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The structure of the Tajik Basin is characterized by a series of NE-trending fold-thrust belts that share a common detachment layer composed of Upper Jurassic evaporite rocks. These fold-thrust structures, thrusting face to face, converge toward the Vakhsh Depression. Due to limitations of seismic and drilling data, the controlling factors of the formation of the fold-thrust belts in the Tajik Basin remain controversial. Taking the Tajik Basin as a geological prototype, structural physical simulation experiments were conducted to decipher the controlling factors of salt-related structure deformation. The experiment results indicate that the tectonic deformation of the strata above the Jurassic evaporite rocks in the Tajik Basin is mainly controlled by the detachment layer of the Upper Jurassic evaporite rocks. The early salt diapirs in the Upper Jurassic played a key role in the formation of the thrust belts. Additionally, tectonic stress near the mountain front was rapidly transmitted to the inner basin due to the load of the structural wedge. Based on the results of physical simulation experiments, we speculate that the tectonic deformation of the subsalt strata and the basement in the Tajik Basin is primarily controlled by a deep detachment layer. The deformation of the subsalt strata is relatively gentle, which is conducive to the formation of large-scale, broad and gentle anticlinal structures. The anticlinal structures of the subsalt strata can form effective traps due to the sealing effect of the Upper Jurassic evaporite layer, offering promising exploration potential.

The interpretation of high-precision seismic data reveals that the tectonics of the western part of the southern margin shows new tectonic superposition characteristics and more complex superposition composite tectonic style, and the superposition tectonics has obvious zoning characteristics in spatial distribution. Combined with the field geological investigation, seismic interpretation, equilibrium section restoration, and the use of wedge tectonic theory and tectonic geology analysis methods, the complex superposition tectonic deformation differences and zoning characteristics were investigated. The study shows that: the western part of the southern margin develops a spatial folding system under the joint and differential control of basement involvement and downstream sliding, and the development of folds is controlled by faults, which are superimposed on each other to form a tectonic wedge, double tectonics, sudden tectonics and other composite tectonic styles. The western part of the southern margin is divided into three tectonic belts, namely, the pre-mountain retrograde thrust-overthrust tectonic belt, the basement-involved fold-rupture belt, and the cover-slip fold-rupture belt, according to the nature of the tectonic deformation and the difference of the deformation, among which the basement-involved fold-rupture belt is overlapped with the first row of the fault belt and controlled by the basement-involved rupture system, and the large-scale tectonic wedge of basement-involved, the dual structure of the dorsal stacking and double-tectonics, and the double-tectonics of the forward-dipping tectonics are devel-oped, and the dorsal axes overlap the planes of faults with high coincidence degree. The slip-type fold-rupture zone includes the second and third rows of fold zones, which are controlled by the downstream slip-type rupture system, with the development of break-spreading folds, low overlap between the dorsal axes and the fault line planes, and layered differences in the vertical direction of the tectonics; the coverall degree of tectonic deformation from the south to the north shows that it is decreasing from strong to weak. The period and intensity of extrusion stress, the northward slip of the slip fault, the wedge length of the tectonic wedge and the pushing distance, the thickness of the slip layer and the thickness of the overlying strata, the depositional age, the depositional rate, and the difference in lithology are the causes of the vertical stratification of the tectonics of the western part of the southern margin and the north-south division of the zone. The explicit construction of deformation differences and the refined division of zoning have important implications for clarifying the development of geological structures in research areas and guiding oil and gas exploration activities. [ABSTRACT FROM AUTHOR]

Studying the structural evolution of the piedmont fold and thrust belt is one of the most important methods to interpret the mechanism of intracontinental collision orogeny. In this study, we have discovered a long-distance large-scale thrust nappe with a width of approximately 20 km in the southwestern margin of the Santanghu Basin, which provides a good evidence for studying the Mesozoic–Cenozoic tectonic evolution mechanism of Moqinwula Mountain. Using the electromagnetic and high-resolution seismic profiles, we have determined that the hanging wall of the nappe is composed of the pre-growth strata of the Carboniferous–Middle Jurassic period and the syntectonic strata of the Cretaceous–Quaternary period. The nappe is subjected to two branch faults of the Baiyishan thrust, forming a breakthrough fault-propagation fold and a fault-bend fold along the detachment layer of the Haerjiawu Formation, and a large monoclinic is formed by the basement structural wedge near the mountain root. The growth strata and unconformity structure record that the fold–thrust belt has experienced five episodes of thrusting from the Late Triassic to Quaternary period. Based on sequential restoration and forward modeling, we propose that the southwestern margin of the Santanghu Basin has been shortened by at least 55 km, especially in the Late Jurassic and Late Cretaceous. Our results provide an excellent example for studying the mechanism of the transition from Yanshanian transpression to Himalayan thrust compression in the Eastern Tianshan region.

The northern part of the Jurassic Sichuan Basin has long been thought of as a foreland basin in relation to the post-collisional compression along the northern margin of the Yangtze block. However, the exact coupling mechanism between mountain building and basin formation remains unclear. Here, we integrate stratigraphic correlation, basin subsidence analysis and flexural simulation to quantitatively assess the extent to which the fold-thrust belts have controlled basin subsidence. Flexural backstripping of the stratigraphic record, spanning from 201 to 149 Ma, along two cross sections that are perpendicular to the Micangshan fold-thrust belt and the Dabashan fold-thrust belt, respectively, reveals a limited flexural control of mountain loading on basin subsidence. Owing to the short-wavelength nature of plate flexure, the basin-adjacent thrust belts exerted dominant control on basin subsidence only along its margin, with the width of the foredeeps not exceeding ca. 120 km, failing to drive subsidence in the forebulge and backbulge regions. Flexural modeling results suggest that crustal thickening was relatively weak during the Early to Middle Jurassic. This was followed by a more rapid and intense phase of crustal growth in the Late Jurassic, possibly extending into the earliest Early Cretaceous. Compared to the Micangshan region, the Dabashan region has experienced more intense compression during the Late Jurassic. Additionally, our results reveal spatial variations in plate rigidity along the northern margin of the Yangtze block, with greater plate stiffness in the Dabashan region. The presence of residual subsidence, an anomalous long-wavelength subsidence component corrected for both basin-adjacent thrust loading and associated sediment loading, highlights the necessity for an additional driving mechanism for basin subsidence. This residual subsidence was likely dynamic subsidence induced by the flat subduction of the Paleo-Pacific plate (the Izanagi plate) beneath East Asia as the flat slab progressively migrated inland.

This article presents an interpretation of geophysical data that characterizes the structure of the piedmont folded zone of the Urals and Pay-Khoi, which shows the diversity of structural styles of deformations in the study region. The following structural styles of deformations are considered: classical thrust zones, which are imbricated overlapping of thrust plates (i); areas of development of wedge-shaped allochthons, composed of duplex tectonic plates that do not have direct expression in the overburden strata (ii); inversion zones where faults are associated with the Ural rifting are transformed into thrust faults (iii); areas whose structure is determined by the deformation of salt diapirs and extrusion of salt (iv); zones of tectonic thickening of the Precambrian complexes overlain by the Paleozoic cover (v). Interpretation of historical and new data on the structure of fold belts makes it possible to significantly update our understanding of the structure and development of areas such as zones of wedge-shaped thrusts, areas of development of squeezed salt diapirs, and areas where reactivation and tectonic thickening of Precambrian complexes occurred due to the reactivation of pre-existing faults. The new seismic data provide constraints on the magnitude of horizontal displacements in the thrust zones as well as timing of phases of deformation. For the first time they have revealed the development of zones of low-amplitude proto-thrusts. [ABSTRACT FROM AUTHOR]

Using a database consisting of sub-bottom profiles, 2D and 3D seismic data, a series of seep structures and acoustic anomalies associated with a plumbing system in the subsurface of the southern part of the Malvinas Basin off the Argentine coast are presented. The seep morphologies consist of mounds, pockmarks, and a carbonate mound, derived from hydrocarbons migrating from the Early Cretaceous Springhill and Lower Inoceramus formations through extensional faults and overthrusts of the Malvinas Fold-Thrust Belt and accumulating in the gas hydrate stability zone. This configuration is widely observed in the anticlines of the Malvinas Fold-Thrust Belt, which are characterized by a vertical structure highlighting a Bottom Simulating Reflector (BSR) overlain by a blanked-out zone at the seabed, interpreted as a gas hydrate stability zone. The plumbing system is influenced by active transtensional tectonics, as shown by two sets of extensional faults concentrated over some anticlines. These faults lead to displacements that, in many cases, reach the seabed. One nuance of the influence of tectonic activity on fluid escape is most evident in the Malvinas anticline, where all the pockmarks and the carbonate mound are concentrated. In the western part of the Malvinas anticline, five pockmarks are observed in an area characterized by a shallow BSR. In contrast, in the eastern part of the Malvinas Basin, one pockmark and one carbonate mound are derived from a series of extensional faults. The presented data, as well as a comparison between the western and eastern parts of the Malvinas anticline, indicate that the anticlines are the main cause of seepage in this area, as they allow the accumulation of migrating fluids. Likewise, the seepage morphologies outside the anticlines are much less pronounced, as can be observed in the mounds that overlie the bottom vents. • Genesis of seep sites varies within the same anticlinal structure. • Seabed extensional faults drive the formation of pockmarks and a carbonate mound. • Anticlines are the most important regulators in the fluid plumbing system. • Staggered BSRs allowed fluids to seep into the seafloor. [ABSTRACT FROM AUTHOR]

The gas-rich Wufeng-Longmaxi shale has been intensely deformed within the fold-thrust belt of the Yangtze Block. To better understand the impact of structural deformation on the shale pore system, this paper systematically investigated the matrix components, porosity and pore structures in core samples from the Wufeng-Longmaxi shale, newly collected from various structural domains in the first commercial shale gas field of the Central Yangtze Block, the Anchang Syncline. The shale porosity generally showed a positive relationship with total organic carbon content. Nevertheless, even at a constant total organic carbon content, the shale porosity decreased from the syncline limb to the syncline hinge zone and with a decreasing interlimb angle in the syncline hinge zone, which aligned with the structural deformation strain during folding. The artificial axial compression of shale samples also confirmed that the decrease in shale porosity was stronger at an elevated axial compression stress and was relatively higher in samples with higher total organic carbon content. The organic pore size decreased with higher structural deformation strain, but the aspect ratio of the pore shape increased. Even quartz failed to resist the effective stress under the intensive structural deformation, changing the correlation between porosity and quartz from positive to negative. In contrast, pore spaces generated by the slipping between clay flakes under intensive deformation accounted for a positive relationship between clay content and bulk porosity. Considering the shale porosity reduction caused by the intensive structural deformation of shale pores, the Wufeng-Longmaxi shale, that is rich in fracture networks between roof and floor layers, may still be an excellent exploration target in the fold-thrust belt of the Yangtze Block. [ABSTRACT FROM AUTHOR]

