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Piana, Fabrizio, Luca Barale, Carlo Bertok, Anna d’Atri, Andrea Irace, and Pietro Mosca. "The Alps-Apennines Interference Zone: A Perspective from the Maritime and Western Ligurian Alps." Geosciences 11, no. 5 (April 25, 2021): 185. http://dx.doi.org/10.3390/geosciences11050185.
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In SW Piemonte the Western Alps arc ends off in a narrow, E-W trending zone, where some geological domains of the Alps converged. Based on a critical review of available data, integrated with new field data, it is concluded that the southern termination of Western Alps recorded the Oligocene-Miocene activity of a regional transfer zone (southwestern Alps Transfer, SWAT) already postulated in the literature, which should have allowed, since early Oligocene, the westward indentation of Adria, while the regional shortening of SW Alps and tectonic transport toward the SSW (Dauphinois foreland) was continuing. This transfer zone corresponds to a system of deformation units and km-scale shear zones (Gardetta-Viozene Zone, GVZ). The GVZ/SWAT developed externally to the Penninic Front (PF), here corresponding to the Internal Briançonnais Front (IBF), which separates the Internal Briançonnais domain, affected by major tectono-metamorphic transformations, from the External Briançonnais, subjected only to anchizonal metamorphic conditions. The postcollisional evolution of the SW Alps axial belt units was recorded by the Oligocene to Miocene inner syn-orogenic basin (Tertiary Piemonte Basin, TPB), which rests also on the Ligurian units stacked within the adjoining Apennines belt in southern Piemonte. The TPB successions were controlled by transpressive faults propagating (to E and NE) from the previously formed Alpine belt, as well as by the Apennine thrusts that were progressively stacking the Ligurian units, resting on the subducting Adriatic continental margin, with the TPB units themselves. This allows correlation between Alps and Apennines kinematics, in terms of age of the main geologic events, interference between the main structural systems and tectonic control exerted by both tectonic belts on the same syn-orogenic basin.
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Schmid, Stefan M., Eduard Kissling, Tobias Diehl, Douwe J. J. van Hinsbergen, and Giancarlo Molli. "Ivrea mantle wedge, arc of the Western Alps, and kinematic evolution of the Alps–Apennines orogenic system." Swiss Journal of Geosciences 110, no. 2 (March 29, 2017): 581–612. http://dx.doi.org/10.1007/s00015-016-0237-0.
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Lickorish, W. H., M. Ford, J. Bürgisser, and P. R. Cobbold. "Arcuate thrust systems in sandbox experiments: A comparison to the external arcs of the Western Alps." GSA Bulletin 114, no. 9 (September 1, 2002): 1089–107. http://dx.doi.org/10.1130/0016-7606(2002)114<1089:atsise>2.0.co;2.
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Abstract In the external Western Alps, two regional structural arcs were generated during Tertiary northwest-directed collision between the Apulian indenter and the European passive margin. These arcs, distinguished by their geographic position and their age, are examined by using a new compilation of structural data and comparing these to the results of sandbox-analogue experiments. The principal Western Alpine arc comprises two orthogonal, synchronous thrust systems. In the late Eocene–early Miocene, major shortening (105 km) was toward the northwest to west-northwest, and minor shortening (11 km) was toward the southwest. Shortening in each branch decreased toward the core of the arc. During the late Miocene and Pliocene, the Jura arc accommodated 35 km of northwest- directed shortening, while 10.5 km of southwest- to south-southwest–directed shortening was accommodated on the Digne thrust system. Sandbox experiments were used to investigate the role of the motion vector of a rigid rectangular indenter (orthogonal, diagonal, curved, or rotational paths) and the mechanical stratigraphy of the foreland in the evolution of upper-crustal arcuate systems (e.g., presence of a basal easy-slip [silicone] horizon). Comparison of experimental results with the external Alpine arc suggests that the indenter followed a slightly diagonal path with respect to the European margin from the Eocene to the early Miocene and curved counterclockwise by 10°–15° in the middle Miocene. Mechanical stratigraphy experiments support the hypothesis that thick Triassic evaporites played a primary role in the evolution of the Jura arc. The influence of mechanical stratigraphy was most prominent during weak deformation at the external boundaries of the Alpine orogen (Jura fold-and-thrust belt, Digne thrust).
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Giardino, Marco. "Spatial and temporal dimensions in the neotectonic evolution of the arc-shaped Western Alps." Quaternary International 279-280 (November 2012): 165–66. http://dx.doi.org/10.1016/j.quaint.2012.08.209.
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Larroque, C., N. Béthoux, E. Calais, F. Courboulex, A. Deschamps, J. Déverchère, J. F. Stéphan, J. F. Ritz, and E. Gilli. "Active and recent deformation at the Southern Alps – Ligurian basin junction." Netherlands Journal of Geosciences 80, no. 3-4 (December 2001): 255–72. http://dx.doi.org/10.1017/s0016774600023878.
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AbstractThe Southern Alps – Ligurian basin junction is one of the most active seismic areas in Western Europe countries. The topographic and the structural setting of this region is complex because of (i) its position between the high topography of the Southern Alps and the deep, narrow Ligurian oceanic basin, and (ii) the large number of structures inherited from the Alpine orogeny. Historical seismicity reveals about twenty moderate-size earthquakes (up to M=6.0), mostly distributed along the Ligurian coast and the Vésubie valley. A recent geodetic experiment shows a significant strain rate during the last 50 years in the area between the Argentera massif and the Mediterranean coastline. Results of this experiment suggest a N-S shortening of about 2-4 mm/yr over the network, this shortening direction is consistent with the seismological (P-axes of earthquakes) and the microtectonic data. The Pennic front (E-NE of the Argentera massif) and the northern Ligurian margin are the most seismically active areas. In the Nice arc and in the Argentera massif, some seismic lineaments correspond to faults identified in the field (such as theTaggia-Saorge fault or the Monaco-Sospel fault). In the western part of the Alpes Maritimes, no seismic activity is recorded in the Castellane arc. In the field, geological evidence, such as offsets of recent alluvial sediments, recent fault breccia, speleothem deformations, radon anomalies and others indicates recent deformation along these faults. Nevertheless, to this date active fault scarps have not been identified: this probably results from a relatively high erosion rate versus deformation rate and from the lack of Quaternary markers. We also suspect the presence of two hidden active faults, one in the lower Var valley (Nice city area) and the other one at the base of the Argentera crustal thrust-sheet. Offshore, along the northern Ligurian margin, the seismic reflection data shows traces of Quaternary extensional deformation, but the accuracy of the data does not yet allow the construction of a structural map nor does it allow the determination of the continuity between the offshore and onshore structures. From these data set we propose a preliminary map of 11 active faults and we discuss the questions which remain unsolved in the perspective of seismic hazard evaluations.
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Ivančič, Kristina, Rok Brajkovič, and Mirijam Vrabec. "Geochemical and Mineralogical Approaches in Unraveling Paleoweathering, Provenance, and Tectonic Setting of the Clastic Sedimentary Succession (Western Central Paratethys)." Applied Sciences 14, no. 2 (January 8, 2024): 537. http://dx.doi.org/10.3390/app14020537.
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Pronounced tectonic and paleogeographic changes were detected in the Alpine–Pannonian region during the Miocene at the interface between the Alps, the Dinarides, and the Pannonian Basin. To understand the major tectonic, paleogeographic, and paleoclimatic changes during this period, geochemical and mineralogical investigations were carried out on the fine-grained clastic sedimentary rocks in the Tunjice Hills. The paleoweathering indicates a cold and/or arid to a warm and humid period. The paleoclimate and the regional climatic conditions correspond well with the Middle Miocene Climatic Optimum. The mineral composition shows an abundance of quartz and calcite. Quartz is associated with detrital origin from volcanic and metamorphic rocks of the Eastern and Southern Alps and with authigenic processes in sediments. Calcite is related to authigenic origin formed in shallow marine environments and to detrital provenance from the Southern Alps. Not all discriminant functions based on major oxides provided adequate results in determining the tectonic setting. The source rocks were subjected to oceanic island arc and collision. Moreover, sedimentation was influenced by both active and passive margin settings. The former is related to the Alpine collision, which continued from the Cenozoic onward, and the latter is connected to the processes associated with the formation of the Pannonian Basin System, which began in the late Early Miocene.
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Bernet, Matthias, and Pierre Tricart. "The Oligocene orogenic pulse in the southern Penninic arc (western Alps): structural, sedimentary and thermochronological constraints." Bulletin de la Société Géologique de France 182, no. 1 (January 1, 2011): 25–36. http://dx.doi.org/10.2113/gssgfbull.182.1.25.
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Abstract The Oligocene evolution of the southern branch of the western Alpine arc, more precisely the stack of metamorphic Briançonnais and Piedmont nappes composing the southern Penninic arc (SPA), are the focus of this study. We review published structural, sedimentological and thermochronological data in order to discuss exhumation of the SPA. At first, we compare bedrock zircon and apatite fission-track (FT) data from the SPA with detrital thermochronologic data (zircon FT, white mica 40Ar/39Ar) from Oligocene molasse deposits. Using improved stratigraphic ages for the Barrême basin, samples from the uppermost Rupelian “Conglomérat de Clumanc” and the Chattian “Molasse Rouge” provided zircon FT lag times of ~3.5 and 8 m.y., indicating source exhumation rates on the order of ~1.5 and ~0.75 km/m.y. respectively. These short lag times are consistent with lag times of 40Ar-39Ar ages of detrital white mica from the same formations in the same basin, and also from Oligocene molasse sediments in the Tertiary Piedmont basin. The sediment source for these grains as for the associated clasts of blueschist, is identified as the HP-LT metamorphic units of the SPA. The source cannot be the Ubaye-Embrunais nappes as classically considered, because these nappes do not bear the required metamorphic imprint. This interpretation is consistent with fast Oligocene cooling of the SPA, as attested by in situ zircon and apatite FT analyses. Such fast and relatively old cooling is a peculiarity of the southern branch of the western Alpine arc, when considering the entire arc. A second range of data concerns the structural building of the SPA. The initial stacking of metamorphic nappes in a poorly elevated accretionnary wedge was completed before the end of the Eocene. During the Early Oligocene collision, this wedge was severely refolded, acquiring its fan structure, as visible in cross section, and its curvature in map view. In such a context, we propose that fast exhumation and cooling of the SPA during the Oligocene resulted from active erosion of rapidly raised high topography. This is consistent with the sudden arrival of metamorphic Penninic clasts in the molasse basins along both flanks of the belt. Moreover, detrital and in situ thermochronological ages, suggest a strong slowing down of cooling and exhumation from the Miocene onwards, coinciding with brittle extension that dominates in the SPA during this long period. The brief Early Oligocene rise of a SPA cordillera, contrasts with the preceding and subsequent period of poor relief of the SPA. The mountainous character of the SPA today is not directly inherited from the Oligocene orogenic climax, as modern high relief and elevation are most likely related to rejuvenation under climatic control during the Quaternary.
