic velocity and high electrical conductivity zones identified at depth indicate crustal weakening and deep exhumation during ongoing orogenic processes. This study investigates the formation and exhumation mechanisms of the low-viscosity mid-lower crust using 3D visco-elasto-plastic numerical modelling. The results reveal that a high Moho temperature (> 500 degrees C) is a necessary prerequisite to form lowviscosity crust. Increasing Moho temperature and strain localization can significantly promote this weakening process. Rapid exhumation of deep, low-viscosity crustal materials may result from the dynamic coupling of early crustal shortening and subsequent large-scale strike-slip deformation. Initial compression forms buoyant, lowdensity crustal "roots" in lower crust, and later strike-slip shear triggers gravitational instability. Vertical buoyancy forces, dip-slip components in transpressional or transtensional deformation, and localized erosion jointly drive rapid exhumation of deep low-viscosity crustal materials. These findings provide key insights into the evolution of crustal rheological structure and exhumation mechanism of mid-lower crust, contributing to a better understanding of the orogenic processes within continental convergent zones.

In multi-source bay systems, short-source river contributions are typically underestimated compared to distal large rivers. Core BH2101 from southern Laizhou Bay—receiving both Yellow River and central Shandong Mountain river inputs—provides an ideal record for investigating their interactions. Using OSL/AMS ¹⁴C dating, grain-size, foraminifera, and detrital zircon U-Pb data, this study examines Late Pleistocene depositional evolution in the Bohai Sea.Results show three marine transgressions (MIS 5, 3, 1) with alternating provenance dominance. The Middle Pleistocene was Yellow River-dominated (93.3%). MIS 5 saw increasing small river contributions (47.6% by MIS 5.1) due to enhanced summer monsoon. MIS 4 arid conditions favored small rivers (74.4%). Post-MIS 3, Yellow River dominance returned, reaching 95.2% in the late Holocene through strengthened coastal currents and human activity.Synthesizing regional core data, this study further reveals multiple Yellow River diversions into the Yellow Sea since the Late Pleistocene: beyond brief Holocene southward flows, the river more likely discharged into the South Yellow Sea for extended periods during MIS 4–MIS 3. This finding expands our understanding of the Yellow River's geological history of "channel migration," provides a representative case for comprehending large river source-to-sink response mechanisms under glacial-interglacial cycles, and offers new evidence for resolving long-standing fundamental geological debates such as whether the Late Pleistocene Yellow River flowed through the Bohai Bay.

[Objective]The Eastern Himalayan Syntaxis and its southeastern region serve as a critical channel for the eastward extrusion or/and expansion of Tibetan Plateau material.The deformation/rheology mechanisms and seismic anisotropy of the lithosphere provide key insights into plateau uplift and lateral growth.[Methods]This study investigates lower-crustal garnet pyroxenites(27-44 km depth)and lithospheric mantle spinel lherzolites(50-78 km depth)from the Ailao Shan-Red River shear zone and adjacent regions.This study integrates petrographic analysis,microstructural observations,measurements of crystallographic preferred orientations(CPOs),metamorphic-deformation thermobarometry,and whole-rock seismic velocity modeling to constrain the lithospheric seismic anisotropy and its tectonic implications.[Results]Our key findings include:(1)Microstructural analysis reveals that garnet in lower-crustal pyroxenites behaves as a rigid phase with rotational deformation,while clinopyroxene accommodates strain via dislocation creep.In the lithospheric mantle,olivine exhibits both A-type(high-temperature,low-pressure simple shear)and AG-type(melt-present)CPOs;orthopyroxene and clinopyroxene also deform predominantly by dislocation creep,indicating polyphase plastic deformation and static recrystallization.(2)Seismic velocities show distinct layering:garnet pyroxenites exhibit VP=8.01-8.07 km/s and VS=4.54-4.57 km/s with weak anisotropy(AVP=0.6%-1.4%,AVS=0.7%-1.1%),whereas spinel lherzolites display higher velocities(VP=8.03-8.08 km/s,VS=4.60-4.61 km/s)and stronger anisotropy(AVP=3.8%-8.0%,AVS=3.0%-6.6%).(3)The velocity controls differ between lithologies:in pyroxenites,the garnet content dominates the bulk seismic velocity,while the anisotropy correlates with the clinopyroxene content;in lherzolites,the seismic properties are primarily controlled by olivine,while orthopyroxene and clinopyroxene exert a diluting effect,and the deformation intensity significantly influences the anisotropy.(4)From the middle crust to the lithospheric mantle,a vertical velocity model reveals stepwise increases:mica schist(VP=6.12-6.46 km/s)→granodiorite(VP=6.69-6.78 km/s)→amphibolite(VP=6.30-6.69 km/s)→ garnet pyroxenite(VP=8.01-8.07 km/s)→ spinel lherzolite(VP=8.03-8.08 km/s),with the amphibolite layer(VS=3.59-4.01 km/s)acting as a key interface for crust-mantle velocity transitions.[Conclusion]Integrated with published geophysical data,we propose a tectonic model wherein:(1)mid-lower crustal amphibolites and partial melts are the primary sources of crustal anisotropy;(2)mantle anisotropy reflects southeastward lithospheric extrusion driven by asthenospheric upwelling,with clear crust-mantle decoupling.[Significance]Our new data provide critical constraints on the lithospheric deformation and crust-mantle decoupling beneath the Eastern Himalayan Syntaxis and its southeastern region by linking mineral-scale deformation mechanisms with large-scale seismic anisotropy.This enhances our understanding of the uplift and lateral growth of the Tibetan Plateau in the Cenozoic.

