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Articles de revues sur le sujet "Transcurrent and subduction tectonics"
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Dominique, Cluzel, Iseppi Marion et Chen Yan. « Eocene pre- and syn-obduction tectonics in New Caledonia (Southwest Pacific), a case for oblique subduction, transcurrent tectonics and oroclinal bending ; structural and paleomagnetic evidence ». Tectonophysics 811 (juillet 2021) : 228875. http://dx.doi.org/10.1016/j.tecto.2021.228875.
Texte intégral
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Muhtar, M. N., Chang-Zhi Wu, M. Santosh, Ru-Xiong Lei, Lian-Xing Gu, Si-Meng Wang et Kai Gan. « Late Paleozoic tectonic transition from subduction to post-collisional extension in Eastern Tianshan, Central Asian Orogenic Belt ». GSA Bulletin 132, no 7-8 (23 décembre 2019) : 1756–74. http://dx.doi.org/10.1130/b35432.1.
Texte intégralRésumé :
Abstract Late Paleozoic large-scale transcurrent tectonics and synkinematic intrusions are prominent features in the Eastern Tianshan segment of the southwestern Central Asian Orogenic Belt. However, the spatial and temporal relationship between synkinematic intrusions and crustal-scale shear zones remains unclear. Here we report petrology, geochemistry, and geochronology of the Qiziltag pluton associated with the Kanggur-Huangshan Shear Zone (KHSZ) with a view to characterize the spatial and temporal relationship between synkinematic intrusions and large-scale transcurrent shearing. Field relations and zircon U-Pb ages indicate that the Qiziltag pluton was formed through two stages of magmatism, with earlier stage granitoids (gneissic biotite granite: 288.9 ± 1.9 Ma, biotite monzogranite: 291.5 ± 1.7 Ma, K-feldspar granite: 287.9 ± 3.1 Ma), and later stage bimodal intrusions (biotite quartz monzonite: 278.5 ± 1.8 Ma, gabbro: 278.1 ± 2.3 Ma). The earlier stage granitoids are high-K calc-alkaline, enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs; e.g., Rb, Th, and U), and depleted in high field strength elements (HFSEs; e.g., Nb, Ta, and Ti). Combined with their depleted isotopic compositions (εNd(t) = +6.29 to +7.48) and juvenile model ages (TDM2 = 450–610 Ma), we infer that the granitoids were derived from juvenile lower crust in a post-collisional tectonic transition (from compression to extension). The structural and temporal features indicate that the earlier stage (ca. 290 Ma) granitoids formed prior to the regional large-scale dextral strike slip. The later stage bimodal intrusions are dominated by biotite quartz monzonite as the felsic member and gabbro as the mafic component. The biotite quartz monzonite is high-K calc-alkaline with enriched LREEs and LILEs (e.g., Rb, Th, and U), and depleted HFSEs (e.g., Nb, Ta, and Ti), whereas the gabbro is subalkalic with depleted LREEs and HFSEs (e.g., Nb and Ta), resembling normal mid-ocean ridge basalt features. The bimodal intrusions show similar isotopic compositions (εNd(t) = +6.41 to +6.72 and εHf(t) = +9.55 to + 13.85 for biotite quartz monzonite; εNd(t) = +9.13 to +9.69 and εHf(t) = +4.80 to +14.07 for gabbro). These features suggest that the later stage (ca. 280 Ma) bimodal intrusions were derived from partial melting of depleted mantle and anatectic melting of lower crust materials induced by synchronous underplating of basaltic magma in a post-collisional extension. The structural features of the bimodal intrusions indicate that the later stage (ca. 280 Ma) magmatism was coeval with the development of the KHSZ. In conjunction with spatial and temporal evolution of magmatism and sedimentary records of Eastern Tianshan, we infer that transition between the northward closure of the North Tianshan Ocean and subsequent collision between the Central Tianshan Massif and the Qoltag Arc belt occurred at ca. 300 Ma.
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Verstappen, Herman Th. « Indonesian Landforms and Plate Tectonics ». Indonesian Journal on Geoscience 5, no 3 (28 septembre 2010) : 197–207. http://dx.doi.org/10.17014/ijog.5.3.197-207.
