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In the southeastern Tibetan Plateau, region‐scale dextral strike‐slip shear zones, crucial for India‐Asia convergence, were investigated along the Dulongjiang shear zone near the Eastern Himalayan Syntaxis (EHS). Structural, kinematic, and geochronological data from Dulongjiang and Nabang regions in western Yunnan, China, reveal dextral strike‐slip shearing between 30 and 15 Ma. Various rocks were affected by moderate‐temperature shear deformation (∼450–550°C), inferred from microstructures and quartz CPO patterns, during dextral strike‐slip and exhumation of the shear zone. Combined with structures of pre‐, syn‐, and post‐shearing leucogranites, zircon U‐Pb dating indicates that the dextral shear along the shear zone began in the Early Oligocene (30–29 Ma) subsequent to the India‐Asia collision. Micas in mylonitic granites yield 40Ar/39Ar ages, suggesting that the principal dextral shear deformation occurred approximately between 18 and 15 Ma. The Dulongjiang shear zone is linked to the Parlung, Nabang shear zone, and Sagaing Fault, forming a regional Cenozoic dextral shear system around the EHS. The study, combined with tomographic anomalies beneath the India‐Asia collision zone, highlights distinct lithospheric‐scale evolution in southeastern and eastern Tibet. Continuous intracontinental strike‐slip shearing indicates a tectonic shift from Tibetan extension to block rotation around the EHS. From 30 to 15 Ma, slab tear, accompanied by clockwise rotation and dextral strike‐slip shearing, suggests a warmer geodynamic setting influenced by hot mantle flow associated with ongoing subduction of the Indian lithosphere. Oligocene‐Miocene dextral strike‐slip shearing around the EHS, linking southwards with the Sagaing Fault, may correspond to the rotation necessary for slab to bend, stretch, and eventually tear beneath the region. Plain Language Summary: The southeastern Tibetan Plateau undergoes active southeastward extrusion and rotation around the Eastern Himalayan Syntaxis (EHS) due to ongoing Indo‐Eurasian continent collision. N‐S, NW‐SE, and NE‐SW ductile strike‐slip shear zones/faults in Tibet and the Indochina Block reveal this tectonic activity. Understanding their kinematics, linkages, and developmental patterns is crucial for investigating the relationship between Cenozoic surface tectonics and Tibetan Plateau lithospheric evolution. This study focuses on the Jiali‐Dulongjiang‐Nabang dextral (relative rightward movement on both sides of the fault) strike‐slip ductile shear zone/fault system, revealing a curved regional‐scale dextral strike‐slip zone system influenced by continuum rotation deformation, driven by slab tear beneath the EHS region. Contrary to the concept of a conjugated strike‐slip shear/fault system dominating extension tectonics, these findings suggest a significant influence of continuum rotation deformation on the initiation, movement, and linkage of curved dextral strike‐slip shearing around the EHS. Key Points: A network of dextral strike‐slip shear zones formed a regional curved belt around the Eastern Himalayan Syntaxis from ∼30 to ∼15 MaSlab tear beneath the Eastern Himalayan Syntaxis induced unique asthenospheric flow pattern, causing the bending and interconnection of dextral shear zonesThe V‐shaped conjugate shear zones are related to indent‐driven system, marking northward penetration of the Indian plate into Eurasia [ABSTRACT FROM AUTHOR]

We present a study in the southern Puna (26°30′–27°30′S), aiming to explore the late Cenozoic evolution of the deformation and the stress field during its uplift. Through U‐Pb geochronology, structural observations, paleostress analysis, and balanced cross‐sections, we propose an structural evolutionary model over the past 24 million years, separated in four stages: Stage 1, in the late Oligocene to middle Miocene, the region experienced E‐W compression. Stage 2, from middle to late Miocene, a transition from predominant compression to an incipient strike‐slip regime is observed. Stage 3, from late Miocene to early Pliocene, showed a further shift in the stress field, resulting in a combination of a predominant strike‐slip regime, and less predominant compressional regime. Finally, Stage 4, from late Pliocene to Quaternary, featured a dominance of strike‐slip regimes. Our results show that the stress field in each stage is associated with the orogen's internal architecture and its evolution. Vertical stress variations are linked to plateau uplift, creating topographic gradients across the orogen. Horizontal rotations of the principal stress axes are caused mainly by an edge effect resulting from the growth of the plateau while it reaches a critical crustal thickness and elevation. This leads to a transfer of compression from high‐lying areas to lower regions. The southernmost Puna region shows no significant evidence of normal faulting, suggesting it is not undergoing orogenic collapse associated with a regional tensional stress regime. Key Points: We present a structural study in the southern Puna region focused on the late Cenozoic evolution of the tectonic stress fieldThe study emphasizes the link between internal architecture of an orogen, plateau uplift and the stress field during Miocene‐PleistoceneThe southernmost Puna is not undergoing extensional orogenic collapse [ABSTRACT FROM AUTHOR]

Constraining the geometry and displacement of crustal‐scale normal faults has historically been challenging, owing to difficulties with geophysical imaging and inability to identify precise cut‐offs at depth. Using a modified workflow previously applied to contractional systems, flexural‐kinematic (Move) and thermal‐kinematic (Pecube) models are integrated with apatite (U‐Th)/He (AHe) and apatite fission track (AFT) data from Teton footwall transects to constrain total Teton fault displacement (Dmax). Models with slip onset at ∼10 Ma and flexure parameters that best match the observed Teton flexural profile require Dmax > 8 km to produce young (<10 Ma) AHe ages observed at low elevation footwall positions in the Tetons. For the same slip onset, models with Dmax of 11–13 km provide the best match to observed AHe data, but displacements ≥16 km are required to produce observed AFT ages (13.6–12.0 Ma) at low elevations. A more complex model with slow slip onset at ∼25 Ma followed by faster slip at ∼10 Ma yields a good match between modeled and observed AHe ages at a Dmax of 13–15 km. However, this model predicts low elevation AFT ages 6–8 Ma older than observed ages, even at Dmax values of 16–17 km. Based on this analysis and integration with previous studies, we propose a unified evolution wherein the Teton fault likely experienced 11–13 km of Miocene‐recent displacement, with AFT data likely indicating a pre‐to early Miocene cooling history. Importantly, this study highlights the utility of using integrated flexural‐ and thermal‐kinematic models to resolve displacement histories in extensional systems. Key Points: Integrating flexural‐ and thermal‐kinematic models with thermochronology data provides constraints on crustal‐scale normal fault evolutionResults show how effective elastic thickness, fault geometry, and detachment depth impact fault evolution and predicted age dataFor the contested displacement history of the Teton fault example, analyses indicate >11 km and potentially >16 km of normal displacement [ABSTRACT FROM AUTHOR]

The interplay between regional tectonics and the development of a major ocean gateway between the Pacific and the Atlantic Ocean has resulted in numerous paleogeographic reconstruction studies that describe the Cenozoic tectonic history of the Scotia Sea region. Despite the multitude of published tectonic reconstructions and the variety of geological and geophysical data available from the Scotia Sea, the geological history remains ambiguous. We present a comparative paleogeographic analysis of previously published tectonic reconstructions to identify agreements and conflicts between these reconstructions. We propose an alternative model to explain the Cenozoic evolution of the Scotia Sea region. The paleogeographic comparison shows that most reconstructions agree on the tectonic evolution of the South Scotia Ridge and the East Scotia Ridge. Major differences between the reconstructions are the role of the westward subducting plate below the South Sandwich plate, and the age and origin of the Central Scotia Sea. Tectonic reconstructions assume that the Central Scotia Sea is either part of a Cenozoic back‐arc basin, or a captured piece of Cretaceous oceanic crust. We propose a new alternative tectonic reconstruction that brings these two prevailing hypotheses elegantly together. Here, we identified new geographical blocks consisting of thinned continental or Cretaceous oceanic fragments that originate from the Paleo‐Pacific Weddell Sea gateway from high‐resolution bathymetry. These fragments are now part of the Central Scotia Sea and have been affected by early back‐arc tectonic activity of the South Sandwich subduction zone, leading locally to the formation of Cenozoic‐aged crust in the Central Scotia Sea. Key Points: New tectonic reconstruction based on qualitative comparison endmember reconstructionsThe Central Scotia Sea consists of fragments of Cretaceous and Cenozoic oceanic crustA shallow gateway at Drake Passage potentially existed already during the Eocene [ABSTRACT FROM AUTHOR]

Compared to the thin‐skinned Subandean foreland fold‐and‐thrust belt of northern Argentina and Bolivia, the tectonically active morphotectonic province of the Santa Bárbara System in the Andean broken foreland of northwestern Argentina is characterized by a temporally and spatially disparate deformation style. Although there is no well‐defined orogenic deformation front associated with the uplift of these basement‐cored, reverse‐fault bounded mountain ranges, there has been an overall eastward trend in Andean compressional deformation since the Miocene. While reactivation of basement anisotropies, such as early Paleozoic metamorphic fabrics and Cretaceous normal faults, has been proposed to have profoundly affected deformation processes in the Santa Bárbara System, other mechanisms involving Mesozoic and Cenozoic cover rocks may also have played an important role in orogenic deformation in this sector of the Andean foreland. We present structural field observations, interpretations of seismic reflection profiles, and kinematic modeling from the basins bordering the Candelaria Range in the southern sector of the Santa Bárbara System at 26°S. Our analysis features a 110‐km‐long structural cross section that images and links deep‐seated structures with shallow neotectonic faults. We find that regional shortening has been facilitated by several faults associated with a regional detachment at a depth of 23 km, resulting in total horizontal shortening of about 17% (18.4 km). While the deep‐seated first‐order structures seem closely linked to seismogenic processes in the Andean foreland, shallow second‐order structures within the sedimentary cover modify the intermontane landscapes and appear to be associated with aseismic creep. Key Points: Kinematic model for the Santa Bárbara System shows a 1st‐order detachment at 23 km depth, contributing to 18.4 km of Cenozoic shorteningDeformation shows spatiotemporal variations, linked to reactivation of Cretaceous extensional faults and/or basement heterogeneitiesSeismicity is closely associated with deep faults rather than shallow structures affecting the sedimentary cover [ABSTRACT FROM AUTHOR]

The evolution of topography in forearc regions results from the complex interplay of crustal and mantle processes. The Southern Apennines represent a well‐studied forearc region that experienced several tectonic phases, initially marked by compressional deformation followed by extension and large‐scale uplift. We present a new structural, geomorphic and fluvial analysis of the Pollino Massif and surrounding intermontane basins (Mercure, Campotenese and Castrovillari) to unravel their evolution since the Pliocene. We constrain multiple tectonic transport directions, evolution of the drainage, and magnitude and timing of long‐term incision following base level falls. Two sets of knickpoints suggest two phases of base level lowering and allow to estimate ∼500 m of long‐term uplift (late Pleistocene), as observed in the Sila Massif. On a smaller spatial scale, the evolution and formation of topographic relief, sedimentation, and opening of intermontane basins is strongly controlled by the recent increase in rock uplift rate and fault activity. At the regional scale, an along‐strike, long‐wavelength uplift pattern from north to south can be explained by progressive lateral slab tearing and inflow of asthenospheric mantle beneath Pollino and Sila, which in turn may have promoted extensional tectonics. The lower uplift of Le Serre Massif may be explained as result of weak plate coupling due to narrowing of the Calabrian slab. The onset of uplift in the Pollino Massif, ranging from 400 to 800 ka, is consistent with that one proposed in the southern Calabrian forearc, suggesting a possible synchronism of uplift, and lateral tearing of the Calabrian slab. Key Points: Topographic evolution constrained by structural, geomorphic and river analysis of the Pollino range and surrounding extensional basinsAt short spatial scale, increase in rock uplift and fault activity controls the endorheic‐exorheic transitionAt regional scale, uplift increases between 400 and 800 ka, due to progressive lateral slab tearing, and inflow asthenospheric mantle [ABSTRACT FROM AUTHOR]