Striking changes in kinematics and deformation styles often occur in convergent orogens in the later stages of their tectonic evolution, such as in the southeastern Tibetan Plateau, which transitioned from transpression to transtension and experienced kinematic reversal on regional fault systems since the Miocene, approximately 40 Ma after the initial collision. This shift has long been identified, but the spatial patterns of onset and driving mechanisms are controversial, hindering an understanding of the processes and dynamics of intracontinental orogeny. This issue is addressed for the NW Yunnan basin region in the SE Tibetan Plateau, by an integrative study of apatite (U-Th)/He and fission track thermochronology along with structural and sedimentary analysis. Late Eocene to Oligocene/early Miocene approximately E-W shortening resulted in thrust and fold systems, widespread exhumation, and topographic uplift. Combined with existing data, this region underwent a transition to transtension during the late Miocene-Pliocene, forming basin-and-range style landscapes. The crustal deformation and kinematics of major active faults based on newly processed geophysical data indicates crustal thickening in a hyper-oblique convergent zone may have raised the crustal temperature at depth and weakened the long-term strength of the lower crust and upper mantle, especially in the presence of water. Such lithospheric conditions are more prone to localized tectonics and can cause late-stage orogenic gravitational collapse, driving striking structural transition in the NW Yunnan basin region.

The Himalayan Mountains exhibit extreme topography, with the highest peaks and most incised rivers on earth. Rapid uplift, surface erosion and geomorphological changes have been taking place in the Himalaya throughout the late Cenozoic. Although the interactions among tectonics, climate, and surface erosion have been intensively studied over the past several decades, the landscape evolution and formation of extreme topography in the Himalaya are still unclear. Here, we present low-temperature thermochronology and thermal history modeling results that reveal the Makalu massif (similar to 87 degrees E) in the central part of the Himalayan orogen may have experienced over 4 km of exhumation since 2 Ma. Combined with 1442 previously published cooling ages, we derive temporal and spatial variation in exhumation rates since 10 Ma for the entire Himalaya and reveal rapid cooling and exhumation since the Pleistocene. The isostatic response to this erosional unloading exhumation is quantified using a two-dimensional flexural model. Calculated results show that vertical uplift reached nearly 3200 m in the highest parts of the Himalaya orogen, suggesting that the isostatic response may play an important role in the building of relief and extreme topographic elevations since the Pleistocene.