Texte intégralRésumé :
DOI: 10.17014/ijog.v5i3.103The horizontal configuration and vertical dimension of the landforms occurring in the tectonically unstable parts of Indonesia were resulted in the first place from plate tectonics. Most of them date from the Quaternary and endogenous forces are ongoing. Three major plates – the northward moving Indo-Australian Plate, the south-eastward moving SE-Asian Plate and the westward moving Pacific Plate - meet at a plate triple-junction situated in the south of New Guinea’s Bird’s Head. The narrow North-Moluccan plate is interposed between the Asia and Pacific. It tapers out northward in the Philippine Mobile Belt and is gradually disappearing. The greatest relief amplitudes occur near the plate boundaries: deep ocean trenches are associated with subduction zones and mountain ranges with collision belts. The landforms of the more stable areas of the plates date back to a more remote past and, where emerged, have a more subdued relief that is in the first place related to the resistance of the rocks to humid tropical weathering Rising mountain ranges and emerging island arcs are subjected to rapid humid-tropical river erosions and mass movements. The erosion products accumulate in adjacent sedimentary basins where their increasing weight causes subsidence by gravity and isostatic compensations. Living and raised coral reefs, volcanoes, and fault scarps are important geomorphic indicators of active plate tectonics. Compartmental faults may strongly affect island arcs stretching perpendicular to the plate movement. This is the case on Java. Transcurrent faults and related pull-apart basins are a leading factor where plates meet at an angle, such as on Sumatra. The most complicated situation exists near the triple-junction and in the Moluccas. Modern research methods, such as GPS measurements of plate movements and absolute dating of volcanic outbursts and raised coral reefs are important tools. The mega-landforms resulting from the collision of India with the Asian continent, around 50.0 my. ago, and the final collision of Australia with the Pacific, about 5.0 my. ago, also had an important impact on geomorphologic processes and the natural environment of SE-Asia through changes of the monsoonal wind system in the region and of the oceanic thermo-haline circulation in eastern Indonesia between the Pacific and the Indian ocean. In addition the landforms of the region were, of course, affected by the Quaternary global climatic fluctuations and sea level changes.
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Bussy, François, Jean Hernandez et 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.
Texte intégralRésumé :
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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Hinschberger, Florent, Jacques André Malod, Jean Pierre Réhault et Safri Burhanuddin. « Contribution of bathymetry and geomorphology to the geodynamics of the East Indonesian Seas ». Bulletin de la Société Géologique de France 174, no 6 (1 novembre 2003) : 545–60. http://dx.doi.org/10.2113/174.6.545.
Texte intégralRésumé :
Abstract Southeastern Indonesia is located at a convergent triple junction of 3 plates : the Pacific (including the Caro-line and Philippines plates), the Australian and the Southeast Asian plates (fig. 1). The age of the different basins : the North Banda Sea (Sula Basin), the South Banda Sea (Wetar and Damar Basins) and the Weber Trough has been debated for a long time. Their great depth was a reason to interpret them as remnants of oceanic domains either of Indian or Pacific ocean affinities. It has now been demonstrated from geochronological studies that these basins have formed during the Neogene [Réhault et al., 1994 ; Honthaas et al., 1998]. The crust has been sampled only in the Sula Basin, where basalts or trachyandesites with back-arc geochemical signatures have been dredged. Their ages range from 11.4 ± 1.15 to 7.33 ± 0.18 Ma [Réhault et al., 1994 ; Honthaas et al., 1998]. The study of the magnetic anomaly pattern of these basins confirms this interpretation and defines an age between 12.5 and 7.15 Ma for the North Banda Basin and between 6.5 to 3.5 Ma for the South Banda Basin [Hinschberger et al., 2000 ; Hinschberger et al., 2001]. Furthermore, the existence of volcanic arcs linked to subducted slabs suggests that these basins resulted from back-arc spreading and subduction slab roll-back. Lastly, the Weber Trough which exceeds 7 300 m in depth and is one of the deepest non subduction basins in the world, remains enigmatic. A compilation of existing bathymetric data allows us to present a new bathymetric map of the region (fig. 2 and 3). A comparison with the previous published maps [Mammerickx et al., 1976 ; Bowin et al., 1982] shows