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Germann, Christoph. "Hypera temperei Hoffmann, 1958 – first discovery of the western alpine element in the Swiss Alps with biological details, and new morphological insights (Coleoptera, Curculionidae)." Alpine Entomology 5 (March 9, 2021): 5–13. http://dx.doi.org/10.3897/alpento.5.61597.
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Since its description based on a single female from the Maritime Alps in France, no other localities of this enigmatic alpine species have become public. In a scree slope in the Valais at high montane altitude Hypera temperei Hoffmann, 1958 was discovered for the first time elsewhere, in Switzerland. The species’ biology is unravelled, its habitat is described, and photographs of the male, larvae and pupa are presented. The re-investigation of the species morphology revealed that Hypera temperei is closest to H. postica (Gyllenhal, 1813), and not to H. viciae (Gyllenhal, 1813) as previously supposed. A revision of specimens in collections revealed that H. temperei is distributed even more eastern in the alpine Arc in Grisons at high montane to high alpine altitudes. Hence the species shows a considerably wider distribution in the Alps than supposed before.
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Champagnac, Jean-Daniel, Bastien Delacou, Pierre Tricart, Christian Sue*, Martin Burkhard, and Cécile Allanic. "Regional brittle extension in Quaternary sediments of Lanslebourg (Haute-Maurienne valley, western Alps)." Bulletin de la Société Géologique de France 177, no. 4 (July 1, 2006): 215–23. http://dx.doi.org/10.2113/gssgfbull.177.4.215.
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Abstract Brittle tectonics of the internal zones of the Western Alps is characterized by important normal faulting and minor transcurent faulting. Two different directions of extension occur through time, but the age of transition remains unconstrained. In order to fill this gap, and to provide new neotectonic data, we studied faulted Quaternary peri-glacial deposits in the core of the W-Alpine belt (Contamines Quarry, Lanslebourg, Haute-Maurienne/Vanoise area). These glaciolacustrine and fluvio-glacial sediments are capped by a ground moraine, which is related to a small glacier advance that occurred during the latest deglaciation of the Arc Valley (Pleistocene-Holocene transition). The faults cross-cut the moraine and are younger than this latest glacier advance. They are not affected by ice-related loading and movement. These faults show normal components with moderate to high dips (50° to 80°) and small to medium vertical offsets (mm- to m- scale). Offsets are visible due to contrasted lithologies of the sediments. Conjugated dihedra with two fault orientations are recognized, namely N-S and NW-SE. These fault orientations are consistent with an E-W to ENE-WSW direction of extension, and an unknown (but possibly minor) part of transcurrence. This direction of extension is parallel to the Arc Valley, and to the downstream direction of the paleo-glacier, as well as to the shear direction of the loadcast structures created by the ice weight and flow. The different possible origins of the faults are discussed, but their orientation is likely to be tectonically driven. The directions of faulting are consistent with N-S and NW-SE regional faulting within the Cretaceous Schistes lustrés inferred by in situ analyses and remote sensing measurements. The distribution of faults in the quarry near a km-scale fault, as well as their cross-cutting relationships to the moraine and the shear figures, suggest that the faulting of the Quaternary sediments is guided by a regional (i.e. tectonic) stress field. Since the faulting is younger than the latest glacier advance (ca. 10 to 15 ky) and is consistent with the current orogen-perpendicular extension, we propose that the seismogenic extension occurred from (at least) the latest Pleistocene onward.
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Tricart, Pierre, Stephane Schwartz, Christian Sue, Gerard Poupeau, and Jean-Marc Lardeaux. "La denudation tectonique de la zone ultradauphinoise et l'inversion du front brianconnais au sud-est du Pelvoux (Alpes occidentales); une dynamique miocene a actuelle." Bulletin de la Société Géologique de France 172, no. 1 (January 1, 2001): 49–58. http://dx.doi.org/10.2113/172.1.49.
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Abstract In the western Alps, to the southeast of the Pelvoux massif (Champsaur-Embrunais-Brianconnais-Queyras transect), the Brianconnais zone consists of the southern tip of the Zone Houillere and small nappes of Mesozoic sediments, emplaced during the Eocene in HP-LT metamorphic conditions. During the Oligocene this tectonic pile was thrusted onto a late Eocene to early Oligocene flexural basin, deformed in low grade metamorphic conditions and belonging to the Ultradauphine zone. This major thrust, called here CBF [Chevauchement Brianconnais Frontal: Tricart 1986] represents the boundary between the external and the internal zones of the western Alps. It contains thin tectonic lenses of Subbrianconnais origin, so that the Brianconnais Front and the Penninic Front almost merge. Late Alpine extension. - We have recently discovered that the CBF was subsequently reactivated as an extensional detachment. This major negative inversion is associated with widespread extension in the internal (Brianconnais and Piemont) zones, resulting in multiscale normal faulting. Current field work in the Queyras area shows that this brittle multitrend extension is a continuation of the ductile extension that accompanied the exhumation of blue-schist bearing metamorphic units. Along the same transect, the external (Ultradauphine) zone was not affected by late-Alpine extension. This is still the present situation: to the east of the aseismic Pelvoux massif, the CBF bounds the Brianconnais seismic arc, the activity of which may be the continuation of the late-Alpine extension. At the scale of the western Alpine arc, active extensional-transtensional tectonics dominate in the internal zones while compressional uplift affects the external zone. In this contrasted stress field, the thrust-fault zone between internal and external arcs plays a major role of decoupling that can be demonstrated in several sites between the area analysed here and the Central Alps, including along the Ecors profile. Contribution of thermochronology. - In this paper, we compare apatite fission track (FT) ages from both sides of the inverted CBF to the southeast of the Pelvoux massif. In the hangingwall of the CBF, two ages were obtained from magmatic intrusions within the Zone houillere, close to Briancon. They are compared to recently published ages from the Champsaur Sandstones unit in the footwall of the CBF, along the same transect.
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McCarthy, Anders, Julie Tugend, and Geoffroy Mohn. "Formation of the Alpine Orogen by Amagmatic Convergence and Assembly of Previously Rifted Lithosphere." Elements 17, no. 1 (February 1, 2021): 29–34. http://dx.doi.org/10.2138/gselements.17.1.29.
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The tectonic and magmatic characteristics of the Alps and Pyrenees during convergence are quite distinct from characteristics associated with classic Benioff-type oceanic subduction. From the initiation of subduction at passive margins until the onset of continental collision, the closure of the Western Tethys never produced a long-lived magmatic arc. This is a consequence of the 3-D architecture of the Western Tethys (a series of hyper-thinned basins and continental blocks) and its narrow width (<500–700 km) prior to convergence. Subduction primarily involved the slow and amagmatic subduction of a narrow domain of dry lithospheric mantle. This type of congested Ampferer subduction led to the sequential and coherent accretion of inherited rifted domains which today form the Alpine and Pyrenean orogens.
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Ring, Uwe, and Axel Gerdes. "Kinematics of the Alpenrhein-Bodensee graben system in the Central Alps: Oligocene/Miocene transtension due to formation of the Western Alps arc." Tectonics 35, no. 6 (June 2016): 1367–91. http://dx.doi.org/10.1002/2015tc004085.
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Schmid, S. M., and E. Kissling. "The arc of the western Alps in the light of geophysical data on deep crustal structure." Tectonics 19, no. 1 (February 2000): 62–85. http://dx.doi.org/10.1029/1999tc900057.
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Gabrieli, J., L. Carturan, P. Gabrielli, N. Kehrwald, C. Turetta, G. Cozzi, A. Spolaor, et al. "Impact of Po Valley emissions on the highest glacier of the Eastern European Alps." Atmospheric Chemistry and Physics 11, no. 15 (August 9, 2011): 8087–102. http://dx.doi.org/10.5194/acp-11-8087-2011.
