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Key in understanding the geodynamics governing subduction and orogeny is reconstructing the paleogeography of ‘Greater India’, the Indian plate lithosphere that subducted since Tethyan Himalayan continental collision with Asia. Here, we discuss this reconstruction from paleogeographic, kinematic, and geodynamic perspectives and isolate the evolution scenario that is consistent with all three. We follow recent constraints advocating a ~58 Ma initial collision and update a previous kinematic restoration of intra-Asian shortening with a recently proposed model that reconciles long-debated large and small estimates of Indochina extrusion. Our new reconstruction is tested against paleomagnetic data, and against seismic tomographic constraints on paleo-subduction zone locations. The resulting restoration shows ~1000–1200 km of post-collisional intra-Asian shortening, leaving a 2600–3400 km wide Greater India. From a paleogeographic, sediment provenance perspective, Eocene sediments in the Lesser Himalaya and on undeformed India may be derived from Tibet, suggesting that all Greater Indian lithosphere was continental, but may alternatively be sourced from the contemporaneous western Indian orogen unrelated to India-Asia collision. A quantitative kinematic, paleomagnetic perspective prefers major Cretaceous extension and a ‘Greater India Basin’ opening within Greater India, but data uncertainty may speculatively allow for minimal extension. Finally, from a geodynamic perspective, assuming a fully continental Greater India would require that subduction rates close to 20 cm/yr was driven by a down-going lithosphere-crust assemblage more buoyant than the mantle, which seems physically improbable. We conclude that the Greater India Basin scenario is the only sustainable one from all three perspectives. We infer that old pre-collisional lithosphere rapidly entered the lower mantle sustaining high subduction rates, whilst post-collisional continental and young Greater India basin lithosphere did not, inciting the rapid India-Asia convergence deceleration ~8 Myr after collision. Subsequent absolute northward slab migration and overturning caused flat slab subduction, Tibetan shortening, arc migration and arc volume decrease.

A possible Mesozoic-Cenozoic trajectory for the North American craton is outlined from latitude changes of the craton derived from a revised apparent polar wander path, and from westward movement of the craton based on the assumption that Africa has been the least mobile continent geographically since the latest Paleozoic. During each of five time intervals that span 220 million years, the craton trajectory had a different vector. Each vector appears to be reflected in the Canadian Cordillera by the dominant style and orientation of structures formed during that interval. For much of the past ~ 220 million years, the ~meridionally-oriented western margin of the Pangea-Laurasia-North America Plate has been the site of arc magmatism where weak arc/back arc lithosphere, sandwiched between strong ocean-floor and craton lithospheres at times coupled across convergent or transform plate boundaries, focused and recorded strain. When the craton apparently moved due westward, between ~180–160 Ma and ~120–60 Ma, the dominant structures formed then record orogen-normal compression and were accompanied by orogeny. Structures formed during the earlier episode are mainly in the eastern and interior Cordillera and their formation shortly followed or coincided with accretion of most terranes to the craton margin. In the later episode, compressional structures span the entire Cordillera, which emerged as a tectonic and physiographic entity. Before and between these intervals, when the craton apparently moved mostly northwestward, mainly geological and paleomagnetic considerations indicate some terranes moved southward (sinistrally) relative to the craton. After ~60 Ma, southwestward movement of the craton was concurrent with large northward (dextral) strike-slip faults that disrupted the newly-established ancestral Cordillera. The coincidence between the age of structures that record dominant orogen-normal compression at times when the craton apparently moved due westward, and orogen-parallel displacements when the craton had either northward or southward components of motion, suggests the craton, acting as a “Continental Bulldozer”, was the primary driver of Cordilleran deformation and orogenesis.

Due to uncertainty of single-method interpretation we applied 2-D integrated lithospheric modelling along three CELEBRATION 2000 profiles CEL01, CEL04 and CEL05. Modelling of the lithospheric thermal structure is based on the joint interpretation of gravity, geoid, topography and surface heat flow data with temperature-dependent density. The models for each profile were constrained by seismic modelling results of the large-scale international project CELEBRATION 2000. The results indicate large variations of the lithosphere thickness from the old and cold East European Craton (~200 km) and the Trans European suture zone via the Western Carpathian orogeny to the young and hot Pannonian Basin (~90 km). Important differences in the lithospheric thickness were also found along-strike of the Western Carpathian orogeny and the Trans-European Suture Zone. The western part of the Western Carpathians is characterized by weak thickening of the lithosphere (only about 145 km), while their eastern segment presents strong lithospheric thickening (~190 km). The Malopolska unit in southern Poland has a lithospheric thickness of about 130 km. Thickest lithosphere (220 km) is observed around the junction of the Carpathian Foredeep and the East-European Craton. The crustal thickness follows generally the course of the lithosphere-asthenosphere boundary. The results suggest different geodynamic evolution of the collision of the ALCAPA microplate with the European platform on the one hand and the East-European Craton on the other hand. It is suggested that the tectonic evolution of this very complex area consisting of different tectonic units has changed in time and space.

