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The Transverse Ranges of southern California are a region of active transpression on the western margin of North America that hosts some of the world's highest uplift rates at the Ventura anticline. Yet, the manner in which rock uplift rates change along strike from Ventura to the westernmost Transverse Ranges and the structures that may be responsible for this uplift remain unclear. Here, we quantified rock uplift rates within the westernmost 60 km of the Transverse Ranges by obtaining new age constraints from raised beach and shoreface deposits from marine terraces along the Gaviota coast. Twelve radiocarbon (seven sites) and eight luminescence (six sites) ages, ranging from ca. 50 to 40 k.y. B.P. and ca. 56 to 43 ka, respectively, consistently suggest that the first emergent terrace dates to marine isotope stage (MIS) 3, rather than MIS 5a as previously reported for the western Gaviota coast. These younger ages yield rock uplift rates between 0.8 ± 0.3 and 1.8 ± 0.4 m/k.y., i.e., over five times higher than previous estimates for this region. The spatial distribution of rock uplift rates and the abrupt along-strike changes in marine terrace elevations favor a regional tectonic model with a step-wise change in rock uplift across the south branch of the Santa Ynez fault. The south branch of the Santa Ynez fault appears to separate two regional tectonic blocks, characterized by rock uplift rates of ∼1.3–1.6 m/k.y. to the east and slightly lower rates to the west (∼0.8–1.4 m/k.y.). Our observations suggest that coastal rock uplift is primarily accommodated by deeply rooted far-field structures such as the offshore Pitas Point–North Channel fault system and the Santa Ynez fault, and that smaller through-going structures impart second-order controls and locally accommodate short-wavelength (1 m/k.y.) rock uplift rates at a significant distance (>50 km) from the rapidly uplifting (6–7 m/k.y.) Ventura anticline, and >100 km from the prominent restraining bend (“Big Bend”) in the San Andreas fault. The new constraints on the geometry of Quaternary-active structures and regional rates of fault-related deformation have implications for regional earthquake source models and seismic hazard assessment in the highly populated southern California coast region.

Jhelum Fault is the north–south-oriented major structural lineament originating from the Hazara-Kashmir Syntaxis and extending southwards towards the Mangla Lake. Geographic extent, nature and significance of Jhelum Fault are the subjects which have been approached by different researchers in the past. The previous research provides enough evidence for the presence of Jhelum Fault as well as they discourse its surface extent. None of the previous research addresses the subsurface model of this fault; consequently, its surface extent has been ambiguous and variably reported. The current research takes into account both the surface lineament as well as the subsurface behaviour of the deformed strata to draft the most reasonable depiction of this fault. Field data were coupled with satellite image of 1.5 m ground resolution to produce the geological map of the study area at 1:25,000 scale. The subsurface model was created along four traverse lines by considering the lateral extent of the structures and their shifting trends on the geological map. The stratigraphic package was taken from the nearby hydrocarbon exploratory well data (Missakeswal-01 well of OGDCL) as no rocks older than middle to late Miocene were exposed in the area. The consistent through-going map extents of many faults in the study area prove that faults are playing the major role in the tectonic evolution of the Jhelum Fault Zone. In the subsurface model, the same faults show very little stratigraphic throw, which signify the major stress component to be associated more with wrenching than pure compression. Therefore, most faults in the area are of transpressional nature having dominant lateral component with relatively smaller push towards west on steeply east dipping faults. The model also shows the positive flower structure with dominantly west verging fault system with few east verging back thrusts. The subsurface proposed model shows that the Jhelum Fault is extendible southwards to the Mangla Lake in the subsurface; however, it acts like a continuous shear zone on the surface where there all the shearing is accommodated by tight refolded fold axes. The east–west shortening does not exceed 14.5% which shows smaller compression in the study area. The 3D model further clarifies the model by showing the consistency of the fault system along strike.

Research subject. The gold-sulphide-quartz deposits of Central Chile are typical prospecting objects, having small ore intervals (from the first tens of centimetres to 1 m), intermittent and nested ore distribution and extremely uneven gold contents.Materials and methods. The patterns of ore mineralization distribution are considered against the background of the results of modern geophysical studies of the lithosphere: the Moho surface, density and thermal regime of the upper mantle. Detailed studies were conducted on the Yapin ore field.Results. It was shown that the faults controlling gold-sulphidequartz mineralization are derivatives of shear tectonics under the conditions of a transpression regime along the Chilean active margin. At an early stage, these faults developed in a right-shift environment, which was accompanied by the introduction of diabase dikes into the northeastern faults, and gold-sulfide-quartz mineralization superimposed on the dikes was deposited during the left-shift stage. The geological structure of the deposits in the ore field Yapin was characterized. It was shown that a diverse mineralization is developed in the ore field - copper-porphyry, IOCG-type and gold-sulphide-quartz. According to geochemical data, the latter is characterized by a clear enrichment of chalcophilic elements (Au, As, Ag, Cd, Cu, Bi, Pb, Zn, Te, Co). The marked enrichment of Bi, Te and Co ores indicates the participation of magmatic fluid in ore formation and the similarity of the mineralization of the Escondida deposit with the type of gold deposits associated with granitoid intrusions. According to geochemical features, gold-sulphide-quartz mineralization in the general zoning pattern occupies a boundary position between IOCG-type objects and copper-porphyry deposits.Conclusions. The conclusion is drawn about the independence of gold-sulphide-quartz mineralization and its difference from epithermal gold deposits. It is noted that, in the volcanic belts of the North-East of Russia, the prospects for discovering unconventional gold-sulphidequartz deposits similar to those of Central Chile are rather real.

This article gives a chronological review of the main published research results concerning the Cenozoic crustal stress-strain state in Mongolia and adjacent territories. The studies commenced in the southern Baikal rift zone in the 1970s and were extended further southwards to cover mobile regions neighbouring the Siberian platform. Geological, structural and morphostructural data were collected and analysed to define the crustal stress types and spatial characteristics. The authors have consolidated their reconstructions of the crustal stress-strain state of Mongolia, which were based on tectonic fracturing data and displacements along fractures in fault zones active in the Cenozoic. We consolidated a database of reconstructed stress tensors, which now contains more than 750+ solutions. The Late Cenozoic stress field was mapped. The map shows domains differing in types of the paleostress state of the crust. The reconstructions were compared to our calculations of the present-day crustal stress state, which were based on earthquake focal mechanisms, and to calculations by other authors. At the Late Cenozoic and current stages, the maximum horizontal compression axis (S Hmax ) has varying orientations, from submeridional (Western Mongolia) to NE and ENE (Eastern Mongolia). The role of compression increases from the northern domains, where the reconstructions show shear and transtension, to the southern domains with prevailing transpression and compression. Regular changes occur in the stress state and rupture parageneses along the largest latitudinal faults, North Khangai and Dolinoozersky; such changes are related to left-lateral strike-slip faulting. We analysed the sequence of the occurrence of stress fields differing in types and spatial characteristics, and revealed the main regularities in the evolution of the crustal stress-strain state in time. In the Cenozoic history of crust deformation in Mongolia, we can distinguish several episodes that differ in the dominant impacts of various tectonic force sources or combinations of such impacts. At the beginning of the Cenozoic, tectonic structures developed mainly under the influence of the interaction of East Asia and the Pacific Plate, which was manifested in the southeastern domains of the study area. The long-term SE-trending asthenospheric flow caused crustal stretching, which initiated the formation of tectonic structures comprising the Baikal rift system. Starting from the Pliocene, crustal stretching took place in combination with NNE compression caused by the India–Eurasia convergence. As a result, shearing occurred along the large faults. At this background, the Khangai and Khentei uplifts (including crust extension zones at their crests) are large structures that developed due to the dynamic effect of local mantle anomalies.

