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Recent studies of the northeastern part of the Tibetan Plateau have called attention to two emerging views of how the Tibetan Plateau has grown. First, deformation in northern Tibet began essentially at the time of collision with India, not 10-20 Myr later as might be expected if the locus of activity migrated northward as India penetrated the rest of Eurasia. Thus, the north-south dimensions of the Tibetan Plateau were set mainly by differences in lithospheric strength, with strong lithosphere beneath India and the Tarim and Qaidam basins steadily encroaching on one another as the region between them, the present-day Tibetan Plateau, deformed, and its north-south dimension became narrower. Second, abundant evidence calls for acceleration of deformation, including the formation of new faults, in northeastern Tibet since ~15 Ma and a less precisely dated change in orientation of crustal shortening since ~20 Ma. This reorientation of crustal shortening and roughly concurrent outward growth of high terrain, which swings from NNE-SSW in northern Tibet to more NE-SW and even ENE-WSW in the easternmost part of northeastern Tibet, are likely to be, in part, a consequence of crustal thickening within the high Tibetan Plateau reaching a limit, and the locus of continued shortening then migrating to the northeastern and eastern flanks. These changes in rates and orientation also could result from removal of some or all mantle lithosphere and increased gravitational potential energy per unit area and from a weakening of crustal material so that it could flow in response to pressure gradients set by evolving differences in elevation. Key Points The north-south limits of Tibet were set by lateral variations in strength Roughly 15 million years ago, deformation of NE Tibet accelerated Since 20-15 million years ago, the orientation of shortening rotated eastward ©2013. American Geophysical Union. All Rights Reserved.

New geothermometry using laser‐Raman data on carbonaceous material from low and intermediate grade rocks on Santa Catalina Island, California, together with existing thermobarometric data, show that there is a quasi‐continuous increase in peak metamorphic temperature from 327 ± 8°C in lawsonite blueschist facies rocks at the lowest structural levels, through ∼433°C in overlying epidote blueschists, 546 ± 20°C in albite‐epidote amphibolite facies rocks, to 650–730°C in amphibolite facies rocks at the top of the sequence. Rocks of different metamorphic grade are separated from one another by tectonic contacts across which temperature increases by ∼100°C in each case. Previously published geochronological data indicate that peak metamorphism in the highest grade rocks at 115 Ma preceded deposition of blueschist facies metasediments by ∼15 million years, so that the present inverted grade sequence does not represent an original inverted temperature gradient. The present structure results from progressive underplating of oceanic rocks in a cooling subduction zone following a high‐T metamorphic event at 115 Ma. An inverted temperature gradient of ≥100°C/km across the subduction channel likely existed during the high‐T event, decreased during underplating, and reached zero by ∼90 Ma. Key Points: New geothermometry shows that high‐pressure rocks on Catalina define an inverted metamorphic temperature zonationThe zonation is disrupted, and the present structure does not represent an original inverted thermal gradientThe zonation formed by progressive underplating in a cooling subduction zone following a high‐T metamorphic event [ABSTRACT FROM AUTHOR]

Understanding the propagation of shortening, especially the interaction of shallow and deep structural levels in space and time is important to understand the accretion process of a compressional orogen as well as to fully understand earthquake hazards to populated foreland basins. Here we combine evidence from geologic maps and stream‐terrace surveys to construct a set of retrodeformable cross‐sections of the western North Qilian Shan foreland. The uplifted, severely tilted Mesozoic and older rock units suggest the presence of both deep and shallow décollements in western and central part of our research area, and that these structures alternated activity since commencement of the latest phase of the North Qilian Shan uplift. Conversely, in the east, the absence of foreland fold‐and‐thrust belt and the moderately tilted Mesozoic rocks indicate the deformation is dominated by thick‐skinned uplift. Based on our cross‐sections, we estimate the long‐term shortening rate of the Jiuxi foreland basin of 1.2–1.8 m/Kyr. Deformed foreland terraces show that, from west to east in our research area, active deformation switches between different structural levels. This trade‐off between deformation styles in time and space shows that two décollement levels bound a crustal‐scale duplex as the foreland is incorporated into the orogen. We suggest the complex and out‐of‐sequence deformation pattern may relate to pre‐existing weakness within the basement rocks and is likely a common characteristic of the North Qilian foreland. This may impose an additional challenge for seismic hazard estimation of the region. Plain Language Summary: Qilian Shan ("Shan" as mountains) and Hexi Corridor (basin) are located at the NE margin of the Tibetan Plateau and formed due to the northeastern movement of the Tibetan Plateau. The mountain front of the North Qilian Shan and the adjacent low hills have shown various deformation styles, that is, different depth levels of active faults, which proposes a challenge to understand the deformation history of the area. Our study shows that the deformation styles not only vary in space but also change with time, forming a duplex (imbricate faults of different depth levels) which controls the northeastward propagation of the mountain front. We suggest this variation may be resulting from the complex pre‐existing weak structures within the bedrocks, which presents an additional challenge for seismic hazard estimation of the region. Analysis of the duplex suggests the western North Qilian mountain front has experienced compression at a rate of 1.2–1.8 m/Kyr. Key Points: The North Qilian is likely dominated by out‐of‐sequence deformation, resulting from reactivating pre‐existing structuresAlternatively active crustal‐scale duplex leads to various deformation styles of the North Qilian mountain frontLong‐term shortening rate of the mountain front and foreland area is 1.2–1.8 m/Kyr [ABSTRACT FROM AUTHOR]

The central Betic Cordillera, southern Spain, is affected by an uplift related to the NNW–SSE Eurasia‐Nubia convergence and shallow ENE–WSW orthogonal extension accommodated by the extensional system of the Granada Basin. The combination of geophysical, geodetic, and geological data reveals that the southwestern boundary of this extensional system is a seismically active compressional front extending from the W to the SW of the Granada Basin. The near‐field Global Navigation Satellite System data determine NNE–SSW shortening of up to 2 mm/yr of the compressional front in the Zafarraya Polje. In this setting, the normal Ventas de Zafarraya Fault developed as a result of the bending‐moment extension of the Sierra de Alhama antiform and was last reactivated during the 1884 Andalusian earthquake (Mw 6.5). The uplift in the central Betic Cordillera together with the subsidence in the Western Alborán Basin may facilitate a westward to southwestward gravitational collapse through the extensional detachment of the Granada Basin. The heterogeneous crust of the Betic Cordillera would generate the compressional front, which is divided into two sectors: thrusting to the west, and folding associated with buttressing to the south. Our results evidence that basal detachments, linking extensional fault activity with compressional fronts, may determine the activity of local surface structures and the geological hazard in densely populated regions. Plain Language Summary: A combination of geological, geophysical, and geodetic methods is used to understand the evolution in the frontal area of the extensional system of Granada Basin, near the Zafarraya Polje. In particular, this approach improves our knowledge of the Ventas de Zafarraya Fault (VZF) that hosted the 1884 Andalusian earthquake. Seismic data provide information on the distribution of stress and deformation in the region and made it possible to identify a compressional front linked to the extensional system of the Granada Basin. Global Navigation Satellite System (GNSS) data accurately locate the sites of the Zafarraya GNSS network surrounding the VZF, and repeated measurements provide deformation rates of the area that suggests shortening. Thus, we locate the VZF within the former compressional setting. Meanwhile, electrical‐resistivity tomography images sub‐surface structures given its electrical properties and, together with the field geological observations, suggests the extensional behavior of the fault. Therefore, it is considered to be a fold‐related fault formed due to the extension of the outer arc of the Sierra de Alhama antiform. As in the research presented here, a joint interpretation of data from different methods makes it possible to propose active seismic tectonic extensional models in a compressional setting applicable to other regions. Key Points: Shortening up to 2 mm/yr suggests activity of the Ventas de Zafarraya normal Fault simultaneous to foldingThe Sierra de Alhama‐Zafarraya Polje area belongs to a compressional front located to the W and SW of the extensional Granada BasinShallow normal faults may constitute the surface expression of deep main faults developed in a complex crustal compressional setting [ABSTRACT FROM AUTHOR]

The tectonic deformation on the eastern margin of the Qaidam Basin, which has preserved complete sedimentary records, significantly influences the evolutionary model of the northeastern margin of the Tibetan Plateau. However, the deformation history in this area during the Holocene remains unclear. This study is based on the high‐precision digital elevation model obtained through drone mapping technology, which identifies three active faults on the eastern margin of the Qaidam Basin: the Xiariha Fault (XRHF) and Yingdeerkang Fault Yingdeerkang Fault (YKF) are NW‒SE‐orientated dextral faults, whereas the Reshui‐Taosituohe Fault (RTF) is a nearly east‒west‐orientated sinistral fault. Based on the optically stimulated luminescence dating of the landform surfaces, the rates of strike‐slip offset are as follows: those of the XRHF range from 1.12 ± 0.07 to 1.68 ± 0.12 mm/yr and those of the YKF are from 0.99 ± 0.06 to 2.29 ± 0.13 mm/yr. Recent paleoseismic events occurred along the RTF at approximately 714–1,792 years BP and at 700 ± 18 years BP, implying a recurring millennial pattern. Together, these faults possibly form a complex cross‐fault system along the southeastern edge of the basin, heightening seismic risk. Deformation in the western part of the northeastern Tibetan Plateau is driven by slip on the Altyn Tagh Fault and compression in the Qaidam Basin. The central part experiences slip on the East Kunlun Fault, along with secondary faults, shortening, and block rotation. The eastern part primarily experiences slip along the Haiyuan Fault. Key Points: The Xiariha, Yingdeerkang, and Reshui‐Taosituohe faults (RTF) on the eastern margin of the Qaidam Basin have been active during the HoloceneThe paleoseismic recurrence interval of the RTF is estimated to be approximately 1,000 yearsThe eastern margin of the Qaidam Basin is expected to include a complex system of cross‐faults, increasing the seismic hazard [ABSTRACT FROM AUTHOR]

The ∼400‐km‐long Litang fault system (LTFS) is a major intracontinental strike‐slip fault inside the Chuandian block, eastern Tibet, but its evolution and role in accommodating the India‐Asia convergence remain poorly known. Structural analysis shows that the LTFS splits into 5 strands as a left‐lateral, right‐stepping en‐echelon pattern formed under NW‐directed compression, subsequently reactivated by transtensive faults under NNE‐directed extension. Displaced geological and morphological markers yield a cumulative left‐lateral offset of 28.9–42.8 km. Inverse thermal‐history modeling of thermochronological data of the faulted rocks reveal accelerated cooling at 38–35 Ma, 16–13 Ma, and 7–5 Ma. The late Eocene rapid cooling is ascribed to the reactivation of the Garze‐Litang suture. Rapid cooling events at 16–13 Ma and 7–5 Ma record the onset of transpression and transtension of the LTFS, respectively, yielding a geologic slip rate of 2.6 ± 0.7 mm/yr. Both bifurcated geometry and slow slip rate of the LTFS since 16–13 Ma indicate diffuse deformation inside the Chuandian block, contrasting with strain localized on fast‐slip strike‐slip faults on the block margins. This implies a significant kinematic transition in the middle Miocene, such that the extrusion of the segmented mega‐blocks has been accommodated by both localized and distributed deformation in eastern Tibet. This tectonic transition could be explained by a change in lithospheric rheology from an earlier rigid state to a viscous state underneath the Chuandian block due to thermal weakening of the lower crust. We thus reconcile the end‐member geodynamic models of block extrusion and lower crustal flow in late Cenozoic times. Plain Language Summary: The role of the Litang fault system in Chuandian block, eastern Tibet in accommodating deformation from the India‐Asia convergence remains unclear due to the lack of robust constraints on its deformation history. Structural analysis shows that the fault system has 5 left‐lateral splays formed under oblique compression and later reactivated in transtension. Displaced lithology and landforms yield a cumulative left‐lateral offset of 29–43 km. Thermochronology of apatite and zircon crystals, which measures how fast rocks have cooled as they move from depth to the surface, reveal that rock cooling during 16–13 Ma and 7–5 Ma were controlled by uplifted rocks related to the onset and propagation of the fault system. The long‐term slip rate is 2.6 ± 0.7 mm/yr. The bifurcated pattern with low slip rate of the Litang fault system indicates distributed deformation inside the Chuandian block concurrent with localized deformation on the block margins since ∼16–13 Ma. This could be explained by a hybrid geodynamic model of micro‐block (mega‐block sliced by strike‐slip faults) extrusion and weakened lower crust preceded by mega‐block extrusion accommodated by terrane‐bounding strike‐slip faults. We propose that this kinematic change has occurred in the middle Miocene, leading to the formation of present‐day tectonic configuration in eastern Tibet. Key Points: The geometry, kinematics, and age of the Litang fault system are reappraisedThe splayed Litang fault system was initiated at 16–13 Ma and expanded at 7–5 MaActive tectonic regime in eastern Tibet has been established since 16–13 Ma [ABSTRACT FROM AUTHOR]