A prominent positive gravimetric and magnetic anomaly stands out in the region of the Guadalquivir-Portimao Banks, Gulf of Cadiz, off SW Iberia. The bathymetric and gravimetric highs have been interpreted as resulting from basement uplift occurred during Mesozoic rifting followed by overthrusting during the Alpine orogeny. However, we show that basement uplift alone does not account for the observed magnetic anomaly, implying that an additional magnetic source must be considered for an integrated model that fits with all the data. We present a new magnetic study that calls for the existence of a large magmatic body intruded beneath the Guadalquivir and Portimao Banks, the Guadalquivir-Portimao intrusion. We perform 3D inversion of magnetic data to obtain a susceptibility model that estimates the shape and extension of the intrusion. The modeled volume is constrained by estimation of regional Curie depth and the susceptibility model is limited to a realistic range, allowing interpretation in terms of rock nature. To clarify the relationship between the intrusion and the local lithospheric structure, we build 2D cross-sections integrating the modeled intrusion with recent crustal models and use 2D forward modeling to ensure that both the predicted magnetic and gravimetric fields fit the observed data. These sections show the Guadalquivir-Portimao intrusion emplaced along a lithospheric decollement within the necking domain of the Algarve rifted margin, across the lower and upper crust. It is suggested that is crosscuts Jurassic sedimentary sequences, suggesting that it intruded after continental rifting. Given the similarities with other onshore magnetic anomalies corresponding to Late Cretaceous alkaline intrusions, it is likely that the Guadalquivir-Portimao intrusion represents the southernmost expression of the Late Cretaceous alkaline magmatic event that affected both onshore and offshore West Iberia, becoming the fourth element of the enigmatic NNW-SSE trending alignment of Sintra-Sines-Monchique plutons, whose significance remains to be fully understood.

In the Tien Shan belt, Cenozoic to active deformation is guided by structures and rheological contrasts partly inherited from the Paleozoic Variscan orogeny and reactivated by the India-Asia collision. Cenozoic deformation net estimates are constrained by lithospheric scale geological cross-sections, which rely on reconstructions of the Paleozoic Central Asian Orogenic Belt (CAOB). However, several geodynamic scenarii have been proposed for its formation including a south or a north dipping subduction, which are still debated due to lack of constraints. Here, we designed numerical experiments to test different hypotheses about the initial geometry and the effective rheology of the paleo-sutures and especially the one located between the Tien Shan and the Tarim basin, where most Cenozoic deformation localizes. The different geometries of Paleozoic structures are used as input variables in the thermo-mechanical models, which are then run forward in time. After a finite amount of shortening, the structures that develop self-consistently out of the proposed heterogeneities are then compared to the current Cenozoic finite and active deformations. We find that a crustal south-dipping suture zone lying on a resistant lithospheric mantle best explains the localization of the deformation, the current geometry of the structures and the Moho depth variations. Using the model results, we propose a mechanically consistent depth-interpolated crustal cross-section of the Kyrgyz Tien Shan, which incorporates both geological and geophysical data.

Continent-continent collisions are responsible for the formation of large mountain ranges like the Himalayas and the Alps and play a primary role in the development of the continents. The continental collision between the Iberian and European plates during the Alpine Orogeny resulted in the formation of the Pyrenees. In this study new electromagnetic data from the Eastern Pyrenees were complemented with older data from the Central Pyrenees, constraining the physical and geological processes at the eastern end of the Pyrenean mountain range. The electrical resistivity distribution beneath the Central-Eastern Pyrenees was characterized by means of three-dimensional (3-D) joint inversion of three electromagnetic datasets: (1) the MT impedance tensor (Z), (2) the geomagnetic transfer function (T), and (3) the inter-station horizontal magnetic transfer function (H). The main finding was the non-continuity to the east of the major conductive anomaly observed previously beneath the Central and West-Central Pyrenees related to partial melting of the Iberian subducted lower crust. Lower amounts of water (related to the presence of muscovite and biotite) in the subducted lower crust beneath the Eastern Pyrenees were suggested to explain the lack of partial melting in this part of the mountain range. The electrical resistivity model also revealed higher electrical resistivity values for the lithospheric mantle beneath the Eastern Pyrenees than beneath the Central Pyrenees, thus supporting the hypothesis of an heterogeneous Iberian plate inherited from the Variscan Orogeny. A less clear signature was the lateral variation along the strike direction of the lithosphere-asthenosphere boundary beneath the Eastern Pyrenees (relatively flat, between 110 km and 140 km depth) and the Central Pyrenees (north dipping, between 80 km and 120 km depth beneath the Iberian Plate and between 110 km and 160 km depth beneath the European plate), supporting the hypothesis of a missing lithospheric root beneath the Eastern Pyrenees.

Xenoliths play a crucial role in interpretation of mantle deformation and geochemistry. The classic work of Mercier and Nicolas (1975) introduced the concept of the peridotite deformation cycle, which connected observed microstructures to a physical sequence of deformation. We revisit Mercier and Nicolas' original concept, bringing in new constraints using large area EBSD maps and associated microstructural datasets, analysis of water contents in nominally anhydrous minerals, and trace element chemistry of pyroxenes and garnets. We apply these techniques to a well-characterized suite of peridotite xenoliths from the Eocene-age Homestead and Williams kimberlites in the northwestern Wyoming Craton. Pyroxene water content and trace element mineral chemistries reveal ubiquitous hydrous metasomatism beneath the craton, most likely linked to the Cenozoic Laramide Orogeny. Homestead xenoliths primarily exhibit coarse protogranular and equigranular textures, B-type olivine fabrics, and generally elevated mineral water contents compared to Williams. Xenoliths from Williams are strongly deformed, with porphyroclastic and transitional textures containing annealed olivine tablets, mostly A-type olivine fabrics, and generally lower mineral water contents. As a whole, mantle from Homestead to Williams reflects a cratonic scale deformation cycle that likely initiated in Laramide times and lasted until the end of orogeny in the Eocene. At Williams, evidence for a rapid deformation “sub-cycle” within the main deformation cycle is preserved in the tablet-bearing xenoliths, corresponding to the enigmatic “transitional” texture of Mercier and Nicolas (1975) . Our results suggest that this texture reflects interruption of the main deformation cycle by processes possibly related to a rapidly forming lithospheric instability and generation of the kimberlite magma – offering a new interpretation of this ambiguous peridotite texture. Collectively, our results incorporate typically disparate geochemical and textural datasets on xenoliths to shed new insights into how metasomatism, volatiles, and deformation are connected in the deep cratonic lithosphere.