Inverted structures provide traps for petroleum exploration, typically four-way structural closures. As to the degree of inversion, based on a large number of worldwide examples seen in various basins, the most preferred petroleum exploration targets are mild to moderate inversion structures, defined by the location of the null points. In these instances, the closures have a relatively small vertical amplitude but are simple in a map-view sense and well imaged on seismic reflection data. Also, the closures typically cluster above the extensional depocenters which tend to contain source rocks providing petroleum charge during and after the inversion. Cases for strong or total inversion are generally not that common and typically are not considered as ideal exploration prospects, mostly due to breaching and seismic imaging challenges associated with the trap(s) formed early on in the process of inversion. Also, migration may become tortuous due to the structural complexity or the source rock units may be uplifted above the hydrocarbon generation window, effectively terminating the charge once the inversion has occurred. Cases of inversion tectonics can be grouped into two main modes. A structure develops in Mode I inversion if the syn-rift succession in the preexisting extensional basin unit is thicker than its post-rift cover including the pre- and syn-inversion part of it. In contrast, a structure evolves in Mode II inversion if the opposite syn- versus post-rift sequence thickness ratio can be observed. These two modes have different impacts on the petroleum system elements in any given inversion structure. Mode I inversion tends to develop in failed intracontinental rifts and proximal passive margins, and Mode II structures are associated with back-arc basins and distal parts of passive margins. For any particular structure the evidence for inversion is typically provided by subsurface data sets such as reflection seismic and well data. However, in many cases the deeper segments of the structure are either poorly imaged by the seismic data and/or have not been penetrated by exploration wells. In these cases the interpretation in terms of inversion has to rely on the regional understanding of the basin evolution with evidence for an early phase of crustal extension by normal faulting.

The Eocene tectonic evolution of the easternmost Caribbean Plate (CP) boundary, i.e. the Lesser Antilles subduction zone (LASZ), is debated. Recents works shed light on a peculiar period of tectonic duality in the arc/back-arc regions. A compressive-to-transpressive regime occurred in the north, while rifting and seafloor spreading occurred in Grenada basin to the south. The mechanism for this strong spatial variation and its evolution through time has yet to be established. Here, using 3-D subduction mechanical models, we evaluate whether the change in the trench-curvature radius at the northeast corner of the CP could have modulated the duality. We assume asymmetrical CP boundaries at the north (from east to west: oblique subduction to strike-slip) and at the south (subduction-transform edge propagator-like behavior). Regardless of the imposed trench curvature, the southern half of our modeled CP always undergoes a NWto-W-oriented extension due to the tendency of the southernmost part of the South-America slab to rollback. In contrast, the tectonic regime in the northeast corner of the CP depends on the trench-curvature radius. A low radius promotes transtension-to-transpression, with a NE-oriented compressive component of the principal stress. A high trench-curvature largely reduces the compressive component and promotes an extensive regime similar to that in the south. We thus propose that an initially low-curvature radius of the NE-LASZ triggered the tectonic N-S duality in the Eocene and led to an ephemeral period of transpression/compression at the north, although an additional mechanism might have been required to locally enhance compression

The Central Asian Orogenic Belt, as the largest accretionary orogen on Earth, is an ideal candidate to study the geodynamics of convergent plate boundaries through a prolonged period. The evolution of this orogen has been explained by different tectonic models, which incorporated one, or a combination, of the following mechanisms: lateral stacking of arc systems along major shear zones, arc amalgamation, oroclinal bending, and trench migration. Here we elucidate major mechanisms responsible for the tectonic evolution of the Central Asian Orogenic Belt, focusing on the Chinese Tianshan Orogen in the southern Central Asian Orogenic Belt. Structural observations from the ∼50-km-long Gangou section show evidence of polyphase deformation. The earliest episode of orogen-parallel sinistral shearing, constrained to the Early Devonian (ca. 399 Ma) by syn-deformational intrusions, was possibly controlled by oblique subduction. This was followed by an episode of ∼NE–SW contractional deformation, dated at ca. 356 Ma (40Ar/39Ar age of syn-deformational hornblende), and likely associated with an episode of trench advance. The third stages of deformation during the latest Carboniferous and Permian involved ∼NE-SW contraction, orogen-parallel extension, and dextral transpression. Our new geochronological data constrain the timing of orogen-parallel extension to ca. 303–293 Ma, and confirm that dextral activation along shear zones occurred during the Permian. The results highlight the role of trench migration, oblique tectonics, and syn-collisional orogen-parallel extension in the build-up of the Central Asian Orogenic Belt, and contribute to the pre-collisional reconstruction of this orogenic system.

African seismicity is predominantly localized along the East African Rift System (EARS), which is the major active tectonic feature of Sub-Saharan Africa. Besides the EARS, however, significant seismicity also occurs along a wide belt bounding the Mediterranean coastline. This tectonically active region extends discontinuously from Morocco to Egypt and its activity is controlled by the complex interaction between the Nubian and Eurasian plates, varying from transpression in the Atlas orogen in the west to transtension in the east. A record of large earthquake events is documented for the whole region, some of them causing moderate to severe levels of damage, mostly because of the high vulnerability of local buildings and structures, a condition which is still largely persistent in many areas. Currently, a number of seismic hazard models exist at local and national scales for North Africa, developed within independent projects and created using inhomogeneous data sources and different processing techniques. Unfortunately, such diversity makes their direct comparison problematic, obscuring the differences in seismic hazard across neighbouring areas and preventing the development of comprehensive long-term risk mitigation strategies. In fact, the last effort to produce a homogenized model for the whole Africa continent dates back to the GSHAP project, which is almost 20 years old. The creation of a unique seismic hazard model for North Africa, uniform across countries, is therefore a main concern. Since its inception, the Global Earthquake Model Foundation (GEM) is committed to the creation of a worldwide mosaic of high-quality, reproducible and openly accessible seismic hazard models, uniformly represented using the format adopted by the OpenQuake engine (OQ), a state-of-the-art, free and open-source software package for seismic hazard and risk assessment. We describe the development of a new comprehensive PSHA model for North Africa using GEM tools. The source model combines active faults and distributed seismicity, the former constrained from published geological descriptions and geodetic data, while the latter from the harmonisation of published earthquake catalogues.

