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The 1,900‐km‐long Sumatran fault plays an important role in accommodating oblique plate motion between the Indo‐Australian and Sunda plates. Although fault geometry, kinematics, and seismic activity are well‐studied, the onset of dextral motion on the Sumatran fault and uplift of adjacent Barisan Mountains is unclear; this hinders an understanding of the late Cenozoic evolution of Sumatra and the forearc region. In this study, we use low‐temperature thermochronology to measure cooling histories of rocks within and outside of the Sumatran fault. An accelerated exhumation within the fault zone began at ∼2 Ma. The Barisan Mountains may have experienced uplift and associated river incision in the late Miocene to Pliocene. The fault systems in the forearc region were inferred to be kinematically linked to the Andaman Sea and Sunda Strait and accommodated early relative plate convergence, then relocated the strike‐slip component of deformation to the Sumatran fault at ∼2 Ma. Plain Language Summary: The 1,900‐km‐long trench‐parallel Sumatran fault plays an important role in accommodating the oblique plate motion between the Indian Ocean lithosphere and Sunda continental crust. Although fault geometry, kinematics, and seismic activity are well‐studied, the onset of motion on the Sumatran fault and uplift of adjacent Barisan Mountains is unclear, hindering an understanding of the late Cenozoic evolution of Sumatra and forearc region. Fault movement with dip‐slip components affects bedrock exhumation rates of the fault zone, which should be recorded by low‐temperature thermochronologic data. We present new apatite and zircon (U‐Th)/He data collected from the Sumatran fault zone and adjacent Barisan Mountains to examine their exhumation histories, which has previously been unconstrained. We then discuss the driving mechanism based on structural, sedimentary and chronologic observations. Our AHe and ZHe data help to provide timing constraints on the late Cenozoic tectonic and landscape evolution of the Sumatran fault and Barisan Mountains, which in turn can be related to broader plate tectonic setting. Key Points: A Pleistocene accelerated exhumation is identified within the Sumatran fault zoneThe Barisan Mountains may have experienced uplift and rapid exhumation in the late Miocene to PlioceneForearc faults likely accommodated early oblique plate motion and deformation relocated to the Sumatran fault around 2 Ma [ABSTRACT FROM AUTHOR]

Planform drainage patterns in orogens reflect the initial control of local structures, resulting in strike‐parallel longitudinal drainage, and the subsequent influence of regional slopes that result from crustal thickening and reorganizing rivers into strike‐perpendicular transverse drainage. However, in broken forelands, out‐of‐sequence range uplift along steep faults results in significant basin‐range relief, suggesting that such regions may not follow the transition from strike‐parallel to strike‐perpendicular drainage and require a distinct model of drainage evolution. Using the broken foreland of NW Argentina as an example, we describe modern and paleo‐topography, planform drainage patterns, and drainage evolution using geomorphic observations and a synthesis of existing thermochronologic, structural, and sedimentologic data. We find three distinct drainage patterns in NW Argentina: (a) major long‐lived, strike‐parallel longitudinal rivers, (b) outlets localized between along‐strike faults, and (c) sharp changes in flow direction that developed as rivers passively deflected around growing structures and top‐down drainage reorganization (e.g., divide overtopping). These drainage patterns formed during Oligocene‐Miocene basin fragmentation and reflect a strong tectonic control. Rivers, unable to incise into rapidly uplifting bedrock, instead deflected and formed major longitudinal rivers that flow along ranges and through structural gaps, and frequently reorganized through top‐down processes. Sustained high relief between basins and ranges suggest that longitudinal drainages are entrenched and unlikely to reorganize into transverse rivers. These drainage patterns and their evolution are distinct from the expected longitudinal‐transverse progression in thin‐skinned and thick‐skinned tectonic wedges. We therefore suggest the fluvial evolution of broken forelands may be more comparable to extensional landscapes. Key Points: Common drainage patterns in NW Argentina include longitudinal rivers, structurally controlled outlets, and passive fluvial reorganizationDrainage patterns are controlled by local structures and diachronous deformation along steep reverse faults with short strike lengthsComplex regional topography and high relief between basin and ranges will prevent a transition from longitudinal to transverse drainage [ABSTRACT FROM AUTHOR]