The Solonker-Xar Moron-Changchun-Yanji Suture (SXCYS) is regarded as a tectonic boundary between the Central Asian Orogenic Belt and the North China Craton. Formed during the closure of Paleo-Asian Ocean and modified by the subsequent magmatic activities, this suture might have recorded complex processes of accretionary orogeny and crustal recycling. Thus, seismic reflection profiling was conducted along a length of 160 km from Naiman to Ar Horqin Banner, Inner Mongolia, and the lithospheric structures of central SXCYS have been examined. A prominent feature is a group of strong reflections from the middle crust to the topmost mantle beneath the center of the profile, which consists of massive south dipping reflections and a few middle crustal reflections with a opposite vergence. This group of strong reflections is interpreted to be the subduction relict formed during the final closure of the Paleo-Asian Ocean. The estimated lateral extent of the suture zone is ca. 100 km across strike, and its subduction polarity is southward with an apparent dip angle of 15 to 20°. The upper crust along the whole profile is characterized by weak reflectivity, which also extends to the middle crust. This absence of reflective structures may be attributed to the magmatic activities during or after the continental convergence. Two strong reflection clusters extending from the bottom of upper crust to the lower crust are also identified, which may be caused by distinct magmatic intrusions. Overprinted on the dipping reflections, the Moho is identified at a depth of 33 to 36 km, which is inferred to be formed at an extensional background contemporary with the subsurface Mesozoic sediments and extensional faults. A detailed model of the evolution processes of the central SXCYS is proposed, which includes the oceanic subduction, the final collision, and the modification by subsequent magmatic activities.

In the present contribution, we apply forward modelling and subsidence analysis to determine the initial lithospheric structure and the Neuquen Basin central area's stretching factor. The forward models determined that the initial thickness of the crust and the lithosphere would have been around 30 km and 100 km, respectively. Airy and regional isostasy models were considered for the calculation of the tectonic subsidence in outcrops and the subsurface. In both cases, results are very similar due to an elastic thickness of ~3 km for the beginning of the basin, which allows considering the Airy isostasy model as the representative for the analyzed period in the study area. Regarding the stretching factor, the results suggest that the extension varies between 1 and 1.32 for the analyzed area. Although these values seem to be higher than the previous estimations for the Neuquen Basin, they are consistent with those mentioned in the literature for the back-arc basins around the world with similar lithosphere structure and tectonic subsidence values. Furthermore, it should be mentioned that similar tectonic subsidence values could be obtained for the same area considering a lower stretching factor and a westward lithospheric thickening associated with the Neopaleozoic orogeny.

With the purpose of exploring the widely distributed Mesozoic granitoids in SE China and the related mineralization, we carried out a new 530-km-long seismic wide-angle reflection and refraction (WARR) profile along the transect Wanzai- Hui'an. Based on a previous exploration in 2012 and the analysis of this WARR profile, we have deduced a detailed P-wave velocity model of the crust and uppermost mantle. The main results are: (1) The crustal thickness is about 30 to 32 km beneath the Yangtze Block and West Cathaysia, and 29 to 30 km below the East Cathaysia, which represents a significant thinning with respect to the worldwide average thickness of shields and platforms. (2) The variation in seismic velocity between the upper crust and middle-lower crust in the Yangtze Block and the Cathaysia Blocks indicates that the Shaoxing-Jiangshan-Pingxiang Fault (SJPF) is the tectonic boundary between the Yangtze and Cathaysia and the Zhenghe-Dapu Fault (ZDF) is the tectonic boundary between the west and east Cathaysia. (3) The middle crust exhibits a low P-wave velocity layer of 6.2 km/s below the Wuyishan Metallogenic Belt (WMB). This low velocity layer can be attributed to the delamination during the Caledonian orogeny and the Yanshanian extension. (4) The middle-lower crust shows a clear lateral velocity variation from west to east in Cathaysia. The subduction of the Paleo-Pacific plate is believed to be the main reason for the extensional tectonic environment and magmatism during the Yanshanian (Jurassic-Cretaceous) period, leading to significant crustal and lithospheric thinning. Relatively high velocity in the middle-lower crust and widely disseminated Cretaceous volcanic rocks in East Cathaysia may be related to the slab rollback of the Paleo-Pacific plate in the late Yanshanian (Cretaceous) period.

The Eurekan Orogeny, which created much of the high topography of Ellesmere Island and adjacent Greenland, exhibits a crustal architecture linked to intraplate orogenesis in the Cenozoic. It is generally considered that the rotation of Greenland in the Eocene (related to sedimentary basin formation in Baffin Bay) produced compressional intraplate tectonics. Deformation in the region is notably localized to the Central Ellesmere Domain and the Northern Ellesmere Domain. However, an important tectonic feature of Ellesmere Island is the Hazen Stable Block, which shows horizontal Paleogene Eureka Sound group strata overlying Palaeozoic-age steeply dipping beds. The intense deformation in the Hazen Stable Block is related to continental orogenesis in the Late Silurian–Devonian. Therefore, the Hazen Stable Block is thought to have undergone only minor Eurekan-age (55–35 Ma) deformation, while surrounding (highly deformed) units may have re-activated faults from Paleocene continental amalgamation. Here, high-resolution thermal–mechanical numerical experiments are implemented to explore lithospheric deformation (related to continental shortening) for a range of tectonic scenarios, namely, the presence of inherent deformational “scars” and rheologically strengthened crust/mantle lithosphere (both due to ancient continental accretion). This study marks the first geodynamic excursion to this high Arctic region, and we present some of the first interpretations of the development of Eurekan-age lithospheric evolution. Our results show that a rheologically strong Hazen Stable Block crust produces tectonics similar to the Eurekan Orogeny. Furthermore, lithospheric scars can generate more localized deformation and topography than rheological changes to the lithosphere and may offer a new interpretation on enigmatic intraplate tectonics.