The tectonic features of the Baltic–Mezen shear zone that developed along the border of the Fennoscandian Shield and the Russian Plate in the north of the East European Platform are considered. It is established that tectonic evolution of the considered zone was associated with strike-slip displacements in the basement rocks, which occurred and were dispersed in cover deposits in the form of low-amplitude faults and diagonal fold-and-thrust systems associated with sublayer detachments. The dynamic relationship of the geological–structural and geomorphic anomalies of the Baltic–Mezen zone with segments of bending of its mainline and virgation, as well as with the nodes of intersection of the main shear zone with transverse faults, is noted. Based on a study of structural and kinematic parageneses, it has been established that the Baltic–Mezen shear zone in the Phanerozoic developed mainly under dextral strike-slip displacement and transpression conditions during eight activation phases of the Caledonian, Hercynian, and recent deformation stages. Periodically there was a change in deformation regimes and kinematic inversions, and a shear zone evolved in conditions of transtension and sinistral strike-slip displacements. The kinematics of the Baltic–Mezen shear zone is consistent with the general dynamic patterns of the evolution of the East European Platform, in particular, with the formation of collision structures of the Scandinavian Caledonides, with extensive Late Devonian tectonic–magmatic events and features of the recent development of the Euro–Arctic region.

The Urf Al-Mahib area, located to the southern part of the Eastern Desert (SED) of Egypt, is covered mainly by juvenile Neoproterozoic crust and Nubian sandstones. Field investigation and structural analyses give evidence that the area of Urf Al-Mahib developed through four successive phases of deformation (D1, D2, D3 and D4). D1 was an attenuated phase represented by tight to isoclinal folds (F1), tightly appressed fold closures and sheared-out hinges, and axial plane foliation (S1), as well as mineral and stretching lineations (L1). Structural fabrics formed during the D2 phase embrace minor- and map-scale prominent F2 overturned folds with NW (to NNW)-dipping long upper limbs and short lower overturned limbs and axial planes striking NE (to ENE)‒SW (to WSW) and dipping to the NW at moderate angles. F2 folds are geometrically- and kinematically-related to thrust propagation, and often have SE (to SSE) vergence. Thrust faults, that striking NE (to ENE)‒SW (to WSW) and dipping NW to NNW, are also common in this stage. D3 structures contain pervasive vertical to inclined mesoscopic open to very open folds (F3), whose axes plunge NW (to NNW) and SE (to SSE) at moderate to steep angles. The latest D4 deformation phase is represented by abundant small- and large-scales WNW‒ESE trending dextral semi-ductile-semi-brittle-shear zones.

The geodynamic setting of the Agnie–Afanas’evskaya auriferous rotational structure, genetically related to a transtensional left-lateral duplex zone which was formed against the background of the regional roughly north–south lateral contraction (transpression), is discussed. Regional dislocations are accompanied by local dislocations caused by internal stresses, which account for the details of the structural pattern of the gold deposit. This enables us to forecast auriferous stockwork bodies on a new basis.

The area of the Vinodol Valley and Bakar Bay represents a NW‒SE oriented valley in the NW Adriatic characterised by prominent historical and instrumentally recorded seismicity. As part of the greater geodynamic domain including the Ilirska Bistrica–Rijeka–Senj seismogenic fault zone, new geological and structural data addressing the tectonic evolution of the area were collected in order to better understand the focal mechanisms of previous earthquakes and to enable identification of potential seismogenic sources. Mapped informal lithostratigraphic units mostly correspond to the Upper Cretaceous, Palaeogene and Quaternary successions described in other parts of the External Dinarides. However, a shorter stratigraphic range of the Gornji Humac fm., the youngest Cretaceous unit in the study area, was determined and suggests that the uplifted area in the central NW part of the Adriatic Carbonate Platform already comprised several thousand km2 (from W and NW Istria to Krk and Vinodol area) at the end of the Turonian. Structural measurements of the fault planes in the study area generally correspond to the existing structural model of the tectonic evolution of the Dinarides. However, in contrast to the SW vergences typical of the Dinarides, NE-vergent reverse structures are common, especially along the SW margin of the Vinodol Valley. Cross-cutting relationships suggest that transpressional (NW–SE and NE–SW striking dextral and sinistral faults) and extensional features (NW–SE and NE–SW striking normal faults) are structurally concurrent or younger than the reverse faults, suggesting a change in the palaeostress field during the Neogene–Quaternary, with prevalent transpression and radial extension. Comparison of results of the palaeostress field analysis and the constructed synthetic focal mechanisms on one side, with available focal mechanism solutions for earthquakes within the Ilirska Bistrica–Rijeka–Senj seismogenic fault zone on the other, shows a favourable orientation of the observed NW‒SE and NE‒SW striking faults with respect to the recent compressional/transpressional stress field (N‒S oriented P-axis), indicating these as potential seismogenic sources within the study area.

The evolution process and petroleum significance of two groups of fault structures, the NW-SE trending and near EW trending ones in the Cenozoic of Dongping-Niuzhong area of the Altyn slope, Qaidam Basin, were investigated using high precision 3-D seismic data. The NW-SE faults were generated in Oligocene, causing the formation of a series of folds related to transpression faults in the Niuzhong and Dongping area. After the Miocene, with the continuous extension of the Altyn Tagh strike-slip fault zone, the EW trending faults began to develop massively in Altyn slope. The activity of near EW trending faults and large-scale uplift of the bedrock in the northern Niuzhong area shared most of the compression torsion in Niuzhong and Dongping area, consequently, the activity of NW-SE trending faults weakened significantly after the Miocene. Then good hydrocarbon source rocks developed in the inherited Jurassic sags. The faults were effective pathways for oil and gas migration in Dongping and Niuzhong areas, and the oil and gas charging time matched well with the formation period of the NW-SE trending faults and their related structures, making the fault-related anticlines favorable targets for oil and gas accumulation. The Niuzhong area has been less affected by the Cenozoic movement after the Miocene, and thus has better conditions for gas reservoir preservation. Key words: Qaidam Basin, Altyn slope, Cenozoic, tectonic analysis, strike-slip fault, petroleum significance, Dongping-Niuzhong area

For permanent nuclear waste disposal sites, crystalline rocks, especially granitic/granodioritic batholiths, are considered an appropriate host rock. Principally, three types of granitic plutons occur in the extra-alpine crystalline basement of Germany that were consolidated during the late Paleozoic Variscan orogeny of Central Europe: (i) Pre-Variscan voluminous granodiorites that are hardly affected by the subsequent continent–continent collision; (ii) voluminous granites in various tectonic settings intruded during the late orogenic stage of the Variscides; (iii) post-orogenic granites related to vast Permian intracontinental extension. Thus, in terms of the syn-intrusive tectonic setting and post-intrusive processes there are significant differences. Although it can be expected that different tectonic environments caused significant differences in the material properties, for Germany, however, there is no systematic study regarding the fabric of such plutonites. In order to find the most suitable “granite” we investigate the primary anisotropy of granites evolved during the emplacement and crystallization of the melt. For this we sample rocks of all three principal types and various syn-intrusive tectonic settings, i.e., compression, extension, strike-slip, transtension, and transpression. By means of combined measurements of the “Anisotropy of the Magnetic Susceptibility” and the “Shape Preferred Orientation” we characterize the syn-intrusive flow pattern, i.e., the magmatic foliation and lineation. The Crystallographic Preferred Orientation is analyzed by a combination of neutron time-of-flight experiments and electron backscatter diffraction measurements at the Frank Laboratory of Neutron Physics at JINR, Dubna, Russia, and the TU Bergakademie Freiberg respectively. Furthermore, special attention is given to the systematic mapping of annealed microcracks evolved during late magmatic fluid escape and/or post-crystallization hydrothermal activity. In a second step we compare the primary anisotropy with the post-magmatic fracture pattern of the particular granites. Those fractures constitute probable fluid pathways and, thus, the first-order risk for a potential permanent nuclear waste disposal. All datasets are organized in a Geological Information System allowing for a complete traceability of the different investigation steps. The results of this study will serve as a basis for a future detailed exploration.