Trench‐parallel translation of the Central American Forearc (CAFA) is the result of strain partitioning along the Cocos and Caribbean (CA) convergent margin. Unlike the tectonics of northwestern Costa Rica and El Salvador, CAFA‐CA relative motion in Nicaragua is not accommodated on margin‐parallel fault systems. Rather, the northwest‐trending dextral shear is accommodated on margin‐normal sinistral strike‐slip faults that approximate the motion of a margin‐parallel fault (i.e., bookshelf faulting). We compare a new Global Positioning System interseismic horizontal velocity field to analytical and numerical models to show that the bookshelf faulting model can produce the observed velocity field and provide insight into the kinematics and configuration of the margin‐normal fault system. We find that a fault system with 20 km‐long parallel to sub‐parallel margin‐normal sinistral faults, spaced ∼5 km apart, locked from the surface to 5 km depth, and with interseismic slip deficits of 4 mm yr−1, can replicate the observed velocity field. These findings have implications for the region's seismic hazard where shallow moderate‐magnitude earthquakes will have reoccurrence intervals of ∼50 years. These findings are also important for volcanic hazard estimation and unrest forecasting because the margin‐normal faults are in the volcanic arc and magma‐tectonic interactions have been documented along the CAFA. Plain Language Summary: The Central American Forearc (CAFA) is a northwest‐moving tectonic block that is located between the Middle America Trench and the Central American Volcanic Arc (CAVA). Northwest‐oriented faults (i.e., faults parallel to the CAVA motion), have been found in Costa Rica, El Salvador, and Guatemala, representing the boundary between CAFA and CAVA. In eastern El Salvador, Nicaragua, and western Costa Rica, a different fault style has been identified where the faults are oriented perpendicular to the motion of the CAVA (bookshelf faulting). These faults are ancient structures that take up the motion between the CAFA and CAVA, which is easier than creating new faults parallel to the motion. We show that, in northwestern Nicaragua, the bookshelf faulting can produce the observed GPS data. We find that these faults should move at 4 mm/yr, are close to populated areas, and will produce M5 to M6 earthquakes every 50 years. Key Points: Bookshelf faulting accommodates northwest‐directed forearc motion on margin‐normal sinistral faultsStrain accumulation on margin‐normal sinistral faults agrees with GPS‐derived horizontal velocity field in northwestern NicaraguaShallow M > 5 upper‐plate earthquakes in the region will have reoccurrence intervals of ∼50 years [ABSTRACT FROM AUTHOR]

As the world's glaciers recede in response to a warming atmosphere, a change in the magnitude and frequency of related hazards is expected. Among the most destructive hazards are glacier lake outburst floods (GLOFs), and their future evolution is concerning for local populations and sustainable development policy. Central to this is a better understanding of triggers. There is a long‐standing assumption that earthquakes are a major GLOF trigger, and seismic activity is consistently included as a key hazard assessment criterion. Here, we provide the first empirical evidence that this assumption is largely incorrect. Focusing on the Tropical Andes, we show that, of 59 earthquakes (1900–2021) the effects of which intersect with known glacier lakes, only one has triggered GLOFs. We argue that, to help develop climate resilient protocols, the focus for future assessments should be on understanding other key GLOF drivers, such as thawing permafrost and underlying structural geology. Plain Language Summary: Climate change is increasing glacier melt in high mountains and increasing the size and number of glacial lakes. Over time, these lakes may drain catastrophically to generate glacier lake outburst floods (GLOFs), which can devastate downstream communities and destroy valuable infrastructure such as roads, bridges, and hydroelectric power facilities. As a result, many risk assessments have been carried out to understand what the triggers of GLOFs might be, in order to better predict their occurrence. One of the main triggers has been assumed to be earthquakes, but this association has not been properly tested. In this paper, we use earthquake and GLOF data from the Peruvian and Bolivian Andes to test this and find that there is little association between earthquakes and GLOFs. We conclude by arguing that focus needs to be on other GLOF triggers, and earthquake activity should be used as a secondary – not primary – indicator in GLOF susceptibility studies. Key Points: Glacier lake outburst floods (GLOFs) are a major risk concern, with earthquakes being commonly considered effective triggers in hazard assessmentsOf 59 earthquakes (1900–2021), the effects of which intersect lakes in the Tropical Andes, only one triggered GLOFsWe suggest that earthquake activity should be used as a secondary – not primary – susceptibility indicator for GLOFs [ABSTRACT FROM AUTHOR]

This document provides a summary of various scientific articles and discoveries. It begins by discussing Japan's Moon lander, which successfully resumed operations after a rough landing. Australian geologists used plate tectonic modeling to understand an ice-age climate in Earth's history, while amateur paleontologists found well-preserved fossils in France that shed light on polar ecosystems. The document then highlights articles on Shap Granite production in the UK, Triassic vertebrate fossils in Antarctica, dental wear in dinosaurs, snake traces in South Africa, vulcanian bombs in Ecuador, and a salt diapir in Iran. These articles offer valuable insights into a range of scientific topics. [Extracted from the article]

As typical carbonate geothermal reservoirs with low porosity in northern China, the Jixianian System in the Xiong'an New Area is the main target for geothermal fluid exploration. The Jixianian System comprises the Gaoyuzhuang, Yangzhuang, Wumishan, Hongshuizhuang, and Tieling formations. The characteristics, formation periods, and controlling factors of reservoir tectonic fractures have been determined based on analyses of outcrops, cores, thin sections, and image logs. The results show that unfilled fractures account for over 87% and most tectonic fractures are high‐angle shear fractures with angles concentrated at 40° to 70° and the fracture porosity increases linearly with an increased fracture aperture. Within the same tectonic setting and stress field, the lithology and layer thickness are the dominant factors governing the development of tectonic fractures, which are the most developed in dolomites and thin layers. Tectonic fractures were most likely formed in regions near faults or areas with larger stress gradients. The tectonic fractures in the carbonate geothermal reservoirs are roughly divided into four sets: NNW–SSE and NNE–SSW oriented 'X'‐conjugated shear fractures formed from the Paleozoic to the pre‐Yanshanian Movement; NE–SW‐oriented shear fractures, formed in episode B of the Yanshanian Movement, occurred at the Early Cretaceous; nearly E–W‐oriented tensional fractures formed in the late Yanshanian Movement at the Late Cretaceous to Paleogene, and NEE–SW‐oriented shear fractures formed during the Himalayan movement. [ABSTRACT FROM AUTHOR]

The internal structure and architecture of evaporite sequences is often overlooked, with attention frequently concentrating on the external geometries that salt bodies form. The availability of extensive 3D seismic data affords the opportunity to interpret the internal structures within these evaporite sequences and comprehensively characterise the different structural facies over large areas. This paper concentrates on the Zechstein Supergroup evaporite deposits within the Southern North Sea of the United Kingdom's Continental Shelf. This analysis of the internal structural complexity and stratigraphic heterogeneity utilises 26,000 km2 of 3D seismic data together with over 96 wells from the Southern North Sea. Characterisation of the different structural facies present was undertaken alongside mapping their spatial distribution to understand the relationship they have with one another and the structural evolution that may have been taken. This work has (1) characterised and mapped six different internal structural facies present within the Zechstein with increasing levels of deformation; (2) shown the internal lithological heterogeneity is indicative of variations in the vertical strength profile of layered evaporite sequences; (3) discontinuous high‐amplitude reflections within the Zechstein are as a result of the geometries being too steeply dipping for the seismic data to image; and (4) the ability to possibly predict the internal heterogeneity of areas of poorly imaged salt, such as within large diapiric salt structures, from surrounding structural facies. These findings suggest that there is significant internal complexity even within areas of the basin with minor mobilisation to the external salt geometry. [ABSTRACT FROM AUTHOR]

The Java ‐ Lesser Sunda margin, which features multi‐scale subducting oceanic basement relief, is classified as neutral (Lombok and Sumbawa) to erosional (Central Java to Bali) in comparison to its accretionary counterpart offshore Sumatra. However, a comprehensive analysis of how plate boundary and upper plate structure across the neutral to erosional transition are modulated by the subduction of oceanic basement relief is lacking to date. To shed light on the tectonic parameters that push the margin into the neutral or erosional domain, we combine multi‐channel reflection seismic images derived through a grid‐based P‐wave velocity inversion, and multibeam bathymetric maps. The data document how different scales of subducting topography modify seafloor morphology, upper plate structure, and décollement position. Large‐scale subducting features cause a landward shift of the deformation front, shortening of the accretionary wedge, and seafloor steepening at the relief's trailing edge. Small‐scale subducting ridges primarily impact the frontal prism resulting in over‐steepening at the trench and localized slope failure. Ahead of subducting relief, deformation of the accretionary wedge encompasses enhanced compression and a reduction in seafloor slope but appears independent of the size of the relief. Ridge and seamount subduction induce frontal erosion and basal erosion offshore Lombok and Bali, respectively. Our P‐wave velocity models indicate that the rigidity of the upper plate's base along the eastern Sunda margin is significantly lower than the worldwide trend. We conclude that this favors the genesis of tsunami earthquakes that have occurred on the Java margin. Plain Language Summary: The convergence of the tectonic plates drives a wide variety of geological processes along the plate margins, including the formation of the forearc accretionary wedge, volcanic activities, and megathrust earthquakes. Over the past 40 years, marine research shows that different sizes of oceanic reliefs (seamounts and ridges) are widely distributed over the seafloor, approaching the trench, and eventually subducted underneath the overriding plate. An accurate observation of the subducted reliefs and their tectonic impact on the overriding plate depends on different observation approaches, data processing methods, and the evolutionary history of the forearc. In the Java margin, the oceanic seafloor features massive seamounts with different scales and shapes, and the bathymetry of the overriding plate is highly disturbed. This provides us with the best opportunity of studying the rugged seafloor's seismogenic and geological impacts. By using state‐of‐the‐art seismic imaging techniques, we image the subsurface structures, obtain the forearc velocity, identify the seamounts, and discuss the seamounts' effect on structural deformation and megathrust earthquake occurrence. Distinctively, the marine forearc gets shortened and thickened significantly by seamount subduction. Structural images sharply illustrate different deformation patterns and stress regimes at the seamount's different flanks and reveal the possible process of subduction erosion. Key Points: Upper plate deformation scales with variable subducting relief, as observed along the Java Trench in seismic sections and bathymetrySubduction of seafloor topography induces progression from an accretion‐dominated domain toward a phase of subduction erosionThe overall low rigidity of the upper plate's base may contribute to the Java margin earthquake's tsunami‐genesis [ABSTRACT FROM AUTHOR]

One of the key challenges related to glaciofluvial aquifers is understanding how the underlying bedrock structures and the associated bedrock surface topography contributed to the deposition of the glaciofluvial sediments and the generation of groundwater flow pathways. In this study from Western Finland, we present a new digital elevation model of the Precambrian crystalline bedrock surface buried up to 100 m beneath the glaciofluvial sediments along the Kurikka depression. We link bedrock topography to structural anisotropy using additional data from rock outcrops, boreholes and gravity data. Brittle deformation zones are seen in the bedrock‐digital elevation model (DEM) as sharp breaks in the rock surface. These vertical fracture zones contributed to the development of interlinked elongate bedrock depressions and delimit rock blocks with different elevations. A narrow, zigzagging trench, with a stepped floor, follows WNW‐ESE and NE‐SW oriented fracture zones and forms a major hydraulic connection between two major parts of the aquifer. Furthermore, the conductive fracture zones are conduits which connect the shallow glacifluvial aquifer system to deep groundwater in the bedrock. Understanding bedrock structures and buried topography is critical for successful groundwater modelling in crystalline, fractured bedrock. [ABSTRACT FROM AUTHOR]