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Abstract. In June 2009, we conducted the first extensive glaciological survey of Alto dell'Ortles, the uppermost glacier of Mt. Ortles (3905 m a.s.l.), the highest summit of the Eastern European Alps. This section of the Alps is located in a rain shadow and is characterized by the lowest precipitation rate in the entire Alpine arc. Mt. Ortles offers a unique opportunity to test deposition mechanisms of chemical species that until now were studied only in the climatically-different western sector. We analyzed snow samples collected on Alto dell'Ortles from a 4.5 m snow-pit at 3830 m a.s.l., and we determined a large suite of trace elements and ionic compounds that comprise the atmospheric deposition over the past two years. Trace element concentrations measured in snow samples are extremely low with mean concentrations at pg g−1 levels. Only Al and Fe present median values of 1.8 and 3.3 ng g−1, with maximum concentrations of 21 and 25 ng g−1. The median crustal enrichment factor (EFc) values for Be, Rb, Sr, Ba, U, Li, Al, Ca, Cr, Mn, Fe, Co, Ga and V are lower than 10 suggesting that these elements originated mainly from soil and mineral aerosol. EFc higher than 100 are reported for Zn (118), Ag (135), Bi (185), Sb (401) and Cd (514), demonstrating the predominance of non-crustal depositions and suggesting an anthropogenic origin. Our data show that the physical stratigraphy and the chemical signals of several species were well preserved in the uppermost snow of the Alto dell'Ortles glacier. A clear seasonality emerges from the data as the summer snow is more affected by anthropogenic and marine contributions while the winter aerosol flux is dominated by crustal sources. For trace elements, the largest mean EFc seasonal variations are displayed by V (with a factor of 3.8), Sb (3.3), Cu (3.3), Pb (2.9), Bi (2.8), Cd (2.1), Zn (1.9), Ni (1.8), Ag (1.8), As (1.7) and Co (1.6). When trace species ratios in local and Po Valley emissions are compared with those in Alto dell'Ortles snow, the deposition on Mt. Ortles is clearly linked with Po Valley summer emissions. Despite climatic differences between the Eastern and Western Alps, trace element ratios from Alto dell'Ortles are comparable with those obtained from high-altitude glaciers in the Western Alps, suggesting similar sources and transport processes at seasonal time scales in these two distinct areas. In particular, the large changes in trace element concentrations both in the Eastern and Western Alps appear to be more related to the regional vertical structure of the troposphere rather than the synoptic weather patterns.
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Di Giulio, Andrea, Chiara Amadori, Pierre Mueller, and Antonio Langone. "Role of the Down-Bending Plate as a Detrital Source in Convergent Systems Revealed by U–Pb Dating of Zircon Grains: Insights from the Southern Andes and Western Italian Alps." Minerals 10, no. 7 (July 16, 2020): 632. http://dx.doi.org/10.3390/min10070632.
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In convergent zones, several parts of the geodynamic system (e.g., continental margins, back-arc regions) can be deformed, uplifted, and eroded through time, each of them potentially delivering clastic sediments to neighboring basins. Tectonically driven events are mostly recorded in syntectonic clastic systems accumulated into different kinds of basins: trench, fore-arc, and back-arc basins in subduction zones and foredeep, thrust-top, and episutural basins in collisional settings. The most widely used tools for provenance analysis of synorogenic sediments and for unraveling the tectonic evolution of convergent zones are sandstone petrography and U–Pb dating of detrital zircon. In this paper, we present a comparison of previously published data discussing how these techniques are used to constrain provenance reconstructions and contribute to a better understanding of the tectonic evolution of (i) the Cretaceous transition from extensional to compressional regimes in the back-arc region of the southern Andean system; and (ii) the involvement of the passive European continental margin in the Western Alps subduction system during impending Alpine collision. In both cases, sediments delivered from the down-bending continental block are significantly involved. Our findings highlight its role as a detrital source, which is generally underestimated or even ignored in current tectonic models.
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Sue, Christian, Philippe Calcagno, Gabriel Courrioux, Pierre Tricart, Julien Frechet, and François Thouvenot. "Relationships between inherited crustal structures and seismicity in the western Alps inferred from 3D structural modeling." Bulletin de la Société Géologique de France 181, no. 6 (November 1, 2010): 583–90. http://dx.doi.org/10.2113/gssgfbull.181.6.583.
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Abstract We developed a 3-D structural model of a key area in the southwestern Alps, at the boundary between the external and internal zones. Six geological bodies are analyzed: internal and external basements, Briançonnais and Piemontais zones (internal sedimentary cover nappes), exotic flyschs, and external sedimentary cover. 3D volumes of each geological body are modeled using the structural map of the area projected on the Digital Elevation Model (DEM) and 5 cross-sections. The global model is interpolated from the map, DEM, and cross sections, using the potential field method, and represented by a Voronoï diagram. The final 3D-model is used as a structural frame to plot the earthquakes of the GéoFrance3D database, allowing to precisely and quantitatively investigate the relationships between crustal structures and current seismic activity of the belt. The boundary between external and internal zones corresponds to the so-called Crustal Penninic Thrust (CPT), which is a former Oligocene major thrust. Our model establishes that this former thrust represents the western limit of the seismic activity along the Briançonnais seismic arc, currently undergoing extensional tectonics.
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Guillot, Stéphane, Silvia di Paola, René-Pierre Ménot, Patrick Ledru, Maria Iole Spalla, Guido Gosso, and Stéphane Schwartz. "Suture zones and importance of strike-slip faulting for Variscan geodynamic reconstructions of the External Crystalline Massifs of the western Alps." Bulletin de la Société Géologique de France 180, no. 6 (October 1, 2009): 483–500. http://dx.doi.org/10.2113/gssgfbull.180.6.483.
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Abstract This paper reviews the geodynamic evolution of the Belledonne, Grandes Rousses and Oisans massifs in the western Alps from Early Ordovician to Permian times. Three domains are distinguished. The eastern domain, which includes the NE Belledonne massif and the inner Oisans massif, records the subduction of the Central-European ocean along a NW dipping subduction zone. The western domain is marked by Cambro-Ordovician back-arc rifting (Chamrousse ophiolite) initiating the opening of the Rheic ocean. It was followed by Mid-Devonian obduction of the back-arc Chamrousse ophiolite, towards the NW in relation with the SE dipping subduction of the Saxo-Thuringian ocean. The central domain, including the SW part of the Belledonne massif, the Grandes Rousses massif and the outer Oisans massif, records the Devonian to Carboniferous orogenic activity that produced calc-alkaline magmatism, Mg-K granite intrusions and syn-collisional sedimentation related to Visean nappe stacking that we relate to the closure of the Saxo-Thuringian ocean. Based on tectonostratigraphic correlations we propose that these domains initially correspond to the northeastward extension of the Bohemian massif. During the late Carboniferous, the External Crystalline Massifs including Sardinia and Corsica were stretched towards the SW along the > 600 km long dextral External Crystalline Massifs shear zone. Offset of the Saxo-Thuringian and eo-Variscan suture zones from the Bohemian massif to the ECM suggests a possible dextral displacement of about 300 km along the ECM shear zone.
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Goričan, Špela, Josip Halamić, Tonći Grgasović, and Tea Kolar-Jurkovšek. "Stratigraphic evolution of Triassic arc-backarc system in northwestern Croatia." Bulletin de la Société Géologique de France 176, no. 1 (January 1, 2005): 3–22. http://dx.doi.org/10.2113/176.1.3.
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Abstract Middle Triassic arc-related extensional tectonics in the western Tethys generated a complex pattern of intra-and backarc basins. We studied volcano-sedimentary successions of subsided continental-margin blocks (Mts. Žumberak and Ivanščica) and of dismembered incomplete ophiolite sequences interpreted as remnants of a backarc basin (Mts. Medvednica and Kalnik) in northwestern Croatia. We dated the successions with radiolarians, conodonts, foraminifers, algae, and sponges. The continental margin experienced a phase of accelerated subsidence in the late Anisian that was approximately coincident with the onset of intermediate and acidic volcanism; pelagic sediments with volcaniclastics accumulated atop subsided carbonate platforms. These relatively shallow basins were later infilled completely by prograding platforms in the late Ladinian-Carnian. In the backarc basin, sea-floor spreading initiated near the Anisian-Ladinian boundary and continued into the late Carnian. Pillow basalts were erupted and interlayered with radiolarian cherts and shales. The studied area was a part of a larger Triassic arc-backarc system preserved in the southern Alps, Alpine-Carpathian Belt, Dinarides, and Hellenides. Volcano-sedimentary successions of Mts. Medvednica and Kalnik are relics of the Meliata-Maliak backarc basin. In comparison to other previously dated oceanic remnants of this system, the longest continuous sea-floor spreading is now documented in one restricted tectonic unit.
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SCHWARTZ, S., S. GUILLOT, P. TRICART, M. BERNET, S. JOURDAN, T. DUMONT, and G. MONTAGNAC. "Source tracing of detrital serpentinite in the Oligocene molasse deposits from the western Alps (Barrême basin): implications for relief formation in the internal zone." Geological Magazine 149, no. 5 (January 31, 2012): 841–56. http://dx.doi.org/10.1017/s0016756811001105.
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AbstractWe present the first contribution of tracing the source area of ophiolitic detritus in the Alpine molasse deposits by Raman spectroscopy. The lower Oligocene molasse deposits preserved in the Barrême basin, in the SW foreland of the western Alpine arc, are known for the sudden arrival of the first ‘exotic’ detritus coming from the internal Alpine zones. Among them, the pebbles of serpentinized peridotites have so far not been studied. We show that they only consist of antigorite serpentinite, implying that they originate from erosion of high temperature blueschists. In contrast, the upper Oligocene/lower Miocene molasse shows mixed clasts of serpentine including antigorite and lizardite without any evidence of chrysotile. This suggests that they were derived from a less metamorphosed unit such as the low temperature blueschist unit. Taking into account the sediment transport direction in the basin and the varied metamorphic characteristics of the other ocean-derived detritus, we constrain the lithologic nature of the source zones and the location of the relief zones, identified as the internal Alps, SE of the Pelvoux external crystalline massif. Available structural data andin situthermochronological data allow the reconstruction of the Oligocene to early Miocene collisional geometry of the Palaeogene subduction wedge. This phase corresponds to two major phases of uplift evolving from a single relief zone located above the Ivrea body during early Oligocene times and persisting up to early Miocene times; then during late Oligocene/early Miocene times a second relief zone developed above the Briançonnais zone. At that time, the internal western Alps acquired its double vergency.
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Rolland, Yann, Antonin Bilau, Thibaut Cardinal, Ahmed Nouibat, Dorian Bienveignant, Louise Boschetti, Stéphane Schwartz, and Matthias Bernet. "Bridging the Gap between Long–Term Orogenic Evolution (>10 Ma Scale) and Geomorphological Processes That Shape the Western Alps: Insights from Combined Dating Approaches." Geosciences 12, no. 11 (October 25, 2022): 393. http://dx.doi.org/10.3390/geosciences12110393.