The Andes of western Argentina record spatiotemporal variations in morphology, basin geometry, and structural style that correspond with changes in crustal inheritance and convergent margin dynamics. Above the modern Pampean flat‐slab subduction segment (27–33°S), retroarc shortening generated a fold‐thrust belt and intraforeland basement uplifts that converge north of ∼29°S, providing opportunities to explore the effects of varied deformation and subduction regimes on synorogenic sedimentation. We integrate new detrital zircon U‐Pb and apatite (U‐Th)/He analyses with sequentially restored, flexurally balanced cross sections and thermokinematic models at ∼28.5–30°S to link deformation with resulting uplift, erosion, and basin accumulation histories. Tectonic subsidence, topographic evolution, and thermochronometric cooling records point to (a) shortening and distal foreland basin accumulation at ∼18–16 Ma, (b) thrust belt migration, changes in sediment provenance, and enhanced flexural subsidence from ∼16 to 9 Ma, (c) intraforeland basement deformation, local flexure, and drainage reorganization at ∼12–7 Ma, and (d) out‐of‐sequence shortening and exhumation of foreland basin fill by ∼8–2 Ma. Thrust belt kinematics and the reactivation of basement heterogeneities strongly controlled tectonic load configurations and subsidence patterns. Geo/thermochronological data and model results resolve increased shortening and combined thrust belt and intraforeland basement loading in response to ridge collision and Neogene shallowing of the subducted oceanic slab. Finally, this study demonstrates the utility of integrated flexural thermokinematic and erosion modeling for evaluating the geometries, rates, and potential drivers of retroarc deformation and foreland basin evolution during changes in subduction. Key Points: New geo/thermochronological results and flexural thermokinematic models constrain Andean retroarc thrust belt and foreland basin evolutionModels highlight the influence of deformation kinematics and thrust belt/basement load configurations during retroarc subsidenceSubduction shallowing at ∼12 Ma drove increased shortening and flexurally controlled topography/subsidence with no residual dynamic signals [ABSTRACT FROM AUTHOR]

The Aure fold-thrust belt is an important area for oil and gas exploration in Papua New Guinea, but the structural deformation and evolution of the fold-thrust belt are not well understood.In this paper, 2D and 3D seismic data, drilling and geological data covering the structural belt, combined with previous geological research results, were used to identify the structure and kinematics characteristics of the Aure fold-thrust belt.Guided by the theory of fault-related folds, the seismic data are interpretation.The Aure fold-thrust belt can be divided into three sections along the strike, and the structural deformation of the belt has obvious differences, which are mainly reflected in the following aspects: ①In the trend from NE to SW, the deformation level is gradually shallow, the involved strata are gradually new, and the deformation degree is gradually weaker; ②Along the strike from NW to SE, the extension range becomes smaller, the foreland sedimentary strata become newer, the tectonic deformation time becomes later, the shortening rate becomes larger, and the shortening amount becomes smaller; ③The western section and the middle section are disintegrated vertically, and the eastern section is inherited deformation.The results can provide basin evidence for oil and gas exploration in Papua New Guinea and regional tectonic evolution in the northern margin of Australia.

The Qilian Mountains are a typical active fold-thrust belt. A series of large and elongated drainage basins are oriented almost parallel to the Mountain Chain. Conversely, on North flank of the Qilian Mountains, transverse rivers dominate the drainage network. However, the evolution of these drainage patterns is still poorly understood. Here, we first review the evolutionary history of the drainage pattern of major rivers in the Qilian Mountains. We find that early transverse-dominated river networks are progressively replaced by longitudinal-dominated rivers during mountain building. Because the incision rate of transverse rivers is defeated by the uplift rate of mountains, the transverse rivers would be diverted toward the fold tips and gradually lengthened. Then, we analyze the evolutionary trends of drainage networks using topographic metrics. We suggest that longitudinal rivers, especially the upper reach of longitudinal rivers, will be captured by transverse rivers. Our study shows that the evolution of drainage patterns in active fold-thrust belts has two stages: in the early stage, transverse rivers would be replaced by longitudinal rivers; in the later stage, the upper longitudinal rivers would be captured by transverse tributaries. Moreover, the evolution model of drainage patterns in active fold-thrust belts is validated by using the TopoToolbox Landscape Evolution Model (TTLEM). Tectonics and deformation impart a lasting impression on the planform pattern of drainage networks. However, the drainage network will show different patterns in various evolution stages, even with consistent tectonic conditions. The results of this study may help investigate the drainage network evolution process in other active fold-thrust belts.

Measuring penetrative strain is critical for understanding the 3D strain field of structural systems. Here, we investigate ductile strain and kinematics in two Cordilleran structural systems in north-central Idaho: the Salmon River suture zone (SRSZ), which is a west-vergent ductile fold-thrust system that accommodated shortening associated with terrane collision between ∼144 and 105 Ma, and the north-striking, subvertical western Idaho shear zone (WISZ), which accommodated dextral-transpressional shearing between ∼105 and 86 Ma. We collected finite strain data from stretched clasts in three SRSZ thrust sheets, which define 56–87% average thrust-parallel stretching and 35–48% average thrust-normal thinning. Thrust-parallel stretching contributed >27 km of cumulative displacement to the up-dip portion of the fold-thrust system, comparable to the 34 km of total thrust displacement estimated at down-dip levels. In the WISZ, we documented dextral kinematics in lineation-normal planes, and we measured boudinaged and folded granitic dikes to estimate late-stage (∼91-86 Ma) strain, which yielded 65% minimum lineation-parallel stretching and 50% minimum east-west shortening. Subvertical stretching in the WISZ accommodated >9–10 km of exhumation relative to the Idaho batholith to the east. The SRSZ and WISZ both demonstrate the 1st-order importance of ductile stretching for accommodating the large-scale transfer of mass and exhumation in fold-thrust and transpressional systems. • Penetrative strain is a critical component of the 3D strain field in thrust systems. • Thrust-parallel stretching can greatly increase displacement in thrust systems. • Thrust-parallel stretching and thrust-normal thinning enhance exhumation. • Lineation-parallel stretching drives exhumation in transpressional shear zones. [ABSTRACT FROM AUTHOR]

[Display omitted] • Late Jurassic to Cenozoic tectonostratigraphic evolution of the Andes at 36°S. • End of backarc sedimentation during the Late Cretaceous. • Upper Cretaceous compression did not generate a well-developed fold-thrust belt. • Modest shortening, tectonic quiescence, and extension during most of the Paleogene. • A well-developed fold-thrust belt was only achieved in the Neogene. Many studies propose a significant shift in the tectonic and paleogeographic evolution of the Andes in south-central Chile and Argentina during the Late Cretaceous. It has been proposed that the preceding Jurassic-Early Cretaceous extensional regime that resulted in a low-relief volcanic arc and the backarc Neuquén basin came to an end, giving way to shortening and Andean growth from the Late Cretaceous onward. Nevertheless, there are disagreements regarding the timing and nature of this transition to Andean orogenesis. To address these issues, we conducted geochronologic (U–Pb and 40Ar/39Ar), sedimentologic, and structural studies on Mesozoic-Cenozoic sedimentary and volcanic rocks in the Río Maule area (Principal Cordillera, Chile, 36°S). From our findings and prior analyses, we propose the following tectono-stratigraphic evolution of the region. (1) Marine deposition of the Tithonian-Hauterivian Baños del Flaco Formation took place in an extensional backarc basin. (2) After a ∼ 40 Myr hiatus, fluvial deposits of the Colimapu Formation and volcanic rocks of the Plan de los Yeuques Formation accumulated during the Cenomanian-Danian. Whereas the Colimapu Formation displays evidence of syndepositional shortening, the Plan de los Yeuques Formation exhibits synextensional growth strata. Contrary to other studies, our results suggest that the Chilean part of the Principal Cordillera was largely a zone of active deposition rather than an elevated fold-thrust belt during the Late Cretaceous. We propose that sedimentation occurred within a series of relatively stable intermontane subbasins generated by shortening, followed by extension. (3) After a ∼ 20 Myr hiatus, middle Eocene to early Miocene (Lutetian-Aquitanian) accumulation of a thick succession of andesitic lavas and minor clastic sediments of the Abanico Formation occurred in an intraarc extensional basin. (4) Finally, major shortening and uplift of previously deposited Mesozoic-Cenozoic rocks took place throughout the Neogene. This phase constituted the primary contractional deformation in the Andes of south-central Chile and Argentina. In terms of the transition to early Andean deformation, we propose that structural deformation did not generate a major, regional-scale fold-thrust belt during the late Albian-Santonian. Modest extension, tectonic quiescence, or low-magnitude shortening seem to have dominated during the early to middle Cenozoic. [ABSTRACT FROM AUTHOR]