We combined field mapping, structural and microstructural analyses, stable‐clumped isotope geochemistry, and U‐Pb dating of calcite veins and syn‐tectonic slickenfibres, to assess the regional scale fault‐related fluid flow during the evolution of the External Hellenides fold‐and‐thrust belt. We show that fluid circulation during forebulge uplift was characterized by cold meteoric water‐derived fluids, from which calcite precipitated and sealed bed‐perpendicular joints. Fluid circulation during foreland flexuring and early layer‐parallel shortening was characterized by warm fluids buffered by the carbonate host rock, which circulated through normal faults and bed‐parallel veins. Mixing with meteoric‐derived fluids also occurred at this stage of tectonic evolution. Fluid circulation during the late stage of thrust wedge accretion and post‐orogenic extension at 1.6 ± 1 Ma was characterized by increasing dominance of cold meteoric water circulating in strike‐slip and normal faults. The ingress of meteoric‐derived fluids was controlled by throughgoing fault conduits, while host rock‐buffered fluids were confined in isolated structures such as minor faults and veins. We developed a conceptual model of fault‐related fluid circulation, which invokes a transition from an open fluid system during forebulge uplift, to a semi‐closed fluid system during foreland flexuring and early layer‐parallel shortening, and to an open system during late thrust wedge accretion and post‐orogenic extension. This type of fluid circulation may have impacted fluid migration/leakage, including hydrocarbons, into or outside potential reservoirs in the highly prospective Hellenides‐Albanides fold‐and‐thrust belt, a renovated frontier for hydrocarbon exploration in the Mediterranean area. Key Points: Throughgoing faults are fluid conduits for external, meteoric‐derived fluids, minor faults and veins host rock‐buffered warm fluidsBed‐perpendicular joints sealed during forebulge uplift, rock‐buffered fluids circulated during foreland flexure and wedge accretionMeteoric water moved through strike‐slip faults during late wedge accretion and through post‐orogenic (at 1.6 Ma) normal faults [ABSTRACT FROM AUTHOR]

Lunar floor‐fractured craters are characterized by the occurrence of radial and concentric grabens, and while their formation mechanism was broadly studied in literature, the relationships between displacement and length of the faults, together with the fault growth, were never examined. We produced a semiautomated Python‐based script able to analyze all the parameters required for this study: displacement, length, width of the grabens, and power law relationship between displacement and length. The results of our investigation, carried on in Komarov, Humboldt, and Atlas craters, showed a sublinear fault growth, suggesting that for some reason the increase in displacement is not linear with respect to length. This can result from the interplay of mechanical discontinuities related to the stratigraphy (which cause a vertical fault restriction, preventing the displacement from developing in depth), and to linkage phenomena. The Dmax/L ratios that resulted from our analyses are higher than previously predicted for the Moon and appear more similar to the values observed on Earth. The slip distribution revealed different stages of fault interaction within the same crater, while the overall maturity of the grabens seems to be significantly high based on the observed symmetry of the grabens. Moreover, our code (public and accessible) can facilitate future works that aim to widen our knowledge about the lunar faults' growth, with all the implications that can improve our understanding of the faults' behavior. Plain Language Summary: Floor‐fractured craters are a particular type of lunar craters that present polygonal faults on the floor. Faults are characterized by a certain amount of displacement and a certain length. We can relate these two parameters and study their scaling laws, getting information on the fault growth. Our results, obtained through a new semiautomated methodology that we developed, show a sublinear fault growth in the three studied craters. Sublinear fault growth consists of nonlinear growth between length and displacement, with the latter being prevented from developing in‐depth. Such impediment might be caused by a stratigraphic or mechanical barrier beneath the crater that would hamper the displacement of the faults, perhaps indicating a complex geological setting and stratigraphy below and within the crater. Key Points: D/L scaling analyses revealed new information on the fault growth of the faults affecting Floor‐Fractured cratersThe nonlinear relationship between displacement and length, and low Dmax/L values, can be attributed to linkage and/or vertical restrictionWe introduced a new semiautomated methodology (public and accessible) to help investigate further areas in future works on D/L analyses [ABSTRACT FROM AUTHOR]

The article offers information on the journal Tectonics, which presents original scientific contributions describing and explaining the evolution, structure, and deformation of Earth's lithosphere. Topics include field, laboratory, and modeling studies relevant to tectonics; multidisciplinary studies across various geologic times; and the publication process, including submission guidelines, editorial contacts, and publication charges.

Crustal configuration beneath the northeastern region of India has been investigated with the help of receiver function (RF) analysis of teleseismic earthquakes recorded by 19 broadband seismological stations. We adopted the H‐k stacking method to estimate crustal thickness and Poisson's ratio beneath each recording station. The study reveals a large variation in crustal thickness and Poisson's ratio which are correlated with the complex geology and tectonics of the region. The crust is observed to be thinner (36.5–41.6 km) beneath Bengal Basin, Shillong Plateau, and the Brahmaputra valley compared to the Indo‐Burma Ranges (IBR) (~40–54 km) and Arunachal Higher Himalaya (TAWA station, ~45 km) and Sikkim Himalaya (GTK station, ~46.5 km). A large variation of Poisson's ratio is observed in the region (~0.230–0.306). Poisson's ratio is generally low‐to‐intermediate in the Shillong‐Mikir Plateau, Bengal Basin, and the Brahmaputra Valley, while it is intermediate‐to‐high in the Tripura Fold Belt and the northern part of the IBR. The high Poisson's ratio in the Tripura Fold Belt is due to the presence of basaltic basement rock and clay minerals existing in the sedimentary rocks, whereas the presence of partially serpentinized rock in the ophiolitic mélange complex causes a high Poisson's ratio in the IBR. [ABSTRACT FROM AUTHOR]

The structurally complex region of Tempe Terra, located in the northeast of the Tharsis Rise on Mars, preserves deformation related to the growth of Tharsis and lies along the trendline formed by the Tharsis Montes volcanoes. We characterize the spatiotemporal tectonic evolution of Tempe Terra based on comprehensive structural mapping. From this mapping, we identified 16 cross‐cutting fault sets and placed these in relative time order, based on a hybrid approach using cross‐cutting relationships and buffered crater counting. We are thus able to provide a broad framework for understanding the timing of development for the Tharsis Rise and Tharsis Montes axial trend (TMAT). Our work shows that Tempe Terra has experienced three distinct stages of tectonic activity from the Middle Noachian to the Late Hesperian. Stage 1 involved E–W extension followed by localized NE–SW extension, which produced local zones of N and NW faulting through the center and west of Tempe Terra in the Noachian. Stage 2 produced intense NE‐oriented faulting concentrated along the TMAT in the Early Hesperian as a result of a discrete period of NW–SE extension and local volcanism. Stage 3 involved NW–SE extension coinciding with Tharsis volcanic activity, which generated a regional fabric of ENE‐trending graben distributed across Tempe Terra from the Early to Late Hesperian. We observe an overall peak in tectonic activity in the Early Hesperian and find that Tharsis‐related extensional deformation in the form of NE‐oriented radial faulting did not start in Tempe Terra until this time. Plain Language Summary: Despite decades of research into the Tharsis Rise, Mars's largest volcanic province, there is still uncertainty around the timing and mechanism of its development. Examining the deformation associated with Tharsis can help us understand these factors. Tempe Terra, an ancient plateau in the northeast of the Tharsis Rise, provides an excellent opportunity to do this because it preserves rocks and structures from Tharsis's early evolution and falls along a volcanic and structural trendline formed by the Tharsis Montes volcanoes. However, addressing the larger‐scale evolution first requires understanding when and where structures in Tempe Terra evolved. We characterize the nature of these structures through time using comprehensive structural mapping. Our work shows that Tempe Terra experienced three distinct stages of tectonic activity across many hundreds of millions of years early in Martian history. We find that the majority of tectonic activity in Tempe Terra occurred in the Early Hesperian period (approximately 3.5 billion years ago). This time is also when we first see evidence in the area for the growth of Tharsis in the form of NE‐oriented faults. We are thus able to provide a broad framework for understanding the timing of development for the Tharsis Rise and Tharsis Montes trendline. Key Points: We present a comprehensive map of structures in Tempe Terra which is available in GIS formatTempe Terra has experienced three distinct stages of tectonic activity which peaked in the Early HesperianTharsis‐related extensional deformation did not begin in Tempe Terra until the Early Hesperian [ABSTRACT FROM AUTHOR]

Riedel shear structures (RSS) are often observed in the embryonic stage of strike‐slip fault development, which can be depicted in the field through outcrops and coseismic surface ruptures. It is a critical concept linking the geomechanical behavior of individual earthquakes to structural geology at both local and regional scales. However, the influence of long‐term fluid injections on the developing process of RSS, as manifested by the common occurrences of injection‐induced earthquakes, has been rarely addressed. Here we document for the first‐time subsurface RSS expedited by long‐term wastewater disposal injections in western Canada. We study an earthquake sequence consisting of 187 events (ML ranging 1.3–3.9) between 1 January 2018 and 15 July 2021 in an area without any previous seismic history. According to 31 well‐constrained focal mechanism solutions, the injection‐related earthquake sequence exhibits various faulting types with the vast majority (87%) being compatible with the background stress regime (SHmax azimuth = N38°E). The orientation of derived nodal planes collectively indicates a model of RSS that consists of four primary strike‐slip structures striking 19° (R′), 79° (R), 94° (PDZ), and 109° (P), respectively. Moreover, six fault segments delineated from the relocated local seismicity are parallel to the substructures of RSS. Mohr‐Coulomb failure analysis further suggests a cumulative stress perturbation of up to 10.0 MPa. Our observations suggest that long‐term fluid injection can expedite the development of local fault systems. Therefore, it is probably important to consider the dimension of local/regional RSS in the assessment of the overall seismic hazard due to fluid injections. Plain Language Summary: Under a shear stress regime, randomly distributed small fault segments would evolve into a mature strike‐slip fault system. During the early stage, a network of shear structures with favored orientations for rupturing are often observed, called Riedel shear structures (RSS). The depiction of RSS can help understand the geomechanical behavior of individual earthquakes. It is well accepted that long‐term fluid injections can cause earthquakes, yet their influence on the developing process of RSS is rarely discussed. Here we document a clear case in western Canada where the development of a local RSS system is expedited by 25 years of wastewater injection. The RSS system is manifested by an earthquake sequence consisting of 187 small‐to‐moderate‐sized events. Focal mechanisms of these events exhibit various faulting types with the majority being compatible with the background stress regime. The orientation of derived nodal planes and six fault segments depicted from the refined earthquake distribution collectively define the overall geometrical characteristics of the RSS. Mohr‐Coulomb failure analysis further suggests a cumulative stress perturbation of up to 10.0 MPa. The dimension of RSS could be important in the assessment of the overall seismic hazard due to fluid injections. Key Points: A seismically quiet area becomes active after 25 years of fluid injectionInduced earthquake source characteristics indicate Riedel shear structuresLong‐term fluid injection can notably expedite the reactivation and development of local fault system [ABSTRACT FROM AUTHOR]

This study proposes a unique workflow to unravel complex burial diagenetic histories of overpressured basins based on the integration of seismic and well log data, biostratigraphy, petrography, clumped isotope analyses and basin modelling. This approach is demonstrated with an example from the Chalk Group in the Danish Central Graben, where a seismic‐scale palaeo‐lithification front has been observed and studied in detail to elucidate the timing of the establishment of overpressured conditions and its relation to changing diagenetic activity. The palaeo‐lithification front separates high‐porosity chalks above, that dominantly underwent mechanical compaction and contact cementation, from low‐porosity chalk below, that dominantly underwent severe pressure dissolution and pore‐filling cementation. Analysis of chalk buried under hydrostatic conditions shows a strikingly similar lithification front between 1000 and 1200 m burial, much shallower than the lithification front in the Danish Central Graben at a current depth between 2100 and 2400 m below seafloor. The discrepancy of 1200 m is due to the establishment of overpressured conditions that limited the increase in effective stress as burial continued, finally halting burial compaction when formation fluids started to carry the lithostatic weight. Basin modelling data indicate that this occurred at the end of the Oligocene for large parts of the Danish Central Graben, which is much earlier than the Middle Miocene timing that is currently assumed. The results imply a regional occurrence of a relict lithification front in the North Sea Basin, its position guided by stratigraphy, but mainly dependent on the maximum effective stress experienced during its burial history. The study shows that the porosity bipartition is a remnant of the past and not from ongoing compaction as has previously been suggested. Since it was established before the thermal maturity of the main source rocks, chalk below the lithification front must have formed a sealing unit during hydrocarbon migration. The recognition of the lithification front is also of importance to velocity modelling and depth‐conversion since a non‐linear increase between velocity and depth is expected across this boundary. The methodology may be applied in other overpressured basins where the diagenetic state of reservoir rocks at the end of hydrostatic conditions must be constrained. [ABSTRACT FROM AUTHOR]