Total organic carbon (TOC) content, a classic indicator of rock organic richness, is widely used in geological archives for paleoenvironmental interpretation and petroleum system modeling. However, organic carbon (OC) undergoes significant alteration and loss upon burial, rendering present-day TOC measurements inadequate for reflecting original OC levels. Many approaches have been developed to restore such OC loss based on mass balance principles and Rock-Eval parameters, yet these methods rely on implicit assumptions that introduce uncertainties and have not been tested. Based on a reevaluation of previous restoration methods, this study proposed a mass balance framework with a refined algebraic scheme to reconstruct buried (pre-catagenesis) TOC. A one-at-a-time sensitivity analysis method was introduced to quantify the propagation uncertainties in the model by examining the responses of TOC restoration outputs (TR, f, and sigma TOC) to variations in key inputs (TOCpd, BIpd, HIpd, HIo, Cc, alpha, and beta). Simulated Rock-Eval data, derived from HI-Tmaxsigmoid models, was utilized in sensitivity analysis to avoid the influence of source rock heterogeneity and organo-facies variations. Both the simulated and experimental results demonstrate that the proposed model improves the TOC restoration accuracy by accounting for the rock mass changes and OC deductions due to hydrocarbon expulsion. Furthermore, the uncertainties arising from S1 "carry-over" and mineral matrix effects are resolved through the new equations. This study, from a sensitivity analysis perspective, summarizes the impacts of input parameters in perspectives of kerogen kinetics and thermal maturation, offering a guideline for more robust TOC restoration and evaluation.

The intense seismicity observed across East Asia, particularly in the southeastern Tibetan Plateau, cannot be adequately explained by classical plate tectonics. Instead, the concept of active block tectonics-viewing the continental lithosphere as a mosaic of deformable yet kinematically independent blocks bounded by active faults-provided new insights into the intracontinental deformation. In this study, we integrate active tectonic, seismological, and geophysical data sets to delineate a hierarchical system of first- to fourth-order active block tectonics models in the southeastern Tibetan Plateau. Block rotations and internal strain rates are quantified using the TDEFNODE modeling framework applied to GNSS velocity data. The results reveal that present-day deformation is partitioned among multiple blocks and accommodated through both rigid block rotation and distributed internal strain, reflecting strong lithospheric heterogeneity and mechanical segmentation. Based on these observations, we propose updated criteria for delineating active blocks in continental interiors. Our findings provide new insights into the late-stage evolution of orogenic systems and establish a seismologically validated, geophysically constrained framework for interpreting intracontinental deformation and assessing seismic hazards in the southeastern Tibetan Plateau.

Structural geology is a scientific discipline that investigates the structure and properties of the Earth's crust (lithosphere), as well as its formation processes and evolution. It serves as a traditional foundational branch of solid Earth sciences, particularly geology. The theory of plate tectonics marked a milestone in the development of Earth sciences in the 20th century. With the rapid development of society, humanity is currently confronted with issues such as the depletion of natural resources, drastic environmental changes, and frequent natural disasters. These challenges have compelled geologists to deepen and expand the theory of plate tectonics within the framework of Earth system science theory, explore key scientific questions related to continental tectonic dynamics, enhance the leading role of structural geology in solid Earth sciences, and provide crucial theoretical support for addressing resource and environmental dilemmas, preventing and mitigating geological disasters, and protecting the Earth's environment and human development. The National Natural Science Foundation of China plays a pivotal role in promoting the development of basic research in natural sciences, advancing disciplinary construction, and cultivating outstanding scientific and technological talents, thereby garnering significant attention from researchers. The funding system for geology (D02) encompasses seventeen research directions (secondary application codes). "Tectonics and Structural Geology (D0211)" primarily targets applications within the branch discipline of structural geology. Over the past five years, the annual application volume of D0211 for General Programs, Young Scientist Fund Programs (Category C), and Regional Science Fund Programs has accounted for approximately 10% of the total applications in the geology discipline. This underscores the significant position of D0211 within the funding system of the geology discipline. To elucidate the developmental trends in this disciplinary direction, this study conducts an in-depth investigation into the applications of the General/Youth/Regional/ Key Programs in the field of tectonics and structural geology over the past five years. The Chinese mainland is situated at the complex intersection of several global mega-tectonic systems, including the Paleo-Asian, the Pacific, and the Tethyan-Himalayan tectonic domains, providing a natural lab for research in tectonics and structural geology. This study systematically reviews the major scientific questions in this field, focusing on the Tibetan Plateau and its surrounding areas, the Central Asian Orogenic Belt, South China, and the North-Northeast China regions. The study reveals that the evolution and dynamics of the Tethyan and Central Asian orogenic belts, the Mesozoic-Cenozoic evolution of the Western Pacific tectonic belts and marginal sea basins, the assembly and dispersal of supercontinents and their dynamic mechanisms, continental accretion and reworking, the growth of the Tibetan Plateau, intracontinental deformation and earthquakes, and the interactions between tectonics, climate, and surface processes remain key scientific issues of focus in the field of structural geology in China. Traditional research directions, such as tectonic settings, deformation, and chronology, as well as active tectonics and paleoseismology dominate the approved projects over the past five years. Applications for tectonophysics, numerical modeling and continental dynamics remain relatively scarce. With the advancement of technologies such as deep geophysical exploration, space-based Earth observation, deep geological drilling, and high-precision geochemical analysis, the accumulation of vast amounts of data has propelled structural geology from qualitative description to data-driven quantitative research. Guided by Earth System Science, future tectonics and structural geology will explore cross-scale sphere interactions, advancing continental dynamics theory and modernizing plate tectonics. The synergy of observational, experimental, and computational approaches, empowered by data-driven quantification, is revolutionizing our understanding of continental lithosphere dynamics through decoding its multiscale deformation and genetic processes.