Quantifying the kinematic evolution of an orogenic system, recorded in its 3-D displacement field, across a range of spatial and temporal scales is challenging, yet crucial for quantifying crustal shortening budgets, determining origins of mountain belt curvature, restoring paleostress-strain trajectories, and understanding relations of orogenesis to plate dynamics. In this review paper, we integrate structural, paleomagnetic, and thermo/geochronologic data sets to explore evolution of the Sevier fold-thrust and Laramide foreland belts within the North America Cordillera. These belts record an entire orogenic cycle, from onset of shortening to extensional collapse, and formed within different crustal rock packages and during changing subduction dynamics. Like other Cordilleran-style systems, these belts show progressive deformation stages that include a pre-orogenic stage in the distal foreland, an early layer-parallel-shortening (LPS) stage in the proximal foreland, and a main stage of large-scale faulting-folding. These belts also display differences in structural styles, timing, shortening directions, and rotation patterns. The Sevier belt has a thin-skin style with a western thrust system that developed in thick passive margin strata and an eastern thrust system that developed in transitional strata. The Laramide belt has a thick-skin style with reverse faults that continue to mid-crustal depths and developed in cratonic basement overlain by a thin sedimentary cover. Thrusts in the Sevier belt were emplaced progressively forelandward (W to E) spanning 125–50 Ma and formed a tapered wedge, whereas Laramide arches were uplifted from 70 to 50 Ma and separated by broad basins. Large-scale folds and thrusts of the Wyoming salient of the Sevier belt display curvature about a regional N–S trend and accommodated ∼170 km (∼50%) overall W-E shortening. The western thrust system experienced early layer-parallel shortening (LPS) at upper levels with a switch to shear and vertical flattening by viscous flow at deeper levels (T > 300 °C). The eastern system experienced early LPS (5–20%) with development of cleavage and minor faults. Paleomagnetic analysis shows systematic vertical-axis rotations that increased curvature and led to a final radial pattern of LPS directions. Fluids promoted vein formation during episodes of high fluid pressures and alteration concentrated along weak fault zones. Laramide arches form an anastomosing network about a NW-SE structural grain and accommodated ∼50 km (10%) regional SW-NE shortening. The foreland experienced limited (<5%) LPS with development of minor faults and refraction of paleostress directions along variably trending arches. Differences in shortening directions, paleo-topography, and geographic distribution of the Sevier and Laramide belts suggest differences in origins and transmission of paleostress. Topographic stresses were likely important within the Sevier belt that formed a low-taper wedge tied to the hinterland with W-E shortening subperpendicular to the prior passive margin. Stress transfer from a flat slab was likely important for the Laramide belt, with SW-ENE shortening subparallel to the direction of relative plate motion. Although integrated studies have improved our understanding of Cordillera-style systems, key questions remain with future research areas including geodynamic modeling of oblique convergence, importance of terrane accretion, nature of fluid pressure transients and fault strengths, and modulation of orogenic systems by internal feedbacks. [ABSTRACT FROM AUTHOR]

The article presents a brief overview of the currently existing ideas about the seismotectonic situation in the Earth's crust of Iran, which is experiencing intense compression in the northeastern direction as a result of collision of the Arabian and Eurasian lithospheric plates. The survey also involved geodetic data in the form of modern GPS measurements of horizontal surface displacements. The stress-strain state of the Earth's crust of Iran (construction of the average focal mechanism) was assessed based on data on the total set of 945 focal mechanisms of earthquakes of average strength (4.4 ≤ MW ≤ 6.5) according to the ISC catalog, which occurred from 1975 to 2020, within 12 spatial samplings. The focal mechanisms of the strongest earthquakes in the last 50 years (MW = 6.0–7.4) for one event in each of these samplings are also considered. The calculated parameters of the average mechanisms and focal mechanisms of strong earthquakes are compared both with each other and with the surrounding tectonic situation and the distribution of deformation velocity vectors according to GPS observations. A satisfactory correspondence has been established between all the comparable values. The differences in the type of formation of the seismogenic layer of the Earth's crust of Iran in different regions are demonstrated. These differences are manifested in different ratios of shear and thrust components in the reconstructed mean mechanism in different spatial samplings. A similar difference is noted in individual focal mechanisms of the strongest earthquakes. However, it is possible to describe the observed nature of deformation of the crust of Iran within a single concept of collisional tectonics, caused by collision of the Arabian and Eurasian plates in the last 5 Ma. [ABSTRACT FROM AUTHOR]

Thrust wedges are common in nature, but not all of their origins can be properly explained by the classic Coulomb wedge theory, which considers only a 2D perspective. A few analogue models, however, revealed that lateral shear stress (inherent in both analogue models and nature) may strongly affect the development of thrust wedges and the lateral/basal shear stress (τs/τd) ratio might have controlled the structural vergence of thrust wedge, suggesting that origin of thrust wedges needs to be considered from a 3D perspective. The origin of the Eastern Sichuan–Xuefeng fold‐thrust belt (ESXFTB), which is characterized by two oppositely vergent thrust systems at different crustal levels and may contain another large purely backward‐vergent thrust wedge on the world, is still problematic. Revealing the relationship between τs/τd ratio and structural vergence may prompt a deep understanding of the origin of thrust wedges as well as the ESXFTB. This relationship, however, is still not very clear due to the lack of systematic experiments. For these reasons, we performed systematic experiments of two types of analogue models under different τs/τd ratios. Our model results revealed, for the first time, that structural vergence of thrust wedges lying on a weak décollement may progressively change from frontward (when τs/τd <0.09) to dual (when τs/τd = 0.09–1.15) and then to backward (when τs/τd >1.15) and the two oppositely vergent thrust systems in the ESXFTB can be produced simultaneously by the single northwestward Mesozoic shortening probably due to their apparently different τs/τd ratios. Key Points: Structural vergence of thrust wedges may change progressively with the increase of lateral/basal shear stress (τs/τd) ratioUnder the condition of one weak décollement, frontward, dual and backward vergence occurred when τs/τd <0.09, = 0.09–1.15 and >1.15, respectivelyESXFTB can be a product of the single northwestward Mesozoic shortening because their two thrust systems have different τs/τd ratios [ABSTRACT FROM AUTHOR]

Based on the latest geological, seismic, drilling and outcrop data, we studied the geological structure, tectonic evolution history and deformation process of the southwestern Sichuan fold-thrust belt to find out the potential hydrocarbon exploration areas in deep layers. During key tectonic periods, the southwestern Sichuan fold-thrust belt developed some characteristic strata and structural deformation features, including the Pre-Sinian multi-row N-S strike rifts, step-shaped platform-margin structures of Sinian Dengying Formation, the western paleo-uplift in the early stage of Late Paleozoic, the Late Paleozoic–Middle Triassic carbonate platform, foreland slope and forebulge during Late Triassic to Cretaceous, and Cenozoic multi-strike rejuvenated fold-thrusting structures. The fold-thrust belt vertically shows a double-layer structural deformation controlled by the salt layer in the Middle Triassic Leikoupo Formation and the base detachment layer at present. The upper deformation layer develops the NE-SW strike thrusts propagating toward basin in long distance, while the deeper deformation layer had near north-south strike basement-involved folds, which deformed the detachment and thrusting structures formed earlier in the upper layer, with the deformation strength high in south part and weak in north part. The southern part of the fold-thrust belt is characterized by basement-involved fold-thrusts formed late, while the central-northern part is dominated by thin-skin thrusts in the shallow layer. The Wuzhongshan anticlinal belt near piedmont is characterized by over-thrust structure above the salt detachment, where the upper over-thrusting nappe consists of a complicated fold core and front limb of a fault-bend fold, while the deep layer has stable subtle in-situ structures. Favorable exploration strata and areas have been identified both in the upper and deeper deformation layers separated by regional salt detachment, wherein multiple anticlinal structures are targets for exploration. Other potential exploration strata and areas in southwestern Sichuan fold-thrust belt include the deep Sinian and Permian in the Wuzhongshan structure, pre-Sinian rifting sequences and related structures, platform-margin belt of Sinian Dengying Formation, and Indosinian paleo-uplift in the east of the Longquanshan structure.

The Apennines are a retreating collisional belt where the foreland basin system, across large domains, is floored by a subaerial forebulge unconformity developed due to forebulge uplift and erosion. This unconformity is overlain by a diachronous sequence of three lithostratigraphic units made of (a) shallow‐water carbonates, (b) hemipelagic marls and shales and (c) siliciclastic turbidites. Typically, the latter two have been interpreted regionally as the onset of syn‐orogenic deposition in the foredeep depozone, whereas little attention has been given to the underlying unit. Accordingly, the rate of migration of the central‐southern Apennine fold‐thrust belt‐foreland basin system has been constrained, so far, exclusively considering the age of the hemipelagites and turbidites, which largely post‐date the onset of foredeep depozone. In this work, we provide new high‐resolution ages obtained by strontium isotope stratigraphy applied to calcitic bivalve shells sampled at the base of the first syn‐orogenic deposits overlying the Eocene‐Cretaceous pre‐orogenic substratum. Integration of our results with published data indicates progressive rejuvenation of the strata sealing the forebulge unconformity towards the outer portions of the fold‐thrust belt. In particular, the age of the forebulge unconformity linearly scales with the pre‐orogenic position of the analysed sites, pointing to an overall constant migration velocity of the forebulge wave in the last 25 Myr. [ABSTRACT FROM AUTHOR]

Abstract Isotopic studies of Canadian Rocky Mountain thrust faults preserve the timing and identity of orogenic fluids and their fault zone pathways. Using previously dated samples, we measure the O‐ and H‐isotopic compositions of fault gouge. These nearly 100% neomineralized gouges and their associated damage zones act as primary orogenic fluid pathways. As such, they provide a specific and local look into the nature of the Late Jurassic to Early Eocene orogenic plumbing system in the Alberta Rockies. Considering clay polytype stability and regional temperature conditions, we obtain a range of geofluid isotopic compositions during Jurassic‐Eocene thrust faulting: δ18Ofluid ranged from ∼−3.3 to 9.2 ± 3.2‰; δDfluid ranged from −119 to −46 ± 13‰ VSMOW. The range of O‐ and H‐isotopic compositions reflects mixing of fluid sources, including the pervasive presence of surface‐sourced fluids (up to ∼90%). The interpreted prevalence of a surface fluid source in fault rocks is in agreement with regional isotopic trends previously observed in undated veins of fractured host rock. Our results confirm that thrust faults of the Alberta Rocky Mountains acted as major fluid‐focusing conduits during orogenic activity. We further show that these faults incorporated both deeply sourced and surface‐sourced fluids into zones of enhanced and dynamic permeability, heterogeneously distributing fluids along fault planes across the fold‐thrust belt, promoting the growth of fault‐zone weakening clay minerals.

