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Mississippi Valley-type (MVT) Zn–Pb deposits generally form in both orogenic forelands and thrust belts, but the tectonic and structural controls on ore formation in the latter tectonic setting remain poorly understood. This study examines MVT deposits in the late Mesozoic–Cenozoic Tethyan and Cordilleran orogenic thrust belts that have ages determined mainly by paleomagnetic methods or that are well constrained by other geological relationships. Some deposits predated regional thrusting but most deposits formed during regional transpression or extension after early stages of thrusting during convergence. Extensional faults rather than compressional (reverse or thrust) faults control the distribution of ore zones at the deposit or district scale. Post-thrusting MVT mineralization within thrust belts occurs as a result of synorogenic stress transition from compression to transpression/extension. This stress change appears to favor the generation of local extensional faults due to reactivation of pre-existing structures, simple shearing-related tension or dilation, or other mechanisms such as gravitational spreading of weak crust, lower crustal flow, and removal of lithosphere. In comparison, ore-controlling extensional faults in forelands are generated by means of the flexure of the foreland plate during orogenic convergence. Exploration for MVT ores in orogenic thrust belts should focus on extensional zones and extensional faults at district and deposit scales.

In this study, we explore thrust system, flower structures and transpressive duplexes in the Zeidun-Kareim belt (ZKB) in the Egyptian Nubian Shield (ENS; northwestern ANS). Filed observations and the measured stretched lineations along thrust planes reveal two main thrusting directions; ESE- (to NE- and NNE-)- and NW- (to WNW-)-directions belonging to two main phases of contraction. The timing of both phases is indirectly constrained. The older ESE- (to NE- and NNE-)-vergent thrusting is attributed to the E-W Gondwana assembly. The younger NW- (to WNW-)-vergent thrusting is akin to the Najd Orogeny. The poles to the in-sequence thrusts lie close to the poles of stretching lineations. The mean orientations of thrust propagation are, respectively, 059° and 309°. Propagation of thrusting along the two main thrusting directions resulted in the formation of a complete geometry of thrust duplex system, imbricate nappe stacking, flower structures and thrust-related folding. The top-to- ESE- (to NE- and NNE-) transpression reflects dextral sense, whereas the top-to- NW- (to WNW-) transpression exhibits sinistral sense, in compatible with those recorded and argued by many authors elsewhere in the ENS and the entire ANS. Our study fully constraints the ZKB spathio-temporal tectonic evolution which involves three main stages.

Multi-sensor satellite imagery data promote fast, cost-efficient regional geological mapping that constantly forms a criterion for successful gold exploration programs in harsh and inaccessible regions. The Barramiya–Mueilha sector in the Central Eastern Desert of Egypt contains several occurrences of shear/fault-associated gold-bearing quartz veins with consistently simple mineralogy and narrow hydrothermal alteration haloes. Gold-quartz veins and zones of carbonate alteration and listvenitization are widespread along the ENE–WSW Barramiya–Um Salatit and Dungash–Mueilha shear belts. These belts are characterized by heterogeneous shear fabrics and asymmetrical or overturned folds. Sentinel-1, Phased Array type L-band Synthetic Aperture Radar (PALSAR), Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER), and Sentinel-2 are used herein to explicate the regional structural control of gold mineralization in the Barramiya–Mueilha sector. Feature-oriented Principal Components Selection (FPCS) applied to polarized backscatter ratio images of Sentinel-1 and PALSAR datasets show appreciable capability in tracing along the strike of regional structures and identification of potential dilation loci. The principal component analysis (PCA), band combination and band ratioing techniques are applied to the multispectral ASTER and Sentinel-2 datasets for lithological and hydrothermal alteration mapping. Ophiolites, island arc rocks, and Fe-oxides/hydroxides (ferrugination) and carbonate alteration zones are discriminated by using the PCA technique. Results of the band ratioing technique showed gossan, carbonate, and hydroxyl mineral assemblages in ductile shear zones, whereas irregular ferrugination zones are locally identified in the brittle shear zones. Gold occurrences are confined to major zones of fold superimposition and transpression along flexural planes in the foliated ophiolite-island arc belts. In the granitoid-gabbroid terranes, gold-quartz veins are rather controlled by fault and brittle shear zones. The uneven distribution of gold occurrences coupled with the variable recrystallization of the auriferous quartz veins suggests multistage gold mineralization in the area. Analysis of the host structures assessed by the remote sensing results denotes vein formation spanning the time–space from early transpression to late orogen collapse during the protracted tectonic evolution of the belt.