Within the Central Andes of NW Argentina, the spatiotemporal distribution and style of deformation is strongly influenced by pre‐Cenozoic heterogeneities, mostly related to the Salta rift extension in the Cretaceous. At the enigmatic junction of the thin‐skinned Subandean belt and the thick‐skinned Santa Barbara System, the Tilcara Range and adjacent San Lucas block, located within the Eastern Cordillera, show thermochronological and field evidence of multiple exhumation events. Mesozoic (140‐115 Ma), pre‐Andean exhumation of basement highs is constrained by unconformities between basement and syn‐rift strata, as well as zircon (U‐Th‐Sm)/He cooling ages. Cenozoic Andean exhumation is quantified by apatite (U‐Th‐Sm)/He and fission track cooling ages, which were reset between the Late Cretaceous and Miocene. These data show that the westernmost Tilcara Range began exhuming in the late Oligocene‐early Miocene (26‐16 Ma), after which exhumation propagated to the border of the Eastern Cordillera in the middle Miocene (22‐10 Ma). The onset of rapid exhumation in the San Lucas block, which is located east of the Tilcara Range, occurred in the late Miocene (10‐8 Ma) in its western part, and in the late Miocene‐early Pliocene (6‐4 Ma) in its eastern part. Internal deformation of the San Lucas block, disturbing zircon (U‐Th‐Sm)/He and apatite fission track age patterns, predates propagation of rapid exhumation. The here presented low‐temperature thermochronology data set thus quantifies the multi‐phase exhumation history of the Eastern Cordillera of NW Argentina and constrains the timing of Andean propagation of exhumation within the Eastern Cordillera and the adjacent structural transition zone. Key Points: Zircon (U‐Th‐Sm)/He data suggests that pre‐Andean exhumation of Salta rift basement highs occurred in the Early Cretaceous (140‐115 Ma)Apatite (U‐Th‐Sm)/He and fission track data indicate a late Oligocene‐early Miocene (26‐16 Ma) onset of exhumation in the Tilcara RangeAndean exhumation overall propagated in‐sequence eastward, but thermal models indicate the possibility of local out‐of‐sequence movement [ABSTRACT FROM AUTHOR]

We combine a ∼485 km‐long seismic reflection profile and a S‐wave speed transect from surface‐wave tomography, to reveal the lithospheric deformation mode of the intracontinental Qinling orogeny, central China. We observe a thick lithosphere keel in the convergence zone between the Yangtze Block and the North China Craton (NCC) and a shallow‐crustal (8–15 km depth) décollement that extends into the lower crust of the Qinling Orogen. Combining with surface structural geology and magmatism, we interpret these seismic findings as kinematically linked features formed by renewed intracontinental convergence between the NCC and the Yangtze Block in the late Mesozoic. We highlight that the ∼40 km lithospheric thickening in the convergence zone was likely balanced by > 130 km thin‐skinned crustal shortening along a crustal‐scale strain‐transfer décollement, and was responsible for the occurrence of late Mesozoic magmatism (∼160–100 Ma) at the southern edge of the NCC. Plain Language Summary: Here we reveal the lithospheric deformation mode of the intracontinental Qinling orogeny, central China, through a seismic reflection profile and a S‐wave speed transect from surface‐wave tomography. Our results suggest a thick lithosphere keel in the convergence zone between the Yangtze Block and the North China Craton (NCC), and a shallow‐crustal (8–15 km depth) décollement that extends into the lower crust of the Qinling Orogen. Coupled with published surface data, we suggest that these seismic findings document the lithospheric deformation induced by late Mesozoic intracontinental convergence between the NCC and the Yangtze Block. It appears that the ∼40 km lithospheric thickening was balanced by >130 km thin‐skinned crustal shortening along a long‐distance strain‐transfer décollement. Key Points: We reveal the lithospheric deformation mode of the intracontinental Qinling orogeny, central ChinaThe ∼40 km lithospheric thickening was likely balanced by >130 km thin‐skinned crustal shorteningThe long‐distance strain‐transfer décollement plays a vital role in accommodating the crustal shortening and lithospheric thickening [ABSTRACT FROM AUTHOR]

A New Zealand-led team of scientists have been mapping the underwater volcano and discovered that it has not changed much following the eruption, the BBC reported. This history has been reconstructed by identifying archaeological finds in sequences that often contain ash (tephra) layers from some of the numerous volcanic eruptions from Campi Flegrei and the other volcanoes in the region that were active at the time (Vesuvius and Ischia). Tongan volcano "surprisingly intact" The Tonga underwater volcano that erupted in January 2022, covering the island nation in ash, is still surprisingly intact, scientists have said (Holly Bancroft, I The Independent i , 23 May 2022). Gl The long and intertwined record of humans and the Campi Flegrei volcano, Italy The Campi Flegrei volcano (or Phlegraean Fields), Campania, Italy, generated the largest eruption in Europe in at least the last 200 ka. [Extracted from the article]

The southwestern Yangtze Craton hosts more than 400 carbonate‐hosted Pb–Zn deposits, and is well endowed with enormous base metals. The giant Maoping deposit is one of the most representative deposits, and the mineralization mainly occurs in the Devonian to Carboniferous dolomitic rocks. Its metallogenesis has been thoroughly discussed from many perspectives by previous studies, but it remains controversial, especially about the relationship between the structural process and the Pb–Zn mineralization. In this paper, we conducted large‐scale structural mapping and whole‐rock geochemical analysis to investigate the structural process and its control on the mineralization at Maoping. Three stages of deformation have been recognized, including the NE–SW‐striking folds and thrusts (D1), the N–S‐striking transtensional faults (D2), and the NW–SE‐striking transpressional structures (D3). The geochemical analysis shows relatively higher contents of the ore‐related trace elements in the tectonites from the N–S‐striking faults, indicating a close relationship between the N–S‐striking faults and the mineralization. Combined with field evidence and geochemical analysis, we propose that the N–S‐striking transtensional faults are likely the major ore‐conducting structures, and the NE–SW‐striking interlayer fractures serve as the assistant structures at the deposit scale. The regional NE–SW‐striking fold‐and‐thrust belts are suggested to dominate the spatial distribution and location of the Pb–Zn deposits in northeastern Yunnan at the regional scale. Our study enhances the understanding of the metallogenesis at Maoping and provides new insights into the Pb–Zn prospecting at both the regional scale and the deposit scale. [ABSTRACT FROM AUTHOR]

In the past two decades, algorithms for multiple‐point statistics (MPS) have been applied in many fields. However, 3D training datum or data (TD) is difficult to be obtained. Two‐dimensional geological cross‐sections from boreholes or geophysical data with high reliability are usually used to explain geological phenomena and are relatively easier to be acquired. In this study, a step‐wise algorithm that combines sequential process and global optimization is presented. Constructing 3D TD set and corresponding pattern databases that extended from 2D cross‐sections at each scale is one of the key steps after presetting the simulation parameters. The following step is constructing an initial model at the coarsest scale with the pattern databases. The iterative Expectation Maximum‐like (EM‐like) optimization process is implemented to obtain the final realization. Each iteration is conducted with a multiscale strategy. Simulation examples of the regional geological structures show that the stratigraphic sequence can be reasonably kept and reproduced. Also, the randomness and effectiveness of the microstructure model are verified by calculating the proportion of grains, fractal dimension and the curve of two‐point connectivity probability function. Key Points: A novel multiple‐point statistics simulation method for constructing 3D geological structures based on 2D geological cross‐section(s) is presentedBased on initial model constructed by the sequential process at the coarsest scale, final realizations are optimizedThe simulation of regional geological structures and microstructures proved that the algorithm can reconstruct 3D structures effectively [ABSTRACT FROM AUTHOR]

Asteroid 4 Vesta hosts two sets of enormous troughs, Divalia Fossae that encircle two‐thirds of the equator and Saturnalia Fossae located in the northern hemisphere. These troughs were interpreted as grabens, thus invoking faulting. The trough sizes, their linear arrangement, and overall morphology leave no doubt that their origin is tectonic, but structures other than faults have not been considered. To test if they are fault‐related or formed by accommodating opening‐mode displacement (i.e., jointing) without subsequent shear, we investigate the map patterns, cross‐sectional geometries, and variations of relief and width along the trough lengths. Relief and width could relate to the vertical displacement of faults and aperture of joints, respectively, and they therefore reveal differences in fracturing behavior. We analyzed six major troughs on Vesta, four belonging to Divalia Fossae, and two to Saturnalia Fossae. No map patterns are diagnostic of faulting or jointing. For each pair of trough‐bounding scarps, the maximum relief does not lie at the trough center, and the two maxima occur at different positions along the trough. In contrast, troughs are widest near the centers of the troughs. These characteristics are inconsistent with graben formation but are consistent with jointing. Furthermore, rock‐mechanical calculations that account for Vesta's low gravitational acceleration and degree of fracturing reveal that faulting is not favored to be initiated at depths above at least ∼3 but as much as 55 km within Vesta's lithosphere. Therefore, jointing or mixed‐mode fracturing, both involving opening‐mode displacements, are more plausible fracturing mechanisms for the Divalia Fossae. Plain Language Summary: The camera on the Dawn spacecraft captured two sets of large linear depressions, or troughs, on asteroid Vesta. Previous studies hypothesized that these troughs are fault‐bounded valleys with a distinct scarp on each side that together mark the downward drop (sliding) of a block of rock. However, cracking of rock can also form troughs, an origin that has not been considered before. Structures formed by sliding and cracking form different map patterns, have different morphologic expressions, and are controlled by different stresses acting on the rock volume. Although trough shape does not display any diagnostic map patterns, the morphology of the troughs is consistent with cracking because troughs are widest at the middle and narrow toward both ends. Calculated stresses are not favorable for sliding to be triggered within the uppermost ∼3–55 km of Vesta's rock volume, but instead, the physics shows that rocks are favored to crack apart. Therefore, the formation of these troughs must involve the opening of cracks, which is also important for understanding landforms on other small planetary bodies elsewhere in the Solar System. Key Points: Trough morphology is inconsistent with the previously proposed fault origin and points to an opening‐mode fracture originNormal faulting is not expected to be initiated above ∼3–55 km in Vesta's lithosphereOpening displacements from jointing contributed to the topographic expressions of large‐scale troughs [ABSTRACT FROM AUTHOR]

Late to post‐Caledonian, Devonian extension remains unresolved in the SW Barents Sea, despite considerable knowledge from onshore Norway, East Greenland and Svalbard. We analyse intrabasement seismic facies in high‐resolution 3D and reprocessed 2D data to investigate evidence for Caledonian deformation and post‐Caledonian detachment faulting in the central SW Barents Sea. These results are compared to published potential field models and analogue field studies from onshore Svalbard and Bjørnøya, substantiating that structures inherited from post‐orogenic extension influenced the Late Paleozoic and Mesozoic basin evolution. The Late Paleozoic Fingerdjupet Subbasin is underlain by a NNE‐striking, ESE‐dipping extensional detachment fault that records a minimum eastwards displacement of 22 km. The detachment fault and associated shear zone(s) separate post‐orogenic metamorphic core complexes from the syn‐tectonic deposits of a presumed Devonian supradetachment basin. Spatial variability in isostatically induced doming likely governed Devonian basin configurations. Pronounced footwall corrugations and faults splaying from the detachment indicate eastward extensional transport. This ultimately led to two interacting but subsequent, east‐stepping detachments. Local reactivation of the detachment systems controlled the extent of Carboniferous carbonate and evaporite basins in the Bjarmeland Platform area. Further, the Mesozoic Terningen Fault Complex and Randi Fault Set testify to how the inherited Devonian structural template continued to control spatial localisation and extent of rift structures during subsequent periods of extensional faulting in the Fingerdjupet Subbasin. [ABSTRACT FROM AUTHOR]