A new structural model is presented for the Permo‐Carboniferous Lorraine Basin (NE France), a major intramountain basin that developed during the latest stages of the Variscan orogeny (ca. 315–270 Ma). Digitalized well logs and reprocessed seismic data were used to decipher the kinematic evolution of this basin located along the Rhenohercynian orogenic suture zone. The basin was initiated during the late collision stage (Early to Middle Pennsylvanian) in a wedge‐top position upon the Saxothuringian retro‐wedge. The syn‐orogenic sequence is delimited to the north by the major SE‐verging Metz Thrust, which is part of the backthrust system that propagated during Middle Pennsylvanian (Late Westphalian). Seismic data provide evidence of negative tectonic inversion, allowing the formation of syn‐rift depocenters (Late Pennsylvanian‐Early Permian) above the former anticlines. Erosion of these anticlines results in a major unconformity marking the onset of post‐orogenic collapse. The late Early Permian shortening (Saalian phase) is suggested to reactivate former thrusts and normal faults, thus generating late uplift of the basin. The post‐orogenic phase is complex and diachronous at basin scale, and both compression and extension can be recorded in the same area over a short period (<10 Myr). The Late Carboniferous negative tectonic inversion along the Rhenohercynian suture zone is proposed to result from the lithospheric delamination of the Variscan orogenic roots. The associated upwelling of asthenospheric material is recorded by intense magmatic activity, and can be, in turn, considered as the main trigger for the subsequent thermal subsidence of the Mesozoic Paris Basin. Key Points: A new structural model of the Permo‐Carboniferous Lorraine Basin (NE France) is proposed based on 438 km of reprocessed seismic dataThis major intramountain basin developed during Early‐Middle Pennsylvanian times as a wedge‐top basin upon the Variscan Saxothuringian retro‐wedgeExtensional reactivation of thrusts controlled the development of syn‐rift depocenters above the former thrust‐related anticlines [ABSTRACT FROM AUTHOR]

The NNW‐trending Jiayuguan Fault (JYGF) is an actively developing thrust fault that delimits the SW margin of Jiayuguan, a major industrial city in the northwestern Hexi Corridor, China. In this study, we document the geometry, kinematics, and slip rates of the JYGF based on analysis of satellite imagery, low‐altitude photogrammetry, field observations, paleo‐seismic trenching, and Quaternary dating. The JYGF hanging‐wall contains a NE‐vergent asymmetric anticline of Cretaceous redbeds unconformably overlain by faulted, tilted and folded alluvial fan and fluvial terrace surfaces. Subsidiary fault scarps are associated with anticlinal flexure and contractional strain. The vertical uplift and crustal shortening rates are both ∼0.1 mm/a since ∼420 ka and geomorphic markers and dated landforms indicate southeastward fault propagation and hanging‐wall uplift from the Heishan toward the modern Beida River channel. The NW end of the fault appears to connect with the Altyn‐Tagh‐Heishan‐Jinta'Nanshan sinistral strike‐slip fault array suggesting that the JYGF is one of several parallel, splay faults that transfer strike‐slip motion to active folding and thrusting in the region. We relocate the 1992 Ms 5.4 earthquake epicenter using the NonLinLoc method and suggest that the JYGF may link southeastward with Quaternary‐active faults and folds in the Wenshushan. A seismic rupture along the total fault length of 25–40 km for the JYGF‐Wenshushan deforming belt corresponds to a potential earthquake magnitude in the 6.6–7.0 range. Compartmentalized faulting and folding in the NW–most Hexi Corridor defines a triangular block of active deformation where NE‐directed contractional deformation of the Qilian Shan foreland interacts with E‐W left‐lateral displacement along the Altyn‐Tagh‐Heishan‐Jinta'Nanshan sinistral strike‐slip system. Key Points: The Jiayuguan Fault (JYGF) is an actively developing thrust with a dextral strike‐slip component that borders Jiayuguan cityThe JYGF slips at a rate of ∼0.1 mm/a since ∼420 ka and has laterally propagated SENNW‐trending oblique‐slip thrust faults compartmentalize the NW Hexi Corridor and link to the Altyn Tagh‐Heishan‐Jinta'Nanshan strike‐slip corridor [ABSTRACT FROM AUTHOR]

The factors that control strain partitioning along plate boundaries and within continental interiors remains poorly resolved. Plate convergence may be accommodated via distributed crustal shortening or discrete crustal‐scale strike‐slip faulting, but what controls these differing modes of deformation is debated. Here we address this question by examining the actively deforming regions that surround the Tarim Basin in central Asia, where deformation is uniquely partitioned into predominately strike‐slip faults in the east and distributed fold‐thrust belts in the west to accommodate Cenozoic India‐Asia plate convergence. We present integrated geological and geophysical observations to elucidate patterns in crustal deformation and compositional structure in and around the Tarim Basin. The thrust‐dominated western Tarim Basin correlates with a strongly‐magnetic lower crust, whereas strike‐slip faulting along the eastern margins of the Tarim Basin lack such magnetic signals. We suggest that the lower crust of the western Tarim is more mafic and stronger than in the east, which impacts intra‐plate strain partitioning. A stronger lower crust results in vertical decoupling to drive mid‐crust horizontal detachments and facilitate thrust faulting, whereas a more homogenized crust favored vertical transcrustal strike‐slip faulting. These rheological differences likely originated from the impingement of the Permian Tarim plume focused in the west. A comparison with the Longmen Shan of eastern Tibetan Plateau reveals remarkably similar strain partitioning that correlates with variations in foreland rheology. Our results highlight how variations in lower‐crust viscosity impact strain partitioning in an intra‐plate setting and how plume processes exert a strong control on later continental tectonic processes. Plain Language Summary: Crustal deformation propagates far into the continental plate interior when continental plates collide and converge. Sometimes intra‐plate deformation is expressed via distributed crustal shortening in fold‐thrust belts and sometimes it is manifested as discrete vertical strike‐slip faults that accommodate lateral plate motion. It remains unclear what dictates which mode of deformation operates within the continental interior. Here we examined the patterns and compositional structure of deformational belts around the Tarim Basin in central Asia using integrated geological and geophysical datasets. The western Tarim Basin is characterized by distributed shortening and the eastern basin is characterized by strike‐slip faulting, and these differences correlate strength variations in the lower crust imaged via magnetic surveys and inversions. Specifically, we hypothesize the stronger crust of the western Tarim Basin allows the upper crust to detach to develop fold‐thrust belts, whereas the eastern Tarim Basin has a more homogenously strong crustal column that is cut by vertical strike‐slip faults. Our proposed model with lower‐crust rheology controlling the mode of intra‐plate deformation may be broadly applicable to zones of continental deformation. Key Points: Crustal deformation around the Tarim Basin is uniquely partitioned into predominately strike‐slip faults in the east and distributed fold‐thrust belts in the westLower crustal viscosity impacts crust‐scale deformation and strain partitioning in an intraplate settingPlume‐driven crustal modification exerts a strong control on later continental tectonic process [ABSTRACT FROM AUTHOR]

The Olkhon Terrane is thought to preserve a record of the initial collision of the Siberian Craton with its peripheral orogenic system during the early Paleozoic. However, the related tectono‐metamorphic process and its time‐scale remain obscure. To address this issue, new structural observations combined with U‐Pb zircon and monazite and 40Ar/39Ar biotite geochronology were conducted in the migmatitic‐granitic Anga‐Sakhurta Zone of the terrane. An earliest syn‐collisional event associated with the development of a c. 500–480 Ma sub‐horizontal migmatitic fabric is confirmed. This early fabric was affected by later extensional doming in association with emplacement of partial melts (in terms of c. 470–445 Ma granite sills) parallel to the sub‐horizontal mechanical anisotropy. Subsequent upright folding leading to amplification of extensional domal structures and heterogeneous vertical transposition of composite horizontal fabric occurred soon after the doming, as indicated by intrusions of residual melts into the axial planes of the upright folds. The latest episode of deformation was marked by development of greenschist‐facies sinistral shear zones surrounding the Anga‐Sakhurta Zone at c. 420–400 Ma. An updated tectonic model involving (a) Middle–Late Ordovician crustal thinning associated with horizontal crustal flow, (b) Silurian crustal shortening related to northwards movement of Cambrian magmatic arc of the Birkhin Complex to the south, and (c) Early Devonian lateral extrusion and sinistral shearing associated with progression of the Birkhin Complex promontory, is proposed. Results from this study shed lights on the collisional evolution of peri‐Siberian orogenic system during the early stage evolution of the Central Asian Orogenic Belt. Key Points: The Olkhon Terrane underwent Cambrian–Silurian shortening‐extension cycles and Devonian lateral extrusion and shearingCambrian to Devonian tectonic switches in the Olkhon Terrane mark the collisional evolution of peri‐Siberian orogenic systemGeodynamic evolution of the Olkhon Terrane closely matches to that of central segment of the Mongolian Collage [ABSTRACT FROM AUTHOR]

Austroalpine nappes in the Eastern European Alps have preserved the record of orogenies in the Cretaceous and Cenozoic but their cooling and exhumation history remains poorly constrained. Here we use low‐temperature thermochronology and thermokinematic modeling to unravel the exhumation history of the Austroalpine nappes in the Gurktal Alps. Our data reveal marked differences between the exhumation of units located at different positions within the nappe stack and relative to the Adriatic indenter. Units located at a high structural level and farther away from the indenter cooled through the zircon fission track closure temperature in the Late Cretaceous and have resided at depths of ≤5–6 km since the Oligocene, as indicated by apatite fission track ages of 35–30 Ma. Thermokinematic modeling constrained that these units experienced enhanced exhumation (∼0.60 km/Ma) between ∼99 and ∼83 Ma due to syn‐ to late‐orogenic Late Cretaceous extension. After a phase of slow exhumation (∼0.02 km/Ma), the exhumation rate increased to ∼0.16 km/Ma at ∼34 Ma due to the onset of the Europe‐Adria collision. In contrast, zircon fission track ages from units at a lower structural level and near the indenter indicate cooling during the Eocene; apatite fission track ages cluster at ∼15 Ma. These units were rapidly exhumed (∼0.76 km/Ma) from ∼44 to ∼39 Ma during an Eocene phase of shortening prior to the Europe‐Adria collision. After slow exhumation (∼0.13 km/Ma) between ∼39 and ∼18 Ma, the exhumation rate increased to ∼0.27 km/Ma in the wake of Miocene escape tectonics in the Eastern Alps. Key Points: Austroalpine nappes in the Gurktal Alps east of the Tauern Window experienced alternating phases of enhanced and slow exhumationNappes at higher structural levels were exhumed during Late‐Cretaceous extension and have been at upper‐crustal levels since thenThe Radenthein and Millstatt Complexes experienced enhanced exhumation during the Middle Eocene and since the Early Miocene [ABSTRACT FROM AUTHOR]