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Constraining the relative roles of erosion and tectonics in the evolution of mountain belts is a challenging scientific goal. In this review article on the Western Alps, we show how it becomes possible to “bridge the gap” between the long–term (>Ma) orogenic evolution controlled by tectonics and exhumation processes and the recent geomorphological evolution that is accessible on an annual–decadal basis. Advances in mineral dating that have grown in relation to deformation in the ductile and brittle crustal fields have allowed us to constrain the evolution of deformation through time and depth. A drastic change from early collision, dominated by rapid underthrusting of the European plate, to a more stagnant syn–collisional tectonic context is documented since about 26–20 Ma by syn–kinematic phengites and vein–hosted monazites along the Alpine arc. The overall dextral kinematic context is accompanied by local extensional domains in the Simplon and High Durance Valley. Activation of the Simplon ductile fault is documented from 20 Ma, whereas the High Durance extensional system commenced after 10 Ma. The application of cosmogenic nuclide dating of incised river gorges demonstrates that the erosion pattern of the Western Alps follows a different evolution within the valleys dominated by upstream glacial erosion than in peripheral watersheds devoid of glaciers. The very low peripheral incision is found to be similar to the vertical GPS signal, suggesting equilibrium of tectonic uplift and incision, whereas the glacial–dominated valleys exhibit significantly increased and transient river incision during interglacials and a constant ongoing tectonic regime.
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Michard, André, Ahmed Chalouan, Hugues Feinberg, Bruno Goffé, and Raymond Montigny. "How does the Alpine belt end between Spain and Morocco ?" Bulletin de la Société Géologique de France 173, no. 1 (January 1, 2002): 3–15. http://dx.doi.org/10.2113/173.1.3.
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Abstract The Betic-Rif arcuate mountain belt (southern Spain, northern Morocco) has been interpreted as a symmetrical collisional orogen, partly collapsed through convective removal of its lithospheric mantle root, or else as resulting of the African plate subduction beneath Iberia, with further extension due either to slab break-off or to slab retreat. In both cases, the Betic-Rif orogen would show little continuity with the western Alps. However, it can be recognized in this belt a composite orocline which includes a deformed, exotic terrane, i.e. the Alboran Terrane, thrust through oceanic/transitional crust-floored units onto two distinct plates, i.e. the Iberian and African plates. During the Jurassic-Early Cretaceous, the yet undeformed Alboran Terrane was part of a larger, Alkapeca microcontinent bounded by two arms of the Tethyan-African oceanic domain, alike the Sesia-Margna Austroalpine block further to the northeast. Blueschist- and eclogite-facies metamorphism affected the Alkapeka northern margin and adjacent oceanic crust during the Late Cretaceous-Eocene interval. This testifies the occurrence of a SE-dipping subduction zone which is regarded as the SW projection of the western Alps subduction zone. During the late Eocene-Oligocene, the Alkapeca-Iberia collision triggered back-thrust tectonics, then NW-dipping subduction of the African margin beneath the Alboran Terrane. This Maghrebian-Apenninic subduction resulted in the Mediterranean basin opening, and drifting of the deformed Alkapeca fragments through slab roll back process and back-arc extension, as reported in several publications. In the Gibraltar area, the western tip of the Apenninic-Maghrebian subduction merges with that of the Alpine-Betic subduction zone, and their Neogene roll back resulted in the Alboran Terrane collage astride the Azores-Gibraltar transpressive plate boundary. Therefore, the Betic-Rif belt appears as an asymmetrical, subduction/collision orogen formed through a protracted evolution straightfully related to the Alpine-Apenninic mountain building.
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Biagi, Paolo. "The Late Palaeolithic and Mesolithic Settlement of Northern Italy: Problems and Perspectives." Quaternary 7, no. 1 (January 4, 2024): 2. http://dx.doi.org/10.3390/quat7010002.
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This paper considers some problems of the Late Palaeolithic and the Mesolithic periods in Northern Italy. More precisely, it deals with chronology, settlement pattern, techno-typological characteristics of knapped stone assemblages, and climatic changes that have taken place in the region from the discovery of the first sites in the 1960s and the excavations that soon followed to the present state of research. The Italian Alps, the Piedmont, and the valleys that descend from the high massifs have yielded important traces of Late Palaeolithic (Final Epigravettian) and Mesolithic (Sauveterrian and Castelnovian) sites and findspots, some of which are rock shelters that were settled throughout several millennia. This paper describes and discusses the evidence available mainly from two regions of the western and eastern Alpine arc, which are characterised by very different landscapes and yielded a great variety of archaeological features.
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Romagny, Adrien, Laurent Jolivet, Armel Menant, Eloïse Bessière, Agnès Maillard, Albane Canva, Christian Gorini, and Romain Augier. "Detailed tectonic reconstructions of the Western Mediterranean region for the last 35 Ma, insights on driving mechanisms." BSGF - Earth Sciences Bulletin 191 (2020): 37. http://dx.doi.org/10.1051/bsgf/2020040.
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Slab retreat, slab tearing and interactions of slabs are first-order drivers of the deformation of the overriding lithosphere. An independent description of the tectonic evolution of the back-arc and peripheral regions is a pre-requisite to test the proposed conceptual, analogue and numerical models of these complex dynamics in 3-D. We propose here a new series of detailed kinematics and tectonic reconstructions from 35 Ma to the Present shedding light on the driving mechanisms of back-arc rifting in the Mediterranean where several back-arc basins all started to form in the Oligocene. The step-by-step backward reconstructions lead to an initial situation 35 Ma ago with two subduction zones with opposite direction, below the AlKaPeCa block (i.e. belonging to the Alboran, Kabylies, Peloritani, Calabrian internal zones). Extension directions are quite variable and extension rates in these basins are high compared to the Africa-Eurasia convergence velocity. The highest rates are found in the Western Mediterranean, the Liguro-Provençal, Alboran and Tyrrhenian basins. These reconstructions are based on shortening rates in the peripheral mountain belts, extension rates in the basins, paleomagnetic rotations, pressure-temperature-time paths of metamorphic complexes within the internal zones of orogens, and kinematics of the large bounding plates. Results allow visualizing the interactions between the Alps, Apennines, Pyrenean-Cantabrian belt, Betic Cordillera and Rif, as well as back-arc basins. These back-arc basins formed at the emplacement of mountain belts with superimposed volcanic arcs, thus with thick, hot and weak crusts explaining the formation of metamorphic core complexes and the exhumation of large portions of lower crustal domains during rifting. They emphasize the role of transfer faults zones accommodating differential rates of retreat above slab tears and their relations with magmatism. Several transfer zones are identified, separating four different kinematic domains, the largest one being the Catalan-Balearic-Sicily Transfer Zone. Their integration in the wider Mediterranean realm and a comparison of motion paths calculated in several kinematic frameworks with mantle fabric shows that fast slab retreat was the main driver of back-arc extension in this region and that large-scale convection was a subsidiary driver for the pre-8 Ma period, though it became dominant afterward. Slab retreat and back-arc extension was mostly NW-SE until ∼ 20 Ma and the docking of the AlKaPeCa continental blocks along the northern margin of Africa induced a slab detachment that propagated eastward and westward, thus inducing a change in the direction of extension from NW-SE to E-W. Fast slab retreat between 32 and 8 Ma and induced asthenospheric flow have prevented the transmission of the horizontal compression due to Africa-Eurasia convergence from Africa to Eurasia and favored instead upper-plate extension driven by slab retreat. Once slab retreat had slowed down in the Late Miocene, this N-S compression was felt and recorded again from the High Atlas to the Paris Basin.
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Teston, Francesca, and Alberto Bramanti. "EUSALP and the challenge of multi-level governance policies in the Alps." Worldwide Hospitality and Tourism Themes 10, no. 2 (April 9, 2018): 140–60. http://dx.doi.org/10.1108/whatt-12-2017-0079.
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Purpose “Wide area cooperation” may be the ultimate challenge within transnational cooperation processes. Although the Alps share a remarkable history of mutual collaboration, they are facing the challenge of a new sustainable-coordination paradigm. The Alpine territories are at a turning point. They are striving for a new governance arrangement and trying to avoid both the Scylla of top-town dirigisme and the Charybdis of poor local governments. This paper aims to address the recent literature on the EU Strategy for the Alpine Region (EUSALP) macro-regional strategy; provide some insights into the role that EUSALP could play as ultimate coordinator of the numerous networks operating in the Alpine space; and discuss a workable division of labour among the different actors that can ensure a renewed focus on sustainable development. Design/methodology/approach The review addresses two main strands of literature related to “wide area cooperation” and “multi-level governance” to synthesise the debate on the most appropriate governance structure for the Alps. The paper examines, dating back to 2000, the recent history of bottom-up projects related to sustainable tourism in the western arc of the Alps. The study uses a subset of best practices to evaluate the emerging governance frame. Findings The main outcomes of this study are a framework for a theoretical debate on the most appropriate governance structure for the Alps, guidance for policymakers on a division of labour among different stakeholders that can promote sustainable tourism in the Alps and a set of suggestions for practitioners. Further, the study acknowledges “sustainable tourism” as a highly relevant field to the emergence of bottom-up arrangements aimed at developing workable governance agreements. Research limitations/implications The paper provides a state-of-the-art framework for “wide area cooperation” in the Alps and serves as a basis for discussion between academics and practitioners. As EUSALP is still in its infancy, its success will depend on the pro-active involvement of national stakeholders. In the case of Italy, this is all but granted because of the current unstable political situation. Originality/value This paper provides a rigorous framework for addressing top-down strategies and bottom-up planning in the Alpine space. The study also makes a practical contribution by addressing some topics of interest to policymakers.
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Ramsay, J. G. "Fold and fault geometry in the western Helvetic nappes of Switzerland and France and its implication for the evolution of the arc of the western Alps." Geological Society, London, Special Publications 45, no. 1 (1989): 33–45. http://dx.doi.org/10.1144/gsl.sp.1989.045.01.02.