International audience; The left lateral strike-slip Bucaramanga Fault exhibits a transpressional southern termination located towards the axial zone of the Eastern Cordillera of Colombia, where the Boyacá and Soapaga Faults are also identified as inversion-related structures. To unravel their exhumation history, we obtained apatite and zircon: fission-track and (U–Th)/He ages from samples collected along different structural domains, along five vertical profiles. Joint Bayesian inverse modeling of these data reveals at least four different episodes of cooling. These are: (i) 50 ± 5 Ma, (ii) 20 ± 5 Ma, (iii) 12 ± 3 Ma, and (iv) 5 ± 3 Ma. The earliest pulse is associated with reactivation of the Boyacá and Soapaga Faults. The second pulse is related to the transpressive reactivation along the southern termination of the Bucaramanga Fault and coincides with a marked increase in relief. The Miocene-Pliocene pulses are related to Bucaramanga Fault strike-slip reactivation. Older fission-track ages previously reported from other areas of the Santander Massif suggest migration of exhumation from north to south. The four cooling episodes identified in this study can be related, within a broader geodynamic context, to interaction between the Cocos, Nazca, Caribbean, and South American plates, and the accretion of large tectonic domains of different affinity (oceanic or continental) against the South American plate during the Cenozoic. Our results are consistent with previous work reported in the Santander Massif. The ages observed in the in-situ data correspond with the ages found in modern river sediments and support relief development from the Eocene to the present.

The Midelt area in Morocco, located between the Middle Atlas and the High Atlas, was shaken on November 17th, 2019, by a strong earthquake that was felt with intensity VI MSK. The epicenter was at 32.677°N; 4.126°W, with a depth of 2.1 km. The event was followed by a series of aftershocks and another series of small events later in February 2020. Moment tensors of the main event mainly show strike-slip faulting with a P-axis oriented NW-SE. The review of the available seismic data around the epicentral area encompassing the Middle Atlas, the Eastern High Atlas, and the Missour basin shows three main clusters located in the Southern Middle Atlas, the north-eastern Middle Atlas, and the Central High Atlas, while the Missour basin is almost devoid of seismic activity. The available focal mechanisms and moment tensors show various tectonic regimes, mainly transpression and thrusting, while the Tabular Middle Atlas is undergoing transtension. Detailed review of neotectonic data leads to the conclusion that the area is tectonically active, as witnessed by the deformations of the Mio-Plio-Quaternary foreland formations especially at the master border faults. The review of all data including GPS measurements shows good accordance between tectonics, seismicity, and block motions with respect to fixed Nubia. Transtension in the Tabular Middle Atlas may be explained by a change of kinematics across the Northern Middle Atlas Fault. Comparison of various models set for the Eastern Meseta suggests that the whole area from the Anti-Atlas to the Tabular Middle Atlas is undergoing transpression and/or shortening.

Previous paleomagnetic studies performed in the central North-Algeria (Chellif and Mitidja basins) on Neogene formations pointed out tectonic clockwise blocks rotations. This deformation pattern was interpreted as resulting from a bookshelf neotectonics, consequence of the Africa-Eurasia plates convergence. A new paleomagnetic study was conducted on the Neogene volcanic rocks outcropping in the northwestern Algeria (Marset Ben Mhidi, Ain Temouchent, Tifaraouine area). The obtained stable remanent magnetization is mainly carried by Ti-poor titanomagnetite. The paleomagnetic data show that, since the lava emplacement, the northwestern Algeria underwent a mean moderate clockwise block rotation of 9.3° ± 4.5°. For the Algerian margin, this confirms a context of transpression and blocks rotations in a strike-slip tectonic setting. A decreasing deformation gradient from the E to the W affected the different basins of this margin, from strong rotations within the Mitidja, to the moderate ones in the Chellif and to Marset Ben Mhidi, Ain Temouchent, Tifaraouine area, where rotation magnitudes are significantly lower.

The Inner California Borderland (ICB) records a middle Oligocene transition from subduction to microplate capture along the southern California and Baja coast. The closest nearshore fault system, the Newport-Inglewood/Rose Canyon (NIRC) fault complex is a dextral strike-slip system that extends primarily offshore approximately 120 km from San Diego to Newport Beach, California. Holocene slip rates along the NIRC are 1.5–2.0 mm/year in the south and 0.5 mm/year along its northern extent based on trenching and well data. High-resolution 3D seismic surveys of the NIRC fault system offshore of San Onofre were acquired to define fault interaction across a prominent strike-slip step-over. The step-over deformation results in transpression that structurally controls the width of the continental shelf in this region. Shallow coring on the shelf yields a range of sedimentation rates from 0.27–0.28 mm/year. Additionally, a series of smaller anticlines and synclines record subtle changes in fault trends along with small step-overs and secondary splay faults. Finally, sedimentary units onlapping and dammed by the anticline, place constraints on the onset of deformation of this section of the NIRC fault system. Thickness estimates and radiocarbon dating yield ages of 560,000 to 575,000 years before present for the onset of deformation.

Highlights • Seismic reflection profiles evidence tectonic inversion and active strike-slip faults offshore SW Sicily foreland • Pliocene-Quaternary transpressional inversion of Late Miocene extensional basins • Transpressional fold growth rates were high in Latest Miocene-Pliocene and decreased during Quaternary Joint analysis of high-penetration multi-channel and high-resolution single-channel seismic reflection profiles, calibrated by deep well boreholes, allowed a detailed reconstruction of the Late Miocene to Recent tectonic history of the Capo Granitola and Sciacca fault systems offshore southwestern Sicily. These two fault arrays are part of a regional system of transcurrent faults that dissect the foreland block in front of the Neogene Sicilian fold and thrust belt. The Capo Granitola and Sciacca faults are thought to reactivate inherited Mesozoic to Miocene normal faults developed on the northern continental margin of Africa. During Latest Miocene-Pliocene, the two ~NNE-SSW striking faults were active in left transpression, which inverted Late Miocene extensional half-grabens and created push-up ridges along both systems. Tectonic activity decreased during the Pleistocene, but transpressional folds deform Middle-Late Pleistocene sediments as well, suggesting that the two fault systems are active. The ~40 km long longitudinal amplitude profile of 1st order folds (Capo Granitola and Sciacca anticlines) shows ~15–20 km bell-shaped undulations that represents 2nd order folds. The length of these undulations together with the map pattern of faults allowed to divide the CGFS and SFS into two segments, northern and southern, respectively. Total uplift of the Sciacca Anticline is twice than the uplift of the Capo Granitola Anticline. Incremental fold growth rates decreased during time from 0.22 mm/yr (Capo Granitola Anticline) and 0.44 mm/yr (Sciacca Anticline) in the Pliocene, to 0.07 and 0.22 mm/yr, respectively, during the last ~1.8 Ma.