Exhumation and cooling pathways of mid‐crustal metamorphic rocks in the western Nepal Himalaya can be replicated by fold‐thrust belt structures with displacement localized along discrete décollements. New and published muscovite 40Ar/39Ar, zircon U‐Th/He, and apatite fission track cooling ages, peak temperature estimates, geologic mapping, and basin data are integrated with thermokinematic forward models to constrain the geometry, kinematics, and rates of shortening in far western Nepal. The best fit to peak temperatures, cooling ages, and basin accumulation data is achieved with a largely in‐sequence kinematic order, with out‐of‐sequence motion on the Ramgarh‐Munsiari thrust. Fast rates (∼20–40 mm/yr) are required during shortening on early, large displacement faults at ∼23–12 Ma and decrease to ∼10–15 mm/yr during formation of the Lesser Himalayan duplex until ∼1 Ma. Thermokinematic models highlight the relationship between peak temperature, geometry, and shortening on the large displacement Main Central and Ramgarh‐Munsiari thrusts. In the thermokinematic models, we observe a relationship between the location of frontal ramps for the faults that displace lower Lesser Himalayan units and the ∼375°C isotherm, immediately before the ramp becomes active. These correlations suggest that temperature exerts a first‐order control on thrust geometry in a hot orogen. Viable models highlight the position of active ramps, kinematic order of faults, timing of fault motion, and reduction in shortening rates that are required to reproduce the surface geology, basin accumulation, peak temperature conditions, and timing of exhumation. Cooling ages are far more sensitive to the age of fault motion than the rate of fault motion. Key Points: In‐sequence kinematics, with early and late out‐of‐sequence motion, coupled with variable shortening rates best reproduces measured dataA slowdown in shortening rates from ∼12 Ma until ∼1 Ma started during formation of the Lesser Himalayan duplexDisplacement is predominantly localized along discrete décollements at temperatures up to ∼700°C for the Api cross‐section [ABSTRACT FROM AUTHOR]

The southern Central Andes (SCA, 27°–40°S) exhibit a complex deformation pattern that is influenced by multiple factors, including the present‐day dip angle of the subducting oceanic Nazca plate and the influence of inherited heterogeneities in the continental South American plate. This study employs a data‐driven geodynamic workflow to assess the role of various forcing factors in determining upper‐plate strain localization, both above the flat slab and the steeper segment to the south. These include the dip angle of the Nazca plate, the mechanically weak sedimentary basins, the thickness and composition of the continental crust, the strength of the subduction interface, and the plate velocities. Our modeling results predict two main deformation modes: (a) pure‐shear shortening in the broken foreland above the flat‐slab segment and eastward propagation of deformation, and (b) simple‐shear shortening restricted to the eastern margin of the Andean fold‐and‐thrust belt above the steep‐slab segment. While the convergence velocity and the frictional strength of the subduction interface primarily control the intensity of the deformation, inherited heterogeneities tend to localize deformation, and weak sediments leads to intensified surface deformation. Thicker crust and surface topography also influences strain localization by transferring stress to the eastern orogenic front. Above the flat‐slab segment deformation migrates eastward, which is facilitated by enhanced interface coupling. The transition between the steep and sub‐horizontal subduction segments is characterized by a diffuse transpressional shear zone, likely controlled by the change in dip geometry of the Nazca plate, and the presence of inherited faults and weak sedimentary basins. Plain Language Summary: The deformation patterns in the southern part of the Central Andes, where the oceanic Nazca plate subducts beneath the continental South American Plate, exhibit great variability both along and across the mountain range and the adjacent regions. However, the extent to which each plate contributes to these patterns remains a topic of ongoing discussion. In this study, we use a computer code to numerically simulate the forces that act on specified areas of the mountain belt (stresses) and resulting deformation (strain), by incorporating the present‐day plate geometry, temperature, and composition into our workflow. This enables us to quantify the relative contribution of each plate to observable deformation patterns, including variations in the dip angle of the oceanic plate and the influence of mechanically weak discontinuities within the continental plate that were inherited from previous tectonic processes. Key Points: A data‐driven modeling workflow is applied to the southern Central Andes to assess the contribution of the subducting and overriding plates on strain localization in the overriding plateThe subducting flat slab cools and strengthens the continental lithosphere above it. Stresses related to the interaction between the oceanic Nazca Plate and the continental South American Plate is transmitted toward the eastern Sierras Pampeanas in the broken foreland of the orogenInherited faults amplify surface strain localization in the foreland. High topography inhibits strain localization in the orogen. Consequently, strain migrates toward the Andean foreland [ABSTRACT FROM AUTHOR]

The Eastern Himalayan Syntaxis (EHS) is one of the fastest exhuming regions on Earth since ∼10 Ma, and the mechanism of its fast exhumation is under debate. Different from many other studies based on tectonics‐driven models, we performed analytical analysis and numerical simulations to investigate an erosion‐driven system. Our results show that fast and focused surface erosion alone is able to exhume the lower crust on the timescale of ∼10 Myr. This process leads to the formation of a domal structure, an elevated geothermal gradient, rapid cooling of crustal rocks, and decompression melting in the lower crust. In the upper‐mid crust, the uplift of crustal rocks is caused by isostatic flow driven by pressure gradient, whose rate is limited by the driving erosional forcing. In the mid‐lower crust where decompression melting occurs, rocks entrained in a buoyant diapir experience fast uplift rate exceeding the erosional forcing. Our erosion‐driven model demonstrates an intricate coupling between surface erosion and crustal processes. Positive feedback between surface erosion and rock uplift is possible under certain conditions and crustal diapirism plays a key role in the feedback. Our study shows that both isostatic and diapiric flows play important roles in the uplift and exhumation of crustal rocks in the EHS. We highlight that erosion‐driven crustal diapirism can be one of the missing pieces explaining the evolution of the Eastern Himalayan Syntaxis. Plain Language Summary: Located in southern Tibet, the Eastern Himalayan Syntaxis (EHS) has undergone fast rock exhumation in the past ∼10 million years. Previous studies show that such exhumation can be driven by tectonic or surface processes. In this study, we built a numerical model in which we directly tested how focused surface erosion can cause the crust to deform. We also uses simple math equations to quantify the relationship between surface erosion and crustal deformation. We confirm that crust can flow in response to pressure gradient and buoyancy. The formal type of flow is limited by the surface erosion rate while the latter occurs if the rocks undergo partially melting. The surface erosion and rock uplift can mutually enhance each other, accelerating both rates, if certain conditions are met. Our study highlights that the rapid ascent of partially molten mid‐lower crustal rocks in the form of a diapir. We suggests that crustal flows driven by both pressure gradient and buoyancy are important to understand the evolution of the EHS. Key Points: Analytical and numerical models were performed to study the dynamics of the crustal flow in an erosion‐driven systemSurface erosion generates pressure‐gradient‐driven isostatic flow and buoyancy‐driven diapiric flow in continental crustDiapirism can trigger positive feedback and it can be one of the missing pieces in the evolution of the Eastern Himalayan Syntaxis [ABSTRACT FROM AUTHOR]

The NNW Iranian Plateau and west Alborz within the Arabia‐Eurasia collision zone are characterized by three main tectono‐stratigraphic zones, crosscut by the Qezel‐Owzan River (QOR) Basin. The interplay between present‐day deformation and climate, which control the landscape evolution of the region, is still poorly constrained. We addressed this gap by measuring millennial‐scale erosion rates from 10Be‐concentration in the QOR sands along with topographic/climatic metrics analyses. Results reveal low erosion rates in the Plateau and relatively high in the west Alborz. The regional consistency of topographic parameters with geomorphology suggests that they control sediment fluxes in the Plateau, while the surface uplift, active thrust‐faulting, and shallow crustal seismicity in the west Alborz are the main controlling factors. Climate has a secondary role on erosion rates. Furthermore, we calculated exhumation rates from published thermochronometric AFT/AHe ages to determine their relationship with 10Be short‐term data. Results imply that the exhumation rates increased slightly in the Plateau and west Alborz from ∼26 to ∼10 Ma, simultaneous with hard collision processes between the Arabia‐Eurasia. This trend accelerated from ∼10 to ∼2.8 Ma due to the isolation of the Caspian Sea and extreme base‐level fall. From ∼2.8 to ∼2 Ma, base‐level rise occurred under climate influence, and erosion rates decreased. Millennial‐scale data show the erosion rate decreased from ∼2 Ma to the Present‐day, which is attributed to the change in deformation style and fault kinematics from fold/thrusting to mainly strike‐slip faulting. The significantly lower erosion rates in the Plateau compared to west Alborz suggest a relatively stable plateau surface. Plain Language Summary: The Earth's surface is shaped by interactions between tectonics, climate, and erosion. Tectonic activity with ground motion weakens and fractures bedrock, creating debris and physical erosion, particularly in regions experiencing crustal shortening. There is no doubt that tectonics influence climate primarily by growing high mountain ranges and plateaus. Such high topography may create a barrier to atmospheric circulation and alter precipitation that has significant impact on climatic conditions and erosion. A number of regions around the world have shown the link between tectonic and climatic processes, however, we still lack a comprehensive understanding of ongoing deformation/tectonics and climate on the NNW Iranian Plateau and its margin. We used new 10Be concentration data from river sands and integrate these with topographic‐climatic metrics combined with long‐term data to show how this region has evolved over the past 50 Ma. Our findings suggest that millennial‐scale erosion rates have decreased relative to the long term, mainly due to tectonic impact. A key outcome of this study is that the results indicate that the landscape is in a quasi‐equilibrium in the Iranian Plateau and in a transient state in the west Alborz. Key Points: Acceleration of post‐collisional AFT/AHe derived exhumation rates (∼10 to ∼2.8 Ma) under impact of tectonics and base‐level fluctuationsDeceleration of 10Be millennial‐scale erosion rates compared to the long‐termNearly stable Plateau since Pliocene due to tectonic quiescence, evolving margin due to tectonic/climate coupling in Pliocene‐Quaternary [ABSTRACT FROM AUTHOR]

Orogenic plateaus of continental collision zones exhibit landforms and fluvial networks that retain first‐order information on their topographic evolution and vertical growth. The inversion of river longitudinal profiles allows to reconstruct the base level fall history of plateaus, supporting the study of landscape evolution in the frame of geodynamic models. The Eastern Anatolian Plateau (EAP) of the Arabia‐Eurasia collision zone is a plateau at an early stage of development. It stands at ∼2,000 m, presents endorheic basins, and is drained by three main river networks. Seismic data indicate a thinned lithospheric mantle that explains the late Cenozoic volcanic activity. Despite the number of studies on the EAP uplift, its history is still debated. In this study we investigated the EAP hydrography and topography, and we inverted the longitudinal profile of one of the main rivers: the Arax River. The results describe a high‐standing, low‐relief plateau drained by a hydrography, controlled by active tectonics. Longitudinal profiles and χ‐plots illustrate rivers in disequilibrium with channel steepness increasing downstream. The elevation of marine deposits indicates a surface uplift of ∼2,000 m, ∼500 m of which are of residual topography. This upheaval occurred by two increases: the first one at 10–11 Ma with the opening of a slab window and the arrival of a mantle flow from Arabia and the second one at ∼5 Ma with the continued inflow coupled with isostasy. Our results describe the early stage of collisional plateau development, distinguishing the contribution of deep processes and isostasy to the topographic growth. Key Points: The Eastern Anatolian Plateau (EAP) is a continent‐continent collisional plateau at an early stage of developmentThe EAP was affected by a surface uplift of ∼2,000 m according to geologic and geomorphic data; ∼500 m of it are dynamically supportedThe base level fall history of EAP documents a three steps increase in uplift rate due to the contribution of deep and crustal processes [ABSTRACT FROM AUTHOR]