The Paleoarchean Mt Edgar dome in the East Pilbara Terrane has long been studied as an archetypal dome within Archean dome‐and‐keel terranes, but the history of its formation is debated. Kinematic data presented in this study provide new insights into the late‐stage development of the Mt Edgar dome and East Pilbara Terrane. Quartz crystallographic preferred orientation (CPO), optical microstructures, and field structures all indicate that the granite‐greenstone contact of the Mt Edgar dome experienced reverse (greenstone‐up, dome‐down) sense of shear after the formation of the dominant schistosity. This reverse sense of shear is observed at localities along the entire extent of the sheared margin that rings most of the Mt Edgar dome, but is best documented along the southwest margin in the Warrawoona Greenstone Belt. Additionally, quartz CPO data from a dome triple junction outside of the sheared margin dominantly indicate a constrictional strain geometry, consistent with the previous interpretation that this area represents a zone of vertical foundering in a buoyancy‐instability driven system. However, buoyancy‐instability models do not necessarily predict the occurrence of greenstone‐up sense of shear preserved in solid‐state fabrics along the dome margin. Several geologic explanations are considered, including dome expansion or post‐doming deformation. The data are most consistent with explanations that directly relate to dome formation, especially when considered in tandem with recently published structural data from within the Mt Edgar dome. These kinematic data suggest that late dome development occurred in a near‐static crustal environment rather than an extensional or contractional setting. Key Points: The granite‐greenstone interface at the margin of the granitic Mt Edgar dome is characterized by a late‐stage greenstone‐up sense of shearStrain geometry within the Warrawoona Greenstone Belt varies from constrictional to flatteningThe East Pilbara Terrane domes likely formed as diapiric structures in a near‐static crust [ABSTRACT FROM AUTHOR]

Part 1, "The Pioneers" (chapters 2-5), gives a detailed introduction to the history of research into Lewisian geology up to the 1960s. Chapter 19, "The wider picture: tectonic models", will be the most significant for many - how does the Lewisian sequence fit as a piece of the jigsaw in Precambrian plate evolution? In an advertisement for I The Lewisian i on a catalogue page of geology titles (not from the publisher), I saw it described as the book of the year or some such. It shows how the Lewisian can be related to changing modern concepts such as plate tectonics, ductile shear zones, evolving ideas concerning rare earth elements and geochronology. [Extracted from the article]

The 150‐km seismic gap in the Sea of Marmara is the longest section of the North Anatolian Fault that has not ruptured in the last century. Recent geodetic studies suggest that the interseismic coupling along the Main Marmara Fault (MMF) is heterogeneous with locked and creeping segments. Alternatively, the MMF is fully locked, but the strain is localized asymmetrically around the fault due to the deep basins. In this study, we build a 3‐D model of the region, including the basins and the 3‐D fault geometry, to study the competing effects of deep basins and the interseismic locking distribution using the observed Global Navigation Satellite System velocities. We conclude that the basins along the fault localize the interseismic strain, leading to slightly deeper‐estimated locking depths. The on‐land data are too far to constrain the full interseismic coupling, especially in the Central Marmara. The Western Marmara is better resolved, where we infer a ∼50‐km creeping zone. The transition from the creeping to the locked behavior in Western Marmara is around the Ganos Bend. The creeping zone correlates well with a higher rate of diffuse seismicity and repeating earthquakes, implying that the seismicity could be an indicator of interseismic behavior. Variations of earthquake focal mechanisms and associated regional stresses are also consistent with compressional and dilatational quadrants due to the creeping segment. The significant thrust components observed in the 2019 Silivri earthquake sequence north of the MMF can also be explained by the compressional loading due to the interseismic creep further west. Plain Language Summary: The Sea of Marmara, on the western extension of the North Anatolian Fault, is the only part of the fault that has not ruptured in the last century. Recent studies suggest that the interseismic locking or coupling, which is the ratio of interseismic slip rate deficit to the long‐term plate velocity, changes along the fault. Another suggestion is that the Main Marmara Fault is fully locked, and the deep basins cause strain localization and asymmetrical strain accumulation around the fault. In this study, we build a 3‐D model of the region to understand the fault locking and the basin effects on the deformation by using geodetic data. When the basin effects are considered, the estimated best‐fitting locking depths increase slightly. Especially in the Central and Kumburgaz Basin segments, the on‐land data are too far to constrain the full interseismic coupling behavior. Western Marmara is better resolved, where a transition from the 50‐km‐long creeping segment to the locked segment is well‐constrained to be located at the Ganos Bend. This unlocked segment correlates well with a high rate of earthquake activity and repeating earthquakes. We suggest that the heterogeneous interseismic coupling pattern is consistent with off‐fault focal mechanisms. Key Points: We consider the competing effects of the heterogeneous structure and interseismic behavior along the Main Marmara FaultThe basins that surround the fault lead to a more localized strain and slightly deeper locking depth estimatesThe existing data show creep in Western Marmara, which correlates well with the focal mechanisms, distribution of seismicity and repeaters [ABSTRACT FROM AUTHOR]

Geochronological 40Ar/39Ar investigations in the São Gabriel Terrane, Dom Feliciano Belt, Brazil, associated with previous structural geology and geochronology studies, allow for a better understanding of Neoproterozoic events in this region. The Sanga da Cachoeira Complex and metasedimentary rocks of Arroio Marmeleiro Complex (U–Pb provenance age > 1.5 Ga) show 40Ar/39Ar spectra with no successful plateau age, attributed to the alteration or excess 40Ar. Tonian (ca. 729 ± 9 Ma) 40Ar/39Ar hornblende age of metadiorites of the Cambaí Complex (U–Pb protolith age ca. 750 Ma) is interpreted to register the age of an early structure in this unit, where hornblende is a mineral of the composite banding fabric formed by remnants of original bedding, locally preserved, and added by metamorphic recrystallization. A cooling rate of at least 5°C/Ma is suggested for the Cambaí Complex, from its crystallization to its metamorphic event. The Cryogenian (<690 ± 8 Ma) 40Ar/39Ar hornblende and muscovite ages belonging to the Imbicuí Complex (protolith age ca. 869 Ma) whose ages are related to the late structure formed by a short and intense activity of the Cerro Branco Shear Zone, which experienced a rapid cooling of 12°C/Ma. The ages from the rocks belonging to such a diverse tectonic setting, including continental and intraoceanic island arc, oceanic crust low‐K amphibolites and meta‐harzburgites, and metasediments, presenting similar nature and fabric orientation, indicate that major tectonic‐magmatic–metamorphic activity was responsible for the accretion of these lithotectonic units that gave rise to the São Gabriel Terrane in southern Brazil. [ABSTRACT FROM AUTHOR]

The conglomerate‐sandstone transition (CST) preserved in foreland basins records the stratigraphic equivalent of the gravel to sand transition (GST) which migrates in response to shortening in steady state orogen‐foreland basin systems. Two seismic profiles in the southern Junggar foreland basin provide the first seismic record of migrating CSTs and an opportunity to quantify its migration history in response to the growth of the northern Tian Shan. We identify the horizontal positions of the CSTs based on the distinct seismic signature of conglomerate versus sandstone and estimate their ages according to magnetostratigraphic sections. The linear‐regression analysis reveals that the CSTs migrated northward at 0.4 ± 0.1 mm/yr along 84°E from ∼23 to ∼6 Ma and at 4.0 ± 1.2 mm/yr along 87°E from ∼3.1 to ∼0.7 Ma. The discrepancy relates to variations in crustal shortening along strike of the range. Temporal deviations in the CST positions suggest the second‐order impacts of climatic change. Plain Language Summary: Rivers in foreland basins commonly exhibit a sharp gravel to sand transition of bed sediment (GST), which is preserved in the stratigraphy as the conglomerate‐sandstone transition (CST). Previous studies attribute the migration of the CST in foreland basins to tectonics of the coupled mountain ranges. Migration of the CSTs is considered as a possible archive of long‐term crustal shortening in an orogen‐foreland basin system. In this study, we identify the horizontal position of the CST in the southern Junggar foreland basin north of the Tian Shan based on two seismic profiles. Ages of sedimentary layers imaged by the seismic profiles are estimated according to previous magnetostratigraphic investigations. A linear‐regression analysis between positions and ages of the CSTs indicates the northward migration rates of the CSTs. The rates approximate the long‐term crustal shortening rates in the northern Tian Shan orogen‐foreland basin system. A discrepancy between the migration rates of the CSTs in the eastern and western segments reveals variations in crustal shortening along the range. This work demonstrates that migration of CSTs in a foreland basin setting can act as a proxy of crustal shortening in orogen‐foreland basin systems. Key Points: We provide the first documentation of the migration of the conglomerate‐sandstone transition (CST) preserved in foreland basin successionsThe CST in the southern Junggar foreland basin migrates northward at 0.4 ± 0.1 mm/yr along 84°E and at 4.0 ± 1.2 mm/yr along 87°EDeviations between the measured and predicted CST positions are modulated by climate change [ABSTRACT FROM AUTHOR]

The Main Recent Fault is a major right‐lateral strike‐slip fault in the western Zagros mountains of Iran. Recent geodetic and geological studies estimate a low slip rate of 1–6 mm/yr at an unknown depth which, when combined with a non‐ideal fault geometry, makes the Main Recent Fault a difficult but interesting target for InSAR analysis. This analysis would further cement the estimated slip rate and provide an opportunity of estimate the depth to the base of the locked seismogenic zone, both important constraints on the seismic hazard posed by the fault, as well as for understanding how oblique convergence is accommodated and partitioned across the Zagros. We use 200 Sentinel‐1 SAR images from the past 5 years, spanning two ascending and two descending tracks, to estimate the first InSAR‐derived slip rate and locking depth for a 300 km long section of the fault. We utilize two established processing systems, LiCSAR and LiCSBAS, to produce interferograms and perform time series analysis, respectively. We constrain north‐south motion using GNSS observations, decompose our InSAR line‐of‐sight velocities into fault‐parallel and vertical motion, and fit 1‐D screw dislocation models to three fault‐perpendicular profiles of fault‐parallel velocity, following a Bayesian approach to estimate the posterior probability distribution on the fault parameters. We estimate an interseismic slip velocity of 2.4 ± 1.2 mm/yr below a loosely constrained 14 km locking depth, the first such estimate for the fault, and discuss the challenges in constraining the locking depth for low magnitude interseismic signals. Plain Language Summary: Convergence between the Arabian and Eurasian plates is causing deformation of the Earth's crust in Iran. Some of this motion is taken up by movement at depth on the Main Recent Fault, which is stuck by friction near the Earth's surface and is therefore accumulating strain which may then be released in an earthquake. We use 5 years of satellite radar images to measure the average velocity of the ground surface either side of the fault. By looking at the velocity difference across the fault, along with the gradient, we can estimate the rate at which the fault is accumulating strain and the depth below which this is occurring. Our estimated rate of 2.4 ± 1.2 mm/yr is in agreement with previous estimates from GPS studies, while our locking depth estimate of 14 km with a large uncertainty of 6–40 km, is the first such estimate for the fault. The broad range of possible values for the locking depth highlights the difficulties of studying tectonic signals when they are close in magnitude to the sensing limit of our satellite imagery method (1 mm/yr). Key Points: We derive East and Vertical surface velocities from 5.5 years of Sentinel‐1 synthetic aperture radar images over the western ZagrosWe estimate an interseismic slip rate of 2.4 ± 1.2 mm/yr (2σ) for the Main Recent Fault, in agreement with previous GNSS studiesWe estimate a geodetically‐determined interseismic locking depth of 14 km with a large uncertainty of 6–40 km, a first for this fault [ABSTRACT FROM AUTHOR]