New petrological and U-Pb zircon geochronological information has been obtained from intrusive plutonic rocks and migmatites from the Cap de Creus massif (Eastern Pyrenees) in order to constrain the timing of the thermal and tectonic evolution of this northeasternmost segment of Iberia during late Palaeozoic time. Zircons from a deformed syntectonic quartz diorite from the northern Cap de Creus Tudela migmatitic complex yield a mean age of 298.8±3.8 Ma. A syntectonic granodiorite from the Roses pluton in the southern area of lowest metamorphic grade of the massif has been dated at 290.8±2.9 Ma. All the analysed zircons from two samples of migmatitic rocks yield inherited ages from the Precambrian metasedimentary protolith (with two main age clusters at c. 730-542 Ma and c. 2.9-2.2 Ga). However, field structural relationships indicate that migmatization occurred synchronously with the emplacement of the quartz dioritic magmas at c. 299 Ma. Thus, the results of this study suggest that subduction-related calc-alkaline magmatic activity in the Cap de Creus was coeval and coupled with D2 dextral transpression involving NNW-SSE crustal shortening during Late Carboniferous - Early Permian time (c. 299-291 Ma). Since these age determinations are within the range of those obtained for undeformed (or slightly deformed) calc-alkaline igneous rocks from NE Iberia, it follows that the Cap de Creus massif would represent a zone of intense localization of D2 transpression and subsequent D3 ductile wrenching that extended into the Lower Permian during a transitional stage between the Variscan and Cimmerian cycles.

The Maures–Tanneron Massif and the Corsica–Sardinia Block are two segments of the southern European Variscan belt that separated during the Late Oligocene–Miocene due to the opening of the Western Mediterranean basin. Correlation between the two regions, based mainly on petrologic similarities, is still debated. However, there are no detailed structural and petrochronological constraints on their potential relationships. In northern Sardinia there is well-documented evidence for a dextral transpressive shear zone that initiated after the first stage of frontal collision. In the Maures–Tanneron Massif, despite recognition of an important episode of transpressive deformation, it is still unclear which structures were active during this tectonic regime. We investigate in detail the kinematic of flow, finite strain and the timing of the deformation of the Cavalaire “Fault” (CF), a major ductile shear zone in the Maures–Tanneron Massif. In contrast to previous models, we argue that the CF is a transpressive shear zone characterized by a prevalent component of pure shear, while in-situ monazite geochronology reveals that the CF is initiated at ~ 323 Ma. The new data presented here, based on a multidisciplinary approach document, for the first time, the vorticity of the flow, finite strain and timing of this sector of the East Variscan Shear Zone, a regional-scale shear zone that characterized the Southern European Variscan belt during the late Carboniferous.