The northern margin of the Tibetan Plateau is defined by the left‐lateral Altyn Tagh fault. It remains unclear whether the Cenozoic deformation related to the India‐Asia collision has remained stationary along the Altyn Tagh fault or propagated northward into the southeastern Tarim Basin. The Cenozoic Cherchen fault is located in the southeastern Tarim Basin, ∼90–120 km north of the Altyn Tagh fault, and thus, may play a critical role in addressing this issue. Here, we used a densely‐spaced two‐dimensional seismic reflection survey to investigate the geometry and kinematics of the Cherchen fault and understand its role in the expansion of the northern margin of the Tibetan Plateau. Our seismic study shows that the Cenozoic Cherchen fault is a high‐angle left‐lateral transpressional fault. Kinematic analysis of the Cherchen fault suggests that a restraining bend structure has formed along its central segment. Stratigraphic records suggest that the Cherchen fault initiated in the Paleozoic and reactivated during the middle Miocene (ca. 17–15.7 Ma). We infer that the dip‐slip and strike‐slip rates of the Cherchen fault are ∼0.09 mm/a and ∼1.66 mm/a, respectively. A regional cross section reveals that the northward expansion of the plateau is ongoing, but the range is limited to ∼90–120 km. We interpret that middle Miocene tectonic activity throughout the region was also concentrated along the northern plateau margin, defined by both northeast‐directed crustal shortening and northward expansion of the plateau. Key Points: The Tibetan Plateau is propagating north of the Altyn Tagh fault into the Tarim Basin, evidenced by slip along the Cherchen faultStructural analysis of the Cherchen fault suggests it is a high‐angle transpressional faultThe northward expansion of the Tibetan Plateau is ongoing but limited to ∼90–120 km [ABSTRACT FROM AUTHOR]

In an orogen‐foreland basin system, syn‐orogenic sedimentation and deformation records within the foreland basin provide critical evidence for understanding uplift and erosion processes of adjacent orogenic belts. Foreland fold‐and‐thrust belts (FTBs) are widely developed around the Tian Shan range, Central Asia. Problem of how crustal shortening accumulates and propagates from the Tian Shan to adjacent foreland basins is essential for understanding the overall dynamics of Tian Shan. In this study, we interpreted three high‐resolution seismic reflection profiles to estimate the magnitude and distribution of Cenozoic shortening across the Eastern Kuqa FTB, South Tian Shan foreland. Combined with well‐dated syntectonic stratigraphy, we further evaluate the timing, rate, and migration of the deformation front of the Kuqa FTB. Our results suggest that the Kuqa FTB's total crustal shortening increases westward. The distribution of crustal shortening across secondary structural belts shows a gradual, basinward decrease, which can be explained by the telescoped mechanism. Propagation rates of the Kuqa FTB's deformation front indicate an episodic propagation of the foreland thrust wedge, with an acceleration after ∼12 Ma. Similar episodic propagation pattern has also been observed in other foreland FTBs around the Tian Shan, but they show significant spatio‐temporal variations in the propagation stages and related rates. Plain Language Summary: The Tian Shan range stretches over 2,500 km from east to west and is one of the Earth's largest intracontinental orogenic belts. As the mountains grew, deformation propagated into foreland basins around the range, forming a series of fold‐and‐thrust belts (FTBs). To better understand the spatial distribution of crustal shortening, and basinward propagation process in foreland FTBs, we interpret and reconstruct three high‐resolution seismic profiles across the Eastern Kuqa FTB, South Tian Shan. Our study indicates that the total crustal shortening of the Eastern Kuqa FTB increases westward. Within the Kuqa FTB, a telescoped distribution pattern of crustal shortening is also observed in frontal thin‐skinned structures above the regional salt décollements. In addition, we find that the basinward propagation of Kuqa FTB is episodic, which is featured by a two‐stage evolution pattern. Key Points: The Eastern Kuqa fold‐and‐thrust belt shows a westerly increase in total shortening and a telescoped pattern in shortening distributionThe Cenozoic propagation of the Kuqa thrust belt indicates an episodic process that accelerated after ∼12 MaBasinward growth of the Tian Shan orogenic wedge varies spatiotemporally; propagation stages and rates vary in different foreland basins [ABSTRACT FROM AUTHOR]

The Tianshan orogenic belt, part of the Central Asian Orogenic Belt, offers an opportunity to examine the complexities of an orogenic system that records long‐term intracontinental deformation. The Tianshan have been reactivated multiple times since the Mesozoic, but the mechanisms and driving forces of these various orogenic events are not well constrained. Moreover, the spatial exhumation pattern of the entire Tianshan remains poorly studied. We present new zircon and apatite (U‐Th)/He and apatite fission track thermochronological data for samples from the northwestern part of the Chinese Western Tianshan. They indicate three distinctive phases of rapid cooling in the late Carboniferous‐early Permian, Late Triassic‐Early Jurassic, and Cretaceous. The first phase can be linked to uplift and exhumation related to the subduction/closure of the Paleo‐Asian Ocean, while the episodic cooling during the Late Triassic‐Early Jurassic (250–190 Ma) and Cretaceous (115–80 Ma) are interpreted as related to uplift and exhumation associated with strike‐slip deformation and Mesozoic clockwise or anticlockwise rotation of the Junggar basin. Our new data, in concert with a compilation of previously published data from elsewhere in the region, reveal that the Tianshan underwent a greater amount of exhumation in the southern section, and less exhumation took place to the north. All available data also support the notion that the exhumation process has been essentially the same in tectonic blocks along strike since late Paleozoic. During the Cenozoic, the Tianshan experienced large‐scale, rapid exhumation starting in the late Miocene (12–10 Ma) and not the early Miocene as has been previously proposed. Key Points: Pulsed exhumation episodes in the Tianshan orogenic belt are interpreted as the result of differential rotation of local crustal blocksThe late Paleozoic to Cenozoic regional exhumation was greatest in southwest Tianshan and lessened progressively to the north and eastNew data and regional compilation show that the late Oligocene deformation event was local and did not result in regional exhumation [ABSTRACT FROM AUTHOR]

Continental‐scale strike‐slip shear zones often record significant tectono‐magmatism and dynamic deformation processes of the crustal lithosphere. However, the genetic relationships and timing among the anatexis, deformation, and initial shearing along a strike‐slip shear zone have not been well defined. Here, we carried out detailed field, microstructural, zircon U–Pb geochronology, geochemical and EBSD texture analyses of leucogranites and migmatites in the Chongshan shear zone (CS‐SZ). The results indicate that most migmatites and leucogranites exhibit strong shear deformation and well‐developed high‐temperature mylonitic microstructures. The quartz aggregated from foliated leucogranites developed dominant high‐temperature prism and prism slip systems. The pre‐ and syn‐kinematic crustal anatexis and localized weak zone mainly occurred from 35 to 29 Ma along the CS‐SZ, which is closely related to the post‐collisional extension and collapse of overthickened crust. Biotite dehydration melting formed pre‐ and syn‐kinematic melts and leucogranites that further experienced fractional crystallization of plagioclase and K‐feldspar during melting and subsequent melt migration and emplacement upward along the tectonic weak zone. The thinning and weakening of lithospheric crust further facilitated the initial and formation strike‐slip displacement along the CS‐SZ, which occurred from 29 to 20 Ma or much later to 18 Ma. Finally, we propose that crustal anatexis and upward migrating melts play a key role in controlling the thermal state and rheological strength of the crust, resulting in nucleation and initiation of the localized deep‐seated shear zone that accommodates significant displacement for the India–Asia continental forward collision and intracontinental deformation. Key Points: The Chongshan shear zone experienced large‐scale crustal anatexis from 35 to 18 MaThe anatexis of the migmatites is controlled by biotite dehydration meltingAnatexis plays a key role in nucleation and initiation of the localized deep‐seated shear zone [ABSTRACT FROM AUTHOR]

The Altyn Tagh fault (ATF) is a major intracontinental strike-slip fault system that defines the northern margin of the Tibetan Plateau. The fault system loses its obvious surface expression north of the Qilian Shan fold-and-thrust belt, but may link eastward with multiple faults in the northern Hexi Corridor and southern Alxa block. To better understand the potential connectivity and displacement transfer between the ATF and the northern Hexi Corridor fault array, we carried out a multidisciplinary field and remote sensing-based investigation of the actively deforming Heishan and Jinta'Nanshan region north of Jiayuguan City. We document Quaternary sinistral strike-slip motion on the Heishan fault (HF) system and active sinistral transpression within a 70-km-long, E-W deforming belt east of the Heishan, which is characterized by multiple left-stepping, en-échelon Quaternary folds and linking faults. Cosmogenic 10Be dating of displaced terrace surfaces yields a vertical slip rate of ∼0.2 mm/a for the northern Heishan thrust and a sinistral strike-slip rate of 0.6 ± 0.2 mm/a for the HF. Within the uplifted core of the Heishan massif, the HF contains ductilely deformed Paleozoic basement lithologies with dextral-sense shear fabrics that indicate that the modern HF has reactivated and inverted an older shear zone. A previously published magnetotelluric profile across the HF system suggests that it roots into a steep, deeply penetrating fault that is unlinked to the Qilian Shan thrust wedge. Instead, we suggest that the active sinistral deformation belt of the Heishan-Jinta'Nanshan represents the eastward-evolving, upper crustal expression of the modern ATF system. [ABSTRACT FROM AUTHOR]

The Atlas‐Meseta intracontinental orographic system of Morocco experienced recent, large‐scale surface uplift as documented by elevated late Miocene, shallow‐water marine deposits exposed in the Middle Atlas Mountains. The Anti‐Atlas Mountains do not present any stratigraphic records that document regional vertical movements, however, the presence of a high‐standing, erosional surface, and the transient state of the river network, provides insights into the uplift history of the belt and the mechanisms that drove it. Here, we combine geomorphic and stream profiles analyses, celerity of knickpoints and linear inverse landscape modeling with available geological evidence, to decipher the spatial and temporal variations of surface uplift in the Anti‐Atlas and the Siroua Massif. Our results highlight the presence of a transient landscape and document a long wave‐length topographic swell (∼100 × 600 km) with a maximum surface uplift of ∼1,500 m in the Siroua Massif and ∼1,100 m in the central Anti‐Atlas most likely starting from ∼14 to 10 Ma. Surface uplift occurred in association with the onset of late Miocene magmatism in the Siroua and Saghro Massif and contractional deformation in the High Atlas. Regional surface uplift was most likely due to deep‐seated mechanism, such as asthenospheric upwelling. Additional processes such as magma injection and faulting contributed to the surface uplift of the Siroua Massif. Overall, our approach allows to quantitatively constrain the transient state of the landscape and the contribution of regional surface uplift on mountain building processes. Key Points: The transient state of the stream network and the high‐standing erosional surface document a recent phase of topographic rejuvenationUplift started at ∼14–10 Ma and increases from the western (0.5 km) to the central Anti‐Atlas (1.1 km) and the Siroua Massif (1.5 km)Regional surface uplift is most likely due to astenospheric upwelling, locally combined (Siroua Massif) with magma injection and faulting [ABSTRACT FROM AUTHOR]