For decades, monitoring and identification of the dynamic stress states of rock masses in reservoirs have been challenging tasks owing to the lack of effective observation and analysis methods. In this study, we used deep learning methods to identify whether acoustic emission (AE) signals of rock fractures are created by different loading conditions. We performed Brazilian split and uniaxial compressive experiments on six different engineering materials, and we obtained the AE waveforms. To take advantage of the powerful image processing capabilities of convolutional neural networks (CNNs), we transformed the AE waveforms into time–frequency images. We used five types of CNN to identify the time–frequency images of the AE signals created in the Brazilian split and uniaxial compressive experiments. As a result, we found that Xception model had the highest recognition accuracy. We analyzed the basis of the CNN models to recognize the AE signals using local interpretable model‐agnostic explanations and found that the Xception model mainly used the patterns of the low‐energy region of the time–frequency images to determine the loading modes of the rock fractures. Furthermore, the high‐energy time–frequency region had little effect on recognition. The findings of this work can aid in automatically monitoring the dynamic stress states of fracture areas in reservoir formations and ensure the safety of oil and gas resource exploitation. Plain Language Summary: The monitoring and identification of dynamic stress states of fracture areas in reservoirs is a challenging task owing to the lack of effective observation and analysis methods. With the development of deep learning, the image recognition ability of artificial neural networks has considerably improved. Therefore, we transformed the acoustic emission signal into a picture format using wavelet transform. We used various convolutional neural networks models to recognize the loading modes of rock fractures, and the Xception model had the highest recognition accuracy. We also found that the Xception model identifies the loading modes based on the pattern of the low‐energy region of the time–frequency images, and the high‐energy region has little effect on the discrimination. The method presented in this work can be used to effectively monitor the dynamic stress states of reservoir formations during geological energy exploitation. Key Points: Acoustic emission signals of rock fractures created by uniaxial compression and Brazilian split exhibit differencesThese differences can be identified accurately by the properly pre‐trained convolutional neural networksConvolutional neural networks distinguish acoustic emission types by time‐frequency pattern characteristics rather than high energy [ABSTRACT FROM AUTHOR]

From 2017 to 2019, three destructive earthquakes (27 January 2017 Mw 4.7, 16 December 2018 Mw 5.2, and 3 January 2019 Mw 4.8) occurred in the Changning shale gas field in the southwest Sichuan Basin, China. Previous seismological studies attributed these events to hydraulic fracturing (HF), but were unable to identify the causative seismogenic faults and their slip behaviors. Here, we use Sentinel‐1 synthetic aperture radar data to measure surface deformation triggered by the three events and conduct geodetic inversions to characterize their rupture models. The resulting coseismic interferograms show prominent surface deformation with the maximum line‐of‐sight displacements of up to 4 cm. The inversion results show that all three earthquakes mainly ruptured sedimentary formations above the shale gas bed, in the upper 3 km of the crust, with slip magnitudes ranging from 8.5 to 15 cm, and stress drops ranging from ∼1.8 to ∼3.3 MPa. Their source faults intersect with horizontal HF wells, but do not root in the crystalline basement. Combined with the reported difficulty of increasing HF operation pressures prior to the three events, we argue that they were most likely induced by direct injection of pressurized fluids into the fault zones. Crustal deformation patterns inferred from regional topography and GPS velocities highlight that the Changning field is located within a triple junction region near the southeastern margin of the Tibetan Plateau with large deformation gradients; such conditions are not only favorable to the development of critically stressed faults, but also facilitate the occurrence of at least moderate magnitude earthquakes. Plain Language Summary: The number of earthquakes induced by the process of shale gas extraction through hydraulic fracturing (HF) has been increasing across the globe, with dozens of M > 4 events reported by the end of August 2021. Although most case studies on HF‐induced seismicity are from the United States and Canada, the southwestern Sichuan Basin (China), located to the southeast of the Tibetan Plateau, is another region with notable seismicity linked to HF operations, including dozens of moderate‐to‐large earthquakes. We here focus on the three largest Mw ≥ 4.7 earthquakes that occurred within the Changning shale gas field up to now. We use geodetic techniques to measure ground deformation caused by the three earthquakes and to further infer their ruptures at depth. Our results reveal that the three earthquakes occurred on shallow faults intersecting with horizontal HF wells, with little‐to‐no slip in the crystalline basement below the depth of 3 km. These questions the common theme of HF‐induced earthquakes having hypocenters proximal to basement rock, presumably associated with basement‐rooted faults, and suggests that the potential for ground shaking of HF‐induced earthquakes is more significant than previously understood. Key Points: The three events ruptured shallow faults within sedimentary formations above the shale gas bed rather than basement‐rooted faultsThe faults of the three events intersect with horizontal hydraulic fracturing wells and were likely reactivated by direct fault‐zone pressurizationHigh HF‐induced seismicity rate in the Changning area links to the proximity to a triple junction region with relatively high tectonic strain accumulation rates [ABSTRACT FROM AUTHOR]

The Delaware Basin, Texas is currently a hot‐spot of induced seismicity and ground deformation due to fluid extraction and injection associated with horizontal drilling techniques; however, the driving mechanism behind the seismicity and deformation remains under debate. Using vertical and east‐west horizontal surface deformation measurements derived from Sentinel‐1 interferometric synthetic aperture radar (InSAR), we show that the subsurface responds differently to oil and gas activity in the northern and southeastern portions of the basin. In the north, where there is little seismicity, deformation patterns display long‐wavelengths and equidimensional patterns. In contrast, the southeast region hosts most of the seismicity and displays spatial deformation patterns with narrow linear features that strike parallel to the maximum principal horizontal stress and to trends in seismicity, suggesting movement along normal faults. We model a linear deformation feature using edge dislocations and show that the InSAR observations can be reproduced by slip on normal faults contained within the Delaware Mountain Group (DMG), the formation that hosts local wastewater injection and the majority of earthquakes. Our model consists of three parallel, high‐angle normal faults, with two dipping toward one another in a graben structure. Slip magnitudes reach up to 25 cm and are spatially correlated with injection wells. Measured seismicity can only explain ∼2% of the fault motion predicted by our fault model, suggesting that slip leading to the deformation is predominantly aseismic. We conclude that seismic and aseismic fault motion in the southeastern Delaware Basin is likely driven by wastewater injection near critically‐stressed normal faults within the DMG. Plain Language Summary: In the Delaware Basin, TX, widespread oil and gas operations have been linked to an increase in earthquake frequency and ground deformation. We use satellites to measure the ground deformation and show that the northern and southern portions of the basin respond differently to the pumping and injection of fluids. The southern portion displays narrow linear displacement patterns, whereas the northern region displays wide and equidimensional features. The relationship of the narrow features in the southern portion of the basin to local stress conditions and earthquake locations suggests downward slip on faults. Using analytic models in a small study area, we develop a three‐fault slip model that is consistent with ground displacement measurements, the location and sense of slip of the largest local earthquakes, and wastewater disposal wells. Our findings suggest that wastewater disposal in the Delaware Mountain group is reactivating pre‐existing normal faults, leading to induced earthquakes and non‐seismic slip. Key Points: Linear deformation features in the southeastern portion of the Delaware Basin are attributed to aseismic slip on normal faultsIdentified faults create graben structures that likely belong to a larger graben networkAseismic and seismic fault movement in Texas' Delaware Basin can be linked to wastewater injection in the Delaware Mountain group [ABSTRACT FROM AUTHOR]

Laboratory experiments on partially saturated rocks show that seismic attenuation can be significant. The main mechanism, wave‐induced local fluid flow (WILFF), is affected by the spatial fluid distribution, especially in conditions of patchy saturation at different spatial scales. We propose a theory to obtain the seismic properties of partially saturated rocks based on fractal (self‐similar) patches, leading to an effective frequency‐dependent fluid modulus. The model combines the differential effective medium and Biot‐Rayleigh theories, where the patches are inclusions incrementally added, such that the effective fluid calculated in the current addition serves as host fluid in the next one. The analysis shows that adding identical inclusions in one or several steps produces nearly the same results, but the seismic properties depend on the scale range (radius) of the inclusions, fractal dimension Df of the self‐similar distribution, parameter θ $\theta $ of the exponential distribution, mean radius r0 and variance σr2 ${\sigma }_{r}^{2}$ of the Gaussian distribution. Forced‐oscillation experiments were performed on a limestone sample under partial water‐saturation conditions at seismic frequencies (2–500 Hz), to obtain the velocity dispersion and extensional attenuation. The proposed theory provided a reasonable description of these experimental data as well as other published measurements on tight carbonate and Berea sandstone. Plain Language Summary: Seismic wave velocity dispersion and attenuation in partially saturated rock are affected by the size of the fluid patches, and their fractal dimension. To study this phenomenon, we have developed a wave propagation theory, in which the final partially saturated material is incrementally constructed by adding inclusions in size order into a homogenous frame saturated by a host fluid. We analyze the effects of wave‐induced local fluid flow due to the multi‐scale fluid heterogeneities on wave attributes. The broadband wave anelasticity predicted by the model is strongly affected by the scale range of the heterogeneities and their fractal dimension. The theory was compared with experimental data measured on different rock specimens and the fluid distribution characteristics at different saturations were estimated. Key Points: We present a wave propagation theory for partially saturated rocks with a fractal (self‐similar) distribution of fluid patchesWe analyzed the effects of wave‐induced local fluid flow on seismic attributes due to multi‐scale fluid heterogeneitiesWe estimated variations of the fluid distribution characteristics in partially‐saturated rock samples by tying the data to the low frequency measurements [ABSTRACT FROM AUTHOR]

Understanding the stress state before and after an earthquake is essential to study how stress on faults evolves during the seismic cycle. This study integrates wellbore failure analysis, laboratory experiments, and edge dislocation model to study the stress state before and after the Chi‐Chi earthquake. The post‐earthquake in‐situ stress state observed along boreholes of the Taiwan Chelungpu‐fault Drilling Project (TCDP) is heterogeneous due to lithological variations. Along the borehole, we observe that drilling‐induced tensile fractures are only present in sandstones, whereas breakouts are mostly present in silt‐rich rocks. Laboratory experiments on TCDP cores also show that tensile and compressive strength are weaker in sandstones than in silt‐rich rocks. These observations imply that both maximum and minimum horizontal principal stresses are higher in silt‐rich intervals. Extended leak‐off tests in the TCDP borehole also show lower minimum horizontal stress in sand‐rich intervals, consistent with the above observations. We combine these observations to estimate a profile of stress magnitudes along the well which explains the variability of stress states found in previous studies. The stress heterogeneity we observed underlines the importance of acknowledging the spatial scale that the stress data represent. We then use an edge dislocation model constrained by GPS surface displacements obtained during Chi‐Chi earthquake to calculate the coseismic stress changes. Our inferred pre‐earthquake stress magnitudes, obtained by subtracting the coseismic stress change from the post‐earthquake stress, suggest subcritical stress state before the earthquake despite the large displacements observed during the Chi‐Chi earthquake in the region where TCDP encountered the fault. Plain Language Summary: Stress in the Earth's crust defines the forces acting on faults which drive earthquakes. Therefore, tracking how stress accumulates due to plate motion and is released due to fault slip have been a central topic in the study of earthquake mechanics and associated seismic hazard. Previous studies which analyzed data collected from Taiwan Chelungpu‐fault Drilling Project (TCDP), drilled after the 1999 Chi‐Chi earthquake, show that the post‐earthquake stress inferred from those studies is inconsistent with each other. This study reviewed previous measurements, conducted laboratory experiments, and analyzed borehole data to revisit the stress state after the Chi‐Chi earthquake. We show that stress state varies along the TCDP borehole due to lithology and fault‐related changes in mechanical properties, which explains why past studies indicated significant variability. We also estimated the pre‐earthquake stress before the Chi‐Chi earthquake to understand stress conditions leading to the rupture. We calculated the stress change caused by the Chi‐Chi earthquake and subtract it from the post‐earthquake stress to obtain the pre‐earthquake stress. Our pre‐earthquake stress estimate suggests that the stress before the Chi‐Chi earthquake was low in magnitude compared to the frictional strength of rocks. Key Points: We obtain a near‐continuous stress profile which captures the lithology‐dependent and fault‐related stress variation along the boreholesVariability in stress states reported from previous studies is explained by stress variations caused by lithological variationsThe estimated pre‐earthquake stress profile indicates subcritical stress state within the Chelungpu fault zone prior to the earthquake [ABSTRACT FROM AUTHOR]