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Ryan, Paul D., and John F. Dewey. "The sources of metamorphic heat during collisional orogeny: the Barrovian enigma." Canadian Journal of Earth Sciences 56, no. 12 (December 2019): 1309–17. http://dx.doi.org/10.1139/cjes-2018-0182.
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The problem of the observed very rapid advection of heat into metamorphic thrust stacks is reviewed. Conductive models relying on the thermal relaxation of a thickened crust will not produce the observed Barrovian (medium temperature, medium pressure) assemblages within some short-lived orogens (e.g., western Ireland and Timor). Studies of the rate and timing of metamorphic mineral growth suggest that this is commonly faster than predicted by thermal relaxation. Barrovian assemblages are localised in some orogens (e.g., the Alps) but extensive in others (e.g., the Himalayas). Metamorphic mineral growth brackets deformation; consequently, slow growth is inconsistent with the rapid uplift of many orogens. Thus, no single mechanism can account for the development of Barrovian assemblages during collisional orogeny. The only mechanisms that can supply large amounts of heat for regional metamorphism quickly (<10 Myr) are: rapidly thinning the lithosphere without stretching it (e.g., by plume thermal erosion, slab drop-off, or delamination); by emplacing magma into the crust (modest deep mafic underplate and (or) very large amounts of mafic and silicic magma emplaced into the middle and upper crust); or obducting hot nappes of arc with a thin ophiolite forearc (“hot iron” mechanism). Frictional and viscous heating produces local rapid heating but not fast regional heating. Back-arc or any kind of lithospheric extension increases the geothermal gradient and heat flow but does not heat rocks up. We suggest that magmatic advection of heat-associated lithospheric thinning or “hot iron” overthrusting of an arc/ophiolite are the primary sources of heat in short-lived orogens.
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Scarponi, M., G. Hetényi, T. Berthet, L. Baron, P. Manzotti, B. Petri, M. Pistone, and O. Müntener. "New gravity data and 3-D density model constraints on the Ivrea Geophysical Body (Western Alps)." Geophysical Journal International 222, no. 3 (May 30, 2020): 1977–91. http://dx.doi.org/10.1093/gji/ggaa263.
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SUMMARY We provide a high-resolution image of the Ivrea Geophysical Body (IGB) in the Western Alps with new gravity data and 3-D density modelling, integrated with surface geological observations and laboratory analyses of rock properties. The IGB is a sliver of Adriatic lower lithosphere that is located at shallow depths along the inner arc of the Western Alps, and associated with dense rocks that are exposed in the Ivrea-Verbano Zone (IVZ). The IGB is known for its high seismic velocity anomaly at shallow crustal depths and a pronounced positive gravity anomaly. Here, we investigate the IGB at a finer spatial scale, merging geophysical and geological observations. We compile existing gravity data and we add 207 new relative gravity measurements, approaching an optimal spatial coverage of 1 data point per 4–9 km2 across the IVZ. A compilation of tectonic maps and rock laboratory analyses together with a mineral properties database is used to produce a novel surface rock-density map of the IVZ. The density map is incorporated into the gravity anomaly computation routine, from which we defined the Niggli gravity anomaly. This accounts for Bouguer Plate and terrain correction, both considering the in situ surface rock densities, deviating from the 2670 kg m–3 value commonly used in such computations. We then develop a 3-D single-interface crustal density model, which represents the density distribution of the IGB, including the above Niggli-correction. We retrieve an optimal fit to the observations by using a 400 kg m–3 density contrast across the model interface, which reaches as shallow as 1 km depth below sea level. The model sensitivity tests suggest that the ∼300–500 kg m–3 density contrast range is still plausible, and consequently locates the shallowest parts of the interface at 0 km and at 2 km depth below sea level, for the lowest and the highest density contrast, respectively. The former model requires a sharp density discontinuity, the latter may feature a vertical transition of densities on the order of few kilometres. Compared with previous studies, the model geometry reaches shallower depths and suggests that the width of the anomaly is larger, ∼20 km in west–east direction and steeply E–SE dipping. Regarding the possible rock types composing the IGB, both regional geology and standard background crustal structure considerations are taken into account. These exclude both felsic rocks and high-pressure metamorphic rocks as suitable candidates, and point towards ultramafic or mantle peridotite type rocks composing the bulk of the IGB.
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Bussy, François, Jean Hernandez, and Jürgen Von Raumer. "Bimodal magmatism as a consequence of the post-collisional readjustment of the thickened Variscan continental lithosphere (Aiguilles Rouges-Mont Blanc Massifs, Western Alps)." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 91, no. 1-2 (2000): 221–33. http://dx.doi.org/10.1017/s0263593300007392.
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High Precision U-Pb zircon and monazite dating in the Aiguilles Rouges–Mont Blanc area allowed discrimination of three short-lived bimodal magmatic pulses: the early 332 Ma Mg–K Pormenaz monzonite and associated 331 Ma peraluminous Montées Pélissier monzogranite; the 307 Ma cordierite-bearing peraluminous Vallorcine and Fully intrusions; and the 303 Fe-K Mont Blanc syenogranite. All intruded syntectonically along major-scale transcurrent faults at a time when the substratum was experiencing tectonic exhumation, active erosion recorded in detrital basins and isothermal decompression melting dated at 327-320 Ma. Mantle activity and magma mixing are evidenced in all plutons by coeval mafic enclaves, stocks and synplutonic dykes. Both crustal and mantle sources evolve through time, pointing to an increasingly warm continental crust and juvenile asthenospheric mantle sources. This overall tectono-magmatic evolution is interpreted in a scenario of post-collisional restoration to normal size of a thickened continental lithosphere. The latter re-equilibrates through delamination and/or erosion of its mantle root and tectonic exhumation/erosion in an overall extensional regime. Extension is related to either gravitational collapse or back-arc extension of a distant subduction zone.
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Puglisi, Diego. "Early Cretaceous flysch from Betic-Maghrebian and Europe Alpine Chains (Gibraltar Strait to the Balkans): comparison and palaeotectonic implications." Geologica Balcanica 38, no. 1-3 (December 2009): 15–22. http://dx.doi.org/10.52321/geolbalc.38.1-3.15.
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Early Cretaceous flysch crops out along all the Alpine Chains of the western, central and eastern Europe for more than 7000 km from the Gibraltar Arc to the Balkans. In the different sectors of the Alpine Chain (Maghrebides, Apennines, Alps, Dinarides, Hellenides, Carpathians and Balkans) these flysch deposits, characterized by calcareous turbidites grading upwards into arenaceous turbidites, mark the contact between the internal and external areas. They show a provenance linked to internal areas and are made up by crystalline sources and locally by ophiolitic complexes. Due to the Cretaceous re-organization of the plates, all these successions experienced a Late Cretaceous tectonics, with the only exception of the Maghrebian flysch deposits. In this area, similar tectonic events have never been recorded but only suspected and aged to slightly later times. This paper aims to show the stratigraphic, geological and structural similarities of all these Early Cretaceous flysch sediments by emphasizing the difficulties to imagine that only the Maghrebian sector of the Alpine Tethys escaped the Mid- to Late-Cretaceous tectonics widely recognized in all the other segments of the Alpine Chain. In fact the Late Cretaceous or post-Cretaceous tectonics connected with a “mesoalpine” stage, has been hypothesized for the Maghrebian chain at the beginning of the nineties and recently it has been supported by the presence of Alpine metamorphic overprints recognized within the Hercynian crystalline units of the Calabria- Peloritani Arc (southern Italy). This tectonics seems to be linked to an early segmentation and deformation of the Maghrebian Early Cretaceous flysch with local underthrusting beneath the southern European margin.
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Mathey, M., A. Walpersdorf, C. Sue, S. Baize, and A. Deprez. "Seismogenic potential of the High Durance Fault constrained by 20 yr of GNSS measurements in the Western European Alps." Geophysical Journal International 222, no. 3 (June 15, 2020): 2136–46. http://dx.doi.org/10.1093/gji/ggaa292.
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SUMMARY Due to the steady moderate seismicity observed along the Briançon seismic arc, in the south-western French Alps, three temporary GNSS (Global Navigation Satellite System) surveys took place in 1996, 2006 and 2011, across a ∼50 × 60 km² wide area, to investigate the surface deformation field. The horizontal velocity field computed from these three surveys showed an east–west extension in the network. A fourth campaign was led in 2016, creating a 20 yr observation span, resulting in measurements which reach a sufficient accuracy to assess whether extension found within the Briançon network is localized onto any particular tectonic feature. Several faults in this area are known to be active normal faults. Assessing the localization of the deformation may lead to a better understanding of the active tectonics of the Alpine belt. To address this issue, a robust velocity field was computed from the combination of the different campaign and permanent GNSS data. Strain rate tensors were derived for the first time in this area on a 0.1 × 0.1 deg grid to assess the distribution of the deformation. The regional deformation appears localized in the Briançon area and reaches up to 20 ± 5 nanostrain yr−1 in the centre of the network. The observed velocities were projected on a profile across the network and compared with modelled interseismic deformation to characterize the behaviour of the major active faults known in the study zone. While a two-fault model provides the best fit to the data, a single fault model has only marginally higher residuals, with parameters which are more consistent with the seismotectonics of the region. The localization of the single modelled fault is consistent with the location of the High Durance Fault (HDF). Therefore, we used the known geological location of this structure as a priori information in a block model to compute a fault slip rate at the interface between the two blocks. The velocities on the interface indicate 0.4–0.5 mm yr−1 of extension, and therefore strain accumulates along the HDF throughout the seismic cycle. The geodetically derived fault slip rate is converted into an equivalent seismic moment release rate, which is consistent within its uncertainty bounds with the known historical and instrumental seismicity of the Briançon area.
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Martinod, Joseph, Lucie Roux, Jean-Francois Gamond, and Jean-Paul Glot. "Deformation actuelle de la chaine de Belledonne (massifs cristallins externes alpins, France); comparaison triangulation historique-GPS." Bulletin de la Société Géologique de France 172, no. 6 (November 1, 2001): 713–21. http://dx.doi.org/10.2113/172.6.713.