The subduction of bathymetric highs, such as aseismic ridges, leads to far‐reaching changes in the dynamics of subduction zones with increased plate coupling and deformation in the upper plate. Subduction of the submarine Carnegie Ridge on the Nazca Plate has fundamentally impacted late Cenozoic magmatism and tectonic activity in the northern Andes. However, the timing of onset of Carnegie Ridge subduction has been a matter of debate. Time‐temperature inverse modeling of new thermochronological data from the Western Cordillera of Ecuador reveals two phases of cooling separated by isothermal conditions. The first cooling phase postdates early and middle Miocene magmatism in the Western Cordillera and is attributed to post‐magmatic thermal relaxation. The second cooling phase started after 6 Ma. Inferred to record the onset of tectonically controlled rock uplift and exhumation in the Western Cordillera, this phase is coeval with the last cooling phase recorded in the Eastern Cordillera. Based on these findings, we suggest that the onset of subduction of the Carnegie Ridge at ∼6–5 Ma increased plate coupling at the subduction interface, promoting shortening, regional rock uplift, and exhumation in the northern Andes. Overall, our results highlight the essential role of bathymetric highs in driving regional upper‐plate deformation at non‐collisional convergent plate margins. Plain Language Summary: Topographic growth and morphology of the Andes have been influenced by subduction processes, tectonic inheritance, and climate. Here, we investigate the role of subduction of high topography on the ocean floor in driving deformation in the upper plate at the Nazca‐South America ocean‐continent plate margin. The subduction of the Carnegie Ridge, a linear, topographically high sector on the Nazca Plate, has impacted magmatism and deformation processes in the Ecuadorian Andes. However, the timing of onset of ridge subduction is debated. We employed radioisotopic dating techniques to evaluate the uplift of the Andes. These techniques record the cooling of rocks as mountain ranges are uplifted and eroded. The thermal histories of rocks from the Western Cordillera in Ecuador reveal two distinct cooling phases. The first cooling phase occurred shortly after Miocene magmatic bodies were emplaced in the Western Cordillera. The second cooling phase began at ∼6–5 Ma, coeval with the last cooling phase in the Eastern Cordillera. We attribute this cooling phase to the onset of uplift and erosion in the Western Cordillera. Based on these findings, we suggest that the onset of subduction of the Carnegie Ridge increased plate coupling and promoted shortening and rock uplift in the northern Andes. Key Points: Thermochronological data reveal two cooling phases in the Western Cordillera of Ecuador, during the Miocene and after 6 MaThe onset of cooling at 6 Ma was associated with shortening, rock uplift, and exhumation in the Western CordilleraMio‐Pliocene exhumation was related to stronger coupling of the subduction interface due to the initial subduction of the Carnegie Ridge [ABSTRACT FROM AUTHOR]

Vertical motions that accompany the passage of the lithosphere over a mantle hotspot can shed light on the nature of the hotspot and its effect on the lithosphere. However, quantifying the temporal vertical and spatial extent, is challenging due to the paucity of evidence in the geological record. Here, we utilize dense seismic and well data covering the intersection of the Great Meteor Hotspot (GMH) track with the U.S. Atlantic continental margin to constrain the surface expression of the hotspot passage under the lithosphere. The continuous sedimentary record of the eastern North American margin during its passage over the hotspot allows determination of the timing, magnitude, width and rate of denudation. We find that a ∼300 km wide region was denuded by up to 850 m between ∼97 and 86 Ma, ∼10 m.y. after the passage of the GMH. Stratigraphic relationships suggest a decaying rock uplift rate with time and no subsequent sagging. The broad, long‐lasting, and delayed uplift was modeled as a surface manifestation of either sub‐lithospheric mantle depletion, permanently eroded base of the continental lithosphere, or intrusions of depleted magma. We consider sub‐lithospheric depletion to be the most likely cause, based on seismic imaging results. Key Points: A continental lithosphere surface response to its passage over a hotspot is quantified via stratigraphic analysis of a passive marginTen m.y. after its passage over the Great Meteor Hotspot, the Georges Bank Basin was denuded by up to 850 m across a 300 km wide zoneAsthenosphere depletion, lithospheric thinning or intrusion of depleted material triggered uplift and the consequent denudation [ABSTRACT FROM AUTHOR]

The Shanxi Graben System (SGS) is one of the first‐order Cenozoic tectonic features in North China. Understanding the kinematics of this tectonic system is crucial for deciphering the mechanism of continental rifting and the deformation pattern across North China. Although the SGS has long been thought to be a right‐lateral, transtensional shear zone, the geologic and geomorphologic evidence for dextral strike‐slip along its internal faults was slim and even controversial. Field investigations, interpretations of satellite imagery, and construction of decimeter‐scale digital elevation models from unmanned aerial vehicle surveys were used in this work to investigate the tectonic geomorphology of the eastern segment of the North Liulengshan Fault (NLSF) in the northern SGS. Although this fault segment was previously thought to be a pure normal fault, the presence of geomorphic features such as right‐laterally offset terrace risers and gullies, along with an analysis of fault‐slip data, suggests a component of right‐lateral strike‐slip displacement. Combined with optically stimulated luminescence dating of offset fluvial terraces, the late Quaternary right‐lateral strike‐slip and vertical slip rates of this fault segment are both estimated to be ∼0.2–0.3 mm/yr. The discovery of dextral strike‐slip along the NLSF provides compelling direct evidence for determining the dextral transtensional kinematics of the SGS. This puts new constraints on our knowledge that the evolution of the SGS is primarily driven by the outward expansion and growth of the Tibetan Plateau and supports the "bookshelf" rotation kinematic model for North China. Plain Language Summary: It has long been believed that many right‐lateral strike‐slip faults may exist in the Shanxi Graben System (SGS) in central North China, but exactly which ones are not fully understood. Here, we report on a newly discovered dextral strike‐slip fault—the North Liulengshan Fault in the northern SGS, based on interpretations of historical satellite images and field investigations. The dextral strike‐slip motion along the eastern segment of that fault is evidenced by geomorphic features like right‐laterally offset terrace risers and gullies and fault striations preserved on exposed fault planes. Combining our displacement measurements and geochronology data yields both right‐lateral strike‐slip and vertical slip rates of ∼0.2–0.3 mm/yr for the fault. This discovery provides key geologic and geomorphic evidence for determining the kinematics of the SGS, which is of great significance for better understanding the geodynamics of the SGS and the deformation pattern of North China. Key Points: We present direct and compelling evidence for the dextral shearing of the Shanxi Graben SystemDextral strike‐slip along the eastern segment of the North Liulengshan Fault (NLSF) is significant in addition to normal faultingLate Quaternary dextral strike‐slip and vertical slip rates along the eastern segment of the NLSF are both ∼0.2–0.3 mm/yr [ABSTRACT FROM AUTHOR]

The study of surface ruptures is key to understanding the earthquake occurrence of faults especially in the absence of historical events. We present a detailed analysis of geomorphic displacements along the Dzhungarian Fault, which straddles the border of China and Kazakhstan. We use digital elevation models derived from structure‐from‐motion analysis of Pléiades satellite imagery and drone imagery from specific field sites to measure surface offsets. We provide direct age constraints from alluvial terraces displaced by faulting and indirect dating from morphological analysis of the scarps. We find that the southern 250 km of the fault likely ruptured in a single event in the last 4,000 years, with displacements of 10–15 m, and potentially up to 20 m at one site. We infer that this Dzhungarian rupture is likely linked with a previously identified paleo‐earthquake rupture on the Lepsy Fault through a system of splays in the intervening highlands. Though there are remaining uncertainties regarding consistency in age constraints between the two fault ruptures, most of the sites along the two faults are consistent with a most recent event 2,000–4,000 years ago. Rupture on the Dzhungarian Fault alone is likely to have exceeded Mw 8, and the combined Lepsy‐Dzhungarian rupture scenario may have been up to Mw 8.4. Despite being at the upper end of known or inferred continental earthquake magnitudes, our proposed scenario combining the 375 km of the Dzhungarian and Lepsy ruptures yields a slip‐to‐length ratio consistent with global averages and so do other historical intracontinental earthquakes in Central Asia. Plain Language Summary: Numerous large, destructive earthquakes have occurred on faults inside the continents in recent centuries. However, comparing to plate‐boundary faults, the behaviors of intracontinental faults are not well understood. We undertake a detailed survey of the surface ruptures along the Dzhungarian Fault, one of the major faults in Central Asia. We map and analyze high‐resolution satellite and drone imagery. We identify fresh surface ruptures distributed along the southern 250 km of the Dzhungarian Fault. We suggest that these ruptures were produced in a single event which probably caused displacements of up to ∼20 m and no <6 m. We also present evidence that the Dzhungarian Fault and its neighboring Lepsy Fault may have ruptured together. Using their combined length, we calculate a slip‐to‐length ratio which lies within the expected range instead of an unusually high ratio mentioned previously. Our age constraints indicate the most recent event for the two fault ruptures occurred 2,000–4,000 years ago. We estimate the potential maximum earthquake magnitudes to be Mw 8.2 for the Dzhungarian Fault rupturing alone and Mw 8.4 for the combined rupture of the Lepsy‐Dzhungarian Faults. This second scenario would be one of the largest magnitudes ever inferred for a continental earthquake. Key Points: We present evidence for a large paleo‐earthquake on a major intracontinental strike‐slip fault from analysis of high‐resolution imageryThe Dzhungarian and Lepsy Faults might have ruptured together in a single event (up to Mw 8.4) with fault slip of up to ∼20 m at one siteA compilation of intracontinental earthquakes shows these faults follow the global earthquake scaling relationships of slip and length [ABSTRACT FROM AUTHOR]

The dearth of quantitative studies of Holocene fault slip‐rates makes kinematic modeling of crustal deformation across SE Tibet debatable. The ∼230 km long, WNW‐striking, dextral Beng Co fault (BCF) is the most prominent strike‐slip fault of southern Tibet. Using new UAV topographic data and OSL/14C dating of geomorphic markers, we measure horizontal offsets and ages of fluvial terraces/fans and lacustrine shorelines at eight sites west and east of the Beng Lake pull‐apart. Along the eastern BCF's northern branch, our measurements at two different locations are consistent with offsets of ∼4.7 ± 1.1 and ∼8.7 ± 0.7 m during the past ∼3.1–3.6 and 3.6–5.2 ka, respectively. Along the southern branch, ∼25 ± 5 m of slip have accrued since ∼9 ka. The total Holocene slip‐rate across both faults (4.2–5.4 or 4.8 ± 0.5 mm/yr), consistent with GPS/InSAR values, implies that the BCF contributes significantly to the eastward extrusion of eastern‐central Tibet. This rate is slightly larger than the lower bound of the extension rate (∼6 ± 1.8 mm/yr) recently determined across the middle Gulu rift normal fault, which splays off southwards from the southeastern tip of the BCF's southern branch. Empirical relationships suggest that the reported ∼90 km length of the Mw 7.7, 1951 Beng Co earthquake surface rupture is too short, which implies that the eastern BCF is immature, or requires additional, partly deep slip, along other branches of the eastern BCF. That there is no field evidence of rupturing along the western BCF in the last ∼1,000 yr indicates that the Bange County area, west of Beng Co, may be at risk of an Mw ≈ 7.4? event. Plain Language Summary: Due to the lack of precise slip‐rates along the faults of south‐central Tibet, kinematic models of crustal deformation across the frontal, ∼1,200 × 400 km broad part of the India/Asia collision zone remain controversial. The 230 km long, WNW‐striking, right‐lateral Beng Co fault (BCF) is the most prominent, active strike‐slip fault of southern Tibet. Using high‐resolution UAV topographic data and OSL/14C dating of geomorphic markers, we quantitatively constrain horizontal offsets and ages of fluvial terraces/fans and lake shorelines along this fault west and east of Beng Lake. We obtain a total Holocene slip‐rate of 4.8 ± 0.5 mm/year across the two BCF branches, compatible with GPS/InSAR geodetic estimates, and slightly larger than the lower bound of the extension rate across the middle Gulu rift. The BCF thus contributes significantly to the eastward extrusion of central‐eastern Tibet. Empirical relationships imply that the reported ∼90 km rupture length of the 1951 Mw 7.7 Beng Co earthquake (largest event across the southern Tibet Plateau) has been underestimated or that the eastern BCF is immature. The lack of field evidence for a young (<1,000 yr) surface rupture along the western BCF implies that much of Bange County, southwest of the fault, remains threatened by a large (Mw ≈ 7.4?) earthquake. Key Points: OSL/14C dating of offset terraces/fans/shorelines imply a total Holocene slip‐rate of 4.8 ± 0.5 mm/yr along dextral Beng Co fault (BCF)The BCF thus contributes significantly to the eastward extrusion of central‐eastern Tibet along the Karakoram‐Jiali fault zoneThe Mw ≈ 7.7, 1951 earthquake rupture did not extend much beyond Peng Lake, leaving westwards a ∼135 km long seismic gap at least 1,000 yr old [ABSTRACT FROM AUTHOR]