numerous differences at a local scale. This is especially true for the Banda Ridges or in the Sula Basin where new tectonic directions are expressed. In the North Banda Basin, the Tampomas Ridge, which was striking NE-SW in the previous maps, is actually NW-SE parallel to the West Buru Fracture Zone and to the Hamilton Fault scarp (fig. 6). This NW-SE direction represents the initial direction of rifting and oceanic spreading. In this basin, only the southeastern rifted margin morphology is preserved along the Sinta Ridges. The basin is presently involved in an overall compressional motion and its buckled and fractured crust is subducted westwards beneath East Sulawesi (fig. 4a, 5 and 6). The northern border of the North Banda Basin is reactivated into sinistral transcurrent motion in the South Sula Fracture Zone continued into the Matano fault in Sulawesi. The South Banda Sea Basin is divided in two parts, the Wetar and Damar Basins with an eastward increase in depth. The Wetar and Damar Basins are separated by the NNW-SSE Gunung Api Ridge, characterized by volcanoes, a deep pull apart basin and active tectonics on its eastern flank (fig. 4b and 7). This ridge is interpreted as a large sinistral strike-slip fracture zone which continues across the Banda Ridges and bends towards NW south of Sinta Ridge. The Banda Ridges region, separating the North Banda Basin from the southern Banda Sea (fig. 5 and 7), is another place where many new morphological features are now documented. The Sinta Ridge to the north is separated from Buru island by the South Buru Basin which may constitute together with the West Buru Fracture Zone a large transcurrent lineament striking NW-SE. The central Rama Ridge is made of 2 narrow ridges striking NE-SW with an « en-echelon » pattern indicating sinistral strike slip comparable to the ENE-WSW strike-slip faulting evidenced by focal mechanisms in the northern border of the Damar Basin [Hinschberger, 2000]. Dredging of Triassic platform rocks and metamorphic basement on the Sinta and Rama Ridges suggests that they are fragments of a continental block [Silver et al., 1985 ; Villeneuve et al., 1994 ; Cornée et al., 1998]. The Banda Ridges are fringed to the south by a volcanic arc well expressed in the morphology : the Nieuwerkerk-Emperor of China and the Lucipara volcanic chains whose andesites and arc basalts have been dated between 8 and 3.45 Ma [Honthaas et al., 1998]. Eastern Indonesia deep oceanic basins are linked to the existence of 2 different subduction zones expressed by 2 different downgoing slabs and 2 volcanic arcs : the Banda arc and the Seram arc [Cardwell et Isacks, 1978 ; Milsom, 2001]. They correspond respectively to the termination of the Australian subduction and to the Bird’s head (Irian Jaya) subduction under Seram (fig. 5). Our bathymetric study helps to define the Seram volcanic arc which follows a trend parallel to the Seram Trench from Ambelau island southeast of Buru to the Banda Island (fig. 2 and 5). A new volcanic seamount discovered in the southeast of Buru (location of dredge 401 in figure 7) and a large volcano in the Pisang Ridge (location of dredge 403 in figure 7 and figure 8) have been surveyed with swath bathymetry. Both show a sub-aerial volcanic morphology and a further subsidence evidenced by the dredging of reefal limestones sampled at about 3000 m depth on their flank. We compare the mean basement depths corrected for sediment loading for the different basins (fig. 9). These depths are about 5 000 m in the Sula Basin, 4 800 m in the Wetar basin and 5 100 m in the Damar basin. These values plot about 1 000 m below the age-depth curve for the back-arc basins [Park et al., 1990] and about 2000 m below the Parsons and Sclater’s curve for the oceanic crust [Parsons et Sclater, 1977]. More generally, eastern Indonesia is characterized by large vertical motions. Strong subsidence is observed in the deep basins and in the Banda Ridges. On the contrary, large uplifts characterize the islands with rates ranging between 20 to 250 cm/kyr [De Smet et al., 1989a]. Excess subsidence in the back-arc basins has been attributed to large lateral heat loss due to their small size [Boerner et Sclater, 1989] or to the presence of cold subducting slabs. In eastern Indonesia, these mechanisms can explain only a part of the observed subsidence. It is likely that we have to take into account the tectonic forces linked to plate convergence. This is supported by the fact that uplift motions are clearly located in the area of active collision. In conclusion, the bathymetry and morphology of eastern Indonesian basins reveal a tectonically very active region where basins opened successively in back-arc, intra-arc and fore-arc situation in a continuous convergent geodynamic setting.