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Abstract The present-day active tectonics of the western Alps are poorly known. Permanent GPS stations located in the French and Italian Alps are too recent to give any significant information on the strain-regime within the chain [e.g. Calais et al., 2000a; Caporali and Martin, 2000]. Similarly, the reiteration in 1998 of the 60 points of the "GPS Alpes" temporary network, previously installed and positioned in 1993, did not result in a clear image of the active deformations of this part of the Alpine Arc [Vigny et al., 2001]. Both permanent and "GPS Alpes" data show that the relative motion of most of the points located within, or on both sides of the chain, are probably slower than 5 mm/yr. Another possibility to investigate the present-day deformation of part of the Alps is to use historical triangulation data. In many parts of the French Alps, authors have remeasured historical networks of the French Institut Geographique National, using GPS, for geodynamical purposes [Jouanne et al., 1994; Martinod et al., 1996; Ferhat et al., 1998; Sue et al., 2000; Calais et al., 2000b; Jouanne et al., 2001]. Their comparison confirms that deformations in the French Alps occur slowly, at speeds smaller than 5 mm/yr. Some deformations, however, have been observed in different parts of the chain [Jouanne et al., 1994; Martinod et al., 1996; Sue et al., 2000; Calais et al., 2000b]. Typically, the precision of triangulation data is 10 (super -5) , which means that the motion between benchmarks whose relative distance is 10 km must reach 10 cm to be noticed. Given the age of the triangulation networks that are re-measured using GPS (generally around 50 years), this corresponds to relative velocities of 2 mm/yr, which is quite large in the context of the western Alps. For instance, Martinod et al. [1996] calculate a shortening axis orientated N070 degrees for the southern part of the Belledonne Massif (External Crystalline Massifs), and evaluate the relative speeds to reach possibly 3-5 mm/yr, which is as large as the maximum relative speed between Apulia and Europe! These results are based, however, on the motion of only 3 benchmarks (GGA, REV and GSE) of the historical network. In order to confirm the existence of the rapid deformation noted in this previous paper, we measured in 1998 and 1999, using GPS, the position of 22 historical benchmarks located near the southern part of the Belledonne Massif, which is the area where Martinod et al. [1996] observed their most significant deformations. Geodetic data: 22 geodetic sites were measured using GPS in 1998 and 1999. Measurements were done using bi-frequency Ashtech receivers, in at least two 6-hour sessions for half of the points. 6 of those sites had already been measured in 1993-1994. We also included in the compensation of the GPS data the measurements of 4 sites (BUF, GEN, MCR and NER) that had been done in 1993 and 1994. GPS data have been processed using the Winprism software, and we used the Geolab software to perform the compensation of the 1993-1994 data together with the 1998-99 data. We finally obtain a new position for 26 benchmarks of the "Savoie-Dauphine 1950" triangulation network. We also performed again the compensation of the old triangulation network. We included in the compensation, data concerning the points of the geodetic campaign from the 1st order to the 4th order geodetic points. We calculated the position of 186 stations, using 1174 angle measurements. We assumed the standard deviation of a direction observation to result both from centering and instrumental errors [e.g. Jouanne et al., 1994]. We adopted the following uncertainties: 20 mm for centering errors, 6.3 10 (super -4) grads for Wild T3, and 7.6 10 (super -4) grads for Wild T2 theodolites (values communicated by IGN). The relative accuracy of the coordinates determined in this compensation is approximately 10 (super -5) . Comparison between triangulation and GPS data: It is not possible to obtain displacements vectors comparing GPS measurements with old triangulation data. As a matter of fact, historical geodetic networks only contain precise angle measurements. Neither the size, nor the orientation of the old network can be accurately known. To evidence possible tectonic deformations comparing the two geodetic campaigns, we calculate the strain tensor for triangular elements formed by sets of three neighbouring points of the network. We calculate the eingenvalues epsilon 1 and epsilon 2 of the strain tensor and their azimuth (resp. theta 1 and theta 2 ). We present in table II the values of dgamma /dt = (depsilon 1 /dt-depsilon 2 /dt) and of theta 2 for 33 triangles formed by sets of the 26 historical points remeasured using GPS. Both dgamma /dt and theta 2 are independent of the size and orientation of the old triangulation network. They can therefore be evaluated with precision without any a priori hypothesis [e.g. Ferhat, 1997]. dgamma /dt is the difference between the maximum compressive and extensive strain rate.
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Sun, Min, Kurt Kyser, Mel Stauffer, Rob Kerrich, and John Lewry. "Constraints on the timing of crustal imbrication in the central Trans-Hudson Orogen from single zircon 207Pb/206Pb ages of granitoid rocks from the Pelican thrust zone, Saskatchewan." Canadian Journal of Earth Sciences 33, no. 12 (December 1, 1996): 1638–47. http://dx.doi.org/10.1139/e96-124.
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The Pelican thrust is a major ductile high-strain zone in the Reindeer Zone, Trans-Hudson Orogen, northern Saskatchewan. It is interpreted as the main sole thrust separating stacked juvenile Paleoproterozoic allochthons and underlying Archean microcontinental crust in this central part of the orogen. Exposed nonmylonitic rocks in the footwall of the thrust consist of the Sahli monzocharnockite and the smaller, more highly retrograded MacMillan Point granite. Protomylonitic to ultramylonitic gneisses in the thrust zone derive from a variety of prethrust protoliths. A footwall "internal suite" mainly comprises quartzofeldspathic orthogneisses ("Q" gneisses) and high-grade migmatitic paragneisses. Hanging-wall "external suite" mylonitic gneisses include feldspar-porphyroclastic hornblendic grey gneisses probably derived from arc plutons, and laminated amphibolites derived from volcanic rocks. The overlying allochthon mainly comprises protoliths equivalent to those of the porphyroclastic orthogneisses and laminated amphibolites, together with interfolded and overlying Paleoproterozoic paragneisses of the Kisseynew domain. The Sahli monzoeharnockite yields 207Pb/206Pb zircon and whole-rock Rb–Sr ages of ca. 2500 Ma, and the "Q" gneisses give 207Pb/206Pb zircon ages of up to ca 2900 Ma, implying that most of the internal suite (footwall) mylonite protoliths are Archean. In contrast, external suite (hanging wall) porphyroclastic orthogneisses yield ca. 1880–1840 Ma 207Pb/206Pb zircon ages. Main, peak-metamorphic displacement on the Pelican thrust is interpreted to have occurred mainly between 1840 and 1820 Ma, as indicated by 207Pb/206Pb zircon ages from small, highly deformed synthrusting granite–pegmatite neosomal bodies in the thrust zone. Undeformed postcollisional granites and pegmatites were emplaced~1789 Ma. Total duration from arc development to completion of arc–continent collision was ~100 Ma. The Pelican thrust zone may be similar in significance and style to younger, major, ocean closure related thrusts such as the Frontal Pennine thrust of the western Alps and the Main Mantle, Main Boundary, and Main Central thrusts of the Himalayas. As for the Pelican thrust, these displace oceanic rocks over older basement.
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Jolivet, Laurent, Thierry Baudin, Sylvain Calassou, Sébastien Chevrot, Mary Ford, Benoit Issautier, Eric Lasseur, et al. "Geodynamic evolution of a wide plate boundary in the Western Mediterranean, near-field versus far-field interactions." BSGF - Earth Sciences Bulletin 192 (2021): 48. http://dx.doi.org/10.1051/bsgf/2021043.
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The present-day tectonic setting of the Western Mediterranean region, from the Pyrénées to the Betics and from the Alps to the Atlas, results from a complex 3-D geodynamic evolution involving the interactions between the Africa, Eurasia and Iberia plates and asthenospheric mantle dynamics underneath. In this paper, we review the main tectonic events recorded in this region since the Early Cretaceous and discuss the respective effects of far-field and near-field contributions, in order to unravel the origin of forces controlling crustal deformation. The respective contributions of mantle-scale, plate-scale and local processes in the succession of tectonic stages are discussed. Three periods can be distinguished: (1) the first period (Tethyan Tectonics), from 110 to 35 Ma, spans the main evolution of the Pyrenean orogen and the early evolution of the Betics, from rifting to maximum shortening. The rifting between Iberia and Europe and the subsequent progressive formation of new compressional plate boundaries in the Pyrénées and the Betics, as well as the compression recorded all the way to the North Sea, are placed in the large-scale framework of the African and Eurasian plates carried by large-scale mantle convection; (2) the second period (Mediterranean Tectonics), from 32 to 8 Ma, corresponds to a first-order change in subduction dynamics. It is most typically Mediterranean with a dominant contribution of slab retreat and associated mantle flow in crustal deformation. Mountain building and back-arc basin opening are controlled by retreating and tearing slabs and associated mantle flow at depth. The 3-D interactions between the different pieces of retreating slabs are complex and the crust accommodates the mantle flow underneath in various ways, including the formation of metamorphic core complexes and transfer fault zones; (3) the third period (Late-Mediterranean Tectonics) runs from 8 Ma to the Present. It corresponds to a new drastic change in the tectonic regime characterized by the resumption of N-S compression along the southern plate boundary and a propagation of compression toward the north. The respective effects of stress transmission through the lithospheric stress-guide and lithosphere-asthenosphere interactions are discussed throughout this period.
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Borras, A., J. C. Senar, F. Alba-Sánchez, J. A. López-Sáez, J. Cabrera, X. Colomé, and T. Cabrera. "Citril finches during the winter: patterns of distribution, the role of pines and implications for the conservation of the species." Animal Biodiversity and Conservationa 33, no. 1 (2010): 89–115. http://dx.doi.org/10.32800/abc.2010.33.0089.