Between 81°30ʹE and 83°E, the Himalayan range's "perfect" arcuate shape is interrupted by an embayment. We hypothesize that thrust geometry and duplexing along the megathrust at midlower‐crustal depths play a leading role in growth of the embayment as well the southern margin of the Tibetan plateau. To test this hypothesis, we conducted thermokinematic modeling of published thermochronologic data from the topographic and structural embayment in the western Nepal Himalaya to investigate the three‐dimensional geometry and kinematics of the megathrust at midlower‐crustal depths. Models that can best reproduce observed cooling ages suggest that the megathrust in the western Nepal Himalaya is best described as two ramps connected by a long flat that extends further north than in segments to the east and west. These models suggest that the high‐slope zone along the embayment lies above the foreland limb of an antiformal crustal accretion zone on the megathrust with lateral and oblique ramps at midlower‐crustal depths. The lateral and oblique ramps may have initiated by ca. 10 Ma. This process may have controlled along‐strike variation in Himalayan‐plateau growth and therefore development of the topographic embayment. Finally, we analyze geological and morphologic features and propose an evolution model in which landscape and drainage systems across the central‐western Himalaya evolve in response to crustal accretion at depth and the three‐dimensional geometry of the megathrust. Our work highlights the importance of crustal accretion at different depths in orogenic‐wedge growth and that the midlower crustal accretion determines the location of plateau edge. Key Points: Thermochronologic data and thermokinematic modeling results suggest a complex 3D geometry of the megathrust in the western Nepal HimalayaCrustal accretion along the midlower crustal ramp in the megathrust is a mechanism of maintaining the edge of a plateau‐like landscapeThe development of the 3D megathrust geometry may have controlled the first‐order evolution of an embayment and regional drainage system [ABSTRACT FROM AUTHOR]

The separation of zones of apparent downwelling flow at the ends of the Sierra Nevada suggests a relatively large wavelength (∼500 km) of unstable growth, but Rayleigh-Taylor instabilities for plausible rheological structures with a fixed top boundary condition require much shorter wavelengths (<100 km) for maximum growth rates. To understand this difference, we analyze analytical solutions and perform numerical 2-D plane strain experiments for Rayleigh-Taylor instability of a dense layer overlying a less dense substratum, representing the instability between the mantle lithosphere and the underlying asthenosphere, focusing on the effects of a shear stress free boundary condition at the top. The overall effect of this condition is an enhancement of growth rate factors at long wavelengths, which depends greatly on the exponential viscosity variation with depth of the layer. With large or little variation across the unstable layer, the solutions approximate those with a fixed top boundary condition or for constant viscosity, respectively. An intermediate zone showing the enhanced growth rates includes ratios of layer thickness to viscosity e-folding length, h/L, of ∼1-8 for Newtonian viscosity and ∼1-4 for nonlinear viscosity. The free top condition is likely applicable to geologic situations where the lower crust is weak. Olivine flow laws and low-temperature estimates at 35 km depth (255-355°C) place the Sierra Nevada viscosity scaling ratio, h/L, between 5 and 9. Thus longer wavelengths than commonly assumed for Rayleigh-Taylor instabilities seem permissible when viscosity decreases with depth and the top surface of the layer is only weakly constrained. [ABSTRACT FROM AUTHOR]

Kinematic constraints on the Cenozoic deformation along the northwestern edge of the Tibetan Plateau remain limited. Combining surface geological data and seismic profiles, we document the structural geometry and kinematics of the large‐scale east‐west striking Hotan anticline, along the foothills of the Western Kunlun Range. Four new balanced cross sections are constructed, and the temporal evolution of deformation is deciphered from the exceptionally well‐imaged growth strata at the front of the fold. This anticline results from a broad fault‐bend fold, subsequently deformed by a footwall duplex. The total shortening across the whole structure is relatively constant along strike, from ∼40 to ∼35 km. However, the shortening accommodated by the duplex varies laterally from ∼50–40% to 0% of the total shortening. Two distinct successive patterns of growth strata are recognized and are interpreted to be representative of deformation on the ramp anticline, followed by deformation on the duplex. The onset of deformation initiated by ∼16 Ma. Deformation of the underlying duplex began at ∼12 Ma to the west and subsequently propagated eastward. From these results, we determine a shortening rate of ∼5 mm/yr from ∼16 to ∼8–9 Ma across the Hotan thrust system, followed by a significant decrease in shortening rate, possibly down to <0.5 mm/yr. We explore the significance of this deceleration of deformation at the scale of the Western Kunlun foothills and at a broader regional scale as it may point to a regional kinematic reorganization by the late Miocene. Key Points: Four new balanced cross sections across the Hotan anticline (foothills of the Western Kunlun, China)Measured amount of shortening ranges from ∼40 to ∼34.5 km, and deformation probably initiated by ∼16 MaGrowth strata analysis points to a decrease in shortening rates since ∼8–9 Ma, probably related to a regional kinematic reorganization [ABSTRACT FROM AUTHOR]

The steps of the southeastward stepwise‐descending topography of the Chuandian Fragment (CDF) in the southeastern edge of the Tibetan Plateau coincide with N‐S and NE‐SW trending faults that changed from thrusting to normal activity, indicating that since the Middle‐Late Miocene the CDF maintained an E‐W oriented extensional tectonic environment. However, the anisotropy of magnetic susceptibility (AMS) data sets presented herein, from the Cretaceous and Cenozoic sedimentary strata of the southeastern Tibetan Plateau and its edge, show that since ∼28.0 Ma the CDF remained within a stabilized compressional stress field, oriented NEE‐SWW. A comprehensive analysis of the AMS results, topography, fault systems, and geophysical observations indicate that the northward‐advancing eastern Himalaya syntaxis impeded the southeastward‐flowing viscous lower crust and correspondingly decreased its flux, which could have reduced the thickness of the lower crustal channel beneath the CDF. The original low‐gradient topography of the CDF formed by the viscous lower crustal flow could no longer be supported by the thinned lower crustal channel, and thus gravity drove the collapse of the uplifted CDF. This process reconstructed the topography and remodeled the preexisting fault systems of the CDF, resulting in the coexistence of the E‐W oriented extensional tectonic environment and the stabilized NEE‐SWW oriented compressional stress field of the western part of the CDF, since the Middle‐Late Miocene. Thus, the change in the status of the lower crustal channel related to block interactions provided a major geodynamic setting for shaping the topography of the southeastern edge of the Tibetan Plateau. Plain Language Summary: The present work conducted anisotropy of magnetic susceptibility studies in the Cretaceous and Cenozoic fluvio‐lacustrine strata in the southeastern Tibetan Plateau and the Chuandian Fragment (CDF). The results confirm the coincidence of the geomorphologic steps and N‐S trending normal faults within the stabilized NEE‐SWW oriented compressional stress field in the western part of the CDF, since the Middle‐Late Miocene. This seeming paradox can be perfectly resolved by the crustal collapse of the western part of the CDF. The northward advance of the eastern Himalayan syntaxis since ∼28.0 Ma impeded the southeastward flow of the viscous lower crust and reduced the volume of lower crust flowing into the southeastern edge of the Tibetan Plateau, inducing the collapse of the uplifted CDF along the preexisting strike‐slip fault system, which in turn reconstructed the topography and remodeled the preexisting fault systems of the CDF. Key Points: The Chuandian Fragment (CDF) remained within a NEE‐SWW oriented compressional stress field, since the Middle‐Late MioceneThe northward advance of the eastern Himalayan syntaxis reduced the thickness of the lower crustal channel beneath the CDFThe collapse of the uplifted CDF reconstructed its topography and remodeled the preexisting fault systems [ABSTRACT FROM AUTHOR]

The Qinling orogen formed as a result of the convergence between North and South China Blocks and was reactivated by India‐Asia collision and/or Pacific subduction in the Cenozoic. We presented new apatite U‐Th/He age‐elevation profiles in the northern margin of the Qinling Mountains and observed Oligocene pulse of rapid exhumation. Thermal modeling on our data (by the HeFTy program) revealed another two early cooling episodes, that is, in the early Cretaceous and the early Cenozoic. Besides, increases in the mountain uplift rates since the late Miocene were retrieved from a linear inversion on modern channel longitudinal profiles. Combining previous studies, we proposed possible geodynamic regimes underlying the multi‐stage cooling and exhumation pattern in the north Qinling. We interpreted the early Cretaceous cooling as a result of the southward intracontinental subduction of North China Block beneath South China Block. The early Cenozoic exhumation was under the Pacific back‐arc extension background and might be influenced by a far‐filed response to Eurasian and Indian plate's collision. The Oligocene phase could be mostly driven by West Pacific plate subduction beneath East Asia. And, the mountain uplift since the late Miocene could be triggered by the growth and expansion of the North East Tibetan Plateau. Plain Language Summary: The Qinling orogen locates at the important tectonic unit that not only links the collision of North and South China Blocks but is under the influences of expansion of North East Tibetan Plateau and/or Pacific subduction in the Cenozoic. Knowledge on the mountain cooling/exhumation history helps to understand the underlying geodynamics. We utilized methods of both low‐temperature thermochronology and river longitudinal profile inversion. We reported new apatite U‐Th/He age‐elevation transects in the north Qinling and found pulsed exhumation in the Oligocene. The early Cretaceous and early Cenozoic cooling episodes were revealed by both thermal modeling and a re‐analysis on the previously published multi‐thermochronological age data. Signals of the late Miocene mountain uplift were recorded by the transient state longitudinal profiles of modern channels. Combining our results with those of previous studies, we proposed that the early Cretaceous cooling was the direct result of the Yanshanian magma uprising and lithospheric thinning and that the Cenozoic tectonic movement could result from both the growth and expansion of the Tibetan Plateau and the westward subduction of Pacific plate. Key Points: Pulsed exhumation in the Oligocene was revealed by the slope‐break in the new apatite U‐Th/He vertical profile in the north QinlingThermal modeling on age data deciphered three episodes of rapid cooling in the early Cretaceous, early Cenozoic and the OligoceneIncreases in mountain uplift rate since the late Miocene were retrieved by linear inversion on present channel profiles [ABSTRACT FROM AUTHOR]