In northeastern Algeria, the Souk Ahras foreland basin is a part of the Maghrebides fold-thrust belt and comprises Sellaoua and Medjerda High units in the footwall of Tellian thrust sheets. Detailed geological mapping supported by micro-paleontological, petrographic, and structural data allows us to reappraise its stratigraphy and its structural style and to characterize the relationship between the different structural units (Numidian, Tellian, Sellaoua, and Medjerda High units). Data were collected for a biostratigraphy and field observations along to six (06) sections spread over the Ouled Driss, Dj. Boubakhouch, Dj. Boukebch – Dekma, and the Medjerda High. The Souk Ahras foreland basin substrate is made up by Jurassic and early Cretaceous series and constituted an outer shelf pre-foreland passive margin where salt tectonics occurred. From upper Cretaceous to Miocene, flexural subsidence and thrust wedge propagation took place as the result of the northward drift of Africa plate. The Souk Ahras foreland is finally deformed by thrust-related folds, which affected a pre shortening tectonic pile involving remnant of salt tectonics influenced margin during at least Cretaceous times. [ABSTRACT FROM AUTHOR]

Mesostructures in subhorizontal thinly bedded calcareous mudstones of the Permian Bell Canyon Formation in the western Delaware Basin (Guadalupe Mountains foothills, west Texas) include vertical tectonic stylolites kinematically linked with low-angle thrust faults. Schmidt rebound is high (38–70) for all but a few beds, indicating competent rock. Competent beds exhibit contrasting behavior ranging from (i) no visible tectonic stylolites and numerous small-displacement (<1 cm) thrust faults, to (ii) tectonic stylolites with rare thrust faults. Thrust fault intensity correlates positively with total carbonate, and negatively with clay, clay + quartz, quartz + feldspar, and total organic carbon (TOC). Tectonic stylolites are abundant in beds with 3.5–6.5% clay. Stylolite intensity correlates positively with TOC. Lowest-rebound beds exhibit ductile flowage or internal folding rather than stylolite formation, and tend to terminate small-displacement thrust faults in adjacent beds. Tectonic stylolites and thrust faults are consistent with formation in a thrust faulting stress regime during NE-directed Laramide shortening. Fluid inclusion analyses of vein calcite from thrust faults indicate maximum burial depths of 3.3–4.2 km at the time of deformation. Deformation behaviors are highly sensitive to composition, with coeval thrust faulting in clay-poor beds versus stylolite formation in slightly more clay-rich beds. • Mesostructures in calcareous mudstones in Permian Basin analyzed. • Thrust fault intensity increases with increasing total carbonate. • Thrust fault intensity decreases with clay, quartz, feldspar, and TOC. • Tectonic-stylolite dominated beds have 3.5–6.5% clay. • Stylolite intensity correlates positively with TOC. [ABSTRACT FROM AUTHOR]

The Bolivian Andes are an archetypal convergent margin orogen with a paired fold-thrust belt and foreland basin. Existing chronostratigraphic constraints highlight a discrepancy between unroofing of the Eastern Cordillera and Interandean Zone fold-thrust systems since 40 Ma and the onset of rapid sediment accumulation in the Subandean Chaco foreland after 11 Ma, previously attributed to Miocene climate shifts. New results from magnetostratigraphic, backstripping, erosional volumetric calculations, and flexural modeling efforts are integrated with existing structural and thermochronologic datasets to investigate the linkages between shortening, exhumation, and subsidence. Magnetostratigraphic and backstripping results determine tectonic subsidence in the Chaco foreland basin, which informs flexural models that evaluate topographic load and lithospheric parameters. These models show that Chaco foreland subsidence is consistent with a range of loading scenarios. Eroded volumes from the fold-thrust belt were sufficient to fill the Chaco foreland basin, further supporting the linkage between sediment source and sink. Erosional beveling of the Eastern Cordillera, local intermontane sediment accumulation after 30–25 Ma, and regional development of the high-elevation San Juan del Oro geomorphic surface from 25 to 10 Ma suggest that the western Eastern Cordillera did not store the large sediment volume expected from erosion of the fold-thrust belt, which arrived in the Subandean Zone after 11 Ma. Eocene to middle Miocene foreland basin accumulation was likely focused between the Eastern Cordillera and Interandean Zone, and has been almost completely recycled into the modern Subandean foreland basin. The delay between initial fold-thrust belt exhumation (early Cenozoic) and rapid Subandean subsidence (late Cenozoic) highlights the interplay between protracted shortening, underthrusting, and foreland basin recycling. Only with sufficient crustal shortening, accommodated by eastward advance of the fold-thrust belt and attendant underthrusting of Brazilian Shield lithosphere beneath the Subandes, did the Subandean zone enter proximal foreland basin deposystems after ca. 11 Ma. Prior to the late Miocene, the precursor flexural basin was situated westward and not wide enough to incorporate the distal Subandean Zone. These results highlight the interplay between a range of crustal and surface processes linked to tectonics and Miocene climate shifts on the evolution of the southern Bolivian Andes.

Documenting the spatio‐temporal progression of deformation within fold‐thrust belts is critical for understanding orogen dynamics. In the North American Cordillera, the geometry, magnitude, and timing of contractional deformation across a broad region of Nevada known as the "Sevier hinterland" has been difficult to characterize due to minimal exposures of syn‐contractional sedimentary rocks and overprinting of Cenozoic extension. To address this, we present geologic mapping and U‐Pb zircon geochronology from three exposures of the Cretaceous Newark Canyon Formation (NCF) in central Nevada. In the Cortez Mountains, NCF deposition between ∼119 and 110 Ma is hypothesized to be related to generation of relief by thrusting/folding to the west. In the Fish Creek Range, NCF deposition between ∼130 and 100 Ma was related to motion on an east‐vergent thrust fault. In the Pancake Range, NCF deposition is bracketed between ∼129 and 66 Ma and post‐dated east‐vergent folding. We incorporate these timing constraints into a compilation of deformation timing in the Sevier hinterland. Late Jurassic (∼165 and 155 Ma) shortening, which is largely post‐dated shortening in the Luning‐Fencemaker thrust belt to the west and pre‐dated initial deformation in the Sevier fold‐thrust belt to the east, is interpreted to represent diffuse, low‐magnitude deformation that accompanied eastward propagation of the basal Cordilleran décollement. Cretaceous (∼130 and 75 Ma) hinterland shortening, which includes deformation associated with NCF deposition, was contemporaneous with shortening in the Sevier fold‐thrust belt. This is interpreted to represent long‐duration strain partitioning between the foreland and hinterland during continued coupling above the basal décollement and the progressive westward underthrusting of thick North American lower‐middle crust. Key Points: Deposition of the 130 and 100 Ma Newark Canyon Formation was related to low‐magnitude shortening in the Sevier hinterlandLate Jurassic shortening in the Sevier hinterland coincided with eastward migration of the basal Sevier décollementBetween ∼130 and 75 Ma, shortening was partitioned between the Sevier fold‐thrust belt and the Sevier hinterland [ABSTRACT FROM AUTHOR]

The Sivas Basin overlaps the northern Neotethys suture zone in central Anatolia (Turkey) and contains a ca. 12-km thick succession of Cenozoic strata that provides an exceptional record of major tectonic transitions from subduction to continental assembly and tectonic escape. Consensus regarding the tectonic and palaeogeographic evolution of this segment of the Arabia-Eurasia collision zone has been hindered by uncertainty in the tectonic setting of the early (Palaeogene) Sivas Basin, which has been variably interpreted as a remnant ocean, forearc, foreland, wedge-top or intracontinental extensional basin. Here we integrate new geologic mapping (>5,000 km2), stratigraphy, facies analysis and U-Pb geochronology from the western Sivas Basin to produce a detailed time-stratigraphic framework and a refined Palaeogene tectono-sedimentary model for the Sivas Basin. Earliest marine sedimentation occurred during the Maastrichtian-Palaeocene in a remnant ocean setting due to incomplete closure of the northern Neotethys Ocean. Rapid accumulation of >2 km of basin floor turbidites during the middle to late Eocene reflect a transition to a foreland setting. A major late Eocene unconformity (ca. 38-34 Ma) coincides with the initiation of the north-vergent southern Sivas fold-thrust belt, which inverted and structurally partitioned the basin into a southern wedge-top and a northern evaporitic foreland basin; the entire basin was dominantly nonmarine after this unconformity. Published palaeomagnetic data integrated with a newly discovered tuff dated at 31.9 Ma reveal that the 2.8-km thick Altinyayla Formation was deposited from ca. 34 to 26 Ma in an unconfined braided fluvial system. Close stratigraphic correlations between the western, central and northern Sivas Basin suggest that the entire basin evolved from a remnant ocean to peripheral retro-foreland basin during the middle to late Eocene, and finally a fragmented foreland basin since the Oligocene. This general evolution may be a characteristic of such sedimentary basins formed on suture zones across Anatolia and in other collisional orogens globally. [ABSTRACT FROM AUTHOR]

The northwestern Sichuan Basin has experienced Meso-Cenozoic intracontinental compressional tectonic processes and formed multi-detachment stratigraphic distribution of foreland basins and fold-thrust belts, which have caused complicated structural deformations in the deep buried layers. Rapid uplift with accelerated erosion and two sets of detachments in the Lower Triassic and Lower Cambrian controlled the multilevel deformation structure. We conducted discrete numerical simulations with double weak detachments and erosion under extrusion conditions in order to examine the mechanics and kinematics of the frontalpiedmont zones of the NW Sichuan Basin. The following findings were made. (1) With continuous compression, the weak detachments promoted the decoupled and ladder-like deformation of the thrust belt, where the deformation above the slip layer extended further than it did below it. Rapid uplift and erosion at the thrust front contributed to the formation of a passive roof fault and a monocline in the upper layer, a series of forward and backward thin-skinned thrust-buried structures in the middle layer sandwiched between two weak detachments and stacking structures in the lower layer. (2) Erosion effectively prevents the deformation from propagating above the upper detachment, but can advance a horizontal transition in the deformation style generated within the middle brittle layer: from oblique and tight fault propagation folds to symmetrical, wide, and gentle detachment folds. (3) The model results consistent with tectonic deformation in the NW Sichuan Basin indicate a possible evolutionary mechanism under compression. There is hierarchical deformation of uncoordinated contraction controlled by the Lower Triassic and Early Cambrian weak layers, with the characteristics of the shallow monocline, the middle thin-skinned thrusts, and the deeper basement-involved folds. Continuous compression contributed a sequential pattern of steps as a whole, from the frontalpiedmont zones to the foreland basin, autochthonous stacking thrusts, and the huge buried structure in the NW Sichuan Basin. During the Himalayan period, syntectonic erosion along with the uplifted thrust front maintained the development of a passive-roof duplex and a huge forward buried structure.