The Pyrenees are the result of the structural inversion of a rift of general direction N110E, established at the articulation of the European and Iberian plates. This rift was created by left-lateral transtension with severe crustal thinning during the latest Early Cretaceous and Mid-Cretaceous. Its inversion, which led to the uplifting of the Pyrenean chain, took place gradually, by transpression from east to west, during the Late Cretaceous followed by an Eocene collision. From historical fieldwork, this note mainly focuses on the rifting period at the scale of the Pyrenean domain. It clearly shows the fundamental role of the stratigraphic approach in structural interpretation. Although synchronous at the scale of the Pyrenees, the Cretaceous extension is more important in the western part of the chain, near the Bay of Biscay. It is therefore at this location, within the Tardets-Mauléon Basin, that the various stages of creation and evolution of the rift could be clearly recognized with, successively: (1) an epirogenic pre-rifting stage, during which the facies lines, submeridian during the Jurassic, gradually change into N110E during the Neocomian before giving way, in the Early Cretaceous (Barremian-Gargasian), to a moderate acceleration of subsidence and, consequently, to the gentle uplift of a southern and western margin, future High Primary Belt (also often called Axial Zone) and Landes Plateau, initiating the next stage; (2) a major, brittle, newly identified rifting stage in the Latest Aptian (Clansayesian) and Early Albian. It is characterized by the installation of elongated lows on the downthrown side of transverse N20 normal faults, active diapirism of the Triassic evaporites and central detachment of the post-Triassic cover. During the Mid-Albian, a major surface of stratigraphic unconformity, often associated to uplift, erosion, and local centripetal gliding of the basin borders, marks a new structural organization, a rapid mantle ascent and the end of this episode. Although obscured by the later Pyrenean compression, the reconstructed basin geometry is interpreted as a “pull-apart” basin associated to a modest left-lateral motion; (3) a late rifting stage characterized by the collapse of the internal zones by rapid mantle cooling. The erosion of the coeval uplift of the southern High Primary Belt and the Landes Plateau feeds the accumulation of the thick, deep and transgressive unconformable formation of the Black Flysch of Mid-Albian to Early Cenomanian age in a larger coalescing basin. Faulting associated with a simple NS distension is only active on the last major border faults; (4) finally, a post-rift stage of Late Cretaceous age illustrated by the establishment of a passively subsiding basin, devoid of major deformations and whose heterogeneity of the previous depocenters is gradually erased. The Pyrenean transpression, later and less marked than in the eastern and central Pyrenees, allowed the conservation of most of these Cretaceous transtensive structures. Within the Tardets-Mauléon Basin, the Pernes and Col d’Urdach sector, the only Pyrenean location where the Mid-cretaceous transtension led to a proven underwater mantle exhumation, illustrates from outcrops the various stages that have marked the history of the Pyrenean Trough. Towards the east, along the Internal Metamorphic Zone, the Lourdes-Bagnères, Baronnies, Ballongue, Aulus and Saint-Paul de Fenouillet-Boucheville Basins, or those, further north like the Camarade and Quillan Basins, successively examined, testify to the same sedimentary and structural evolution. As in the case of the Tardets-Mauléon Basin, we deal here again with “pull-apart” type basins established on a thinned crust, arranged in transtensive or locally transpressive relays and separated by zones of thicker crust and shallower facies successions. The Mid-Albian unconformity is always present, heralding a general drowning of the North Pyrenean Trough and cessation of the extensional activity. The Pyrenean deformation, however, constitutes an obstacle for a precise geodynamic reconstruction, in particular in the eastern and central Pyrénées. Towards the west and north-west, in the South Aquitaine, Parentis and Basque-Cantabrian Basins, where Pyrenean deformation has far less obscured the rifting events, a very comparable Cretaceous geodynamic evolution is observed thus strengthening the present interpretation. Les Pyrénées résultent de l’inversion structurale d’un rift d’orientation générale N110E, établi à l’articulation des plaques européenne et ibérique. Ce rift a été créé par transtension sénestre avec amincissement crustal sévère au cours du Crétacé inférieur terminal et du Crétacé moyen. Son inversion qui a conduit à la surrection de la chaîne pyrénéenne s’est opérée graduellement, par transpression d’est en ouest, au cours du Crétacé terminal puis collision éocène. Cette note s’attache surtout à préciser les étapes critiques du rifting à partir des travaux historiques de terrain qui présentent une grande homogénéité à l’échelle pyrénéenne. Elle montre clairement le rôle fondamental de l’approche stratigraphique dans l’interprétation structurale. Bien que synchrone à l’échelle des Pyrénées, l’extension crétacée est plus importante dans la partie occidentale de la chaîne, à