Several major (up to MW 7.5) earthquakes over the past 320 years have shaken the thick‐skinned Sierras Pampeanas region of Argentina, despite exhibiting much lower GPS‐shortening rates than across the thin‐skinned Precordillera region to its west. Whether geodetic shortening rates indicate an actual long‐term shortening gradient, and whether shortening rates translate to higher uplift rates due to steeper faults in the Sierras Pampeanas, remain uncertain due to the limited spatio‐temporal coverage and the inherently large error in the vertical component of deformation of GPS measurements. We measure geomorphic offsets and use 10Be terrestrial cosmogenic nuclide surface exposure dating to determine slip rates on the Las Chacras Fault Zone (LCFZ)—an ∼30 km long, NNW‐trending, steeply dipping (55–65°E) reverse fault that branches off of the longest, westernmost, thick‐skinned Valle Fértil range‐front fault in the western Sierras Pampeanas. Average shortening and uplift rates measured on the LCFZ are ∼0.2 and ∼0.3–0.4 mm/yr, respectively. Despite an uplift rate similar to most other faults in the region, the LCFZ shortening rate is lower than faults to its west; this is in agreement with the inferred west‐east decrease in shortening rates from GPS data, indicating consistent regional deformation patterns since the Late Pleistocene. The decrease in shortening to the east coincides spatially with the termination of the flat portion of the subducted Nazca plate between 67 and 68°W. From scaling relationships among magnitude, slip rate, and fault length, the LCFZ is capable of generating earthquakes of MW 6.7–7.1. Key Point: Intraplate deformation in the Sierras Pampeanas of west‐central Argentina is capable of generating large magnitude earthquakes [ABSTRACT FROM AUTHOR]

The southeastern Tibetan Plateau is a key component in the India‐Eurasia collision zone, which is characterized by spatially prevalent strike‐slip fault systems with devastating earthquakes. However, slip rates on some of these faults are still poorly constrained, hindering an understanding of kinematic and dynamic processes in this region. We analyze contemporary crustal deformation in the SE Tibetan Plateau based on the latest, dense geodetic observations. Slip rates on a set of dextral NW/NNW‐striking faults are determined using a 3‐D elastic half‐space dislocation model. Our results show that boundary faults such as the Red River and Lancangjiang faults yield dextral slip rates ranging from 1 to 3 mm/a, similar to those of other small‐scale sub‐parallel faults such as the Chuxiong, Qujiang, and Wuliangshan faults. Additionally, sinistral slip of the Xiaojiang fault may have partly transferred to transpressional slip on the Qujiang, Jianshui, and central Red River faults, which increase seismicity on these faults. New seismic relocation results, geodetic measurements, and existing structural observations show the geometry of this dextral fault system at the depth, which may be restricted above or within the rheologically weak mid‐lower crust rather than cutting into the mantle. Results confirm that the SE Tibetan Plateau is characterized by on‐going diffuse deformation between the Sagaing and Xianshuihe‐Xiaojiang faults. Driven by the northward advance of the eastern Himalayan syntaxis and southward crustal extrusion, distributed right‐lateral movements occurred along the NW/NNW‐striking fault system. Key Points: A set of NW/NNW‐striking faults in the SE Tibetan Plateau yield dextral slip rates of 1–3 mm/a based on the latest geodetic observationsDextral movements of the NW‐/NNW‐striking faults could be caused by the northward indentation of the EHS and clockwise crustal extrusionThe SE Tibetan Plateau may have transitioned from localized to diffuse deformation in the mid‐late Miocene [ABSTRACT FROM AUTHOR]

• Spatial variability of vegetation predicts fluvial erosion in the central Andes. • Interactions of topography and lithology are secondary influences on erosion rates. • Metrics that capture distribution of controls provide better correlations than basin-wide means. Understanding how tectonics, climate and lithology interact to control fluvial erosion is complicated because these factors are spatially-variable and they may not be well-represented by mean values. We address these complications using eight new and 54 published 10Be catchment-wide fluvial erosion rates from the south-central Andes. We assess how tectonics, climate, lithology, and topography control erosion through bivariate and multivariate Bayesian regression analysis. We first compare catchment-wide mean values of independent variables compared to other summary statistics and find that metrics that capture extreme values (e.g., 90th percentile) and spatial variability (e.g., 90th minus 10th percentile) produce stronger correlations. This suggests that catchment-wide means may oversimplify the roles of tectonics, climate, and lithology in influencing erosion rates. We find that the overall variability of erosion rates in the south-central Andes is best explained by a combination of lithologic resistance and spatial variability in both vegetation (using the normalized difference vegetation index, NDVI) and topography (using specific stream power). Despite poor bivariate correlations, both lithologic resistance and spatial variability of specific stream power are significant regressors in our multivariate modeling. Lithology influences the relationship (i.e., linearity) between topography and erosion rates. Spatial variability of NDVI produces the strongest correlation with erosion rates of any of the variables we consider. Hence, spatial variability of NDVI both accounts for potential non-uniform vegetation responses to climate and also incorporates the role of both humid climates (high 90th percentile) and large bare regions (low 10th percentile) within a single catchment. [ABSTRACT FROM AUTHOR]