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Vanderhaeghe, Olivier, Oscar Laurent, Véronique Gardien, Jean-François Moyen, Aude Gébelin, Cyril Chelle-Michou, Simon Couzinié, Arnaud Villaros et Mathieu Bellanger. « Flow of partially molten crust controlling construction, growth and collapse of the Variscan orogenic belt : the geologic record of the French Massif Central ». BSGF - Earth Sciences Bulletin 191 (2020) : 25. http://dx.doi.org/10.1051/bsgf/2020013.
Texte intégralRésumé :
We present here a tectonic-geodynamic model for the generation and flow of partially molten rocks and for magmatism during the Variscan orogenic evolution from the Silurian to the late Carboniferous based on a synthesis of geological data from the French Massif Central. Eclogite facies metamorphism of mafic and ultramafic rocks records the subduction of the Gondwana hyperextended margin. Part of these eclogites are forming boudins-enclaves in felsic HP granulite facies migmatites partly retrogressed into amphibolite facies attesting for continental subduction followed by thermal relaxation and decompression. We propose that HP partial melting has triggered mechanical decoupling of the partially molten continental rocks from the subducting slab. This would have allowed buoyancy-driven exhumation and entrainment of pieces of oceanic lithosphere and subcontinental mantle. Geochronological data of the eclogite-bearing HP migmatites points to diachronous emplacement of distinct nappes from middle to late Devonian. These nappes were thrusted onto metapelites and orthogneisses affected by MP/MT greenschist to amphibolite facies metamorphism reaching partial melting attributed to the late Devonian to early Carboniferous thickening of the crust. The emplacement of laccoliths rooted into strike-slip transcurrent shear zones capped by low-angle detachments from c. 345 to c. 310 Ma is concomitant with the southward propagation of the Variscan deformation front marked by deposition of clastic sediments in foreland basins. We attribute these features to horizontal growth of the Variscan belt and formation of an orogenic plateau by gravity-driven lateral flow of the partially molten orogenic root. The diversity of the magmatic rocks points to various crustal sources with modest, but systematic mantle-derived input. In the eastern French Massif Central, the southward decrease in age of the mantle- and crustal-derived plutonic rocks from c. 345 Ma to c. 310 Ma suggests southward retreat of a northward subducting slab toward the Paleotethys free boundary. Late Carboniferous destruction of the Variscan belt is dominantly achieved by gravitational collapse accommodated by the activation of low-angle detachments and the exhumation-crystallization of the partially molten orogenic root forming crustal-scale LP migmatite domes from c. 305 Ma to c. 295 Ma, coeval with orogen-parallel flow in the external zone. Laccoliths emplaced along low-angle detachments and intrusive dykes with sharp contacts correspond to the segregation of the last melt fraction leaving behind a thick accumulation of refractory LP felsic and mafic granulites in the lower crust. This model points to the primordial role of partial melting and magmatism in the tectonic-geodynamic evolution of the Variscan orogenic belt. In particular, partial melting and magma transfer (i) triggers mechanical decoupling of subducted units from the downgoing slab and their syn-orogenic exhumation; (ii) the development of an orogenic plateau by lateral flow of the low-viscosity partially molten crust; and, (iii) the formation of metamorphic core complexes and domes that accommodate post-orogenic exhumation during gravitational collapse. All these processes contribute to differentiation and stabilisation of the orogenic crust.
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Percival, John A. « A regional perspective of the Quetico metasedimentary belt, Superior Province, Canada ». Canadian Journal of Earth Sciences 26, no 4 (1 avril 1989) : 677–93. http://dx.doi.org/10.1139/e89-058.