Gneiss domes occur in a wide variety of orogenic and anorogenic domains of the continental crust, and play a major role in lithosphere dynamics by allowing upwards transfer of heat and mass. They commonly contain a core of granites and/or migmatites, overlain by a mantle of lower-grade rocks. Evolutionary models of many gneiss domes are controversial. Here we use new structural and zircon isotopic data to unravel the tectono-magmatic evolution of the Yalgoo dome and surroundings, at the margins of the Neoarchean Yilgarn Orogen, Western Australia. The study area includes at least seven granite–migmatite domes (5–70 km in average diameter), and several subdomes within the larger domes, all showing comparable structural features and age. In each dome, a concentric domal foliation is concordant with granite–greenstone contacts, bearing a radial, outward-plunging lineation. The bulk of the structures in each dome reflect magmatic flow, with pervasive subsolidus fabrics occurring only along the outer dome margins, and reflecting dome-up kinematics. Narrow greenstone keels pinched between domes and subdomes display vertical constriction, in an area regionally dominated by flattening along the steep sides of the deeply-eroded domes, and along the flat-laying dome roofs. The regional structural pattern and the kinematics of the high-strain zones are best explained by sequential emplacement of nested diapirs, which delivered large volumes of granitic magma in a c. 20 Myr time-span. The dome-and-keel regional architecture and the internal structures of each dome resulted therefore from multiscale polydiapirism. These diapirs were later weakly overprinted by a tectonic fabric that developed during the Neoarchean Yilgarn Orogeny. The contrast between the Yalgoo region and the rest of the craton, which was strongly reworked by this orogeny, highlights the dichotomy of tectonic styles in Archean terranes, demonstrating that diapirism dominated in times of tectonic quiescence.

The Cenozoic India-Asia collision reactivated several ancient thrust belts in the interior of the Asian continent, including the West and East Kunlun ranges in central Tibet, and the Tian Shan and Qilian Shan further north. Both basin sedimentary records and thermochronological data show that the uplift of the South Tian Shan and Qilian Shan at the north occurred earlier than that of the West and East Kunlun ranges at the south. Diachronous continental deformation and initiation of uplift during orogeny are contrary to the general notion that the stress transfer in response to the India-Asia collision should propagate sequentially from south to north. Here we systematically conducted 2D thermo-mechanical simulations to investigate possible factors for this diachronous deformation pattern. The results show that a hotter Tian Shan lithosphere, with Moho temperature >100 °C hotter than that of the proto-southern Asia, leads to an earlier and higher uplift of the Tian Shan. Additionally, a faster convergence rate of the India-Asia collision results in a more efficient transfer of boundary force into the upper plate's interior, giving rise to a larger amount of uplift in the Tian Shan. We conclude that intra-continental ranges with weaker lithosphere, such as the Tian Shan or Qilian Shan, uplift earlier than stronger regions, such as the West and East Kunlun ranges. Faster convergence rates amplify this situation. Our results imply that the unique diachronous growth of the Tibetan plateau arises from its complex pre-collisional history, which includes collided arc-continent terranes with hotter and weaker lithosphere that respond to the effects of far-field stress transfer.

The Songpan block in the northeastern Qinghai–Tibet Plateau (QTP) located at the junction of the E–W- and N–S-trending tectonic belts has affected the formation and evolution of the Chinese continent since Mesozoic and is a tectonic node in the central part of the Chinese continent. In this study, the Hezuo-Tangke deep seismic reflection profiling of the 257 km-long was conducted in 2004, which is the first profile across the Songpan block and the West Qinling orogen. We reprocessed the data in 2009, and the results revealed the fine lithosphere structure of the northern margin of the Songpan block and the West Qinling orogen. The results also revealed the connection between the Songpan block and East Kunlun–West Qinling orogeny, indicating that the Songpan block and the West Qinling orogen belong to the same stable continental block and that their lower crusts are both characterized by north-dipping strong reflectors, which provide seismic evidence for subduction of the lower crust of the Songpan block beneath the West Qinling orogen. We found that the sub-horizontal Moho reflectors beneath the West Qinling orogen indicate that it underwent intensive extension after collisional orogeny. The results of this study also indicate that the Kunlun fault did not cut off the Moho. Actually, it terminated at a sub-horizontal decollement in the lowermost crust of Tibet at a depth of ~ 35 km. The data provided through the investigation also are helpful in evaluating prospective oil and gas resources in the Songpan block.

The lithosphere–asthenosphere boundary (LAB) separates the hard and rigid outer layer of the earth (lithosphere) and the weaker, hotter, and deeper part of the upper mantle (asthenosphere) and plays a pivotal role in plate tectonics. However, its definitive detection, especially beneath the cratons, is proving elusive. One of the geophysical tools used to map the LAB beneath the cratons is through magnetotelluric (MT) observations. The resistivity at boundary falls in the range of 5–25 Ω-m and can be explained by the presence of a small amount of water in the asthenosphere, possibly inducing partial melt. Here, we report thickness of the LAB in one of the oldest dated ancient cratons of India—Eastern Indian Craton (EIC) of ~ 3.3 Gyr, from MT studies. The two prominent phase-sensitive strike directions, one each for crust and mantle, and the presence of resistive continental lower crust act as a window to mantle in resolving deeper electrical conductivity structures beneath EIC. Our results show that the LAB beneath the EIC is at 95 km. The region is interesting as the electrical properties of the crust and mantle and the Moho depth are similar to those of the Slave Craton, Canada (~ 4.0 Gyr) but the depth of the LAB beneath the EIC is half that of the Slave craton. As cratonic signatures, depicted by ultrapotassic rocks from Gondwana coal fields close to EIC, are preserved at least till early Cretaceous (117 Ma) it is likely that Himalayan orogeny could have played a major role in delamination of the lithospheric roots of the EIC in addition to attendant seismicity.