The structural features of the Katav-Yuryuzan fault zone are considered. Based on the analysis of mesostructures, paleostress fields with the predominant horizontal northwest compression were determined. The data on earthquakes that occurred in September 2018 near the town of Katav-Ivanovsk are analyzed. Contradictions in determination of the epicentral coordinates and focal mechanisms of these earthquakes calculated by different geological services are revealed. It is shown that the setting of right-lateral transpression, under which the structure of the northwestern part of the Bashkir megaanticlinorium formed, is still maintained at present.

Within the Maritimes Basin of eastern Canada, the onshore Moncton sub-basin is one of the NE-trending second-order depocenters that recorded a complex tectonic history from Late Devonian to Late Carboniferous. Analysis of a 3D seismic volume in the McCully gas field area exemplifies the complex interplay between mainly continental sedimentation and several tectonic episodes that contribute to a net extension or shortening in an overall strike-slip setting. The new interpretation demonstrates the role of normal faults oblique to the sub-basin axis in initial phases of sub-basin development and their influence on the deposition of the Upper Devonian-Lower Mississipian Horton Group sediments. A subsequent episode of transpression is recorded by syn-folding growth strata (base of the Mississipian Sussex Group) preserved on both flanks of an anticline that belongs to a fold system that shows an en echelon geometry relative to sub-basin bounding faults. Deposition of a marine interval (Middle Mississipian Windsor Group), including evaporitic strata is succeeded by an halokinetic growth succession (Upper Mississipian-Pennsylvanian Mabou Group) found in minibasins that formed through drape folding (downbuilding) in response to salt-walls development. This polyphased history illustrates the complexity of strike-slip basins that are often controlled by structures with different geometry and kinematics in time and/or space.

A series of NE and NW-trending Cenozoic faulted basins, located at the north margin of the Eastern Qinling Mountains, document Cenozoic intracontinental extension process in Central China. Based on fault kinematic analysis of the faulted basins, coupling with the stratigraphic sequence, we rebuilt a tectonic stress sequence of the faulted basins since the Cenozoic era. Combined with the previous chronological data, we define the Cenozoic faulted basin formation process including two stages of tectonic evolution. The first stage largely presents the NW-SE extensional rifting in a long period from the Paleocene to the Middle-Late Miocene due to northwestward subduction of the Pacific plate. It is marked by the basin occurrence along the north margin of the Eastern Qinling Mountains (e.g., the Sanmenxia, Lushi, Shangluo, and Weihe Basins) in the Paleocene to the Early-Middle Miocene in accordance with a NW-SE extension, and regional basin inversion in the Middle Miocene as the result of a NW-SE compression. The second stage is featured by the three-episode extension since the Middle-Late Miocene, which is probably affected by the combination of the northeastward growth of the Tibetan Plateau and the northwestward subduction of the Pacific Plate. The earliest episode of NW-SE extension caused by regional NE-SW compression in the Late Miocene to Early Pleistocene, which leads to the formation of the Yuncheng Basin. A gentle NE-SW extension subsequently dominated here in the Late Pleistocene, as represented by the widespread appearance of paleo-lakes in the basins. Then the youngest tectonic regime controlled this region, characteristic of a tectonic transpression (ENE-SWS compression and NNW-SSE extension), causing evidently strike-slip activities on the primary faults in the basins.

The Cuu Long Basin is situated off the southeastern coast of Vietnam. This study utilizes all available seismic data in the Cuu Long Basin, Vinh Chau Basin and coastal Mekong Delta to constrain the tectonic history of the area. The linkage between the Mae Ping Fault Zone and deformation in the Cuu Long Basin is also examined in detail. Two major deformational events are observed: a transtensional rifting event from the mid Eocene to mid-Early Oligocene (40–31 Ma) followed by transpression from mid-Early Oligocene to mid-Late Oligocene (31–25 Ma). The data strongly suggest that all the very straight major tributaries of the Mekong River Delta follow northwest trending faults that link into to the southwestern end of the Cuu Long Basin fault system and that the basin opened between where the Mekong Delta faults enter and a point of zero extension at the NE termination of the basin. The Mekong Delta Fault Zone exhibited left-lateral displacement during extension in the Cuu Long Basin and right-lateral displacement during younger transpression. The orientation, age and sense of displacement of the Mekong Delta Fault Zone are consistent with slip on the Mae Ping Fault Zone in Thailand and Cambodia, and hence are considered to be part of the same regional fault system. Based on a Chainat Duplex analogue and other data, the Mekong Delta and Mae Ping fault zones appear to be linked by a NNW-striking step-over zone, referred to here as the Mekong-Ton Le Sap step-over zone. This zone follows the eastern boundary of the Paleocene to Early Eocene Kampot Fold Belt. Based on structural and stratigraphic similarities, it appears the adjacent Vinh Chau Basin shares a common tectonic history with the Cuu Long Basin, but the linkage to the Mekong Delta Fault Zone is less clear.

The NNW-SSE trending Marianske Lazně Fault (MLF) zone is situated in the western part of the Bohemian Massif (Czech Republic, central Europe) and controls the eastern limit of Cenozoic Cheb Basin. The Cheb Basin is well-known for present-day earthquake swarms, with maximum magnitude not exceeding Mw 4.0, and abundant occurrences of mantle-derived carbon-dioxide emanations. The MLF borders the Cheb Basin towards the Krusne hory Mts. controlling their morphologically pronounced mountain front. However, no large earthquakes required for forming the tectonic morphology (Mw > 6) have been recorded historically. To examine if potential pre-historic earthquakes contributed to mountain front formation along the MLF and to Late Quaternary seismic hazard in the region, we excavated a trench at the Kopanina site where the fault was identified by geomorphological and geophysical surveys. The trench revealed repeated movements along several fault strands within the MLF of various ages, which displaced basin sediments deposited since the Oligocene. The youngest faults cut and deformed Holocene layers at least twice, with a total cumulative vertical displacement on the main fault 0.5 m. The deformations that we documented here suggest transpression within the MLF during Holocene. Based on empirical relationships between magnitude and displacement/rupture length, the MLF has produced earthquakes with a minimum magnitude of Mw = 6.5. The youngest event is dated approximately to the period 792–1020 CE. To match the youngest event with a historical earthquake, several candidates could be considered and further investigated, but the most probable one seems to be the earthquake reported in catalogs for 998 CE. Hence our study revealed the youngest proven surface faulting in central Europe and the largest Holocene event reported so far for the Bohemian Massif, which is of great importance for seismic hazard re-assessment for the broader, slowly moving region.