Texte intégralRésumé :
Alternating greenstone–granite and metasedimentary gneiss belts are a first-order tectonic feature of the southern Superior Province. The tectonic development of the Quetico metasedimentary belt is reviewed with regard to depositional, structural, and metamorphic–plutonic history. Over its 1200 km length, the belt consists of marginal metasedimentary schists of turbiditic origin and interior metasedimentary migmatite and peraluminous leucogranite. Polyphase deformation has resulted in a steep easterly-striking foliation and regional, gently east-plunging stretching lineation. Metamorphic grade varies in a low-P facies series from greenschist at the belt margins to upper amphibolite and local granulite in the central migmatite – intrusive granite zone. Mineral assemblages in the central zone yield estimates of metamorphic pressure that increase systematically eastward over 800 km from about 250 MPa (2.5 kbar) near the Canada – United States border to 600 MPa (6 kbar) in granulites adjacent to the Kapuskasing structural zone.Geochronology suggests that sediments were deposited at approximately the same time as active volcanism in adjacent volcanic belts, although evidence of volcanic–sedimentary stratigraphic contiguity is weak as a result of later transcurrent movement parallel to major lithological boundaries. Adjacent belts are inferred to have been contiguous since common D2 deformation, 2689–2684 Ma ago. Major plutonism and associated metamorphism occurred in the Quetico Belt approximately 2670–2650 Ma ago, significantly later than major plutonism in the adjacent volcanic belts.The linear disposition of greywacke-rich sediments over 1200 km invites an analogy with modern accretionary prisms. However, the high-temperature, low-pressure metamorphism of the Quetico Belt is inconsistent with such a low-heat-flow environment, and a change in tectonic regime would be required to account for the metamorphism and intracrustal plutonism. Simple cessation of subduction beneath the thick sedimentary prism could have led to restoration of isotherms, with possible attendant crustal melting and isostatic recovery.
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Mackie, D. J., R. M. Clowes, S. A. Dehler, R. M. Ellis et P. Morel-À-l'Huissier. « The Queen Charlotte Islands refraction project. Part II. Structural model for transition from Pacific plate to North American plate ». Canadian Journal of Earth Sciences 26, no 9 (1 septembre 1989) : 1713–25. http://dx.doi.org/10.1139/e89-146.
Texte intégralRésumé :
The oceanic-continental boundary west of the Queen Charlotte Islands is marked by the active Queen Charlotte Fault Zone. Motion along the fault is predominantly dextral strike slip, but relative plate motion and other studies indicate that a component of convergence between the oceanic Pacific plate and the continental North American plate presently exists. This convergence could be manifest through different types of deformation: oblique subduction, crustal thickening, or lateral distortion of the plates. In 1983, a 330 km offshore–onshore seismic refraction profile extending from the deep ocean across the islands to the mainland of British Columbia was recorded to investigate (i) structure of the fault zone and associated oceanic–continental boundary and (ii) lithospheric structure beneath the islands and Hecate Strait to define the regional transition from Pacific plate to North American plate and thus the nature of the convergence. Two-dimensional ray tracing and synthetic seismogram modelling of many record sections enabled the derivation of a composite velocity structural section along the profile. The structural section also was tested with two-dimensional gravity modelling. Part I of the study addressed the structure of the fault zone; part II addresses lithospheric structure extending eastward to the mainland.The derived velocity structure has some important and well-constrained features: (i) anomalously low crustal velocities (5.3 km/s with a 0.2 km/s per km gradient) underlain by a steep, 19 °eastward-dipping boundary above the mantle in the terrace region west of the main fault; (ii) a thin crust of 21–27 km beneath the Queen Charlotte Islands; and (iii) a gentle 4 °eastward dip of the Moho below Hecate Strait as crustal thickness increases from 27 km to 32 km. The gravity modelling requires that mantle material extend upwards to a depth of about 30 km below the mainland and indicates that an underlying subducted slab, if it exists, extends eastward no farther than the mainland.Unfortunately, the velocity structure delineated by this study could not unambiguously determine the mode of deformation, because the lowermost crustal block beneath Queen Charlotte Islands and Hecate Strait can be interpreted as subducted oceanic crust or middle to lower continental crust. Thus, two different tectonic models for the transition from Pacific plate to North American plate are discussed: in one, oblique subduction is the principal characteristic; in the other, oceanic lithosphere juxtaposed against continental lithosphere across a narrow boundary zone along which only transcurrent motion occurs is the dominant feature. Based on the thin crust beneath the Queen Charlotte Islands, the lack of a wide zone of deformation along the plate boundary region, and other geological and geophysical characteristics, oblique subduction is the more plausible model.
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Thurston, Phillips C. « Igneous Rock Associations 19. Greenstone Belts and Granite−Greenstone Terranes : Constraints on the Nature of the Archean World ». Geoscience Canada 42, no 4 (7 décembre 2015) : 437. http://dx.doi.org/10.12789/geocanj.2015.42.081.