The Cenozoic North Altyn Fault (NAF) is a major splay of the Altyn Tagh Fault along the northwestern margin of the Tibetan Plateau, but its role in the development of this plateau margin in response to the India‐Eurasia collision is highly debated. Here, we investigate fault geometry, kinematics, and shortening magnitude along the westernmost 120 km of the NAF. Seismic surveys reveal minimal Cenozoic shortening in the subsurface of the Southeast Tarim Basin and support for large‐scale (>120 km) left slip on the NAF. Based on the satellite imagery, two new faults are identified to define the northern boundary of the NAF system, which together with the NAF to the south constitute a narrow transpressional shear zone comprised of three basement‐cored, fault‐bound slivers. Fission track data and thermal modeling indicate that the NAF zone experienced broad reburial during early Cenozoic that was locally interrupted by ∼40 to 35 Ma exhumation proximal to the NAF, followed by widespread but heterogeneous exhumation since ∼17 to 15 Ma associated with ∼9 to 11 km of total shortening across the NAF system via thick‐skinned faulting. We conclude that the NAF initiated as a left‐slip fault at ∼40 to 35 Ma and then became transpressional at ∼17 to 15 Ma during the middle‐Miocene reorganization of the Altyn Tagh Fault system. We find no evidence to support prior inferences of large‐scale (∼100 km) underthrusting of the Tarim Basin beneath the Tibetan Plateau along the NAF. Plain Language Summary: The Cenozoic rise of the Tibetan Plateau has exerted a significant impact on the global climate and migration of Asian hominin. To reveal the growth history of the plateau, geologists rack their brains to learn how the plateau‐bounding faults have evolved in time. Here, we investigate the Cenozoic evolution of the North Altyn Fault (NAF) in the northwestern edge of the Tibetan Plateau, which generates 2–4 km topographic relief between the high plateau and low‐land Tarim Basin. Based on seismic survey, satellite imaging, and geological dating, we find that the NAF initiated with left‐lateral slip at ∼40 to 35 Ma but switched to a transpressional fault accommodating both left‐lateral and dip slips since ∼17 to 15 Ma. Our data show only 9–11 km of shortening across the NAF, which contradicts the prior view that the Tibetan Plateau was thrust over the Tarim Basin by ∼100 km. This study provides independent evidence supporting the reorganization of the Altyn Tagh Fault system at ∼17 to 15 Ma and indicates that the present‐day tectonic and topographic configurations in the northern Tibetan Plateau have developed since the middle Miocene. Key Points: The North Altyn Fault (NAF) is a transpressional shear zone comprised of narrow fault slivers and has absorbed ∼9 to 11 km of Cenozoic shorteningExtensive early Cenozoic burial was locally interrupted by ∼40 to 35 Ma exhumation, implying onset of left slip on the NAFWidespread and heterogeneous exhumation since ∼17 to 15 Ma manifests a transition from left slip to transpression on the NAF [ABSTRACT FROM AUTHOR]

The spatial pattern of slip rates along the Haiyuan fault zone may reveal deformation process along the northeastern margin of the Tibetan Plateau. By applying the 3D_Fault_Offsets code, we reevaluated the displacements of offset markers displaced by the Laohushan fault, the central segment of the Haiyuan fault zone. We introduced the Bayesian Age Model approach to provide optimum age control for the preserved offset markers. Multiple offsets and ages constrain the late Pleistocene slip rate to 4.4–4.8 mm/yr. The spatial pattern of strike‐slip rates of the Haiyuan fault zone indicates that the Madongshan and Liupanshan could be the main uplifts that absorbed the left‐lateral motion along the Haiyuan fault zone, due to a restraining bend between the Haiyuan and Qishan‐Mazhao fault zones. Furthermore, uniform slip rates along the main segments and slip rates decreasing toward fault tips are widely observed along some intensively studied strike‐slip faults, such as the Altyn Tagh, Kunlun, Death Valley‐Fish Lake Valley, Denali, San Andreas and Alpine faults. The results suggest that the constancy or similarity of the slip rates along the strike is closely related to block rotation and internal deformation, and the slip rates of strike‐slip faults usually change at the fault tip area converting from horizontal to vertical motion. In addition, strike‐slip fault can also take slip off of the main fault and distribute it between multiple active parallel strands. Key Points: The late Pleistocene slip rate of the Laohushan fault was reevaluated and the Miocene slip rate of the Laohushan fault was estimatedBy synthesizing the slip rates along the Haiyuan fault, the Madongshan and Liupanshan could be a restraining bend of the Haiyuan faultSlip rates along well‐studies strike‐slip faults were synthesized and changed at the restraining bend or fault termination [ABSTRACT FROM AUTHOR]

The activity of major active faults around the Ordos Block is of great interest to seismologists, as at least four M ≥ 8 earthquakes have been recorded. However, the Linhe Basin, which has the thickest Cenozoic sediments, has no record of large earthquakes. Does this basin have the structural conditions required for large earthquakes? The northern boundary fault of the Linhe Basin is composed of the NE‐striking Langshan piedmont fault (LPF), E‐W‐striking western section of the Seertengshan piedmont fault (WSPF), and NW‐striking eastern section of the Seertengshan piedmont fault (ESPF). Based on large‐scale active fault mapping, this article analyzes data from 23 trenches, using an unmanned aerial vehicle to measure the faulted landform, and combines these data with Quaternary dating methods to acquire the paleoearthquake sequences of the LPF, WSPF, and ESPF. Furthermore, this article explores their rupture modes and discusses the structural evolution of two intersection points. Through paleoseismic comparison, seven trenches revealed historical earthquakes from 7 BC, with a common magnitude of M 8.1. The trenches also revealed seven paleoseismic events since the Holocene, which conformed to the periodic model with a period of 1.37 ± 0.11 ka. The elapsed time since the latest event (2.0 ka) has exceeded the earthquake recurrence period; thus, the area is currently at risk of an M 7.4–8.0 earthquake. The NE‐striking LPF and E‐W‐striking WSPF are connected by two left‐stepping small fault segments. The E‐W‐striking WSPF and NW‐striking ESPF are connected by a large triangular relay ramp. Key Points: Seven trenches revealed 7 BC historical earthquakes, with a calculated magnitude of M 8.1Since the elapsed time of the latest event (2.0 ka) has exceeded the recurrence period, the Linhe Basin is at risk of an M 7.4–8.0 earthquakeThe western section and the eastern section of the Seertengshan piedmont fault are connected by a large triangular relay ramp [ABSTRACT FROM AUTHOR]

The Xianshuihe (XSH) fault in eastern Tibet is one of the most active faults in China, with the next large earthquake most likely to occur along its SE part, where the fault splits into three parallel branches: Yalahe, Selaha and Zheduotang (ZDT). Precisely quantifying their slip rates at various timescales is essential to evaluate regional earthquake hazard. Here, we expand our previous work on the Selaha fault to the nearby ZDT and Moxi (MX) faults, and add observations on the Yalahe fault and on the newly discovered Mugecuo South fault zone. Using tectonic-geomorphology approaches with 10Be dating, we had previously determined average late Quaternary slip rates of 9.75 ± 0.15 and 4.4 ± 0.5 mm/yr along the NW and SE Selaha fault, respectively. Using the same methods here, we determine a slip rate of 3.4-4.8 mm/yr on the ZDT fault and of 9.6--13.4 mm/yr on the MX fault. This is consistent with the southeastward slip rate increase we had proposed along the XSH fault system from 6-8 mm/yr (Ganzi fault) to ~10 mm/yr (Selaha fault), and >9.6 mm/yr (MX fault). We propose a new model for the SE XSH fault, where the large-scale Mugecuo pull-apart basin lies within an even larger scale compressive uplift zone in a restraining bend of the XSH fault, where the highest peak in eastern Tibet is located (Gongga Shan, 7,556 m). Our slip rate determination helps to constrain a relatively high regional Mw ~7 earthquake hazard at present on the SE XSH fault. [ABSTRACT FROM AUTHOR]

The factors that promote stability of Archean cratons are investigated from a combined geodynamic, geological, and geophysical perspective in order to evaluate the relative importance of nature—the initial conditions of a craton—versus nurture—the subsequent tectonic processes that may modify and destabilize cratonic lithosphere. In this review study, we use stability regime diagrams to understand the factors that contribute to the intrinsic strength of a craton: buoyancy, viscosity, and relative integrated yield strength. Cratons formed early in Earth history when thermal conditions enhanced extraction of large melt fractions and early cratonization (cessation of penetrative deformation, magmatism, and metamorphism) promote formation of stable Archean cratonic lithosphere. Subsequent processes that may modify and weaken cratonic lithosphere include subduction and slab rollback, rifting, and mantle plumes—processes that introduce heat, fluids, and partial melts that warm and metasomatize the lithosphere. We examine tomographic models from eight cratons, including four that are thought to be stable and four that have been proposed to be modified or destroyed. Our review suggests that continental lithosphere formed and cratonized prior to the end of the Archean has the potential to withstand subsequent deformation, heat, and metasomatism. Survivability is enhanced when cratons avoid subsequent tectonic processes, particularly subduction. It also depends on the extent and geometry of modification. However, because craton stability decreases as the Earth cools, marginally stable cratons that undergo even modest modification may be set on a path to destruction. Therefore, preservation of Archean cratons depends both on nature and nurture. Plain Language Summary: Because of Earth's dynamic tectonic processes, much of its continental crust has been eroded and recycled and only a fraction of crust older than 2.5 billion years has survived to the present‐day. These areas of old crust, known as Archean cratons, have not experienced deformation or magmatism for a billion years or more. This study investigates whether craton survival is related to their nature, that is, the conditions of their formation, or to nurture, the subsequent events they experienced. Eight case studies are used to evaluate the properties and processes that promote craton stability. Nature is important: surviving Archean cratons tend to be buoyant, viscous, cold, and thick. Some survive because they have not experienced destabilizing geologic processes that introduce heat, magma, and fluids. Others have been modified to various extents by these processes. Some have been weakened and thinned and other, only marginally stable cratons are susceptible to future deformation and destruction. We conclude that both nature and nurture are essential to the survival of Earth's oldest crust. Key Points: The survival of Archean cratons depends both upon their nature—the initial conditions of formation—and nurture—the subsequent tectonic processes that may modify and destabilize cratonic lithosphereSome cratons have survived by avoiding or being shielded from destabilizing tectonic processes. Metasomatism is particularly destructive because it affects buoyancy, viscosity, and integrated yield strengthStability regime diagrams integrate both time and the magnitude of modification, and indicate that marginally stable cratons today may pass into conditions of marginal instability in the future, when even mild deformational stresses could trigger destruction [ABSTRACT FROM AUTHOR]

Part of the continuing northward convergence between India and Eurasia is probably taken up by strike slip displacement, with Tibet as a whole moving eastward away from the collision zone and undergoing east-west extension (Molnar and Tapponnier, 1975; Ni and York, 1978). On the basis of our interpretation of Landsat images we propose that strike slip faulting occurs throughout the Tibetan plateau such that its north-south cross section is being shortened, with little contemporary folding or thrusting. [ABSTRACT FROM AUTHOR]

Differing views on the north‐eastern Indian plate subduction and its seismic potential place the subduction process as relict, ceased, creeping, or fully locked, challenging the seismic hazard uncertainty estimates of Indo‐Burmese Arc (IBA) at either extreme. To clear some of these contentions, we re‐examine the state of the IBA stress field using available earthquake faulting mechanism solutions. Our stress inversion results underline the tectonic complexity and emphasize that the stress of this subduction is primarily driven by the northward oblique motion of the Indian Plate. Models highlight the presence of the least compressive stresses as the margin‐normal component, all along the shallow sinking slab. Furthermore, solutions link the shallow strike‐slip earthquakes with the lateral slab shear due to oblique slip‐partitioning. Spatial variations in the Indian slab stress field indicate higher margin parallel compression at the Naga versus the Chin and Rakhine‐Arakan segments, implying resistance to the northward motion of India, illuminating the buttressing effects on the IBA. Models also depict active ∼E‐W shortening across the Kabaw Fault. Inversion solutions bring out a higher compressional environment toward the south, along the Sagaing Fault. Finally, based on the overall stress field variations, we speculate that the Rakhine‐Bangladesh Megathrust could be a low‐stress forearc, as across the arc interacting stress fields are weak, capable of generating megathrust ruptures. Being weak, the stress replenishment times could be longer than the mechanically strong subduction zones. Due to the spatial stress field variations and buttressing effects, the interface may exhibit a variable rupture mode. Key Points: Oblique convergence of the Indian plate drives IBA stress, causing lateral shear in the slab as well as wedge deformationIndian slab stress regime shows higher margin parallel compression at the north indicating leading‐edge forearc buttressingAcross arc stress field variations indicate a low‐stress forearc and a mechanically weak megathrust capable of generating segmented ruptures [ABSTRACT FROM AUTHOR]