Since the occurrence of the 2019 Mw 6.4 and Mw 7.1 Ridgecrest earthquake sequence in the Eastern California Shear Zone, coseismic deformation following the two earthquakes has been intensively studied, and source modeling with interferometric synthetic aperture radar (InSAR), Global Positioning System (GPS) and seismological datasets has been favored. However, we recently found that the coseismic modeling of the two earthquakes constrained by the dense near‐field Planet‐Lab optical measurements can be more detailed than the previously estimated, which requires an accurate Planet‐Lab displacement. In this study, we improve the long wavelength orbital ramps correction method for obtaining a more accurate Planet‐Lab horizontal displacement field. The corrected dense near‐field Planet‐Lab data are firstly used together with the intermediate‐field GPS data to invert and distinguish the fault slip distribution for the two earthquakes. The same scheme is used to simultaneously invert the InSAR, SAR, GPS, and optical datasets, to improve the constraints on seismic source parameters. Our inversion results show that the joint‐event slip model is rougher than the two single‐event slip models, but it has a more concentrated slip pattern and larger slip amplitude in some zones. We show that adding a near‐field constraint of the Planet‐Lab data in the combined‐data inversion can reduce the slip parameter uncertainty and enhance the model resolution. The Coulomb failure stress changes on the southeastern Blackwater, the southern Owens Valley, and the central Panamint Valley faults are enhanced by about 0.4–0.8 bar by the 2019 Ridgecrest earthquake sequence. Plain Language Summary: In July 2019, an earthquake sequence, including an Mw 6.4 foreshock on 4 July at 17:33 UTC and an Mw 7.1 mainshock that occurred 34 hr later, struck the Ridgecrest, southern California. Previous studies have used the Planet‐Lab data to extract the surface displacement of the respective events but ignored the long wavelength ramps in each block of the Planet‐Lab image displacement field. We improve the correction method for long wavelength orbital ramps to obtain a more accurate Planet‐Lab horizontal displacement field. The source model of individual events during an earthquake sequence is routinely inverted from seismic waveforms and/or GPS data, which, however, have difficulty in obtaining the detailed slip distributions, due to their low spatial density. We use the corrected Planet‐Lab horizontal displacement to improve the near‐field data constraints in source modeling. This work is the first application of using the Planet‐Lab data to separate the fault slip model of the two strongest earthquakes during the Ridgecrest earthquake sequence, highlighting the importance of the high spatiotemporal resolution Planet‐Lab data in refining fault geometry and restoring detailed fault slip distribution. Key Points: Improved the correction method for long wavelength orbital ramps to obtain a more accurate Planet‐Lab horizontal displacement fieldResolved and separated the detailed slip distributions of the foreshock and mainshock using the GPS and dense Planet‐Lab optical dataImproved source modeling through the combined use of InSAR, SAR, GPS, and optical datasets [ABSTRACT FROM AUTHOR]

The Beiya gold polymetallic ore deposit is one of the largest gold deposit in the world. Previous studies have suggested the formation of the Beiya deposit is closely related to the porphyritic alkaline intrusions. Different tectonic models have been proposed by geologists to explain the alkaline intrusions. However, no consensus has been reached and data for imaging of the deep crustal structure is lacking. In this study, we use magnetotelluric data to image the 3‐D crustal structure beneath the Beiya deposit and adjacent areas. The 3‐D electrical resistivity model is characterized by two conductors and three resistors, which depicts the magmatic system and fluids migration path related to the Beiya deposit. One shallow conductor beneath the Beiya deposit is suggested to represent a cooled magma chamber, which provided essential heat and metal‐rich fluids to the Beiya deposit. The shallow conductor is connected to a deep conductor located beneath the Ailaoshan‐Red River shear zone. Thus, magmas originated from mantle upwelling in an extensional tectonic background is believed to provide the heat that melted the crust and generated intermediate melts, the Ailaoshan‐Red River shear zone is proposed to facilitate ascending of partial melts from the base of the crust. Moreover, two resistors encircles the shallow conductor at upper crustal depths could have acted as an impermeable barrier that helped further subtraction of metal‐rich fluids. The Beiya gold polymetallic deposit is believed to be a typical porphyry‐skarn deposit formed closely related to the Ailaoshan‐Red River shear zone in an extensional tectonic setting. Plain Language Summary: The Beiya gold deposit is one of the largest in the world. Previous studies have suggested the formation of it is closely related with one kind of igneous rocks enriched with Na‐ and K‐ bearing minerals. Different geological models have been proposed to explain the formation of these igneous rocks. However, no agreement has been reached. In this study, we use one kind of geophysical data (magnetotelluric) to image the 3‐D crustal structure beneath the Beiya deposit. The data was used to map the electrical resistivity of rocks within the Earth from the surface to a depth of 50 km. One shallow conductor is located beneath the Beiya deposit and is suggested to be the geological body which provided heat and metal‐rich fluids to the Beiya deposit. It is connected to a deep conductor underneath the Ailaoshan‐Red River shear zone, which is a deep and long deformation zone caused by shear strength. Thus, melted materials from the mantle is believed to rise and provide heat for further melting of the crust in a tectonic background where the subsurface rocks are under extensional forces. The mantle and crust melts mixed in a complex way and generated melts of intermediate composition. The Ailaoshan‐Red River shear zone is proposed to facilitate ascending of the intermediate melts from the base of the crust. Key Points: The magmatic system related to the formation of the Beiya deposit is imaged by a 3‐D magnetotelluric surveyA deep magmatic source is imaged beneath the Ailaoshan‐Red River shear zoneThe result supports the Beiya deposit was formed in an extensional tectonic setting and associated with the Ailaoshan‐Red River shear zone [ABSTRACT FROM AUTHOR]

We present hydro‐mechanical measurements that characterize shear on natural fractures in schist, amphibolite, and rhyolite specimens from the enhanced geothermal system (EGS) Collab Project's Experiment 1 and 2 sites (E1 and E2) at the Sanford Underground Research Facility. We employed a triaxial direct shear method augmented with X‐ray imaging to perform hydroshearing (injection‐induced shearing) and mechanical shearing on naturally fractured specimens at in situ stress conditions. Measurements included fracture permeability, strength, stress‐dependent aperture, shear dilation, and frictional strength. Results reveal that in situ natural fractures must be permeable, weak, and shear‐oriented to be hydrosheared, and only a subset of the observable in situ fractures were suitable. When sheared, the fracture permeability typically increased by a factor of 10 or more and this increase was retained over time. However, shear slip did not always result in permeability increase. High phyllosilicate content associated with exceptionally weak fractures exhibited poor or even decreased permeability after stimulation. These measurements in combination with site data were used to conduct a slip‐tendency analysis for different fracture sets, and we selected the top candidate natural fractures for hydroshearing at the EGS Collab sites. We also found that the lower in situ shear stress and stronger fractures at the E2 site make hydroshearing more challenging than at the E1 site. Overall, the methods and analysis used in our work can be applied to any geothermal project to identify in situ joint sets that are best suited for hydroshearing, which in turn can help to optimize well placement and energy production. Plain Language Summary: Geothermal energy is attractive because it is green, clean, and "always on". However, technical challenges and high‐capital costs historically hindered its development. Among the technical challenges, is a need to reliably increase the rock permeability to promote productive geothermal wells. One leading method is called "hydroshearing", where fluid is injected to encourage shear slip along pre‐existing natural fractures and thus open the fractures to increase permeability. Our research focuses on the enhanced geothermal system (EGS) Collab Project's field sites where we characterize actual natural fractures so that we can predict shear slip via hydroshearing and then identify the best locations for drilling wells suitable for hydroshearing. This work included measuring a suite of coupled hydraulic and mechanical properties for crystalline geothermal rocks drilled from this field site. We demonstrate that pre‐existing natural fractures must be mechanically weak, favorably oriented, and sufficiently permeable to be hydrosheared. Combining measured in situ stresses with natural fractures properties, we were able to identify suitable natural fractures for hydroshearing and to better optimize well design at the EGS Collab sites. This positive outcome from our work could be similarly applied to full‐scale geothermal systems to improve well productivity, reduce the risk of failed wells, and to improve economics. Key Points: Hydroshearing requires a natural fracture that is mechanically weak, hydraulically conductive, and favorably orientedFracture shear slip does not always result in permeability enhancement; when phyllosilicate rich, we observed decreasing permeabilitySlip‐tendency analysis improved by hydro‐mechanical measurement helps to select the best candidate fracture for hydroshearing in the field [ABSTRACT FROM AUTHOR]

In an effort to reveal the subsurface hydraulic changes in fractures by seismic monitoring, aperture‐related velocity changes need to be investigated. We developed a numerical approach for calculating changes in elastic wave velocity with fracture aperture opening by determining the internal energy of a digitized fracture model based on natural rough surfaces. The simulated local elastic energy revealed that the interaction energy converged within 1.5 mm of the mean fracture position, and was insignificant unless the fractures intersected. This energetic approach clarified the aperture‐velocity relationship and reproduced the experimental results. Further calculations using digital fractures with various sizes and densities demonstrated that the velocity can be accounted for by the superposition of a linear function of fracture density and quadratic function of aperture, and is insensitive to the fracture size. Although the relationship between fracture permeability and elastic wave velocity (i.e., the k‐V relationship) depends on the fracture density, the offset‐normalized k‐V relationship shows clear linearity with the fracture density. The proposed k‐V relationship as a function of the aperture and fracture density indicates that laboratory‐scale fracture properties of a single fracture can be applied to multiple fractures on a larger scale. Our findings can be used to interpret temporal changes in seismic observations and to monitor fluid flow in fractures. Plain Language Summary: A monitoring of seismic velocity will be useful to find changes in the permeability of fractures, if the relationship between elastic wave velocity and fracture aperture is known. This study presents a numerical approach to calculating changes in elastic wave velocity, based on the elastic energy calculated using a digital rock model having simulated natural fractures. The proposed approach revealed the relationship between fracture aperture and elastic wave velocities propagating through the fracture. Further calculations showed linear decreases of wave velocities with the number of fractured layers per unit thickness (i.e., the fracture density), whereas the velocities do not significantly change with fracture size. Our results will allow us to formulate the relationship between fracture permeability and elastic wave velocity as a function of fracture density. The proposed equation suggests that the properties of a single fracture on the laboratory scale can be used for a large‐scale multiple fracture system. The results will provide a prospective application of seismic data to be used in the sustainable development of fractured reservoirs such as geothermal resources. Key Points: A numerical approach based on internal energy calculations was developed to calculate precise velocity changes with fracture openingVelocity can be accounted for by superposition of a linear function of the fracture density and quadratic function of the aperture sizeNormalized velocity has a linear relationship with normalized permeability, and the trend depends on fracture density [ABSTRACT FROM AUTHOR]

Recent structural and geodetic data define the Guatemala City graben region as the continental triple junction between the North American plate, Caribbean plate, and the Central American Forearc sliver. We present minor fault analysis, geochronological and geochemical analyses, and newly updated GPS velocities in western Guatemala, west of the Guatemala City graben, to characterize the magnitude and timing of extensional deformation in this poorly understood area. Elongations estimated from fault data are parallel (∼east‐west) and perpendicular to the Polochic‐Motagua fault system to the north, similar to geodetically measured active deformation observed east of the Guatemala City graben. Four new 40Ar/39Ar dates and correlation of tephra deposits suggest that faulting was active during the Pliocene, but ceased eastward toward the Guatemala City graben over time. From west to east, fault cessation occurred before the deposition of the Los Chocoyos ash (75 ka) and E tephra (51 ka). Faulting just west of the Guatemala City graben appears to be active, where a major fault cuts the most recent Amatitlán tephras. Based on this data, we propose a time‐progressive strain model for deformation related to North America‐Caribbean plate interactions, whereby distributed elongation of the westernmost Caribbean plate occurred during the Pliocene but localized mostly within the Guatemala City graben and nearby faults during the Pleistocene. Our model supports that: (a) The Guatemala City graben is effectively the western limit of the Caribbean plate; and (b) Western Guatemala, which was the trailing edge of the Caribbean plate, has been transferred to the forearc region. Key Points: Distributed deformation once extended across Guatemala and into Honduras and has localized into the Guatemala City graben region over timeThe Guatemala City graben region is the current North America, Central American Forearc, and Caribbean plate triple junctionFaulting in western Guatemala, representing internal deformation of the Caribbean plate, ceased in an eastward direction over the past ∼4 Ma [ABSTRACT FROM AUTHOR]