Texte intégralRésumé :
Greenstone belts are long, curvilinear accumulations of mainly volcanic rocks within Archean granite−greenstone terranes, and are subdivided into two geochemical types: komatiite−tholeiite sequences and bimodal sequences. In rare instances where basement is preserved, the basement is unconformably overlain by platform to rift sequences consisting of quartzite, carbonate, komatiite and/or tholeiite. The komatiite−tholeiite sequences consist of km-scale thicknesses of tholeiites, minor intercalated komatiites, and smaller volumes of felsic volcanic rocks. The bimodal sequences consist of basal tholeiitic flows succeeded upward by lesser volumes of felsic volcanic rocks. The two geochemical types are unconformably overlain by successor basin sequences containing alluvial–fluvial clastic metasedimentary rocks and associated calc-alkaline to alkaline volcanic rocks. Stratigraphically controlled geochemical sampling in the bimodal sequences has shown the presence of Fe-enrichment cycles in the tholeiites, as well as monotonous thicknesses of tholeiitic flows having nearly constant MgO, which is explained by fractionation and replenishment of the magma chamber with fresh mantle-derived material. Geochemical studies reveal the presence of boninites associated with the komatiites, in part a result of alteration or contamination of the komatiites. Within the bimodal sequences there are rare occurrences of adakites, Nb-enriched basalts and magnesian andesites. The greenstone belts are engulfed by granitoid batholiths ranging from soda-rich tonalite−trondhjemite−granodiorite to later, more potassic granitoid rocks. Archean greenstone belts exhibit a unique structural style not found in younger orogens, consisting of alternating granitoid-cored domes and volcanic-dominated keels. The synclinal keels are cut by major transcurrent shear zones. Metamorphic patterns indicate that low pressure metamorphism of the greenstones is centred on the granitoid batholiths, suggesting a central role for the granitoid rocks in metamorphosing the greenstones. Metamorphic patterns also show that the proportion of greenstones in granite−greenstone terranes diminishes with deeper levels of exposure. Evidence is presented on both sides of the intense controversy as to whether greenstone belts are the product of modern plate tectonic processes complete with subduction, or else the product of other, lateral tectonic processes driven by the ‘mantle wind.’ Given that numerous indicators of plate tectonic processes – structural style, rock types, and geochemical features − are unique to the Archean, it is concluded that the evidence is marginally in favour of non-actualistic tectonic processes in Archean granite−greenstone terranes.RÉSUMÉLes ceintures de roches vertes sont des accumulations longiformes et curvilinéaires, principalement composées de roches volcaniques au sein de terranes granitique archéennes, et étant subdivisées en deux types géochimiques: des séquences à komatiite–tholéite et des séquences bimodales. En de rares occasions, lorsque le socle est préservé, ce dernier est recouvert en discordance par des séquences de plateforme ou de rift, constituées de quartzite, carbonate, komatiite et/ou de tholéiite. Les séquences de komatiite-tholéiite forment des épaisseurs kilométriques de tholéiite, des horizons mineurs de komatiites, et des volumes de moindre importance de roches volcaniques felsiques. Les séquences bimodales sont constituées à la base, de coulées tholéiitiques surmontées par des volumes mineurs de roches volcaniques felsiques. Ces deux types géochimiques sont recouverts en discordance par des séquences de bassins en succession contenant des roches métasédimentaires clastiques fluvio-alluvionnaires associées à des roches volcaniques calco-alcalines à alcalines. Un échantillonnage à contrôle stratigraphique des séquences bimodales a révélé la présence de cycles d’enrichissement en Fe dans les tholéiites, ainsi que des épaisseurs continues d’épanchements tholéiitiques ayant des valeurs presque constante en MgO, qui s’explique par la cristallisation fractionnée et le réapprovisionnement de la chambre magmatique par du matériel mantélique. Les études géochimiques montrent la présence de boninites associées aux komatiites, résultant en partie de l’altération ou de la contamination des komatiites. Au sein des