The Lincang-Inthanon tectonic belt is a major tectonic boundary within the south-eastern Tibetan Plateau and Indo-China Peninsula, which are typical examples of tectonic extrusion in SE Asia. The Lincang strain zone, Lancang-Gengma fault, and Inthanon metamorphic complex make up this nearly N--S-striking tectonic belt, which separates the Baoshan--Shan Thai and Simao-Indochina terranes. New petrographic, structural, and mica 40Ar/39Ar geochronological studies were conducted to reveal their deformation styles and constrain the timing of their tectonic evolution. W--E-directed compression related to the subduction of the Paleotethyan Ocean with subsequent continental collision and sinistral ductile shearing in the early Oligocene are recorded along the Lincang strain zone. The Lancang-Gengma fault zone switched from sinistral shearing to dextral motion in the late Cenozoic and shows a deformation history similar to that of the parallel Red River fault. The Inthanon metamorphic complex may have experienced crustal shortening in the early Cenozoic, followed by sinistral transtension in the early Miocene. The Lincang-Inthanon tectonic belt shows many lithological, tectonic evolutionary, and metamorphic similarities with the Gaoligong, Chongshan, and Ailaoshan--Red River shear zones. Therefore, the sinistral shearing along the Lincang-Inthanon tectonic belt and the Chongshan shear zone in the north, which may have initiated since the early Oligocene, played an important role in adjusting differential extrusion and rotation of the Baoshan--Shan Thai and SimaoIndochina terranes. Our results delineate the regional tectonic framework and provide insights into the characteristics and geodynamics of intracontinental deformation in the eastern India-Eurasia oblique convergence zone. [ABSTRACT FROM AUTHOR]

The most striking structural features in the interior of the Shan Plateau, southeast of the eastern Himalayan syntaxis, are a series of NE-trending faults that exhibit sinistral movement and an arcuate geometry. Their origin and tectonic evolution remain poorly understood. Furthermore, a switch in slip sense is recorded along many of these faults, but the timing of kinematic reversal is still unclear, hindering an understanding of the causal geodynamic mechanisms. We conducted an integrative study of apatite and zircon (U-Th)/He thermochronology, 40Ar/39Ar geochronology, and structural and geomorphic analysis to decipher the evolution of two major NE-trending faults: the Nantinghe and Dayingjiang faults. At least three deformation stages are identified within the Nantinghe fault zone, including top-to-the-SE/ESE thrusting, dextral ductile strike-slip shearing, and sinistral movement. Zircon and apatite (U-Th)/He data, collected from the northeastern terminus of the Nantinghe fault, reveal rapid cooling in the early Miocene. Combined with the 40Ar/39Ar data from sinistrally sheared mylonite, left-lateral movement on the Nantinghe fault is inferred to have initiated as early as ca. 20 Ma. The Dayingjiang fault reactivated as a sinistral brittle fault along the dextral Yingjiang shear zone. A two-stage thermal history is identified along the shear zone, with prominent cooling during dextral ductile shearing in the early- to mid-Miocene followed by a lower-magnitude cooling episode at ca. 11 Ma caused by sinistral transtension along the Dayingjiang fault. The evolution of the Nantinghe and Dayingjiang faults suggests that the NE-trending fault system in the Shan Plateau may have developed along preexisting structures and underwent diachronous slip-sense inversion in the late Cenozoic. The northward advance of the eastern Himalayan syntaxis caused a major change in both the regional stress field and fault geometries in the eastern India-Eurasia oblique convergence zone, contributing to the inversion of fault kinematics. [ABSTRACT FROM AUTHOR]