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The Citril finch Serinus citrinella is a Paleartic endemic species that breeds in the subalpine mountain zones of western temperate Europe. The species seems to be suffering a serious decline in its northern range, mainly in the Black Forest and the NE of the Alps. Numerous reasons have been provided for this decline, but all of them have been related to breeding habitats. Given that the species undergoes an altitudinal migration and that during winter it may use very different habitats, a sound knowledge of the distribution patterns and habitats used outside the breeding period is needed to conduct adequate conservation policies and management. This information, however, is largely lacking. The aim of this paper was to determine the current habitat used by Citril finches in north-eastern Spain during the winter, to analyse habitat suitability and to study movements, by investigating the origin of birds that overwinter in Catalonia. Citril finch distribution was modelled using both discriminant analysis and maximum entropy modelling, on the basis of species occurrences during winter in Catalonia (data from 1972-2009). Results showed that the presence of two tree species, Black pine (Pinus nigra subsp. salzmanii) and Scots pine (Pinus sylvestris), both as part of mixed open forests, and the presence of abundant farmland and arvensic plants -the two vegetation units located in a typical submediterranean context, where the warm temperatures (sunny days) in late winter permit the cones to open-, were the ecological and bioclimatic variables that explain the distribution model. All these variables in tandem seem to be the key for the current potential distribution of the Citril finch in winter (AUCscores: training data AUC= 0.955; test data AUC = 0.953). We analyzed recoveries (N = 238) of 2,368 birds ringed at wintering grounds and 12,648 birds ringed at subalpine localities in the adjacent Pyrenees from 1977-2004. We found that in the study area, we recovered ringed birds from many different locations from across the distributional range of the species, including trans-Pyrenean birds from the Alps. This stresses the high mobility of Citril finch populations to reach wintering areas. From a conservation point of view, the high importance of pines (mainly Black pine) for the wintering distribution of the species stresses that any threat on pines, especially forest fires, will have acute detrimental effects for Citril finch populations.
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Nikolaichuk, V. І., M. М. Vakerich, M. V. Bilkey, O. P. Chechuy, and I. Voloshchuk. "Possible ecologically based ways of preserving and developing the Ukrainian Carpathians." Biosystems Diversity 24, no. 1 (February 27, 2016): 157–63. http://dx.doi.org/10.15421/011619.
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Ukraine has transformed into one of the most environmentally dangerous countries in the world due to the high concentration of industrial production and agriculture and predatory use of natural resources. The current ecological situation in Ukraine is characterized by a deep ecological crisis, which is caused by the laws of operation of the command economy of the former USSR. The majority of the environmental and social indicators of Ukraine are among the worst in Europe. The Carpathian Mountains are among the most significant and interesting landscapes in Europe from the geological and geomorphological, scenic and biological perspectives. The giant arc of the Carpathians begins in southern Romania and passes through Ukraine, Slovakia, Poland, the Czech Republic and Hungary to Austria, crosses all Eastern and Central Europe. A third of the forest reserves of Ukraine are located in the Ukrainian Carpathians, at 53.5% the percentage of forest cover of the area is among the highest in the country. About 50% of the gene pool of Ukraine’s plants, many species of trees and medicinal plants grows there. The geographical location and large area of the rich natural heritage of the Carpathians have multifaceted importance for the conservation of biological, phytocoenotic and landscape diversity and maintaining the ecological balance in the central part of our continent. As with the Alps mountain range, this is an important ecological corridor between Western, Central and Eastern Europe, which promotes the migration of species and their spread into lowland landscapes. In order to preserve biodiversity an inventory of virgin forest ecosystems should be made and strict measures for their protection should be enforced. It is necessary to continue the practice of establishing bilateral areas in cross-border protected areas in order to combine efforts to solve pressing environmental challenges. Conservation of the Carpathians Biodiversity is an urgent problem. Structural changes in the economy of the region are expected to strengthen the recreational value of the Ukrainian Carpathians for the public not only in our country but also in Central and Eastern Europe, reducing the technogenic loading. International cooperation of all countries of the Carpathian region is imperative. The development of tourism in the Carpathians is highly promising, but this should be civilized tourism, taking into account the environmental sustainability of the recreational areas and protected areas.
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Bigot-Cormier, Florence, Françoise Sage, Marc Sosson, Jacques Déverchère, Michelle Ferrandini, Pol Guennoc, Michel Popoff, and Jean-François Stéphan. "Pliocene deformation of the north-Ligurian margin (France) : consequences of a south-Alpine crustal thrust." Bulletin de la Société Géologique de France 175, no. 2 (March 1, 2004): 197–211. http://dx.doi.org/10.2113/175.2.197.
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Abstract Introduction.– The Oligo-Miocene extension phase of the Mediterranean basins rifting (30–25 Ma) [Jolivet and Faccenna, 2000] followed by the Ligurian basin oceanic crust formation (21–18 Ma) [Le Pichon et al., 1971 ; Réhault et al., 1984 ; Carminati et al., 1998 ; Gueguen et al., 1998] occurred during the western Alps compression phase. The deformations were characterised during the Miocene by the southwestward structuration of the Castellane Arc [Fallot and Faure-Muret, 1949 ; Laurent et al., 2000] and during the Mio-Pliocene by the southward structuration of the Nice Arc. This latter arc is bounded on its western side by a dextral strike-slip fault and on its southern side by a thrust inducing an uplift of this arc [Ritz, 1991 ; Guglielmi and Dubar, 1993 ; Clauzon et al., 1996 ; Guardia et al., 1996 ; Schroetter, 1998]. Fission tracks thermochronology data [Bigot-Cormier et al., 2000] suggest a general uplift at ~3.5 Ma of the Argentera massif. Stratigraphical [Irr, 1984 ; Hilgen, 1991 ; Hilgen and Langereis, 1988, 1993] and geomorphological studies [Clauzon et al., 1996 b ; Dubar and Guglielmi, 1997] show evidences for an uplift of the Ligurian coast increasing east of the Var river. The analysis of 70 seismic-reflection profiles allows us to better characterise and quantify the deformation from Antibes to Imperia (fig. 1). We then reconstruct vertical motions in space and time since the Messinian crisis in order to propose a deformation model of the margin related to crustal thickening. Morpho-structural and sedimentary characteristics of the margin. – The morphology of the margin results both from the Oligocene rifting and the Messinian crisis (5.8–5.3 Ma) characterised by a sea level fall of ~1500 m. At the surface, the margin, with a steep mean slope of 6–8o near Antibes [Réhault, 1981] to 12o near Imperia [Savoye and Piper, 1991], is cut by several canyons. At depth, there are two or three tilted blocks covered by Mesozoic sediments and in the Imperia area by the Helminthoïd Flyschs [Sosson et al., 1998]. In the basin, above the Miocene units, we observe some lower evaporites at the bottom, the Messinian salt in the middle and upper evaporites (E) marking the end of the low sea level 5.32 Ma ago [Ryan et al., 1973 ; Mauffret et al., 1973 ; Réhault 1981 ; Savoye and Piper, 1991]. The sedimentary series ends with 1500 m thick of Plio-Quaternary units [Gennesseaux and Le Calvez, 1960 ; Sosson et al., 1998]. At the top of the margin, we observe an erosion surface while toward the basin, two units are evidenced : the Messinian fan (CYL 30–05, fig. 2) unconformity, covered by a seismic facies similar to the one of the upper evaporites in the basin. The “M” surface, that relates the erosional surface of the margin and the upper evaporites of the basin, has a regular slope toward the basin (fig. 3). We will use this surface as a stratigraphic and structural reference for this work. Acquisition and methodology. – We analysed 12 profiles from the MALIGU cruise (1993–1994) [Chaumillon et al., 1994] and ~ 60 from several cruises (1992–2001) with the “Tethys” oceanographic ship to synthesize all stratigraphic and structural observations along the margin. In this paper, we only present 12 of them. We quantify the deformation at the margin/basin limit with a velocity gradient [Le Douaran et al., 1984 ; Rollet, 1999 ; Contrucci et al., 2001] on 50 profiles and we propose a deformation chronology using the “M” surface. Evidence for Pliocene deformation – Between Antibes and the east of Nice : there is no deformation of the “M” surface (fig. 3). – Between the east of Nice and the west of Menton : we observe a deformation at the top of the margin characterised by tilted seismic reflectors (fig. 4A). According to the micro-paleontology study, this deformation is dated at the Lower-Upper Pliocene limit. – From the west of Menton to San Remo : the deformation, observed in the middle of the margin, is characterised by a tilted Messinian fan and the formation of small basins (fig. 4A,B). We note that this deformation increases when the margin strikes ENE-WSW. – From San Remo to Imperia : the deformation increases from the middle to the base of the margin (fig. 4B). The apparent normal throw estimated at ~ 500 m near Antibes increases up to more than 2000 m near Imperia since ~ 5 Ma (fig. 5). This deformation induced (i) the formation of a piggy-back basin located near Imperia, (ii) a decrease of the “M” surface slope with at places a slope inversion compared with the Antibes area (fig. 4B). Space and time reconstitution of vertical motions. – In order to better visualise the geometry of the structure of the margin, we drew seismic profiles with no exaggeration. We interpret the observations seen above and the fact that normal faults on the rifted tilted blocks show a slope between 45–30o as the occurrence of a blind thrust (fig. 6). Motion along the thrusting plane induces the rotation of tilted blocks and is responsible for the margin uplift during the Lower-Upper Pliocene limit following a book-shelf mechanism [Mandl, 1987 ; Jackson and McKenzie, 1983]. At the bottom of the margin, we therefore interpret the apparent normal fault as a gravitary sliding (fig. 7) which enhances the front of the thrust vanishing in the Messinian salt unit. Discussion – Comparison between this model and others previously proposed : contrary to the model proposed by Chaumillon et al. [1994], we can explain the uplift of the margin and the presence of the “normal” faults at the limit margin/basin, only with one mechanism of crustal compression. This mechanism clearly comes from onshore and not from offshore as suggested by Béthoux et al. [1992]. The thrust, dipping toward the continent, can be observed on multichanel seismic reflection profiles [Rollet, 1999] (fig. 8). – The compression of the margin since the end of the lower-Pliocene : our results are chronologically and geometrically in agreement with reversal faults dipping toward the continent, observed along Cap Mele (fig. 1) at the bottom of the Pliocene units [Réhault, 1981]. Both, the important thickness of the Plio-Quaternary sediments near Imperia, far away from the Var river, and the many salt diapirs in the NE area, are consistent with a thrust motion. – The area Argentera massif-Ligurian margin : according to fission track data [Bigot-Cormier et al., 2000] a major uplift was detected at ~3.5 Ma. At the same time, the Ligurian margin recorded a compressive phase with a structural geometry consistent with the deformation onshore (fig. 9). The deformation on the thrust front is the most important at the axis of the main structures of the Argentera. This thrust front is located at the base of the margin near Imperia and propagated toward the top close to the western edge of the Nice arc (fig. 10). Our observations suggest that the deformations propagate offshore in relation with the advance of the Alpine front toward the south. Conclusion. – The analysis of 70 seismic reflection profiles based on stratigraphic and structural studies allows us to quantify and date the deformation of the Ligurian margin increasing eastward. This deformation dated at the Lower-Upper Pliocene limit is due to the propagation of a blind thrust front consistent with the basement tectonic deformation of this period reactivating the Oligocene rifting structures.