The Atlas orogeny in northern Algeria and Tunisia led to the destruction of Tethys oceanic lithosphere and cumulated in a collision of microplates rifted off the European margin with the North African continental margin. The location of the boundary between African plate and Kabylian microplate is expressed in northern Algeria by a crustal wedge with double vergence of thrust sheets, whereas in northern Tunisia the geologic environment is more complex and the location of the plate boundary is ambiguous. In this study, we analyzed gravity data to constrain the crustal structure along the northern margin of Tunisia. The analysis includes a separation of regional and residual gravity anomalies and the application of gradient operators to locate density contrast boundaries. The horizontal gradient magnitude and directional gradient highlight a prominent regional E–W gravity gradient in the northern Tunisian Atlas interpreted as a deep fault (active since at least the Early Mesozoic) having a variable kinematic activity depending on the tectonic regime in the region. The main E–W gravity gradient separates two blocks having different gravitational and seismic responses. The southern block has numerous gravity lineaments trending in different directions implying several density variations within the crust, whereas the northern block shows a long-wavelength negative gravity anomaly with a few lineaments. Taking into account the geologic context of the Western Mediterranean region, we consider the E–W prominent feature as the boundary between African plate and Kabylian microplate in northern Tunisia that rifted off Europe. This hypothesis fits most previous geological and geophysical studies and has an important impact on the petroleum and mineral resource prospection as these two blocks were separated by an ocean and they did not belong to the same margin.

The Paleozoic Variscan orogeny was a large-scale collisional event involving amalgamation of multiple continents and micro-continents. Existing data, suggests oroclinal buckling of an originally near-linear convergent margin during the last stages of Variscan deformation in the late Paleozoic. Closure of the Rheic Ocean resulted in E–W shortening (present-day coordinates) in the Carboniferous, producing a near linear N–S trending, east-verging belt. Subsequent N–S shortening near the Carb-Permian boundary resulted in oroclinal buckling. This late-stage orogenic event remains an enigmatic part of final Pangea amalgamation. The present-day arc curvature of the Variscan has inspired many tectonic models, with little agreement between them. While there is general consensus that two separate phases of deformation occurred, various models consider that curvature was caused by: dextral transpression around a Gondwana indentor; strike-slip wrench tectonics; or a change in tectonic transport direction due to changing stress fields. More recent models explain the curvature as an orocline, with potentially two opposite-facing bends, caused by secondary rotations. Deciphering the kinematic history of curved orogens is difficult, and requires establishment of two deformation phases: an initial compressive phase that forms a relatively linear belt, and a second phase that causes vertical-axis rotation of the orogenic limbs. Historically the most robust technique to accurately quantify vertical axis-rotation in curved orogens is paleomagnetic analysis, but recently other types of data, including fracture, geochemical, petrologic, paleo-current and calcite twin data, have been used to corroborate secondary buckling. A review of existing and new Variscan data from Iberia is presented that argues for secondary buckling of an originally linear orogenic system. Together, these data constrain oroclinal buckling of the Cantabrian Orocline to have occurred in about 10 Ma during the latest Carboniferous, which agrees well with recent geodynamical models and structural data that relate oroclinal buckling with lithospheric delamination in the Variscan.

We review deformation fabrics in mantle xenoliths from the central part of the Carpathian–Pannonian Region (CPR) and, in combination with seismic shear wave splitting data, attempt to define patterns of upper mantle anisotropy. Our interpretations from both lines of evidence support a model for east–west oriented asthenospheric flow, decoupled (at least in part) from the overlying lithosphere. Mantle flow fields resulting from Tertiary indentation of Europe by the Adria micro-plate and the resulting Alpine orogen may thus have been an important factor in driving the eastward extrusion of lithospheric blocks in the CPR accompanied by lithospheric extension, rapid ‘rollback’ of the Carpathian subduction system, and its diachronous collision with the European craton. According to this model, eastward asthenospheric flow would add significantly to the effects of slab rollback and gravitational instability. Thus, opening of the Pannonian Basin, rather than being exclusively driven by ‘slab pull’ and gravitational instability, could have been resulted, at least in part, from mantle flow associated with the Adria–European collision and ensuing Alpine orogeny. Such models have also been proposed for analogous geodynamic scenarios such as the western and eastern Mediterranean, and western and southwestern Pacific regions, offering a potential generic model for back-arc basin opening.