Apatite (U‐Th)/He (AHe) thermochronometric results are integrated with geologic cross sections, structural relationships, and stratigraphic data to reconstruct the growth of the NW Zagros orogenic belt in the Kurdistan region of Iraq. Prolonged exhumation is documented across the belt with deformation advances and retreats from ~14 Ma onward. After in‐sequence propagation of deformation during middle to late Miocene times, preserved growth strata and AHe data show a deformation retreat by latest Miocene time (~5 Ma). In the NW Zagros, the Phanerozoic succession contains two principal décollements in Lower Triassic and middle Miocene units. The Triassic strata are interpreted as the main décollement for a thin‐skinned system that was dominant during most of the Cenozoic. By ~8–5 Ma, the fold‐thrust belt shifted to basement‐involved deformation in association with growth of the mountain front flexure and reactivation of frontal structures. The shift from thin‐skinned to a hybrid thin‐ and thick‐skinned mode of shortening may reflect variations in the mechanical behavior of the upper crust and the presence of inherited basement discontinuities. On the basis of two NE‐SW balanced cross sections spanning the NW Zagros, the estimated total minimum horizontal shortening is ~18.2 km (6%) in the central and ~16 km (7%) in the southern sectors of the Kurdistan region of Iraq. These findings suggest that the evolution of the NW Zagros orogenic belt was likely driven by the mechanical stratigraphy of the sedimentary cover, inherited basement discontinuities, and the dynamic and thermomechanical effects of potential slab breakoff and lithospheric mantle delamination events. Key Points: Apatite (U‐Th)/He thermochronometric data, growth strata, and balanced cross sections reveal chronology of deformation in the NW Zagros beltForward modeled cross sections elucidate shift of tectonic style from thin‐skinned to hybrid thin‐ and thick‐skinned system during ~8–5 MaNW Zagros orogenic growth is tied to mechanical stratigraphy, inherited basement discontinuities, and effects of deep Earth geodynamics [ABSTRACT FROM AUTHOR]

The Bangong–Nujiang Suture Zone (BNSZ), located in the central Tibetan Plateau, experienced a Late Mesozoic transition from oceanic closure to continent–continent collision. Based on sandstone-composition analyses, U-Pb detrital-zircon dating and structural observations, we determined that this transition occurred coeval with the accretion of the Lhasa Terrane to Eurasia. According to our newly observed stratigraphic and geochronological data, we conclude the following: (1) the Upper Triassic-Lower Jurassic Muggar Gangri Group was mainly derived from the Qiangtang Terrane; (2) the Shamuluo Formation composed of Upper Jurassic-Lower Cretaceous shallow marine strata was sourced from both the Qiangtang Terrane and recycled Muggar Gangri Group; (3) the Lower Cretaceous (~125–110 Ma) Duoni Formation shows both Lhasa and Qiangtang detrital zircon fingerprints, indicating closure of the Bangong–Nujiang Ocean at ~120 Ma; and (4) the Upper Cretaceous Abushan Formation is a suite of intramontane molasse deposited after the Qiangtang–Lhasa collision. Therefore, these sedimentary strata record the transition from oceanic closure to continent–continent collision from 125 to 90 Ma within the central BNSZ. Moreover, based on relationships among strata distributions and thrust locations, we propose that thrust movements propagated southward during this transition and controlled sedimentary basin deposition. The Late Mesozoic tectonic transition within the BNSZ occurred well before the India-Asia collision and hence profoundly influenced the Cenozoic formation of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

In the northwestern sector of the Zagros foreland basin, axial fluvial systems initially delivered fine‐grained sediments from northwestern source regions into a contiguous basin, and later transverse fluvial systems delivered coarse‐grained sediments from northeastern sources into a structurally partitioned basin by fold‐thrust deformation. Here we integrate sedimentologic, stratigraphic, palaeomagnetic and geochronologic data from the northwestern Zagros foreland basin to define the Neogene history of deposition and sediment routing in response to progressive advance of the Zagros fold‐thrust belt. This study constrains the depositional environments, timing of deposition and provenance of nonmarine clastic deposits of the Injana (Upper Fars), Mukdadiya (Lower Bakhtiari) and Bai‐Hasan (Upper Bakhtiari) Formations in the Kurdistan region of Iraq. Sediments of the Injana Formation (~12.4–7.75 Ma) were transported axially (orogen‐parallel) from northwest to southeast by meandering and low‐sinuosity channel belt system. In contrast, during deposition of the Mukdadiya Formation (~7.75–5 Ma), sediments were delivered transversely (orogen‐perpendicular) from northeast to southwest by braided and low‐sinuosity channel belt system in distributive fluvial megafans. By ~5 Ma, the northwestern Zagros foreland basin became partitioned by growth of the Mountain Front Flexure and considerable gravel was introduced in localized alluvial fans derived from growing topographic highs. Foredeep accumulation rates during deposition of the Injana, Mukdadiya and Bai‐Hasan Formations averaged 350, 400 and 600 m/Myr respectively, suggesting accelerated accommodation generation in a rapidly subsiding basin governed by flexural subsidence. Detrital zircon U‐Pb age spectra show that in addition to sources of Mesozoic‐Cenozoic cover strata, the Injana Formation was derived chiefly from Palaeozoic‐Precambrian (including Carboniferous and latest Neoproterozoic) strata in an axial position to the northwest, likely from the Bitlis‐Puturge Massif and broader Eastern Anatolia. In contrast, the Mukdadiya and Bai‐Hasan Formations yield distinctive Palaeogene U‐Pb age peaks, particularly in the southeastern sector of the study region, consistent with transverse delivery from the arc‐related terranes of the Walash and Naopurdan volcano‐sedimentary groups (Gaveh‐Rud domain?) and Urumieh‐Dokhtar magmatic arc to the northeast. These temporal and spatial variations in stratigraphic framework, depositional environments, sediment routing and compositional provenance reveal a major drainage reorganization during Neogene shortening in the Zagros fold‐thrust belt. Whereas axial fluvial systems initially dominated the foreland basin during early orogenesis in the Kurdistan region of Iraq, transverse fluvial systems were subsequently established and delivered major sediment volumes to the foreland as a consequence of the abrupt deformation advance and associated topographic growth in the Zagros. [ABSTRACT FROM AUTHOR]

The eastern Sichuan-western Hunan and Hubei belt (ESWHHB) is an important fold-thrust belt in the Middle-Upper Yangtze region of China, and it is also an important area for petroleum and gas prospect in China. The influence of mechanical stratigraphy on the deformation evolution of the ESWHHB is a hot problem that has received widespread attention. However, due to the complexity of geological conditions, this issue has not been sufficiently addressed. Previews geological exploration studies show that the deformation evolution of the belt is closely related to the mechanical stratigraphy. Physical simulation has proven to be effective for studying the deformation evolution of fold-and-thrust belt. Based on the geological conditions of the ESWHHB, six groups of physical models were designed to analyze the influences of the ductile layer and overlap configuration on the structural deformation of the ESWHHB. The results show that the mechanical stratigraphy has significant control on the deformation evolution of the fold-thrust belt. The ESWHHB evolution is related to the lower viscosity of the ductile layer and the larger thickness of the ductile layer, while only gradual propagated fold-and-thrust belt can be resulted from the higher viscosity of the ductile layer and the smaller thickness of the ductile layer. Additionally, the overlap between the stratigraphy at various structural belts leads to significant differences in their mechanical properties, and it critically influences the structural patterns of the ESWHHB. [ABSTRACT FROM AUTHOR]

A source‐to‐sink analysis incorporating geochronometric and thermochronometric data from the Sevier fold‐thrust belt (SFTB) and proximal synorogenic strata of the Canyon Range Conglomerate (CRC) and Indianola Group (IG) provides new insights into orogenic exhumation, erosional unroofing, and the interplay between thrusting and coarse clastic deposition in the Cretaceous Cordilleran foreland basin of western North America. Zircon (U‐Th)/He ages from the Pavant and Nebo thrust sheets record significant Cenomanian cooling indicative of synchronous exhumation and thrusting along a large segment of the SFTB in central and northern Utah. Detrital zircon (U‐Th)/He (DZHe) ages indistinguishable from depositional ages from the Cenomanian Dakota Formation and lower CRC also record rapid unroofing of the SFTB and synchronous deposition. DZHe data from wedge‐top deposits of the CRC record two significant unroofing episodes: Albo‐Cenomanian exhumation of the Pavant thrust and progressive unroofing of the Canyon Range culmination. For the IG, the presence of Paleozoic DZHe ages along with Paleozoic‐Mesozoic DZ U‐Pb ages in the Cenomanian Sanpete Formation suggests derivation from Paleozoic to Jurassic strata exhumed in the frontal Pavant and Nebo thrust sheets. After the Cenomanian episode of rapid exhumation, proximal foredeep strata recorded a widespread DZ provenance shift in the Turonian. Short DZHe lag time values from Campanian CRC and IG deposits reveal rapid exhumation of the SFTB during the Campanian. The synchroneity of major shortening and Campanian and Cenomanian changes in foreland basin architecture and provenance supports models proposing that active shortening in the fold‐thrust belt coincides with coarse clastic influx in foreland basins. Key Points: ZHe ages from the Canyon Range and southern Provo salient constrain major exhumation of both the Pavant and Nebo Thrusts to ~102–96 MaShort lag time ZHe ages in the Cow Canyon Member and Dakota Formation link active thrust belt deformation to major sediment dispersionDZ U‐Pb and DZHe maximum depositional ages in the proximal foreland basin help confirm litho‐ and bio‐stratigraphic correlations [ABSTRACT FROM AUTHOR]