l’approche du Golfe de Gascogne. C’est donc à cet endroit, au sein du bassin de Tardets-Mauléon, qu’ont pu être clairement reconnus les divers stades de création et d’évolution du rift avec, successivement: (1) un stade de pré-rifting de type épirogénique, au cours duquel les lignes d’isofaciès, subméridiennes au Jurassique s’orientent progressivement à N110E pendant le Néocomien avant de laisser place au Crétacé inférieur (Barrémien-Gargasien) à une accélération modérée de la subsidence, et par réaction au soulèvement d’une marge sud et ouest (future Haute Chaîne souvent appelée également Zone Axiale) et Plateau Landais, prélude au stade suivant ; (2) un stade de rifting majeur, cassant, nouvellement identifié dans l’Aptien terminal (Clansayésien) et l’Albien inférieur. Il est caractérisé par la mise en place de gouttières associées à des failles transverses N20 à jeu normal avec diapirisme des évaporites triasiques, décollement et glissement centripète local de la couverture post-triasique bordière et remontée mantellique rapide. À l’Albien moyen, une surface de discontinuité stratigraphique majeure, souvent associée à une remontée des bordures du bassin et à leur érosion, ainsi qu’à l’ascension rapide du manteau, marque la fin de cet épisode. Quoique rendue difficile par la tectonique compressive pyrénéenne, la reconstruction proposée de la géométrie du Bassin de Mauléon s’accorde avec un bassin de type pull-apart associé à un régime décrochant senestre de modeste ampleur ; (3) un stade de rifting tardif caractérisé par l’effondrement des zones internes et le rapide refroidissement mantellique. Le soulèvement et l’érosion de la Haute Chaîne méridionale et du Plateau Landais conduisent à l’accumulation de l’épaisse formation discordante profonde et transgressive du Flysch Noir d’âge albien moyen à cénomanien inférieur, dans un bassin unique associé à une distension N–S sur les dernières failles bordières ; (4) enfin, un stade post-rift d’âge crétacé supérieur illustré par la mise en place d’un bassin subsident passif, dépourvu de déformations majeures et dont l’hétérogénéité des dépocentres précédents est progressivement effacée. La transpression pyrénéenne, plus tardive et moins accusée que dans les Pyrénées orientales et centrales, a permis la conservation de la plupart de ces structures transtensives crétacées. Au sein de ce bassin de Tardets-Mauléon, le secteur des Pernes et du Col d’Urdach, seul emplacement pyrénéen où la transtension mésocrétacée a conduit à une exhumation mantellique sous-marine accomplie, illustre à l’affleurement les diverses étapes qui ont jalonné l’histoire du sillon dans son ensemble. Vers l’est, le long de la Zone Interne métamorphique, les bassins de Lourdes-Bagnères, des Baronnies, de Camarade, de la Ballongue, d’Aulus et de Saint-Paul de Fenouillet-Boucheville, ou ceux, nord ou sous-pyrénéens, de Camarade et Quillan, successivement examinés, témoignent dans l’ensemble de la même évolution sédimentaire et structurale. Comme dans le cas du bassin de Tardets-Mauléon, il s’agit ici encore de bassins de type pull-apart établis sur une croûte amincie, disposés en relais de décrochement transtensifs ou localement transpressifs et séparés par des zones de haut-fond à croûte plus épaisse. La discontinuité de l’Albien moyen y est partout présente. La déformation pyrénéenne constitue cependant un obstacle pour une reconstitution géodynamique précise, notamment dans les Pyrénées orientales et centrales. Vers l’ouest et le nord-ouest, dans les bassins sud-aquitains, de Parentis et basco-cantabrique où cette déformation a beaucoup moins profondément affecté les structures issues du rifting, s’observe une évolution géodynamique crétacée très comparable, renforçant ainsi l’interprétation proposée.

In the Western Alps, a steeply dipping km-scale shear zone (the Ferriere-Mollières shear zone) cross-cuts Variscan migmatites in the Argentera-Mercantour External Crystalline Massif. Structural analysis joined with kinematic vorticity and finite strain analyses allowed to recognize a high-temperature deformation associated with dextral transpression characterized by a variation in the percentage of pure shear and simple shear along a deformation gradient. U–Th–Pb dating of syn-kinematic monazites was performed on mylonites. The oldest ~ 340 Ma ages were obtained in protomylonites, whereas ages of ~ 320 Ma were found in mylonites from the core of the shear zone. These ages indicate that the Ferriere-Mollières shear zone is a still preserved Variscan shear zone. Ages of ~ 320 Ma obtained in this work are in agreement with ages of the dextral transpressional shear zones occurring in the Maures-Tanneron Massif and Corsica-Sardinia. However, transpression in the Argentera-Mercantour Massif started earlier than in other sectors of the southern Variscan Belt. This is possibly caused by the curvature of the belt triggering the progressive migration of shear deformation. Our data allow a correlation between the Argentera-Mercantour Massif and other segments of the Southern European Variscan Belt, in particular with Maures-Tanneron Massif and Corsica-Sardinia, and contribute to fill a gap in the age of activity and in the kinematics of the flow of the system of dextral shear zones of the southern portion of the EVSZ.