During the last two decades teleseismic studies yielded valuable information on the structure of the upper mantle below the Alpine–Mediterranean area. Subducted oceanic lithosphere forms a broad anomaly resting on but not penetrating the 670 km discontinuity. More shallow slabs imaged below the Alpine arc are interpreted as subducted continental lower lithosphere. Substantial advances in our understanding of past and active tectonic processes have been achieved due to these results. However, important issues like the polarity of subduction under the Eastern Alps and the slab geometry at the transition to the Pannonian realm are still under debate. The ALPASS teleseismic experiment was designed to address these open questions. Teleseismic waveforms from 80 earthquakes recorded at 75 temporary and 79 permanent stations were collected during 2005 and 2006. From these data, a tomographic image of the upper mantle was generated between 60 km and 500 km depth. Crustal corrections, additional station terms, and ray bending caused by the velocity perturbations were considered. A steeply to vertically dipping “shallow slab” below the Eastern Alps is clearly resolved down to a depth of ~ 250 km. It is interpreted as European lower lithosphere detached from the crust and subducted during post-collision convergence between Adria and Europe. Below the Pannonian realm low velocities or high mantle temperatures prevail down to ~ 300 km depth, consistent with the concept of a Pannonian lithospheric fragment, which underwent strike–slip deformation relative to the European plate and extension during the post-collision phase of the Alpine orogeny. Between 350 km and 400 km depth, a “deep slab” extends from below the central Eastern Alps to under the Pannonian realm. It is interpreted as subducted lithosphere of the Alpine Tethys. At greater depth, there is a continuous transition to the high velocity anomaly above the 670 km discontinuity.

The tectonic and tectonostratigaphic evolution of foreland basins and related Tertiary depressions are the key to investigate deformation history and the uplifting of the continental lithosphere of the Alpine–Pyrenean Orogeny. The northern part of the Duero basin is the foreland basin of the Cantabrian Mountains, which are, in turn, the western part of the Pyrenean Orogen. We have studied the western sharp end of the Duero foreland basin, and its relation to the Tertiary deposits of the NW Iberian Peninsula and the topography evolution. In order to propose a coherent tectonic and tectonosedimentary model that could explain all Tertiary deposits, we have analysed the depositional environment, stratigraphic sequences, paleocurrents and established a correlation of the main outcrops. Besides, a detailed structural mapping of the Alpine structures that limit and affect the main Tertiary outcrops has been carried out. The Tertiary deposits of the NW Iberian Peninsula depressions are affected and fragmented by Alpine structures that limit their extensions and locations. The stratigraphic succession is similar in the NW Tertiary outcrops; they are mainly terrigenous and carbonated continental deposits formed by assemblage of alluvial fans developed at the mountains front, in arid or semiarid conditions. Three formations can be identified in the main depressions: Toral Fm, Santalla Fm and Medulas Fm. The NW Tertiary outcrops were the western deposits of the Duero foreland basin that surrounded the lateral termination of the Pyrenean Orogen. These deposits were fragmented and eroded by the subsequent uplift of the Galaico–Leoneses Mountains and the NE–SW strike-slip faults activity (broken foreland basin). Only the latest stages of some of these outcrops can be considered as intramontane basins as traditionally have been interpreted. The sedimentation started in the northeast (Oviedo–Infiesto) during the Eocene and migrated to the west (As Pontes) during the Late Oligocene–Early Miocene times. Meanwhile, southern areas were far away from the tectonic activity (El Bierzo, O Barco, Monforte, Sarria depressions).

Gridded aeromagnetic data, 2D forward models and 3D potential field inversions are used in combination with surface geological and petrophysical data to reveal basement and supracrustal architecture of the Wernecke Inlier, northern Canada. Paleoproterozoic crystalline basement is modelled at ∼ 5–10 km depth, and is significantly offset by a major NW-trending normal fault. Basement fault development is interpreted to have occurred during lithospheric extension following accretion during the Wopmay Orogeny (2100–1840 Ma) utilising the existing structural architecture of the Richardson Fault Array. Forward models provided evidence for structural connectivity between basement faults and mapped normal faults within the Wernecke Supergroup. Basement faults appear to project to Wernecke Breccia occurrences, and may have been important fluid pathways during ca. 1590 Ma hydrothermal activity. Syn-breccia faulting also appears to have been important during Wernecke Breccia emplacement, accommodating and focusing brecciation and alteration.

Hudson Bay conceals several fundamental tectonic elements of the North American continent, including most of the ca. 1.9–1.8 Ga Trans-Hudson orogen (THO) and the Paleozoic Hudson Bay basin. Formed due to a collision between two cratons, the THO is similar in scale and tectonic style to the modern Himalayan–Karakorum orogen. During collision, the lobate shape of the indentor (Superior craton) formed an orogenic template that, along with the smaller Sask craton, exerted a persistent influence on the tectonic evolution of the region resulting in anomalous preservation of juvenile Proterozoic crust. Extensive products of 2.72–2.68 Ga and 1.9–1.8 Ga episodes of subduction are preserved, but the spatial scale of corresponding domains increases by roughly an order-of-magnitude (to 1000 km, comparable to modern subduction environments) from the Archean to the Proterozoic. Based on analysis of gravity and magnetic data and published field evidence, we propose a new tectonic model in which Proterozoic crust in the southeastern third of Hudson Bay formed within an oceanic or marginal-basin setting proximal to the Superior craton, whereas the northwestern third is underlain by Archean crust. An intervening central belt truncates the southeastern domains and is interpreted to be a continental magmatic arc. Thick, cold and refractory lithosphere that underlies the Bay is well imaged by surface-wave studies and comprises a large component of the cratonic mantle keel beneath North America. The existence of an unusually thick mantle root indicates that subduction and plate collision during the Trans-Hudson orogeny were ‘root-preserving’ (if not ‘root-forming’) processes. Although the Hudson Bay basin is the largest by surface area of four major intracratonic basins in North America, it is also the shallowest. Available evidence suggests that basin subsidence may have been triggered by eclogitization of lower-crustal material. Compared to other basins of similar age in North America, the relatively stiff lithospheric root may have inhibited subsidence of the Hudson Bay basin.