Along the northern margin of the Arabia‐Eurasia collision zone in the western Greater Caucasus, the Main Caucasus Thrust (MCT) juxtaposes Paleozoic crystalline basement to the north against Mesozoic metasedimentary and volcaniclastic rocks to the south. The MCT is commonly assumed to be the trace of an active plate‐boundary scale structure that accommodates Arabia‐Eurasia convergence, but field data supporting this interpretation are equivocal. Here we investigate the deformation history of the rocks juxtaposed across the MCT in Georgia using field observations, microstructural analysis, U‐Pb and 40Ar/39Ar geochronology, and 40Ar/39Ar and (U‐Th)/He thermochronology. Zircon U‐Pb analyses show that Greater Caucasus crystalline rocks formed in the Early Paleozoic on the margin of Gondwana. Low‐pressure/temperature amphibolite‐facies metamorphism of these metasedimentary rocks and associated plutonism likely took place during Carboniferous accretion onto the Laurussian margin, as indicated by igneous and metamorphic zircon U‐Pb ages of ~330–310 Ma. 40Ar/39Ar ages of ~190–135 Ma from muscovite in a greenschist‐facies shear zone indicate that the MCT likely developed during Mesozoic inversion and/or rifting of the Caucasus Basin. A Mesozoic 40Ar/39Ar biotite age with release spectra indicating partial resetting and Cenozoic (<40 Ma) apatite and zircon (U‐Th)/He ages imply at least ~5–8 km of Greater Caucasus basement exhumation since ~10 Ma in response to Arabia‐Eurasia collision. Cenozoic reactivation of the MCT may have accommodated a fraction of this exhumation. However, Cenozoic zircon (U‐Th)/He ages in both the hanging wall and footwall of the MCT require partitioning a substantial component of this deformation onto structures to the south. Plain Language Summary: Collisions between continents cause deformation of the Earth's crust and the uplift of large mountain ranges like the Himalayas. Large faults often form to accommodate this deformation and may help bring rocks once buried at great depths up to the surface of the Earth. The Greater Caucasus Mountains form the northernmost part of a zone of deformation due to the ongoing collision between the Arabian and Eurasian continents. The Main Caucasus Thrust (MCT) is a fault juxtaposing old igneous and metamorphic (crystalline) rocks against younger rocks that has often been assumed to be a major means of accommodating Arabia‐Eurasia collision. This study examines the history of rocks along the MCT with a combination of field work, study of microscopic deformation in rocks, and dating of rock formation and cooling. The crystalline rocks were added to the margins of present‐day Eurasia about 330–310 million years ago, and the MCT first formed about 190–135 million years ago. The MCT is likely at most one of many structures accommodating present‐day Arabia‐Eurasia collision. Key Points: Amphibolite‐facies metamorphism and plutonism in the Greater Caucasus basement took place ~330–310 MaThe Main Caucasus Thrust formed as a greenschist‐facies shear zone during Caucasus Basin inversion and/or rifting (~190–135 Ma)The Main Caucasus Thrust may have helped facilitate a portion of at least 5–8 km of basement exhumation during Arabia‐Eurasia collision [ABSTRACT FROM AUTHOR]

The southern Central Andes recorded retroarc shortening, basin evolution, and magmatic arc migration during Neogene changes in subduction. At 31–33°S, above the modern flat‐slab segment, spatial and temporal linkages between thin‐ and thick‐skinned foreland shortening, basement‐involved exhumation of the main Cordillera, and lower‐crustal hinterland thickening remain poorly resolved. We integrate new geochronological and thermochronological data for thrust sheets and Neogene foreland basin fill with structural, sedimentological, and passive seismic results to reconstruct the exhumation history and evaluate potential geometric linkages across structural domains. 40Ar/39Ar ages for volcanic horizons and zircon U‐Pb ages for synorogenic clastic deposits in the Manantiales Basin constrain the minimum duration of synorogenic sedimentation to ~22–14 Ma. Detrital zircon age distributions record sequential unroofing of hinterland thrust sheets until ~15 Ma, followed by eastward (cratonward) advance of the deformation front, shutoff of western sediment sources, and a shift from fluvial to alluvial fan deposition at ~14 Ma. Apatite (U‐Th)/He cooling ages confirm rapid exhumation of basement‐involved structural blocks and basin partitioning by ~14–5 Ma, consistent with the timing of the Manantiales facies and provenance shifts and a coeval (~12–9 Ma) pulse of thin‐skinned shortening and exhumation previously identified in the eastern foreland. Late Miocene–Pliocene (~8–2 Ma) cooling ages along the Chile‐Argentina border point to hinterland uplift during the latest stage of Andean orogenesis. Finally, geophysical constraints on crustal architecture and low‐temperature thermochronometry results are compatible with a hybrid thin‐ and thick‐skinned décollement spanning retroarc domains. Key Points: 40Ar/39Ar and zircon U‐Pb ages constrain the minimum duration of synorogenic accumulation in the Neogene Manantiales Basin to ~22–14 MaForeland basin strata record sequential unroofing of hinterland thrust sheets, then regionally synchronous shortening by ~14–12 MaGeo/thermochronological data and thermo‐kinematic models are compatible with hybrid thin‐ and thick‐skinned retroarc deformation [ABSTRACT FROM AUTHOR]

This paper focuses on the analysis of the Southern Patagonian fold-thrust belt at ca. 50° SL, employing a kinematic-structural approach that makes it possible to define its step-by-step structural evolution. Seismic interpretation is combined with outcrop structural data to provide the basis for an integrated evolutionary model including a Jurassic extensional stage, followed by contraction events since the Late Cretaceous. Our interpretation and results reveal a hybrid fold-thrust belt system, with a high decoupling between basement structures and the sedimentary cover. The basement is deformed by tectonic inversion of the Jurassic rift fault system and duplex stacking geometries, while the sedimentary cover is folded by the action of predominantly west-vergent low-angle faults. The Jurassic rifting model identifies listric faults with detachment depths ranging from −6000 to −6500 m.a.s.l. and 11 %–14 % magnitude extension. Shortening calculations yield values of less than 6 %. Growth strata and thickness variations in Cretaceous units suggest that part of the shortening occurred during the Coniacian/Santonian. Overall, this research contributes to the knowledge of fold-thrust belts, highlighting the importance of doing a comprehensive structural modeling including previous deformational stages, and describing steps to provide reliable measurements of deformation. • Kinematic-structural modeling of the Southern Patagonian Andes. • Inversion tectonics mechanisms in fold-thrust belts. • Estimation of crustal shortening and extension, comparison of methodologies. • Detachment depths determination. [ABSTRACT FROM AUTHOR]

Fault vergence in fold-and-thrust belts and accretionary prisms is characterized by mainly forward verging thrusts and pop-up structures, and only few examples exist where backthrusting dominates. However, backthrusting and triangle zones are known from most if not all fold-thrust belts in the world. The circumstances under which backthrusts instead of forethrusts form are still incompletely understood. Previous studies suggest that the strength and dip of the basal décollement of Coulomb wedges plays a key role. However, a systematic study of these parameters is still missing. In this study we model numerically the formation of brittle-ductile wedges, systematically, varying dip and strength of the basal décollement. To characterize wedges, we use cumulative vorticity as a measure of dominant fault vergence within the entire wedge. We find that backthrust-dominated wedges form in setups of very low basal dip (≤ 0.5°) and a weak décollement. Increasing décollement strength or basal dip results in the formation of pop-up-dominated wedges, before forethrust dominated wedges form. While our models corroborate the idea that thrust vergence and basal dip may control thrust vergence, comparison with natural examples indicates this cannot be the only explanation for the formation of backthrusts. Consequently, additional factors such as syntectonic sedimentation or changes of décollement rheology across strike may be required to explain backthrusting in fold-thrust belts. [Display omitted] • We propose to use cumulative vorticity as a parameter to characterize geometries of fold-thrust belts. • Using this parameter, we distinguish three types of fold-thrust belts, backthrust, pop-up, and forethrust dominated. • Backthrusts form systematically in wedges with very weak décollements and shallow décollement dips. [ABSTRACT FROM AUTHOR]

[Display omitted] • Changdong is a typical paleokarst-hosted Zn–Pb deposit in the "Sanjiang" fold- thrust belt. • Bulk Pb isotopic ratios for galena were homogenous and indicated potential metal sources. These sources include Triassic to Early Jurassic volcanic rocks at the western margin of the Simao Basin, Cenozoic intrusive rocks at the eastern margin, and Jurassic clastic rocks. • The spatial distribution of the in situ Pb isotopic ratios, combined with the spatial relationship between the faults and ore bodies, suggest that the tensile faults acted as vertical pathways for the fluid. The galena grains displayed oscillatory zones of As and Sb elements, indicating that alternating ore-forming fluids with varying chemical compositions entered the local reservoir. The metal sources and fluid pathways for Mississippi Valley-type (MVT) Zn–Pb deposits in fold-thrust belts remain open topics of debate. To develop a more comprehensive understanding of these issues, this study presents the sulfide morphology, S and Pb isotopes, and trace element data of the paleokarst-hosted Changdong MVT Zn–Pb deposit in the "Sanjiang" fold-thrust belt. Bulk Pb isotopic ratios for galena were homogenous and indicated potential metal sources. These sources include Triassic to Early Jurassic volcanic rocks at the western margin of the Simao Basin, Cenozoic intrusive rocks at the eastern margin, and Jurassic clastic rocks. The spatial distribution of the in situ Pb isotopic ratios, combined with the spatial relationship between the faults and ore bodies, suggest that the tensile faults acted as vertical pathways for the fluid. The galena grains displayed oscillatory zones of As and Sb elements, indicating that alternating ore-forming fluids with varying chemical compositions entered the local reservoir. The δ 34S V-CDT values of sulfides in substage I range from −19.3 to 29.6 ‰, and in substage II, they range from −21.2 to 52.6 ‰. The high fractionation degree (approximately 38.9 ‰) and the presence of microspherulitic morphology suggest that the reduced sulfur originated from a bacterial sulfate reduction. A GGIMFis geothermometer revealed that the precipitation temperatures of substage I sphalerite ranged from 56.68 to 211.58 °C and were higher than substage II. This indicated that the mixing of Zn–Pb-bearing fluid with reduced sulfur was the main controlling factor for sphalerite precipitation, and the temperature decrease represented another important factor. In the fold-thrust system, the complete process of Zn–Pb mineralization was established as follows: the fluid extracted metals from regional rocks and then migrated laterally over long distances. During the regional transition from compression to extension, metal-bearing fluid was injected into the deposit along the normal faults through seismic pumping. The fluid was then mixed with reduced sulfur to precipitate Zn–Pb sulfides. This study provides new insights into the metal sources and fluid pathways of MVT Zn–Pb deposits developed in a fold-thrust belt. [ABSTRACT FROM AUTHOR]

• Middle Cambrian is the oldest and the most accurate time for initiation of salt diaprisim in Zagros. • Extensional basement faults act as major factors for primary movement of salt into salt walls. • Precursor salt walls led to development of main structural trends in Zagros. • Squeezing of the salt walls stems during the Zagros orogeny turn welded salt walls to thrust welds. In salt-bearing foreland fold-thrust belts, precursor salt structures affect deformation and accommodate fault zones during orogenic shortening. The complex structure and the halokinetic history of these belts, including the spatiotemporal relationship between diapirism and thrust faulting, have yet to be fully understood. The well-exposed Ediacaran–Early Cambrian Hormuz salt diapirs and the Cambrian–Pliocene overburden stratigraphic sequences along the High Zagros Fault (HZF) in Iran are interesting examples in this regard. The detailed field investigation of the diapirs, the halokinetic deformations, and the thickness variations of the sedimentary units toward the flanks of eight salt structures along the fault show that the first movement of the Hormuz salt could be as old as the Middle Cambrian, occurring long before the initiation of regional folding in the early Miocene. This marks the first field-based and the oldest proposed time for the onset of Hormuz salt diapirism in the Zagros fold-thrust belt. Our field and remote-sensing mapping show the presence of precursor linear salt structures like salt walls. The Hormuz salt diapirs likely began to rise as elongated salt walls above extensional basement faults coeval with the Neo-Tethyan rifting in Early Mesozoic. The squeezing of the salt walls during Zagros shortening from Miocene resulted in the partial accommodation of the HZF as thrust welds. This spatiotemporal evolution, showing the interplay between salt diapirism and late thrusting, can be considered as an analog for other fold-and-thrust belts with pre-orogenic diapiric systems. [ABSTRACT FROM AUTHOR]