Based on new structural, petrological and U-Th-Pb geochronological data, a reappraisal of the Variscan tectono-metamorphic history of the Pelvoux Massif (External Crystalline Massif, French Alps) is proposed with the aim to understand the flow pattern and kinematics of the Variscan partially molten crust and the Eastern Variscan Shear Zone. The Pelvoux Massif consists of high-grade metamorphic rocks of middle to lower crust, mostly migmatites, that record a prominent syn-metamorphic deformation event (D 2 ) characterized by a pervasive NE-SW striking, steeply dipping, S 2 foliation, and a network of anastomosed NS and NW-SE trending shear zones, the kinematics of which indicates a sinistral transpression. Relics of an early syn-metamorphic event (D 1 /M 1 ) related to crustal thickening and top-to-the-east nappe stacking are also reported. Both the D 1 and D 2 features are interpreted as reflecting a NW-SE shortening event, firstly marked by dominant nappe stacking, and secondly overprinted by a sinistral transpression that started at peak metamorphism with the onset of crustal partial melting at ca. 650 °C during the late Visean (ca. 335–330 Ma). Ongoing sinistral D 2 transpression in the partially molten middle-lower crust of the Pelvoux involved strain partitioning between C and C’ shear zones and horizontal longitudinal flow in the range 330–300 Ma. Along the anatectic front, vertical shortening and top-to-the-NW shearing (D 3 ) is coeval with D 2 and argue for southeastward motion of the partially molten crust. The contemporaneity between NW-SE directed transpressional flow and vertical shortening is supported by our radiometric data of D 2 and D 3 and attests for strain partitioning between the suprastructure and infrastructure during horizontal crustal flow under transpressive regime. The exhumation of deep-seated rocks during sinistral transpression followed a near isothermal (ca. 700 °C) evolution down to pressure of ca. 0.5 GPa in the period 325–306 Ma. The sinistral transpression recorded in the Pelvoux Massif might corresponds to an antithetic shear zone coeval with the dextral East-Variscan Shear Zone, proposed for this part of the Variscan orogen. Sur la base de nouvelles données structurales, pétrologiques et géochronologiques U-Th-Pb, une réévaluation de l'histoire tectono-métamorphique varisque du massif du Pelvoux (Massif cristallin externe, Alpes françaises) est proposée dans le but de comprendre le style et la cinématique du fluage de la croûte varisque partiellement fondue et de la Zone de Cisaillement Est Varisque. Le massif du Pelvoux est constitué de roches métamorphiques de haut grade, de la croûte moyenne à inférieure, principalement des migmatites, qui enregistrent un événement de déformation syn-métamorphique prédominant (D 2 ) caractérisé par une orientation NE-SW, une foliation S 2 à fort pendage et un réseau anastomosé de zones de cisaillement d'orientation NS et NW-SE dont la cinématique indique une transpression senestre. Des reliques d'un événement syn-métamorphique précoce (D 1 /M 1 ) lié à l'épaississement de la croûte et à l'empilement des nappes à vergence Est sont retrouvées. Les caractéristiques de D 1 et D 2 sont interprétées comme reflétant un événement de raccourcissement NW-SE, d'abord marqué par l'empilement dominant des nappes, qui évolue ensuite en une transpression senestre, initiée au pic du métamorphisme avec le début de l’anatexie crustale dès 650 °C, à la fin du Viséen (335–330 Ma). Dans la croûte partiellement fondue, la déformation transpressive senestre D 2 se partitionne avec la formation de zones de cisaillement C et C’ qui accommodent le fluage longitudinal entre 330 et 300 Ma. Le long du front anatectique, un raccourcissement vertical accompagné d’un cisaillement vers le NW (déformation D 3 ) sont contemporains de D 2 et participent aussi à l’échappement vers le sud-est de la croûte partiellement fondue. La contemporanéité entre le fluage transpressif dirigé NW-SE (D 2 ) et le raccourcissement vertical à cinématique NW (D 3 ) est étayée par nos données radiométriques. L'exhumation des roches profondes lors de la transpression senestre a suivi une évolution quasi isotherme (~ 700 °C) jusqu'à une pression d'environ 0,5 GPa dans la période 325–306 Ma. La transpression senestre enregistrée dans le massif du Pelvoux pourrait correspondre à une zone de cisaillement antithétique contemporaine de la zone de cisaillement dextre Est-Varisque.