Review of the Late Neoproterozoic history of the northern Arabian–Nubian Shield (ANS) reveals that rapid and extensive erosional denudation, widespread late-orogenic calc–alkaline and alkaline igneous activity and intramontane basin formation affected this terrane at 630–590 Ma. Core-complex extension is also recorded at this time interval. To account for this coupling it is suggested that the mantle lithosphere was removed/delaminated from below the northern ANS subsequent to significant crust–mantle thickening in the course of the Late Neoproterozoic orogeny. Because the physical properties of the delamination process are not clear, we use it as a conceptual term accounting for the replacement of mantle lithosphere by an asthenosphere. Removal and replacement of the thickened lithospheric mantle roots potentially caused uplift of the northern ANS to elevations of more than 3 km, thus triggering exceptionally-rapid erosional unroofing of a ca. 10 km thick rock carapace, and some lateral extension. Delamination and erosional decompression potentially caused partial melting of ANS residual upper mantle and lower crust to produce the widespread post-orogenic magmas. We emphasize that removal of the lithospheric mantle also played a key role in lowering ANS topography to sea level. Our data show that lowering ANS down to sea level was significantly accelerated by post-delamination cooling and thermal subsidence. Unlike erosional denudation which is followed by isostatic uplift, thermal contraction causes net surface lowering. We show that thermal subsidence plays a critical role in lowering mountain belts, particularly in the latest stages, when the topography reaches a threshold of ∼ 1.0 km and erosion rates greatly decrease. Post-delamination thermal subsidence can cause 1.3 km of net surface lowering within 100 m.y. regardless of the state of relief and elevation. Therefore, orogenic belts that experienced removal or delamination of their mantle lithosphere (hot orogens) would rapidly rise, but would relatively rapidly fall too.

In many polydeformed Precambrian provinces, the understanding of their tectonic history is limited by insufficient exposure, which leads to difficulty in developing links between local and regional architecture, and results in poorly constrained models of their regional-scale architecture. High-resolution aeromagnetic data allows interpretation and modelling at a scale comparable to structural mapping, and by integrating these methods, these links can be developed with high confidence. As an example, we integrate structural mapping, aeromagnetic data interpretation and 3D magnetic inversions in a multi-scale structural analysis of the polydeformed eastern Musgrave Province in central Australia. Deformation during the ca. 1200 Ma Musgravian Orogeny is characterised by an originally northeast-trending structural grain defined by shear zones and tight to isoclinal folds at all scales. 3D magnetic inversion models of syn-to-post Musgravian granites indicate that this structural grain is predominantly west dipping. This architecture suggests that a northeast-oriented fold and thrust belt developed as a result of northwest–southeast compression in central Australia during the Musgravian Orogeny. The next deformation event is characterised by an array of originally east-southeast trending shear zones that truncate and offset the Musgravian structural grain with apparent dextral displacements of up to 1 km. These shear zones are commonly co-located with mafic and granitic dykes, suggesting a dilational origin, and they are interpreted to have initiated under northeast–southwest extension during the ca. 1080 Ma Giles Event. The architecture of these two Mesoproterozoic events was later extensively overprinted by two deformation events during the Pan-African aged (ca. 550 Ma) Petermann Orogeny. The first is characterised by the widespread reactivation of Mesoproterozoic structures, resulting in a network of shear zones of variable orientation, and the second is characterised by the development of crustal-scale transpressional shear zones, motion on which has caused the rotation of lithospheric blocks and the reorientation of prior structural trends by up to 90°. Collectively, the architecture of these two events suggests broadly north–south crustal shortening in central Australia as an intraplate response to Gondwana assembly. This example demonstrates that the integration of structural geology with aeromagnetic interpretation and modelling can be used to develop high-confidence links between local and regional structures. These links permit the derivation of better constrained models of major tectonic events, particularly in regions where outcrop is poor and the structural architecture is complex.

Mesoscale structures in Paleozoic rocks of the Ozark plateaus reveal four Pennsylvanian deformation episodes in midcontinent North America. The two earliest episodes can be assigned to progressive northwestward docking of the Ouachita terrane with North America. Early extensional structures (Event 1) indicate a northwest/southeast maximum horizontal stress (Hmax) during Early Pennsylvanian Ouachita terrane advance. Event 2 extensional and strike-slip structures indicate Hmax across the Ozark plateaus that varies systematically from north-northwest/south-southeast in the south to northeast/southwest in the north. This suggests development of a slip-line deformation field in response to minor northeastward lateral escape of lithospheric blocks away from the northwestward-moving Ouachita terrane's leading edge, which acted as an indenter in western Arkansas, southeastern Oklahoma, and Texas. Younger contractional and strike-slip structures of Event 3 indicate northeast/southwest Hmax across the entire Ozark plateaus, and deformation orientation and intensity are not readily assigned to Ouachita foreland deformation and may be related to Middle Pennsylvanian Ancestral Rockies contractional deformation. Finally, Event 4 contractional structures indicate northwest/southeast Hmax consistent with southern Appalachian late stage convergence. Deformation episodes are localized along basement fault zones, particularly at major bends, suggesting minor restraining-bend uplifts along strike-slip faults. Geometries of conjugate normal fault and hybrid shear joint arrays indicate localized areas of high differential stress consistent with basement block uplift at these bends. High-angle faults reactivated in a reverse sense and bedding-parallel veins suggest tensile minimum stresses and pore fluid pressures exceeding lithostatic stress, consistent with brine pulses driven into the midcontinent during Late Paleozoic orogeny (as proposed by other authors).