The recently emerged concept of “slope tectonics” suggests that mass movement processes can produce structures similar in morphological expression to that of extensional, strike-slip and compressional tectonic deformations. Further, there has long been debate about the (tectonic or gravitational) origin of lineaments found on hillslopes. Here we present cases of where geological structure and inherited tectonic structures have preconditioned the development of mass movements and creation of slope tectonic features on a monoclinal ridge (Smrk Mt.) in the Outer Western Carpathians, Czechia. Geomorphic mapping from LiDAR-derived topography, structural measurements, electrical resistivity tomography and ground penetrating radar, were used to map synthetic and antithetic scarps, thrusts, and folds, and assess their relation to geological and tectonic structures. The scarps are found to be strongly related to transverse (NNW to NNE trending) inherited normal and strike-slip faults and mainly cross-cut the topography of the mountain ridge. Some of the folds are thought to have originated from buckling or compression in the distal parts of landslides. In other places, transpressional folds have developed oblique to major lateral shear surfaces interpreted to be sackung (mass movement scarps) that have been inherited from tectonic faults. The transpressional folds developed due to localized contraction along bends in the lateral shear surface as mass movement proceeded. Ramp-flat thrust folds developed in the compressional parts of landslides, where the landslide intersects with slope parallel sackung and/or inherited fault planes inclined to the slope. Altogether, this study demonstrates a connection between kinematics of deep-seated gravitational slope deformations (DSGSDs), shallower landslides and the origin of transpressive, ramp-flat thrust, and detachment structures in rock slopes.

Structural data and cross-cutting relationships in the Xolapa Complex around Puerto Escondido, southern Mexico, indicate the development of two pre-Cenozoic folding systems recorded, in part, by migmatites. The older system is defined by gently SW-plunging, vertical open folds (FS1), related to a southwestward extension. A subsequent FS2 folding system is defined in turn by slightly SE-plunging, northwest-facing asymmetric folds, related to a northeastward transpression. The comparison between our structural data and those available in the literature indicate that both FS1 and FS2 are pervasive in the whole Xolapa Complex. In addition to the reciprocal link between orientation, lineation distribution, and kinematics between folding systems, higher strain components of FS2 and FS1 yield a strikingly similar direction but opposite sense, suggesting a paired tectonic cycle of opening (FS1) and closure (FS2) of a Xolapa Complex basin. From the comparison between crosscutting relationships in the study area and a compilation of U-Pb zircon data from the literature, we deduce that the opening of the Xolapa basin occurred sometime between 158 and 129 Ma; this is between the termination of the continental Nazas arc and the early stages of the extensional Guerrero arc. On the other hand, the closure of the Xolapa basin (FS2) took place between 94 and 72 Ma.

Ophiolitic suture zones are characterized by highly deformed rocks of different types and metamorphism in small area. These characteristic conditions make each rock unit is hardly followed on the field and mapped on a small scale. Thus, the present study is suggested to map the rocks and structures of Tharwah part of the Tharwah-Bi'r Umq suture zone in western Arabian Shield using remote sensing techniques and field verification. Rock type, thickness, geometry, isotropism, metamorphism and weathering control mainly the reflectance behavior of the rocks. Thus, the remote sensing works include the spectral signature curves analysis of the present rock units; some relational behavior which led to eight characterized band ratios for distinguished the rock units; moreover four false color band ratios composite were determined to create lithological map of the investigated area which were [7/5, 6/3, 6/7], [6/7, 6/2, (6/5)*(4/5)], [6/2, 7/3, 3] and [6/7, 6/5, 4/2]. Convolution filtering process and resulted lithologic map were used as two components for developing the geologic structure mapping. Although the diversity of rock types and intense structural deformation, the rock units and their affecting structural deformation are mapped clearly on the images and show a significant precised map after field verification, on compared with the other published maps. Tectonically, the thrust sheets affecting the ophiolite sequence were developed initially by a northwestward contractional tectonic event that was followed by an east-west contractional event which induced a transpression movement on the pre-existing thrust and foliation planes.

New structural data collected along five transects across the trend of the Feiran-Solaf metamorphic complex (FSC) in the Sinai, provide a more precise depiction of the macroscopic folds. The two main macrofolds of the complex, the NW-SE trending Feiran and Solaf antiforms , appear to be thrust-related folds with detachments at different stratigraphic levels in the FSC. Contrary to earlier views, there is only one macrofolding event (D2) in the FSC, accompanied by NW-SE trending F2 mesofolds with varying style. While the F2 mesofolds are most commonly open concentric and symmetrical, some of these folds have been modified by inhomogeneous shear strain to become tight “similar” style asymmetric mesofolds in a zone of intense ductile shearing along the SW flank of the Feiran antiform. The recent Najd-related transpression model for FSC D2 deformation is evaluated. An alternative model for D2 as a product of orthogonal convergence is preferred. The D2 event recorded the collision of the FSC with the Sa'al terrane at ∼800 Ma. The Kid arc complex collided with the Feiran and Sa'al complexes during subsequent NNW-SSE convergence at about 620-600 Ma.

How fold and thrust belts (FTBs) evolve over time and space in a transpressional regime remains poorly understood. Based on high-resolution 3D seismic reflection data and remote sensing images, we herein present a detailed structural analysis of the Cenozoic faults in the NW margin of the Qaidam Basin that is bounded to the north by the left-reverse Altyn Tagh fault system. Two sets of orthogonal, basement-involved faults with contrasting geometries, kinematics, and temporal development are identified. One set consists of generally E-W-striking, N-dipping, reverse faults with a component of sinistral shear. They are parallel or subparallel to the Altyn Tagh fault system, led to southward tilting of the basement, and formed a local unconformity between the middle Miocene Shangyoushashan formation and underlying strata. They developed in an out-of-sequence order, and were mostly active during 43.8–15.3 Ma but in relatively tectonic quiescence with limited weak reactivation since then. The second set is mainly composed of the NNW-striking reverse faults with dextral shear components. They are approximately perpendicular to the Altyn Tagh fault system, and intensively active since ∼15.3 Ma, much later than the initiation of the E-W-striking faults. Together with published results, we ascribe the development of these two sets of orthogonal faults as the transition from transpression to left lateral slip on the central segment of the Altyn Tagh fault system. The two fault sets interplayed with each other in two ways: 1) the older E-W-striking faults were offset by younger NNW-striking faults, and 2) the younger NNW-striking faults curved to link with the preexisting E-W-striking faults. Our findings reveal that transpressional-dominated FTBs evolve in a more complicated way than the contractional-dominated ones, and more site-based case studies are needed to reveal the underlying primary principles.