Subduction of the Pacific and Indian-Australian Plates, regional transpression, lateral block extrusion, and structural inversion have all interacted to affect the crustal deformation and enhance local and regional exhumation across Sundaland during the Cenozoic. The Cenozoic tectonics of Sundaland has been studied using various thermochronometric techniques over the past three decades. In this study, we provide new apatite (U-Th)/He data in Vietnam and Borneo and compile published low-temperature thermochronologic ages to estimate temporal and spatial variation of exhumation rates in the Indochina Peninsula and Borneo. Our findings indicate that Early Cenozoic regional transpression controlled the Paleogene widespread exhumation from Peninsular Malaysia, through the Gulf of Thailand, to central Thailand and into Yunnan due to early oblique collision. Local rapid exhumation of lower crustal units, young granite plutons, and hilly terranes occurred during the Oligocene to Miocene driven by rifting, block lateral extrusion, structural inversion, and buoyant doming. Borneo Island experienced diachronous exhumation history likely due to the subduction of Proto-South China Sea, collision between Australia and southeastern Borneo, and dynamic support from the mantle. A synthesis of our (U-Th)/He data, published thermochronologic data, and thermal modeling contribute to revealing the Cenozoic local structural evolution and regional tectono-thermal events across Sundaland and give new insights into the driving dynamic mechanisms.

Rivers adjust their equilibrium profiles to base-level changes induced both by climatic fluctuations and tectonic movements. It is crucial, yet challenging, to differentiate their distinct roles in shaping the evolution of fluvial systems when both forces are involved. In contrast to the broader, regional-scale impact of climatic changes, the various tectonic deformation at local-scale can be recorded as various terrace deformation patterns. The Dongda River, located on the northeastern edge of the Tibetan Plateau, crosses active folds and thrusts, providing a unique opportunity to isolate the effects of climatic and tectonic forces. In this study, we identified five river terraces along Dongda River, designated as T1, T2, T3, T4a, and T4b, from lowest to highest. Radiocarbon and OSL dating results reveal abandonment ages of 4.2 +/- 0.3 ka, 6.1 +/- 0.5 ka, 12.4 +/- 2.5 ka, 16.4 +/- 0.2 ka, and 27.4 +/- 2.5 ka, showing rhythmic alignment with climatic fluctuations since the late Pleistocene. Elevation profiles of the terraces demonstrate base-level aggradation at the footwall of the Fengle fault between T4a/b and T2, highlighting a tectonically dominated process of river incision at its hanging wall. Differential uplift rates were estimated to be 2.2 +/- 0.3 mm/a at the North Qilian Shan hinterland, 1.1 +/- 0.2 mm/a in the Huangcheng Basin, 0.2-0.4 mm/a in the Yangxiang Basin, and 1.1 +/- 0.2 mm/a within the foreland fold-and-thrust belt of Dahuang Shan, respectively. In contrast, an accelerated incision rate (>1.8 mm/a) has been observed throughout the entire basin since the abandonment of T2, coinciding with the adjustments in the Asian monsoon and westerlies systems since the Mid-Holocene. This study provides insights into the complex interplay between climatic variability and tectonic activity in fluvial systems, enhancing our understanding of how these competing forces have shaped the evolution of the fluvial landscape over time.