The results obtained from a suite of spherical, thin sheet, finite element model calculations on the Late Cretaceous–Early Tertiary tectonic evolution of the area of the Central European Basin System (CEBS) are presented and discussed. The calculations incorporate the effects of variations in lithospheric structures and compositions and changes in the imposed boundary conditions. The impact of lateral contrasts such as pre-existing weak domains is quantified through a thermo-mechanical model for the entire CEBS. The obtained predictions have been constrained by comparisons with more recent observed field data and resemble the present-day dynamics and kinematics. A trial and error reconstruction of the development through time of the dynamic of the Alpine orogeny as well as of the Early Atlantic extension have been considered in order to investigate the role of boundary forces in the Late Cretaceous–Early Tertiary tectonic evolution of the CEBS. The observed evolution of subsidence depocentres and areas of uplift for the CEBS during this time-span has been reconstructed. The results are in agreement with previous studies which have related the large-scale Late Cretaceous–Early Tertiary inversion within the CEBS to long-wavelength intra-plate compressive stresses exerted mainly by the Alpine thrust. The models show that lateral heterogeneities have to be considered in order to model more local features such as the observed differential response of adjacent areas to the large-scale stress regime. This indicates that both intra-plate-tectonic forces and rheological structural contrasts must be taken into account to reconcile the style of intra-plate deformation and to model the evolution through time of complex basin systems.

In the southern Uralides, Permian magmatism, tectonism and metamorphism concentrate in the East Uralian Zone, such that this zone provides the key for understanding of the late phase of the Uralian orogeny. Carboniferous distal marine sediments and lenses of amphibolite–serpentinite associations show that the lithospheric precursor of the East Uralian Zone was largely oceanic. In the Latest Carboniferous, the Kazakhstanides collided with the Uralides, but relics of the oceanic basin between both units were conserved and accommodated a large part of Permian deformation. Structural data provide evidence that a NW-directed plate convergence was partitioned in W-directed compression and N-directed strike-slip. Additionally, they show that granitic melts, which had formed in the thickened crust of the Uralides, migrated eastward into the strike-slip belt of the East Uralian Zone. Also the exhumation of the plutonic rocks occurred eastward, oblique to the direction of regional extension, indicating that upper crust and lower crust deformed mainly decoupled from one another. We suggest that the emplacement of the granite–gneiss complexes contributed significantly to the consolidation of the orogenic crust in the eastern Urals.

We propose a simple analytic way to estimate the β- (stretching) factors for basin formation by lithospheric extension. The suggested approach accounts for the stretching and thinning of the sediments in a mass conservative manner. It is shown that the stretching and thinning of the sediments may have an important impact on the magnitude of the β-factors, especially for deep basins with thick pre-rift formations. This mass conservative way to estimate β-factors has been applied to a transect on the Atlantic Voring margin offshore mid-Norway, where it undergoes four rift episodes from the end of the Caledonian orogeny until today. The results for the Voring transect show that the first rift phases may have been more important than previously modeled. These results also show that the magnitude of the Late Cretaceous–Paleocene rift phase becomes reduced by including extension and thinning of pre-rift sediments. The analytic results allow for a study of the sensitivity of the β-factors with respect to various parameters like for instance paleo water depth and rock densities.

The spatial distribution of large-scale crustal domains and their boundaries are investigated in the North Sea area by combining gravity, magnetic and seismic data. The North Sea is situated on the plates of three continents, Avalonia, Laurentia and Baltica, which collided during the Caledonian orogeny in the middle Palaeozoic. The location and continuation of the collisional sutures are debated. We apply filters and transformations to potential field data to focus on the crystalline crust and uppermost mantle on a regional scale in order to extract new information on continental sutures. The transformations reveal intrinsic features of crustal transitions between the Caledonian plates and their relation to later extensional structures. The transformations include the Hough Transform applied to the gravity field, calculation of fractional derivatives and integrals of the gravity and magnetic fields, the pseudogravity field and the horizontal gradient field as well as upward continuation. The results indicate a fundamental difference between the lithosphere of Avalonia, Laurentia and Baltica. The location of the Mesozoic rift system (the Central Graben and Viking Graben), may have been partly determined by the presence of the sutures between these three plate, indicative of extensional reactivation of compressional structures. A significant lineament across the entire North Sea between Scotland and North Germany indicates that the lower crust of Baltica provenance may extend as far south-westward as to this lineament. Comparison of the power spectra of the gravity field in five selected areas shows significant differences in the long wavelength components between the areas north and south of the lineament corresponding to differences in crustal properties. This lineament could represent the suture between lithosphere of Caledonian origin (Avalonia) versus lithosphere of Precambrian origin (Baltica) in the lower crust and upper mantle. If this is the case, the lineament is the missing link in the reconstruction of the triple plate collision.

The Wadati–Benioff Zone (WBZ) is an approximate plane defined by earthquakes hypocentres observed in convergent plate boundaries and that usually dips at angles greater than 30°. In some areas of the Andes, where there are gaps in volcanic activity, and where heat flow is abnormally low, this plane in most studies has nearly horizontal dip at a depth of about 75–100 km, and it has been associated to flat subduction of the oceanic lithosphere. This situation has been taken as the present-day analogue of the Laramide orogeny of western North America for which a ‘flat-slab’ episode has been proposed in the past years. In this work, the observed low heat flow in areas of the Andes is assumed to be due to low radiogenic heat generation in geologically old and allochthonous terranes constituting large regions of western South America. On the basis of geotherms obtained for areas of Ecuador, Peru, Chile and Argentina, and of rheological results describing the partition between brittle and ductile regimes, the seismic activity observed both in the lower crust and at depths of about 75–100 km is thoroughly explained. At these depths, earthquakes occur within the subcontinental upper mantle, and then there is no flat WBZ associated to subduction of the oceanic lithosphere. There is evidence from recent seismological observations that the real WBZ lies not horizontally and deeper in the tectonosphere.