The West Spitsbergen fold‐and‐thrust belt formed along the transform plate boundary between Greenland and the western Barents Sea during Paleocene‐Eocene breakup in the northern North Atlantic. Approximately 20–40 km margin‐perpendicular shortening accumulated in the belt has been attributed to transpression and strain partitioning in a restraining bend but also to head‐on collision. We have applied scaled analog tectonic modeling to test the former hypothesis. A pack of brittle quartz sand with a shallow thin layer of silicon putty was deformed by transpression at a 15° convergence angle by movement of a basal plate. The kinematics was quantified by means of digital particle image velocimetry. The result was a doubly vergent transpressional wedge, consisting of a steeply tapered retrowedge and a strongly internally deformed steeply tapered prowedge separated by a central strike‐slip zone and an adjacent low‐taper thin‐skinned fold‐and‐thrust belt. The doubly vergent wedge evolved through several kinematic phases. Three main stages were identified, namely, (1) initial distributed deformation, (2) development of an oblique doubly vergent wedge with progressive evolution of local strain partitioning along the marginal shear zones, and, finally, (3) a stage of full strain partitioning between a central strike‐slip zone and reverse displacement along marginal shear zones, with folding and thrusting in a thin‐skinned belt on the proside. The analog model convincingly reproduced the geometry and the kinematic evolution of the West Spitsbergen fold‐and‐thrust belt, supporting the hypothesis of its formation by strain partitioning in transpression with a small angle of convergence and significant lateral displacement. Key Points The West Spitsbergen FTB was formed by strain partitioning in transpression The analogue model explains the absence of a counterpart on Greenland New method allows easier comparison between model and field kinematic data

The Tan-Lu fault zone (TLFZ) along the East China continental margin (ECCM) experienced a change from sinistral to normal faulting in the late Mesozoic. Thirty-four laser ablation (LA)-ICPMS zircon U-Pb dates for plutons and volcanic rocks along the TLFZ indicate that extension-related magmatism started as early as 136 Ma. The development of pre-eruption rift basins along the TLFZ during the earliest Early Cretaceous further constrains the onset time of the Tan-Lu normal faulting to the beginning of Early Cretaceous (ca. 145 Ma). Association of extensive rifts, metamorphic core complexes, and magmatism along the margin with the Tan-Lu normal faulting suggests an Early Cretaceous extensional regime for the ECCM that also started at the beginning of the Early Cretaceous, about 145 Ma. An undeformed granite dike that intrudes the sinistral ductile shear zone yields an LA-ICPMS zircon U-Pb age of 122 Ma. Seven 40Ar/39Ar plateau ages of mica samples from mylonites in the Tan-Lu sinistral ductile shear zone range from 129.5±0.8 to 101.8±0.6 Ma, and these are considered to represent cooling ages related to later normal faulting. A white mica 40Ar/39Ar plateau age of 149.8±0.9 Ma is interpreted as the cooling age of sinistral faulting. It is suggested that the sinistral faulting took place before 150 Ma (Late Jurassic), rather than in the Early Cretaceous, as previously proposed. The Tan-Lu sinistral faulting developed under a transpressive regime along the ECCM during the Late Jurassic. It is inferred that the switch from Late Jurassic transpression to Early Cretaceous extension is due to a shift from oblique, shallow subduction of the Izanagi Plate to orthogonal, steep subduction of the Pacific Plate.