As large earthquakes in contractional fold‐and‐thrust belts are usually associated with complex ruptures along multiple faults or fault splays, the evaluation of potential rupture extent and relevant hazards continues to be challenging. We present a case study on the geometry and kinematic evolution of the southern Junggar fold‐and‐thrust belt, northern Tian Shan, where the 1906 M 8 Manas earthquake occurred. Our interpretations of seismic reflection profiles acquired during oil and gas exploration demonstrate that multiple detachments played significant roles in controlling the structural segmentation. We speculate that seismic potential in active fold‐and‐thrust belts can be under‐estimated by relying on the mapped surface fault traces. Structural analysis of subsurface images in sufficient detail may provide important insights into seismic hazard evaluation and hence complement traditional paleo‐seismic studies, particularly in densely populated regions such as the city of Urumqi. Key Points: Hutubi anticline is a pure shear‐dominated detachment fold, which has experienced multi‐stage tectonic shortening since the Late JurassicMultiple detachments have predominantly controlled the structural segmentation in the southern Junggar fold‐and‐thrust beltLateral structural variations and kinematic evolution also need to be considered in seismic hazard assessment [ABSTRACT FROM AUTHOR]

Understanding active tectonics and seismicity in extensional settings requires the analysis of high‐angle normal faults (HANFs) and the transfer of deformation at depth. The debate surrounds the role of low‐angle normal faults (LANFs) in triggering high magnitude earthquakes. The central Betic Cordillera is an active seismic zone affected by the NNW‐SSE Eurasia‐Nubia convergence and orthogonal extension. The seismicity and present‐day stress determined by earthquake focal mechanisms reveals the activity of a NE‐SW extensional system in the shallowest 12 km of the Granada Basin. The structure of the sedimentary infill, as derived by geological field and gravimetric techniques, suggests the formation of a half‐graben tilted to the N‐NE. Seismologic data suggest the activity of HANFs above 6–7 km depth and a LANF zone around 6–12 km depth, with related earthquakes of up to Mw 4.0 and 20° to 30° fault dips. High‐precision leveling lines highlight the importance of the Granada Fault in the system, with average vertical displacement rates of 0.35–1.1 mm/yr. These data suggest creep fault behavior at the surface and increased seismicity at depth. The upper crustal extension in the collisional Betic Cordillera is accommodated by a top‐to‐the‐WSW extensional detachment related to westward motion and rollback in the Gibraltar Arc and the gravitational collapse of the cordillera, in a framework of NNW‐SSE shortening. This comprehensive study draws a new scenario that advances understanding of relationships between HANFs and LANFs. Key Points: Gravimetric data highlight the geometry of the sedimentary infill of the Granada Basin, which constitutes a half‐graben tilted to the N‐NEGranada Basin's high‐angle normal faults might be linked at depth to an active low‐angle extensional deformation zoneThe active Granada Fault zone shows low‐magnitude seismicity and a current average vertical rate that varies from 0.4 to 1.1 mm/yr [ABSTRACT FROM AUTHOR]

The topographic history of the North American Cordillera holds the key to understanding the tectonic and geodynamic processes of orogenesis and post‐orogenic collapse. In southwestern Montana and its adjacent regions, previous studies have suggested that the early middle Eocene rollback of the Farallon flat‐slab caused the latest topographic growth, after which regional mean elevations were progressively lowered due to extensional collapse. In this study, we report 60 new Eocene‐Miocene stable hydrogen isotopic values (δD) of hydrated volcanic glass from southwestern Montana to examine regional topographic history during the extension. The δD values show a two‐stage negative shift of ∼35‰ during the late Paleogene, the timing of which is further refined by published ages and new zircon U‐Pb ages. About 19‰ of the negative shift occurred during the late Eocene‐earliest Oligocene (∼40–32 Ma) when global and regional climate experienced cooling, and the shift can be mostly accounted for by climate change. The remaining 16‰ negative shift occurred during the early Oligocene (∼32–30 Ma), which can be best explained by regional surface uplift of 0.9 ± 0.5 km. This inferred surface uplift occurred more than 17 Myr after the initiation of the Cordilleran extension in this region, and thus challenges the traditional assumption of progressive topographic lowering during the post‐orogenic collapse. This surface uplift, if occurred, may reflect lower mantle lithosphere removal in southwestern Montana. Key Points: 60 new volcanic glass δD values show a late Paleogene, two‐stage negative shift of ∼35‰ in southwestern MontanaThe late Eocene‐earliest Oligocene shift occurred probably as a result of climate changeThe early Oligocene shift most likely reflects regional surface uplift by convective removal of lower mantle lithosphere [ABSTRACT FROM AUTHOR]

The interaction between sedimentation/erosion and faulting represents one of the most intriguing topics in landscape and tectonics evolution. Only few studies have been able to document the feedback between faulting and sedimentary loading from field observations. Here, we focus on how sediment loading/unloading influences the dynamics of fault systems in the Fucino basin, in the Central Apennines (Italy). The Fucino basin represents a remarkable case study with respect to the other main extensional basins in the Apennines because of its large dimension, square shape, significant sediment thickness, and its endorheic nature throughout its evolution. We present a detailed structural and geomorphologic analysis of the Fucino basin and its surroundings, investigating the kinematic and geometry of each main fault strand. The slickenlines analysis reveals multiple families of slip‐vectors and timing of activity, suggesting a change in extension slip‐direction from N240° to N200° during middle Pleistocene. Using a local isostatic model, we estimate that up to the 30% of the vertical geological displacement of the faults, which overall ranges from 0.5 to 2.5 km, is related to the sediment loading/unloading. We demonstrate a positive feedback between sedimentation and faulting which may also lead to a reorganization in fault kinematics related to a significant increase in vertical stress. We propose a conceptual model for the permanent endorheic configuration of the Fucino basin, which includes the effect of sediment loading. Key Points: Role of tectonics and drainage systems in the evolution of extensional basinsExtensional fault network and sedimentary loading keep the Fucino basin internally drained during its evolutionSediment load contributes to incrementing of max 30% the faults total geological throw and locally reorganizes the stress field [ABSTRACT FROM AUTHOR]

The Bilila‐Mtakataka Fault (BMF), at the southern end of the western branch of the East African Rift System (EARS), has been used in various scaling relation studies and arguments about the strength of the lithosphere. We present evidence for a similar, though more degraded, frontal scarp on the graben‐bounding synthetic Chirobwe‐Ntcheu Fault (CNF), showing that this fault is active simultaneously with the BMF. We deployed 17 geophones for ∼60 days around the southern end of Lake Malawi, across the footwall and hangingwall of the BMF. Continuous microseismicity can be seen from the surface to ∼35 km depth highlighting a plane dipping ∼42°E. Lower‐crustal earthquakes have previously been found in the EARS, and based on location and focal mechanism have been hypothesized to occur on planes that line up with the surface traces of large faults. However, no previous study of the EARS has revealed a fault plane throughout the crust that shows seismicity along its full length from the surface to the base of the crust. Rather, the lack of seismicity seen at mid‐lower crustal depths, has led some people to the "jelly sandwich" hypothesis. Our results show that the entire crust is seismogenic, so support the "crème brûlée" model. In our two month deployment we recorded 22 aftershocks ML ≥ 2 from the March 8th, 2018 earthquake 200 km south of our array, 7 months after the mainshock, confirming that aftershock sequences in regions of low strain have a long duration, and could be the main component of seismicity in slowly straining regions. Plain Language Summary: We set out instruments around the southern end of Lake Malawi to detect earthquakes. There is a large fault in the area, the Bilila‐Mtakataka Fault, where a large earthquake has occurred previously. Evidence for this comes from a ∼110 km‐long cliff, averaging 14 m high, showing movement in a past earthquake, which probably happened thousands of years ago. We found a ∼80 km‐long cliff at the base of another large nearby fault, called the Chirobwe‐Ntcheu Fault. This means that large earthquakes could also occur on this fault. There was no previous evidence for what these faults looked like beneath the surface, or whether many small earthquakes were happening on it. We discovered that these faults are probably a continuous straight line underground, highlighted by small earthquakes that occur from the surface to almost 35 km depth. This shows that a very large earthquakes could occur, reaching from this large depth all the way to the surface. We recorded, in 2 months, 40 events from the coal fields at Tete, Mozambique, where previously residents have complained that coal blasting creates shaking and has formed cracks in their homes. The events that we detected are the likely cause of these cracks. Key Points: Microseismicity occurs throughout the entire crust in southern MalawiMicroseismicity highlights a normal fault plane all the way down to 35 kmThe entire crust is capable of hosting earthquakes (i.e., not the jelly sandwich model) [ABSTRACT FROM AUTHOR]

Various kinematic models have been proposed to explain the growth process of wide compressive orogens, and the deformation rate within the entire range of the orogen (rather than that of the leading‐edge fault) provides valuable information for model evaluation. Within the Qilian Orogen, between the central and northern Qilian Shan mountain in China, we studied the deformation of a series of Quaternary fluvial terraces across the North Tuolai Shan Fault (NTF), including optically stimulated luminescence dating of terrace ages. The results show that the six levels of terraces (T6 to T1) were formed at 58.4 ± 4.4 ka, 53 ± 5 ka, 46 ± 5 ka, 38 ± 5 ka, 23.2 ± 1.8 ka, and 4.8 ± 0.4 ka, respectively. Field investigations revealed that these terrace surfaces are faulted and folded by the NTF. Based on the deformation and ages of the terraces across the fault, the vertical slip rate is estimated as 1.5 ± 0.1 mm/yr, and the shortening rate is 0.9 ± 0.1 mm/yr, with a fault dip of 58°–60°. This deformation rate is similar to rates determined along the leading‐edge fault in the northern Qilian Shan and along the fault in the southern Qilian Shan. The widely distributed shortening across the ∼300‐km‐wide Qilian Orogen supports the kinematics of distributed upper crustal shortening across the Qilian Orogen, with a ductile lower crust, rather than a large, gradually propagating crustal‐scale deformation wedge. Key Points: The shortening rate across the North Tuolai Shan Fault is estimated as 0.9 mm/yr, based on optically stimulated luminescence dating of fluvial terracesThe shortening rate within the ∼300 km Qilian Orogen suggests that crustal shortening is widely distributed along several thrust beltsThe distributed shortening supports the kinematics of a distributed upper crustal shortening across the orogen, with a ductile lower crust [ABSTRACT FROM AUTHOR]

Studying the slip rate along major strike‐slip faults is critical to understanding the deformation and kinematics in continental collision zones. The Gyaring Co fault was previously regarded as a segment of the southern boundary of eastward extrusion in central Tibet, and its eastern segment was linked to the Xainza rift. However, the spatial distribution of its slip rates is poorly constrained, which limits our knowledge about how deformation is partitioned between strike‐slip and normal faults in central Tibet. Here, we used optically stimulated luminescence dating to determine the ages of displaced landforms (alluvial fans, lake shorelines, and river terraces) along the Gyaring Co fault. The results demonstrate a southeastward decrease in the late Quaternary slip rate from 2–3 mm/yr to 0.5–1.0 mm/yr over a distance of ∼130 km. Although the slip rate of the middle‐west segment of the Gyaring Co fault seems to have decreased slightly (20%) at ∼10 ka, it remained relatively stable during the late Quaternary. Regional analysis suggested that the Gyaring Co fault is kinematically compatible with the Xainza rift and probably has accelerated rift extension in its northern part since the middle Miocene. This northward‐increasing extension rate may accommodate more than half of the observed strain‐rate gradient along the Gyaring Co fault. The difference observed in strain rate requires a strain of ∼1 × 10−8 per year, comparable with the average present‐day strain rate of the Tibetan Plateau. The Gyaring Co fault separates the crustal blocks that are also deforming internally, suggesting distributed deformation in central Tibet. Key Points: Optically stimulated luminescence dating of displaced alluvial fans, lake shorelines, and river terraces allows us to determine slip rates along the Gyaring Co faultLate Quaternary slip rates of the Gyaring Co fault probably decrease southeastward from 2–3 to 0.5–1.0 mm/yrMore than half of the observed slip rate gradient may be accommodated by extension within the Xainza rift zone [ABSTRACT FROM AUTHOR]