Earthquake nests are anomalous clusters of seismicity located far from active collisional systems in intraplate, locked suture zones, or the deep part of relic subducted slabs, challenging classic earthquake generation mechanism theories. The Vrancea Seismic Zone in Romania is such an upper-mantle seismic nest located in the SE Carpathians, releasing the largest strain in continental Europe. To better understand earthquake generation and the relationship with lithospheric deformation, we estimate earthquake source parameters in Vrancea and surrounding regions between 2014 and 2020, and determine the stress field via focal mechanism inversion and unsupervised machine learning. In the crustal domain, maximum horizontal stress is in agreement with surface fault kinematics and GPS-derived S-SE trending horizontal plate velocities relative to Eurasia, implying that tectonic stress is vertically coherent on a crustal scale. The stress regime changes from transpression beneath the orogen to transtension towards the foreland where movement is accommodated along major crustal faults, and tension further away from the epicentre, in the Moesian Platform and the North Dobrogea Orogen. Inside the seismogenic body vertical tension and an overall compressive regime dominates, implying that vertical elongation may be the driving mechanism for brittle failure and that stress is transmitted along the sinking slab to the surface. However, the retrieved stress ratios are low: ~0.2 for mantle earthquakes Mw>4 and ~0.4 for Mw

Large-scale strike-slip faults are associated with significant strain partitioning in releasing/restraining bends and often display map-view curvatures ending in horse-tail geometries. Such faults are commonly associated with indentation tectonics, where shortening in front of indenters is transferred laterally to transpression, strike-slip and the formation of transtensional/extensional basins. We investigate how these structurally distinct domains are kinematically linked by the means of a crustal-scale analogue modelling approach where a deformable crust is moved against a stable and rigid indenter. The modelling demonstrates that the geometry of the indenter is the major controlling parameter driving strain partitioning and deformation transfer from thrusting and transpression to strike-slip and transtension, whereas the rotation of the mobile plate controls the opening of triangular shaped transtensional basins. Flow of the ductile crust leads to the distribution of deformation over a wider area, facilitating strike-slip splaying into transtension/extension behind the indenter. Our results show a very good correlation with the Moesian indentation in the Carpatho-Balkanides system of South-Eastern Europe, where strain is partitioned around the dextral Cerna and Timok strike-slip faults and transferred to thrusting in the Balkanides part of the Moesian indenter and to transtension/extension in the neighbouring South Carpathians.

This research was supported by the project DAMAGE (AEI/FEDER CGL2016-80687-R) and the Spanish Seismic Hazard and Active Tectonics research group (RNM - 370). The corrections and suggestions of the professors M. Martin-Martin (Alicante) and F. Alonso (Huelva) clearly improved this article. In order to gain in the understanding of the evolution of the Betics, particularly in its Alpine front, is important to know better its western tectonic Alpujarride units. For this reason the Yunquera unit has been studied by analyzing its stratigraphic and tectonic context. This unit is a tectonic slice thrust by the Alpujarride Complex, to which it belongs. In turn, this tectonic slice was thrust over the Dorsal, and the latter was thrust over the Subbetic. During this thrusting, the bottom of the Yunquera unit was beveled, so that in its northern part only the higher stratigraphic levels remain, while to the south also lower levels are preserved. Part of this basal cut could also happen, during the later oblique thinning occurred in the Dorsal, which appears totally laminated in an area of this sector. These deformations happened during the progressive westward drift of the Internal Zone, whose advance was not homogeneous, but as segments, with greater displacement in the more southern ones. Although these deformations can be separated in several stages, actually they correspond to a continuous process spanning from the end of the Oligocene to the Burdigalian. According to its lithological characteristics, the Yunquera unit must be integrated in the upper Alpujarride unit, generally known as Jubrique or Los Reales, whose outcrops practically include all the western sector of this complex. This correlation allows for a better understanding of the structure and the tectonic evolution of this complex. In turn, the Saucillo unit, also present in this area, is clearly linked with the Intermediate units, tectonically situated between the Alpujarride and Malaguide Complexes. This unit is strongly affected by a fault zone formed during the stretching of the Dorsal. In this fault zone, tectonic rests of other units also can be found. Conocer mejor las unidades tectónicas occidentales alpujárrides es importante para la comprensión de la evolución de las Béticas, particularmente de su frente orogénico alpino. Por ello se analiza la estratigrafía y el contexto geológico de la unidad de Yunquera. Esta unidad es una escama tectónica cabalgada por el Complejo Alpujárride del que forma parte. A su vez cabalga a la Dorsal y esta lo hace al Subbético. Por este cabalgamiento, la base de la unidad se encuentra muy biselada de manera que en su parte norte corresponde a niveles estratigráficos altos, conservándose otros más bajos al sur. Parte de ese cepillamiento basal pudo también producirse durante el corte oblicuo que sufrió la Dorsal que en ese sector quedó localmente laminada por completo. Todo ello se produjo en el contexto del progresivo avance de la Zona Interna hacia el oeste, el cual no se hizo de forma homogénea, sino según segmentos, con mayor desplazamiento de los más meridionales. Aunque estas deformaciones pueden separarse en varias etapas, realmente se produjeron en un cuadro de evolución continua que abarcó desde finales del Oligoceno al Burdigaliense. Por sus características litológicas, la unidad de Yunquera formó originalmente parte de la unidad alpujárride superior, generalmente conocida como unidad de Jubrique o Los Reales (este nombre se usa cuando se considera también a las peridotitas situadas en su base), cuyos afloramientos comprenden prácticamente todo el sector occidental de dicho complejo. Esta correlación de unidades permite una mejor comprensión de la estructura y evolución geológica del complejo Alpujárride. Por su parte, la unidad del Saucillo (que se encuentra afectada por una zona de falla formada durante el estiramiento de la Dorsal, en la que también hay restos tectónicos de otras unidades) es claramente relacionable con las llamadas Unidades Intermedias, tectónicamente situadas entre los complejos Alpujárride y Maláguide. project DAMAGE (AEI/FEDER) CGL2016-80687-R Spanish Seismic Hazard and Active Tectonics research group RNM - 370

Eastern Iran, including the Sistan suture zone, comprises the boundary between Lut block and Afghan block. This research aims to reconstruct the stress regime evolution from the upper Cretaceous to Quaternary based on the brittle tectonic analysis. In this study, three episodic changes in stress regimes were recognized in the Shekarab Mountain using data inversion. In places where conglomerate outcrops are present, the Quaternary stress state is obtained using the youngest slickensides. The Quaternary stress state indicates that the direction of σHmax is close to N026°, which is compatible with the present-day Arabia-Eurasia convergence direction. Reconstruction of stress fields using age and sense of motion of faults shows that the stress regime during the Cretaceous was compressional, which caused the uplift of peridotites and ophiolites in the eastern part of the study area. The state of stress in the upper Eocene and Oligocene was transpressional; in the eastern part of the study area, there is a change from transpression to transtension. The exhumation of igneous rocks in the eastern part of the Shekarab Mountains is due to the local change of the stress regime. According to the results of this study, the first stage of stress state in the Shekarab Mountains was compressive and the average direction of maximum stress axis (σ1) was toward N337°. In Eocene, the tectonic regime was transpressional and the average direction of maximum stress axis (σ1) was toward N003°. In Quaternary, the tectonic regime is strike-slip and the average direction of maximum stress axis (σ1) is toward N026°. This implies that at least 49° clockwise rotation of σ1 happened in the Shekarab Mountain.