The architecture, kinematics, and timing of fold-and-thrust belt development provide essential first-order constraints on the structural evolution of continental collision zones. The southern Sivas fold-thrust belt (SSFTB) is a ~300 × 50-km-long, ENE-trending contractional belt located in the Sivas Basin at the western end of the Arabia-Eurasia collision zone, and along the İzmir- Ankara-Erzincan and Inner Tauride suture zones. We present new geologic mapping and the first detailed structural characterization and seismotectonic evidence of active deformation along the western and central segments of the SSFTB that provide new insights into the timing and kinematics of deformation associated with collision and escape in Central Anatolia. The SSFTB is a dominantly north-vergent contractional belt that initiated during the late Eocene and experienced several punctuated episodes of shortening and exhumation, primarily during the late Oligocene and late Miocene. Structural mapping and balanced cross-sections reveal that minimum cumulative shortening increases from west (29%) to east (34%) along the belt, along with a gradual eastward increase in fold asymmetry and a progressive transition from fold-related to overturned fold-and-thrust-related shortening. The kinematics of the central and eastern SSFTB changed from north-vergent thrusting during the late Eocene and Oligocene to predominantly south-vergent during the Miocene. Contraction in the SSFTB ended by ~7–6 Ma and was followed by a switch to distributed and kinematically linked sinistral strike-slip and normal faulting along the northeastern segment of the Central Anatolian fault zone. Offset strain markers suggest a total of at least 1.7–2.4 km of left-lateral slip on the Deliler fault and ~940 m of normal slip on the Hınzır fault. The latest Miocene to Pliocene switch to intraplate strike-slip deformation marks a regional transition to westward tectonic escape of the Anatolian microplate. [ABSTRACT FROM AUTHOR]

The kinematic and exhumational evolution of the Lesser Himalaya (LH) remains a topic of debate. In NW India, the stratigraphically diverse LH is separated into the inner LH (iLH) of late Paleo‐Mesoproterozoic rocks and the outer LH (oLH) of Cryogenian to Cambrian rocks. Contradictory models regarding the age and structural affinity of the Tons thrust—a prominent structure bounding the oLH and iLH—are grounded in conflicting positions of the oLH prior to Himalayan orogenesis. This study presents new zircon (U‐Th)/He and U‐Pb ages from the thrust belt and foreland basin of NW India that refine the kinematic and exhumational evolution of the LH. Combined cooling ages and foreland provenance data support emplacement and unroofing of the oLH via southward in‐sequence propagation of the Tons thrust by middle Miocene time. This requires that, before India–Asia collision, the oLH was positioned as the southernmost succession of Neoproterozoic–Cambrian strata along the north Indian margin. This is further supported by detrital zircon U‐Pb ages from Cretaceous–Paleogene strata (Singtali Formation) unconformably overlying the oLH, which yield diagnostic Cretaceous detrital zircons correlative with coeval strata in the frontal Himalaya of Nepal. A pulse of rapid exhumation along the Tons thrust front at ~16 Ma was followed by east‐to‐west development of a midcrustal ramp at ~12 Ma which facilitated diachronous iLH duplexing. This duplexing shifted the locus of maximum exhumation northward, eroding away Main Central Thrust hanging wall rocks until the iLH breached the surface at ~9–11 Ma near Nepal and by ~3–7 Ma within the Kullu‐Rampur window. Key Points: Zircon (U‐Th)/He ages reveal focused exhumation of outer Lesser Himalayan rocks at ~16–17 Ma along the Tons‐Berinag frontal thrust rampLesser Himalayan duplexing along a midcrustal ramp initiated by 11 Ma and propagated westward to its terminus near the Kullu‐Rampur windowDuplexing shifted focused exhumation northward, removing MCT hanging wall rocks until diachronous unroofing of the inner Lesser Himalaya [ABSTRACT FROM AUTHOR]

Abstract Hydrogen isotopic composition (δ D) and 40Ar/39Ar geochronological data of neomineralized clay minerals from fault rocks and cleavage seams in the Sevier belt record primary involvement of surface-sourced fluids during Cretaceous–Paleogene mountain building events. δ D values of authigenic clays range from − 78.8 ± 1.7 ‰ to − 97.2 ± 3.2 ‰. Given temperature constraints of mineral formation, we calculate δ D values of mineralizing fluids as ∼−63 to −96‰, which fall within the range of δ D values of Cretaceous–Paleogene surface waters in the region. The potential infiltration and presence of surface fluids at depths of several kilometers during deformation implies that pore spaces and fractures acted as conduits for surface water. Uplift of thrust sheets generated topography that favored meteoric recharge and flow of fluids into margins of the foreland basin, which were subsequently incorporated into the propagating thrust wedge. This is in contrast to the hypothesis that the release of overpressured metamorphic fluids dominates during fold–thrust belt evolution. As a result of shortening and tectonic uplift, fluid flows through basin sediments toward the foreland basin as meteoric waters recharge sediments at the basin margins. This study shows that stable isotopic compositions of shallow, deformation-related clay minerals are robust and may be used alongside other surface fluid proxies to probe the origin and composition of ancient fluids in orogenic systems. Highlights • Paired isotopic studies of clays reveal timing and source of fluids in deformation. • H-isotopes are directly comparable to O-isotope proxies for surface fluids. • Ancient fluids in the Sevier belt indicate a low-elevation precipitation source. [ABSTRACT FROM AUTHOR]

The northwestern Sichuan region has experienced multi-stage tectonic evolution including marine cratonic basin from the Sinian to the Middle Triassic and intra-continental basin from the Late Triassic to the Cenozoic. Several regional tectonic activities caused complicated stratigraphic distribution and structural deformations in the deep-buried layers. During the key tectonic periods, some characteristic sedimentary and deformation structures were formed, including the step-shaped marginal carbonate platform of Dengying Formation, the western paleo-high at the end of Silurian, and the passive continental margin of the Late Paleozoic–Middle Triassic. The Meso-Cenozoic intra-continental compressional tectonic processes since the Late Triassic controlled the formation of complex thrusting structures surrounding and inside the northwestern basin. The northern Longmenshan fold-thrust belt has a footwall in-situ thrust structure, which is controlled by two sets of detachments in the Lower Triassic and Lower Cambrian and presents as a multi-level deformation structure with the shallow folds, the middle thin-skin thrusts and the deeper basement-involved folds. The thrust belt in front of the Micangshan Mountain shows a double-layer deformation controlled by the Lower Triassic salt detachment, which is composed by the upper monocline and deep-buried imbricate thrust structures. The interior of the basin is characterized by several rows of large-scale basement-involved folds with NEE strike direction. From the perspective of structural geology, the favorable exploration reservoirs and belts in northwestern Sichuan have obvious zoning characteristics. The favorable exploration layers of Dengying Formation of Upper Sinian are mainly distributed in the eastern and northern areas of the northwestern Sichuan Basin, in which the Jiulongshan structural belt, Zitong syncline and Yanting slope are the most favorable. The Lower Paleozoic was transformed by Caledonian paleo-uplift and late Cenozoic folding, and the midwest area such as the Zitong syncline is a potential area for hydrocarbon exploration. The favorable part of the Upper Paleozoic is mainly distributed in the northern Longmenshan belt and its frontal area, where the deep-buried thin-skin thrust structures in the footwall are the key exploration targets. [ABSTRACT FROM AUTHOR]

Abstract The extended northern continental margin of Africa is currently colliding with and under-thrusting northward below Cyprus. The age of onset of this collision is poorly constrained, but is critical if we are to quantify continental subduction and evaluate its role during spectacular recent uplift of southern Turkey from ~7 Ma to the present. Here, we reevaluate the evolution of northern Cyprus and document the modern structure of the Kyrenia fold-thrust belt in a balanced cross section for the first time, to determine the timing and amount of shortening. The belt deformed an Upper Cretaceous to Miocene stratigraphy, which was deposited onto a metamorphic basement. The fold-thrust belt was previously proposed to have formed during two stages: in Eocene and late Miocene time, based on stratigraphic and limited structural evidence. We revaluate evidence for an Eocene phase of thrusting in Kyrenia and find that 1) repetitions of Eocene and older rocks are explained by Miocene thrusting, and newly documented olistoliths were misinterpreted as pre-Miocene thrust slices 2) uplift in Eocene time was not isolated to Kyrenia but also affected northern Arabia and results from regional dynamic topography or forebulge formation. Based on kinematic constraints from a plate reconstruction, we interpret that metamorphic rocks in Kyrenia were metamorphosed by Cretaceous burial below the Troodos ophiolite and were subsequently exhumed by upper plate extension during latest Cretaceous obduction onto the African margin. The latest Cretaceous-Miocene plate boundary between Africa and the Taurides was located to the north of Kyrenia. The Kyrenia fold-thrust belt accommodated a minimum of 17.5 km of shortening as a result of ~9–6 Ma thrusting as a result of initial Africa-Taurides collision. The northern edge of African continental crust arrived below the Taurides, where it has been seismologically imaged, in late Pleistocene time and may have caused or contributed to recently recognised major Tauride uplift since ~0.5 Ma. Graphical abstract Unlabelled Image Highlights • 17.5 km crustal shortening in N. Cyprus recorded 9–6 Ma Africa-Tauride collision. • Kyrenia part of Africa from Late Cretaceous Troodos obduction until collision • Under-thrusting of Africa margin a viable cause of 0.5 Ma uplift in south Anatolia [ABSTRACT FROM AUTHOR]