The convergence of the Indian Plate and Eurasia shaped the Earth's broadest and highest-elevation colli-sional system and topographic growth, which is not simply illustrated by ongoing contractional deforma-tion. The Cenozoic magmatism along the Ailao Shan-Red River Shear Zone (ARSZ), linking surface geology with deep lithospheric processes, provides additional information regarding the age and progressive defor-mation of the India-Asia collision. In this study, we present new zircon U-Pb geochronological, elemental geochemical and zircon Hf isotopic data for the Eocene-Miocene granitoid to resolve the southeastern Tibetan Plateau deformation history. The Jinping granitoids in the southern ARSZ were dated at 37.5- 33.6 Ma. They show similar geochemical characteristics (whole-rock major oxides, trace element, Sr-Nd- Pb isotopic and zircon in-situ Hf isotopic data) with respect to coeval potassic granitoids in NW Yunnan, suggesting their origination from partial melting of thickened lower crust with additional contribution from enriched mantle-derived magmas. Leucogranite samples within the ARSZ yielded distinctive zircon U-Pb ages of 28.3 Ma and 18.5 Ma. Geochemical features suggest that they were derived from a heterogeneous crustal source consisting of metasediments and metabasites. Our results, along with those previous studies, suggest that the widespread potassic magmatism in the central and southeastern Tibetan Plateau is related to lithospheric mantle upwelling, which resulted in the partial melting of the thickened lower crust and a short-lived crustal extension during a period of decreased convergence rate. Subsequently, the orogenic-scale sinistral strike-slip movement provided shearing heat for generating leucogranites within the shear zones during the late Oligocene-Miocene. The plateau-wide shift in stress reorganization and tectonic reworking led to the lateral extrusion of the SE Tibetan Plateau and its attainment of modern high elevation. (c) 2023 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

The Lancang metamorphic complex is a key component of the Three River Tethys Orogen in the SE Tibetan Plateau, with typical rock assemblages and deformation fabrics recording the subduction of the Paleo-Tethys Ocean and subsequent continental collision. In this study, we present new petrographic and structural observations, together with zircon U-Pb and mica 40Ar/39Ar geochronologic data, to reveal the deformation and kinematics of the Lancang metamorphic complex, thus providing insights into the Permian−Triassic evolution of the eastern Paleo-Tethys domain. The subduction of the Paleo-Tethys Ocean and subsequent collision resulted in a range of structural features, including penetrative regional foliations, thrusts, asymmetric folds at various scales, and ductile deformation fabrics such as asymmetric boudins and porphyroclasts. Zircon U-Pb dating of foliated gabbro and 40Ar/39Ar dating of mica schist and mylonite, which preserve shortening fabrics, suggest that the Paleo-Tethys Ocean was subducted during the Late Carboniferous to Permian−Early Triassic, and the collision of the Baoshan and Simao blocks mainly occurred during ca. 237−230 Ma in the SE Tibetan Plateau. Regional deformation likely shifted from shortening to extension ca. 230 Ma, as reflected by post-collision high-K calc-alkaline magmatism. Our results document regional structural patterns and place timing constraints on the evolution of the Paleo-Tethys Ocean.

Abstract Understanding lithospheric rheology is crucial in investigating tectonic evolution of intra‐continental tectonic boundary. Here, we use geodetic observations to infer lithospheric rheology across the northeastern Tibet based on a 2D viscoelastic model. Our findings reveal a lower‐crust viscosity of <1022 Pa·s underneath its margins, lower than those estimated underneath its vicinities. By comparing deformation patterns and lithospheric rheology here with those observed in the eastern Tibet, we propose that lateral variations in lower‐crust viscosity control deformation patterns and topographic gradients along the Tibet margins. The presence of low viscosity lower‐crust can lead to the development of contrasting topographic gradients and shape the plateau's geomorphology and deformation characteristics during outward growth of the Tibet. We here emphasize the subtle variations in the lower‐crust rheology between deforming blocks and the corresponding mountain ranges, which play an important role in orogeny along the intracontinental convergence boundary.