The Himalayan main frontal thrust (MFT) accommodates most of the present-day Indo–Asia convergence with related periodic earthquakes. The seismicity and deformation mechanism varies considerably across the frontal Himalayas. We mapped a segment (Manzai Ranges) of the MFT at the western margin of the Himalayas and analyzed its deformation mechanism and active tectonics using geomorphic indices and the Interferometric Synthetic Aperture Radar (InSAR) Small Baseline Subset (SBAS) technique. Two frontal thrust faults (Khirgi and Jandola) were mapped using Sentinel-2B band ratios in the study area. Water gaps were present in the form of deflected streams at the tip of the growing anticlines. The C-band RADAR interferometry (Sentinel-1A) showed an average uplift of 5–9 mm/year in the satellite line of sight (LOS) from May 2018 to October 2019. The velocity profiles show an uplift variation across the anticlines and may be related to the displacement transfer from the zone of compression in the Manzai Ranges to the zone of transpression in the Pezu–Bhittani Ranges. Four types of morphometric analyses were carried out to assess the relative tectonic activity, namely mountain front sinuosity index (Smf), valley floor width to height ratio (Vf), normalized longitudinal river profile, and normalized channel steepness index (Ksn). The landscape response to active tectonics in the study area was recorded as a deep fluvial incision in V-shaped valleys, convex river profiles, topographic breaks as knickpoints, and a high Ksn index. The geomorphic parameters show a relative increase in tectonic uplift and deformation from the Kundi anticline to the Khirgi and Manzai anticline. We concluded that the frontal structures in the western Himalayas are still going through an active phase of deformation and landscape development with both seismic and aseismic creep.

This study concerns the structural setting of the central Egyptian-Nubian Shield (El Shalul area) utilizing field-structural, remote sensing, petrological and geochemical data. The exposed basement comprises ophiolitic-melange, arc-related metavolcanics, metasediments, metagabbro-diorites and granitoids. The area experienced two stages of deformation, pre-Najd (∼850-630 Ma) and Najd-related (∼630-580 Ma). The pre-Najd stage is represented by the assembly of arc-terranes and their N-ward extrusion while the Najd-related stage encompasses three deformation phases. D1 is post-collision extensional event, depicting lateral spreading of tectonic terranes and NW-ejection of ophiolites. The emplacement of El Shalul granite (∼ 630 Ma) and deposition of molasse sediments in E-W and NW-SE extensional basins (Zeidun and Meesar) are D1- related. Following extension is a protracted phase of compression, shearing and transpression. It was commenced with NW-SE shortening (D2) and deformed the extensional basins by folding and thrusting with mild effect on the other basement units. Sinistral shearing (D3a) and transpression (D3b) along the NW-trending faults superseded the D2 compression, while dextral shearing (D3c) on the ENE-WSW and NE-SW faults overprinted the NW-SE penetrative structures and controlled the emplacement of post-granitic dykes. The significant conclusions of this study include (1) El Shalul granite complex is a large alkaline granitic sheet emplaced during a post-collision extensional regime and suffered the subsequent ∼630-580 Ma top-to-NW sinistral shearing and SW-directed thrusting (not a gneissic core complex) and (2) The NW-SE and NE-SW structural trends are not conjugated.

The Nugrus Shear Zone (NSZ) of southern central Egypt is a major ductile shear structure with controversial origins. It lies east of the Hafafit Gneissic Complex (HGC) and separates the Central and South Eastern Desert terranes of Egypt. The NSZ has been correlated with the Najd Fault system in Saudi Arabia, and shares orientation and kinematic characteristics with the Najd fault. Previous microstructural studies of the NSZ and HGC have concluded a polydeformation history for the Nugrus area, involving early NW-ward thrusting, followed by NW-SE transcurrent shearing. This contribution reports a combined rock magnetic and palaeomagnetic study of the shear zone and wallrocks that gives a conclusive evidence for the previously mentioned tectonic scenario. Furthermore, the palaeopoles obtained correlate well with the available geochronologically dated poles from Northern Africa, leading to inferred ages for the deformation and thermal events of the area. These ages confirm the previous proposed tectonic models. Three components of Natural Remanant Magnetization (NRM) direction (CA, CB and CD) are identified. Component CA represents the Characteristic Remanent Magnetization (ChRM). Components CB and CD are considered to be secondary magnetization. CA is consistent with arc-related deformation and magmatism at ∼ 700–680 Ma. CB and CD represent the protracted Najd-related shear deformation and transpression at ∼ 650–550 Ma.

The Atlas Mountains of Tunisia belong to the seismically active zone of the Africa (Nubia) - Eurasia plate boundary in the central-western Mediterranean. We study the eastern section of the Maghrebian thrust belt using a subset (6 days) from each of 5 years (2014 to 2018) of permanent (survey-mode) GPS data and active tectonics. WNW to NNW-trending velocities express crustal motion and geodetic strain fields from the Sahara Platform to the Tell Atlas, consistent with African plate convergence. To the south, the velocities and trajectories indicate nearly WNW-ESE-trending right-lateral motion of the Sahara fault-related Atlas fold belt with respect to the Sahara Platform. Farther north and northeast, the significant decrease in velocities between the Eastern Platform (Sahel), Central Atlas and Tell Atlas and the clockwise rotation mark the NNW-trending shortening deformation associated with local ENE-WSW extension visible in the Quaternary grabens. The velocity field and strain distribution associated with the active E-W- to WNW-ESE-trending right-lateral faulting and NE-SW fault-related folds illustrate the transpression tectonics and support the identification of four tectonic domains north of the Africa-Nubia Platform in Tunisia. The transpression reduces northward when reaching the Central and Tell Atlas. These results change our perception of the Africa-Eurasia plate boundary previously located along the western Mediterranean coastline.

The Maghrebian tectonic domain in North Africa is here examined in the light of the recent GPS and seismotectonic results. The region includes the plate boundary in the western Mediterranean previously characterized by transpression and block rotation. The crustal deformation is documented along the Atlas Mountains in terms of the displacement field, with strain partitioning largely controlled by plate motions. The tectonic and seismotectonic analysis is based on our published data on shortening directions of Quaternary faulting and folding compared with present-day seismotectonic characteristics (earthquake moment tensors) of significant seismic events that allow an estimate of local and regional deformation rates in North Africa. Shortening directions oriented NE-SW to NW-SE for the Pliocene and Quaternary, respectively, and the S shape of the Quaternary anticline axes are in agreement with the 2°/Myr to 4°/Myr clockwise rotation obtained from paleomagnetic results on small tectonic blocks in the Tell Atlas. The continuous GPS data and results are obtained from the network in Morocco operative 1999 to 2006, the REGAT network in Algeria since 2007, and the network in Tunisia with data collected from 2014 to 2018. In addition, we add the most recent GPS results in southern Spain and southern Italy. The NW-SE to NNW-SSE 5 ±1.5 mm/yr convergence velocity and strain distribution of the Maghrebian tectonic domain is controlled by crustal block tectonics driven by E-W trending right-lateral faulting and NE-SW thrust-related folding. The correlation between the active transpression tectonic structures and velocity field shows a geodynamic framework consistent with the oblique plate convergence of Africa towards Eurasia.