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Michl, Thomas, Stefan Huck, Peter Haase, and Burkhard Büdel. "Genetic Differentiation among Populations of Cicerbita alpina (L.) Wallroth (Asteraceae) in the Western Alps." Zeitschrift für Naturforschung C 62, no. 9-10 (October 1, 2007): 747–56. http://dx.doi.org/10.1515/znc-2007-9-1019.
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In this study we analyzed the genetic population structure of the hygrophilous tall-herb Cicerbita alpina in the western Alps because this group of mountain plants is underrepresented in the biogeographical literature. AFLP (amplified fragment length polymorphism) fingerprints of 40 samples were analyzed from four populations situated in a transect from the southwestern Alps to the eastern part of the western Alps and one population from the Black Forest outside the Alps. Two genetic groups can be distinguished. The first group (A) comprises the populations from the northern and eastern parts of the western Alps, and the second group (B) comprises the populations from the southwestern Alps and the Black Forest. Group A originates most likely from at least one refugium in the southern piedmont regions of the Alps. This result provides molecular evidence for a humid climate at the southern margin of the Alps during the Würm glaciation. Group B originates presumably from western or northern direction and we discuss two possible scenarios for the colonization of the Alps, i. e. (1) long-distance dispersal from southwestern refugia and (2) colonization from nearby refugia in the western and/or northern Alpine forelands. The study demonstrates that the target species harbours considerable genetic diversity, even on a regional scale, and therefore is a suitable model for phylogeographic research.
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Perrone, G., P. Cadoppi, S. Tallone, and G. Balestro. "Post-collisional tectonics in the Northern Cottian Alps (Italian Western Alps)." International Journal of Earth Sciences 100, no. 6 (April 2, 2010): 1349–73. http://dx.doi.org/10.1007/s00531-010-0534-1.
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Carrapa, Barbara, Jan Wijbrans, and Giovanni Bertotti. "Episodic exhumation in the Western Alps." Geology 31, no. 7 (2003): 601. http://dx.doi.org/10.1130/0091-7613(2003)031<0601:eeitwa>2.0.co;2.
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Ricou, L. E., and A. W. B. Siddans. "Collision tectonics in the Western Alps." Geological Society, London, Special Publications 19, no. 1 (1986): 229–44. http://dx.doi.org/10.1144/gsl.sp.1986.019.01.13.
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Gillet, Ph, P. Choukroune, M. Ballèvre, and Ph Davy. "Thickening history of the Western Alps." Earth and Planetary Science Letters 78, no. 1 (May 1986): 44–52. http://dx.doi.org/10.1016/0012-821x(86)90171-8.
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Müntener, Othmar, Peter Ulmer, and Jonathan D. Blundy. "Superhydrous Arc Magmas in the Alpine Context." Elements 17, no. 1 (February 1, 2021): 35–40. http://dx.doi.org/10.2138/gselements.17.1.35.
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Magmatic rocks in the Alps are scarce. What little arc magmatism there was pre-dates the Eurasia–Adria collision at 43–34 Ma but ends at 30–29 Ma. Conversely, geochemical data for magmatic rocks from the Alps resemble that of subduction-related magmatic arcs. A characteristic of Alpine magmatism is the occurrence of relatively deep (80–100 km) super-hydrous (>8 wt% H2O) low-K primary magmas in the east and shoshonitic K-rich magmas in the west. These features are likely related to the absence of vigorous mantle wedge convection. Superhydrous primary magmas undergo extensive crystallization and fluid saturation at depth, producing high ratios of plutonic to volcanic rocks. We speculate that superhydrous primary arc magmas are a consequence of slow convergence and the initial architecture of subducting crust.
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Bertotti, G., and P. Mosca. "Late-orogenic vertical movements within the arc of the SW Alps and Ligurian Alps." Tectonophysics 475, no. 1 (September 2009): 117–27. http://dx.doi.org/10.1016/j.tecto.2008.08.016.
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Lutz, Joachim, and Ernst Pernicka. "Prehistoric copper from the Eastern Alps." Open Journal of Archaeometry 1, no. 1 (December 31, 2013): 25. http://dx.doi.org/10.4081/arc.2013.e25.
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The rich copper ore deposits in the Eastern Alps have long been considered as important sources for copper in prehistoric Central Europe. It is, however, not so clear which role each deposit played. To evaluate the amount of prehistoric copper production of the various mining regions it was attempted to link prehistoric metal artefacts with copper ores based on the geochemical characteristics of the ore deposits that have been exploited in ancient times. More than 120 ore samples from the well known mining districts Mitterberg, Viehhofen, Kitzbühel and Schwaz/Brixlegg have been analysed so far (lead isotope ratios, trace elements). Furthermore, about 730 archaeological copper/bronze artifacts were investigated and analysed. These results were combined with analytical data generated by previous archaeometallurgical projects in order to compile a substantial database for comparative studies. In the Early Bronze Age, most metal artifacts were made of copper or bronze with fahlore impurity patterns and most finds from this period match excellently the fahlore deposits in Schwaz and Brixlegg. At the end of the Early Bronze Age, a new variety of copper with lower concentrations of impurities appeared. The impurity patterns of these finds match the ores from the Mitterberg district. In the Middle Bronze Age, this variety of copper Dominated while in the Late Bronze Age fahlores from Schwaz and Brixlegg experienced a comeback. The reason for this may be a decline of the chalcopyrite mines or a rising demand for copper which could not be covered by the chalcopyrite mines alone. The finds of the Early Iron Age are of similar composition and continue the traditions of the Late Bronze Age.
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Vavra, G., and W. Frisch. "Pre-Variscan back-arc and island-arc magmatism in the Tauern window (Eastern Alps)." Tectonophysics 169, no. 4 (November 1989): 271–80. http://dx.doi.org/10.1016/0040-1951(89)90091-7.
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Nguyen, Hai Ninh, Philippe Vernant, Stephane Mazzotti, Giorgi Khazaradze, and Eva Asensio. "3-D GPS velocity field and its implications on the present-day post-orogenic deformation of the Western Alps and Pyrenees." Solid Earth 7, no. 5 (September 21, 2016): 1349–63. http://dx.doi.org/10.5194/se-7-1349-2016.
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Abstract. We present a new 3-D GPS velocity solution for 182 sites for the region encompassing the Western Alps, Pyrenees, and southern France. The velocity field is based on a Precise Point Positioning (PPP) solution, to which we apply a common-mode filter, defined by the 26 longest time series, in order to correct for network-wide biases (reference frame, unmodeled large-scale processes, etc.). We show that processing parameters, such as troposphere delay modeling, can lead to systematic velocity variations of 0.1–0.5 mm yr−1 affecting both accuracy and precision, especially for short (< 5 years) time series. A velocity convergence analysis shows that minimum time-series lengths of ∼ 3 and ∼ 5.5 years are required to reach a velocity stability of 0.5 mm yr−1 in the horizontal and vertical components, respectively. On average, horizontal residual velocities show a stability of ∼ 0.2 mm yr−1 in the Western Alps, Pyrenees, and southern France. The only significant horizontal strain rate signal is in the western Pyrenees with up to 4 × 10−9 yr−1 NNE–SSW extension, whereas no significant strain rates are detected in the Western Alps (< 1 × 10−9 yr−1). In contrast, we identify significant uplift rates up to 2 mm yr−1 in the Western Alps but not in the Pyrenees (0.1 ± 0.2 mm yr−1). A correlation between site elevations and fast uplift rates in the northern part of the Western Alps, in the region of the Würmian ice cap, suggests that part of this uplift is induced by postglacial rebound. The very slow uplift rates in the southern Western Alps and in the Pyrenees could be accounted for by erosion-induced rebound.
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Carcaillet, Christopher, and Olivier Blarquez. "Glacial refugia in the south‐western Alps?" New Phytologist 222, no. 2 (February 7, 2019): 663–67. http://dx.doi.org/10.1111/nph.15673.
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Compagnoni, Roberto. "HP metamorphic belt of the western Alps." Episodes 26, no. 3 (September 1, 2003): 200–204. http://dx.doi.org/10.18814/epiiugs/2003/v26i3/008.
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Morasca, Paola, Luca Malagnini, Aybige Akinci, Daniele Spallarossa, and R. B. Herrmann. "Ground-Motion Scaling in the Western Alps." Journal of Seismology 10, no. 3 (October 10, 2006): 315–33. http://dx.doi.org/10.1007/s10950-006-9019-x.
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Escher, Arthur, Henri Masson, and Albrecht Steck. "Nappe geometry in the Western Swiss Alps." Journal of Structural Geology 15, no. 3-5 (March 1993): 501–9. http://dx.doi.org/10.1016/0191-8141(93)90144-y.
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