Abstract The structural evolution of the Keping fold-thrust belt in the South Chinese Tian Shan, NW China is poorly understood. Here, we present the results of a series of scaled sandbox models based on the structural architecture of the Keping fold-thrust belt in our investigation of the effect of overburden thickness on deformation mechanisms in fold-thrust belts. These models simulated the evolution of the Keping fold-thrust belt, where the western segment was shortened with a thicker overburden relative to the eastern segment. Model results confirm that fewer thrust faults with wider spacing develop in thicker cover units, whereas more thrust faults with narrower spacing develop in thinner cover units. Transfer zones also form as a result of faster and farther propagation in a segment with thicker overburden, consistent with the prediction of the critical taper theory. Our modeling further shows that due to the episodic accretion of thrust wedges and non-simultaneous formation of thrust faults, the deformation front may locally propagate farther in the thinner overburden. Alternatively, there may not be so much difference between two parts of sand layers with different thicknesses, an observation that is inconsistent with the theoretical prediction. The similarities between the model and real geological observations suggest that the variations in the overburden thicknesses across the Piqiang Fault transfer zone strongly influenced the development of the structural architecture of the Keping fold-thrust belt. They further indicate that the growth of fold-thrust belts in nature is episodic, and that the propagation of deformation front cannot be simply predicted by the critical taper theory. The overburden thickness variations across the Piqiang Fault transfer zone were produced by high angle reverse faulting along the pre-existing Piqiang-Selibuya Fault during the late Pliocene and associated crustal uplift and erosion of the hanging wall strata. Highlights • The width of a fold-thrust belt and the spacing of its thrusts are controlled by overburden thickness. • Thicker cover units generate fewer thrust faults with wider spacing. • Development of thrust wedges is episodic and formation of thrust faults in a fold-thrust belt is non-simultaneous. • Thickness variations in overburden cause variations in deformation in different segments of a fold-thrust belt. • Propagation of deformation front cannot be simply predicted by the critical taper theory. [ABSTRACT FROM AUTHOR]

Abstract This paper reviews the geology of the Late Ordovician - Silurian Caledonian Moine Thrust zone in the Loch Eriboll region, NW Scotland. We present new detailed mapping and balanced/restored cross-sections to examine its structural evolution. This thrust zone comprises four major thrust slices, carried by the Moine, Lochan Riabhach, Arnaboll and Sole thrusts. Ductile mylonites were derived from lithologies in both the hangingwall (Moine schists) and the footwall (Lewisian basement gneisses, Cambrian quartzites, Ordovician dolomites) of the Moine Thrust. The mylonites are bounded by the Lochan Riabhach thrust below and the Moine thrust above. The Arnaboll thrust sheet comprises Lewisian basement gneisses and Cambrian-Ordovician sedimentary rocks over the Sole Thrust sheet, which exposes a spectacular imbricate sequence of Cambrian-Ordovician sedimentary rocks. Although thrusts sequentially propagated in-sequence from higher (Moine) to lower (Sole) thrusts with time, there is evidence for minor out-of-sequence thrusting and breakback thrusting. Thrusts evolve from deep ductile shears where strain is concentrated along mylonite zones up into the brittle field where they become discrete planar thrust faults. The Early Silurian Scandian metamorphism (~435–415 Ma) is related to a Himalayan style structure with SSE-directed subduction and WNW directed extrusion of a migmatitic core, which we liken to channel flow. We suggest that two major crustal-scale thrusts that extend down into the upper mantle imaged on seismic profiles across the foreland, the Outer Isles and Flannan thrusts, are unrelated spatially or temporally to the Moine thrust sequence. Highlights • We present new detailed mapping, together with cross-, lateral-, and restored-sections from the northern Moine Thrust zone • Restoration shows that the intensely deformed Sole Thrust Sheet experienced c. 60% shortening at Loch Eriboll • We place this mapping in its regional context and review the structural evolution of the northern Moine Thrust Zone • We review orogen wide data from the Moine Thrust hinterland and compare with Himalayan tectonic architecture [ABSTRACT FROM AUTHOR]

Abstract The southern Central Andes of Argentina and Chile (27–40°S) are the product of deformation, arc magmatism, and basin evolution above a long-lived subduction system. With sufficient timing and provenance constraints, Andean stratigraphic and structural records enable delineation of Mesozoic-Cenozoic variations in subsidence and tectonic regime. For the La Ramada Basin in the High Andes at ∼31–33°S, new assessments of provenance and depositional age provided by detrital zircon U-Pb geochronology help resolve deformational patterns and subsidence mechanisms over the past ∼200 Myr. Marine and nonmarine clastic deposits recorded the unroofing of basin margins and sediment contributions from the Andean magmatic arc during Late Triassic to Early Cretaceous extension, thermal subsidence, and possible slab rollback. Subsequent sediment delivery from the Coastal Cordillera corresponded with initial flexural accommodation in the La Ramada Basin during Andean shortening of late Early Cretaceous to Late Cretaceous age. The architecture of the foreland basin was influenced by the distribution of precursor extensional depocenters, suggesting that inherited basin geometries provided important controls on later flexural subsidence and basin evolution. Following latest Cretaceous to early Paleogene tectonic quiescence and a depositional hiatus, newly dated deposits in the western La Ramada Basin provide evidence for a late Paleogene episode of intra-arc and proximal retroarc extension (development of the Abanico Basin, principally in Chile, at ∼28–44°S). Inversion of this late Paleogene extensional basin system during Neogene compression indicates the southern Central Andes were produced by at least two punctuated episodes of shortening and uplift of Late Cretaceous and Neogene age. Highlights • Zircon U-Pb ages constrain provenance during Triassic–Paleogene basin evolution. • Extensional basin geometry influenced later thermal and flexural foreland subsidence. • Cretaceous–Neogene shortening was disrupted by neutral–extensional tectonic regimes. [ABSTRACT FROM AUTHOR]

In many fold‐thrust belts, cross section–derived shortening estimates are significantly lower than predicted based on plate convergence. This has led to controversial hypotheses that shortening may be largely underestimated due to wholesale underthrusting (convergence without shortening) below far‐traveled continent or ocean‐derived nappes. The Late Cretaceous‐Eocene Taurides fold‐thrust belt (southern Turkey) may contain a highly incomplete shortening record of convergence likely caused by wholesale underthrusting. To estimate this underthrusting, we calculate convergence across the belt using a map‐view palinspastic reconstruction that takes into account major rotations of tectonic units during their accretion. We use paleomagnetic and fault kinematic analysis, timing of accretion, and Africa‐Eurasia convergence to constrain our reconstruction. Our paleomagnetic results confirm an ~40° clockwise vertical axis rotation of the Geyikdağı nappe that forms the core of the belt, which we interpret is accommodated by a lateral gradient in underthrusting on faults structurally above and below the Geyikdağı nappe. We reconstruct ~400–450 km of convergence across the Taurides during their accretion. We compare this predicted convergence to shortening calculated from balanced cross sections, in which we reconstruct a minimum of 154‐km shortening: 57 km within far‐traveled nappes, 70‐km thrusting of far‐traveled nappes over the Geyikdağı nappe, and 27‐km shortening within the Geyikdağı nappe. Shortening in the Taurides created a significant nappe stack, but the majority of convergence was accommodated by wholesale underthrusting with barely a trace at the surface, including ~160 km of convergence by rotation of the belt, and 90–130 km related to missing Africa‐Eurasia convergence. Key Point: Wholesale underthrusting was the dominant process in Taurides accretion and led to a highly incomplete shortening record of convergence [ABSTRACT FROM AUTHOR]

New apatite and zircon (U‐Th)/He cooling ages quantify late Cenozoic exhumation patterns associated with fault activity across the Kashmir Himalaya. Apatite (U‐Th)/He (AHe) cooling ages of detrital grains from the Sub‐Himalayan foreland sediments indicate significant resetting. AHe data and thermal modeling reveal cooling and exhumation initiated by 4 Ma at the deformation front and by 2–4 Ma throughout other Sub‐Himalayan structures. Exhumation rates for Sub‐Himalayan structures are ≥1 mm/year. In the hinterland, thrust sheet samples from the Main Boundary thrust and Main Central thrust yield AHe cooling ages between 5.1 and 21.1 Ma. Published apatite fission track cooling ages (<3 Ma) and high exhumation rates (3.6–3.2 mm/year) across the Kishtwar window further to the north are consistent with AHe data from the Sub‐Himalayan structures. The pattern of cooling ages and rates indicates that exhumation occurs in association with changes in the Himalayan basal décollement ramp geometry. Hinterland zircon (U‐Th)/He (ZHe) data show a pronounced abundance and probability spike in cooling ages between 14 and 21 Ma, a period when Main Central thrust motion is well documented throughout the Himalaya. ZHe single‐grain ages from Sub‐Himalayan samples contain a nearly identical cluster from 16 to 23 Ma. Cooling patterns across the Kashmir Himalayas do not correlate spatially with modern monsoon precipitation, suggesting that climate‐related precipitation and exhumation are decoupled. Coeval translation over the basal décollement and distributed imbricate thrust deformation of the foreland in the upper plate characterizes fault‐related exhumation of the Sub‐Himalayan orogenic belt after 4 Ma. Plain Language Summary: Our new data document the timing of cooling of rocks brought to the surface during mountain building of the Kashmir Himalaya. Mineral grains eroded from the Himalaya and deposited in the plain are now exposed in the Sub‐Himalayan belt. The ages of these rocks that we have measured constrain the timing of burial and subsequent return to the Earth's surface (exhumation) during thrust fault‐related deformation. Analysis of apatite grains reveals that cooling and exhumation initiated by 4 Ma on the southernmost structure of the Kashmir Himalaya and by 2–4 Ma on other distributed faults in the Sub‐Himalayan belt. In the core of the mountain range rocks have young cooling ages (<3 Ma) related to high uplift rates within the Kishtwar window, a zone of localized deformation in the High Himalaya. Thus, outward growth of the Sub‐Himalayan belt occurred in concert with uplift in the hinterland over the past 4 Myr. Precipitation rates vary systematically from south to north across the Himalaya, but these variations are not synchronous with the pattern of cooling and exhumation in Kashmir Himalaya. This result suggests that climate does not drive crustal deformation. Instead exhumation patterns primarily reflect the location, geometry, and partitioning of faulting within the Himalaya. Key Points: In the Kashmir Himalaya thrust‐related cooling and exhumation initiated by 4 Ma at the deformation front and by 2–4 Ma throughout the Sub‐Himalayan structuresA ramp geometry to the Himalayan basal décollement explains across‐ and along‐strike variation in uplift rates and exhumation historyDistributed deformation between duplex growth in the hinterland and imbricate thrusts in the foreland since 4 Ma suggests a subcritical wedge state [ABSTRACT FROM AUTHOR]