My two favourite chapters were "Igneous intrusions" (chapter 8), which explains the interactions between intrusions and crustal stress, and "Structural effects of gravity" (chapter 9). The discussion of the classification of eruption types (ch. 4) is another informative chapter. "White peak limestone" (chapter 2) and "Limestone country" (chapter 7) were magnets for me - what were the Mississippian environments and where are the reefs? Again, "Underground" (chapter 8) reminded me of forgotten pleasures and is an enticement to return to the Castleton area sometime soon; it is a long time since I searched for blue john around the Odin Mine ("Mineral riches"; chapter 10). [Extracted from the article]

In this review, we attempted to summarize and interpret the Phanerozoic geology and mineralization following the article (vol. 71 in Resource Geology) which reviewed the Precambrian geology and mineralization of North Korea. The basement of the Korean peninsula was built during the Precambrian and gradually became more evolved and complex during the Phanerozoic. The northern part of the peninsula was in the active and passive continental margins of the Korea–China platform during the Phanerozoic. In the tectonic environments of the Phanerozoic, the tectonic provinces of North Korea comprise several Paleozoic–Mesozoic intracontinental and rift basins as well as Cenozoic ocean border and rift basins. During the Paleozoic, the sedimentary strata were formed within the marine‐to‐nonmarine intracontinental basins, such as the largest Pyeongnam and Hyesan–Iwon basin, Imjingang rift basin, and several small structural basins, and the sedimentary type of limestone, dolomite, and coal deposits were formed. Mesozoic orogenic events in the peninsula were the most overwhelming geologic event causing block movements through collision and subduction of the paleo‐Pacific plate. Songrim orogeny (late Permian to early Triassic) might be caused by continental collision associated with strong deformation, metamorphism, and granite intrusion. Daebo orogeny (Jurassic) resumed the crustal deformation under a contractional setting during the subduction and caused dextral ductile shearing, magmatism, and metamorphism in the entire peninsula. Amnokgang orogeny, corresponding to Bulguksa orogeny in South Korea, during the Cretaceous formed several pull‐apart or transtensional basins probably because of oblique subduction of the Izanagi plate, and nonmarine sedimentary and pyroclastic sequences were deposited in the basin. The mineralization related to the Mesozoic plutonism was the most dominant in the peninsula. The considerable mineral deposits are ultramafic related magmatic Ni deposits owing to rift magmatism and granite related hydrothermal Au–Ag, Cu, Pb–Zn, Fe, W, and Mo deposits caused by the subduction of paleo‐Pacific plate. During the Tertiary, several structural basins under the extensional regime were overprinted on the Mesozoic basins in the northern part of the peninsula. They contain marine and nonmarine sedimentary rocks and felsic–mafic extrusives. Some sedimentary deposits, such as coal, kaolin, bentonite, diatomite, and zeolite, were formed. The Tertiary Pohang basin in South Korea shows basin geology, magmatism, and mineralization similar to those of North Korea. The Phanerozoic geotectonics of the peninsula are characterized by the evolution of the structural basins and violent magmatism. The peninsula is located on the Amur plate, bounded by the Philippine plate, Pacific plate, and Eurasian plate. Since Phanerozoic, the peninsula's geographic position created an important tectonic link between northeastern China and the Japanese Islands throughout geotectonic evolution. [ABSTRACT FROM AUTHOR]

Distinguishing between seismic and aseismic fault slip in the geologic record is difficult, yet fundamental to estimating the seismic potential of faults and the likelihood of multi‐fault ruptures. We integrated chirp sub‐bottom imaging with targeted cross‐fault coring and core analyses of sedimentary proxy data to characterize vertical deformation and slip behavior within an extensional fault bend along the Hayward‐Rodgers Creek fault system in northern San Pablo Bay. We identified and traced four key seismic horizons (R1–R4), all younger than approximately 1400 CE, that cross the fault and extend throughout the basin. A stratigraphic age model was developed using detailed down‐core radiocarbon and radioisotope dating combined with measurements of anthropogenic metal concentrations. The onset of hydraulic mining within the Sierra Nevada in 1852 CE left a clear geochemical and magnetic signature within core samples. This key time horizon was used to calculate a local reservoir correction and reduce uncertainty in radiocarbon age calibration and models. Vertical fault offset of strata younger than the most recent surface‐rupturing earthquake on the Hayward fault in 1868 CE suggest near‐surface vertical creep is occurring along the fault in northern San Pablo Bay at a rate of approximately 0.4 mm/yr. In addition, we present evidence of at least one and possibly two coseismic events associated with growth strata above horizons R1 and R2, with median event ages estimated to be 1400 CE and 1800 CE, respectively. The timing of both these events overlaps with paleoseismic events on adjacent fault sections, suggesting the possibility of multi‐fault rupture. Key Points: Onset of hydraulic mining deposition in 1852 CE is key to unraveling northern Hayward fault earthquake historyNear‐surface aseismic creep detected along the Hayward fault in northern San Pablo BayRecord of two coseismic or triggered slip events provide insight into the potential for multi‐fault rupture in the San Francisco Bay Area [ABSTRACT FROM AUTHOR]

Oceanic transform faults are inferred to be weak relative to surrounding oceanic crust and primarily slip aseismically. Neither their weakness nor tendency to creep are well‐explained. We test the effects of fault‐rock evolution on oceanic transform fault frictional strength and stability using direct‐shear experiments (at room temperature, 10 MPa normal stress, and fluid‐saturated conditions) on dolerite from the East Pacific Rise and natural fault rocks from the exhumed Southern Troodos Transform, Cyprus. Dolerites and cemented breccias are frictionally strong (μ = 0.52–0.85) and velocity‐weakening (strength decreases with increasing slip velocity, characteristic of earthquakes). In contrast, matrix‐rich chlorite‐bearing fault breccias and gouges are frictionally weak (μ = 0.25–0.48) and velocity‐strengthening (characteristic of stable creep). This transition implies that seismic behavior is controlled by degree of damage and alteration, such that earthquakes can nucleate within relatively intact oceanic crust, whereas fault segments of increased damage and chlorite content tend to slip aseismically. Plain Language Summary: Oceanic transform faults are plate boundary faults where motion of oceanic lithosphere is dominantly horizontal and parallel to tectonic motion. Fewer and smaller earthquakes than expected occur along these faults, which are also considered weak structures. The reasons for their weakness and lack of large earthquakes are puzzling. To understand these characteristics, we conducted laboratory deformation experiments using rocks collected from the ocean floor (near Hess Deep in the Pacific) and from an ancient transform fault (in Cyprus). We sheared cylindrical samples, holding one half in place and sliding the other over it, creating laboratory equivalents of geological faults. We find that dolerite, one of the primary rock‐types of the oceanic crust, is strong and capable of starting earthquakes. In contrast, we find that already damaged and altered rocks, found within natural faults (containing an increased proportion of the mineral chlorite), are weak. The same damage and alteration responsible for the weakness also prevents earthquakes. Our findings suggest that variations in the size and number of earthquakes on oceanic transform faults is controlled most of all by how damaged the existing rock is and how much alteration to weak, water‐bearing secondary minerals such as chlorite has occurred along fault planes. Key Points: Dolerite hydrothermally cemented at greenschist facies is strong and velocity‐weakening at 10 MPa normal stress and room temperatureNatural fault rocks comprising chlorite‐rich, fractured, and comminuted metadolerite are frictionally weak and velocity‐strengtheningAlong oceanic transform faults, in the mafic oceanic crust, increased damage and alteration can explain fault weakness and aseismic slip [ABSTRACT FROM AUTHOR]

The Great Basin in the western United States hosts various hydrothermal systems, including both active geothermal systems and ancient systems preserved as mineral deposits. New magnetotelluric and structural geologic data were collected in the Gabbs Valley area of western Nevada to demonstrate the advantage of imaging the full crustal column below known hydrothermal systems. Three‐dimensional models are developed and jointly interpreted where the key findings are bottom‐up and top‐down controls on hydrothermal systems. Bottom‐up control is dictated by weaknesses in the brittle‐ductile transition that allow hydrothermal fluids to propagate into the crust; these are often collocated with Miocene volcanic structures. Top‐down control is dominated by modern Walker Lane and Basin and Range tectonics that control fluid transport through the middle and upper crust. This study demonstrates that the characterization of regional mineral and geothermal resources is better informed by imaging lower crustal structures and preferential pathways to the surface. Plain Language Summary: The Great Basin in the western United States is home to many natural resources including geothermal and mineral resources. Most resources that have surface expressions have been found, but many more lie undercover. New applications of geophysical methods are needed to locate and characterize these resources. In this study, we combine 3‐D models developed from magnetotellurics (MT), a passive electromagnetic method sensitive to fluids, and structural geological data to image the crust from the surface to a depth of 40 km. From these 3‐D models, four important conclusions are developed. (a) Heat/fluid sources related to active hydrothermal systems in the Great Basin are controlled by processes and structures in the lower crust and are commonly found under the basins. (b) Fluids that penetrate into the lower crust are controlled by weaknesses in the crust that are commonly located where past volcanic activity occurred. (c) Heat transport to the near surface is controlled by modern Basin and Range and Walker Lane tectonics. (d) Understanding relations between deep heat/fluid sources and near‐surface mineral deposits and active geothermal systems greatly improves the potential to characterize resources undercover. Key Points: Characterization of mineral and geothermal resources in the Great Basin requires geophysical imaging of the full crustal columnStructures at the brittle‐ductile transition control how heat and fluids flow into the upper crustElectrical resistivity models complemented with structural geology data highlights crustal fluid pathways related to resources [ABSTRACT FROM AUTHOR]

The increase of available seismic data prompts the need for automatic processing procedures to fully exploit them. A good example is aftershock sequences recorded by temporary seismic networks, whose thorough analysis is challenging because of the high seismicity rate and station density. Here, we test the performance of two recent Deep Learning algorithms, the Generalized Phase Detection and Earthquake Transformer, for automatic seismic phases identification. We use data from the December 2019 Mugello basin (Northern Apennines, Italy) swarm, recorded on 13 permanent and nine temporary stations, applying these automatic procedures under different network configurations. As a benchmark, we use a catalog of 279 manually repicked earthquakes reported by the Italian National Seismic Network. Due to the ability of deep learning techniques to identify earthquakes under poor signal‐to‐noise‐ratio (SNR) conditions, we obtain: (a) a factor 3 increase in the number of locations with respect to INGV bulletin and (b) a factor 4 increase when stations from the temporary network are added. Comparison between deep learning and manually picked arrival times shows a mean difference of 0.02–0.04 s and a variance in the range 0.02–0.07 s. The improvement in magnitude completeness is ∼0.5 units. The deep learning algorithms were originally trained using data sets from different regions of the world: our results indicate that these can be successfully applied in our case, without any significant modification. Deep learning algorithms are efficient and accurate tools for data reprocessing in order to better understand the space‐time evolution of earthquake sequences. Plain Language Summary: We focus on the testing and comparison of recently published frameworks for seismic events and seismic waves detection based on deep learning. As an example we use data from an earthquake swarm that occurred in December 2019 in the Mugello basin (N of Florence, Italy). Earthquake swarms analysis is particularly challenging because of the high seismic rates, with events closely occurring in time and space. The results of the automatic analysis are compared with results reviewed by human analysts. The deep learning algorithms used in this application were originally trained on data collected from different regions of the world: Our results indicate their capability to apply the knowledge gained in different contexts to totally unseen data. However, some differences, due to the different design of the algorithms and to training data sets, arise and suggest that careful tuning and benchmarking are required to achieve stable and reliable results in seismic data analysis workflows. Key Points: We analyze the Mw 4.5 Mugello (Italy) earthquakes sequence, December 2019, using deep learning algorithms, and compare with bulletin dataDeep learning performances on detections and phase picking works very well even without ad‐hoc retrainingDeep learning based earthquake catalogs show differences due to different algorithm designs [ABSTRACT FROM AUTHOR]