séquences bimodales, on retrouve en de rares occasions des adakites, des basaltes enrichis en Nb et des andésites magnésiennes. Les ceintures de roches vertes sont englouties dans des batholites granitoïdes de composition passant des tonalites−trondhjémites−granodiorites enrichies en sodium, à des roches granitoïdes tardives plus potassiques. Les ceintures de roches vertes archéennes montrent un style structural unique que l’on ne retrouve pas dans des orogènes plus jeunes, et qui est constitué d’alternances de dômes à cœur granitoïdes et d`affaissements principalement composés de roches volcaniques. Les synclinaux formant les affaissements sont recoupés par de grandes zones de cisaillement. Les profils métamorphiques indiquent que le métamorphisme de basse pression des roches vertes est centré sur les batholites, indiquant un rôle central des roches granitoïdes durant le métamorphisme des roches vertes. Les profils métamorphiques montrent également que la proportion de roches vertes dans les terranes granitiques diminue avec l’exposition des niveaux plus profonds. On présente les arguments des deux côtés de l’intense controverse voulant que les ceintures de roches vertes soient le produit de processus moderne de la tectonique des plaques incluant la subduction, ou alors le produit d’autres processus tectoniques découlant du « flux mantélique ». Étant donné la présence des indicateurs des processus de tectonique des plaques – style structural, les types de roches, et les caractéristiques géochimiques – ne se retrouvent qu’à l’Archéen, nous concluons que les indices favorisent légèrement l’option de processus tectoniques non-actuels dans les terranes granitiques de roches vertes à l’Archéen.
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Doblas, Miguel. « Late hercynian extensional and transcurrent tectonics in Central Iberia ». Tectonophysics 191, no 3-4 (juin 1991) : 325–34. http://dx.doi.org/10.1016/0040-1951(91)90065-z.
Texte intégralThèses sur le sujet "Transcurrent and subduction tectonics"
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Alizadeh, Noudeh Shiva. « Evolution pétrologique des séries volcaniques du massif de Talysh (Iran du NW) à la transition Caucase-Caspienne et implications géodynamiques ». Electronic Thesis or Diss., Chambéry, 2024. http://www.theses.fr/2024CHAMA053.
Texte intégralRésumé :
Le magmatisme cénozoïque de la ceinture orogénique qui relie les zones tectoniques de l'Iran, du bloc arménien méridional (petit Caucase) et de la Turquie, reste un sujet de débat. Cette recherche se concentre sur l'épaisse succession géologique de roches volcaniques shoshonitiques calco-alcalines riches en K exposées dans le massif de Talysh, qui fait partie de la ceinture magmatique de l'Alborz, dans le nord-ouest de l'Iran. L'objectif de cette étude est d'étudier les roches volcaniques relativement peu étudiées du massif de Talysh afin de mieux contraindre le cadre géodynamique du magmatisme pendant la convergence régionale. Une étude complète incluant de nouvelles données de terrain, la chimie minérale, la géochimie des éléments majeurs et traces des roches totales, la composition isotopique (Sr, Nd, Pb, Hf), la géochronologie 40Ar-39Ar, et le zircon U-Pb. Cette montre une série magmatique de basaltes riches en olivine, basaltes à clinopyroxène-phyrique, basaltes à clinopyroxène-phyrique, basaltes à amphibole-phyrique, téphrites, trachy-andésites et roches pyroclastiques. Ils contiennent de multiples populations de cristaux : olivine, clinopyroxène, amphibole et phlogopite, avec des textures de rééquilibrage ainsi qu'une zonation oscillatoire et inverse complexe, des textures criblées et des textures de résorption, ce qui suggère que les magmas ont été stockés dans et différenciés dans des chambres magmatiques avec des réinjections successives avant l'éruption. En outre, les âges 40Ar-39Ar de la biotite et des amphiboles des basaltes et les âges U-Pb du zircon des roches pyroclastiques indiquent que l'activité volcanique s'est déroulée pendant ~ 10 Myr (49-38 Myr). L'enrichissement en LILE et l'appauvrissement en Nb, Ta et Ti sont des caractéristiques des laves de Talysh, qui présentent des caractéristiques géochimiques d'arc. Leurs compositions isotopiques varient : 87Sr/86Sr (i) de 0,7045 à 0,7066, ɛNd(i) de ~-2,2 à +1,7, et ɛHf(i) de -2,5 à +3,6. Les roches ont des compositions radiogéniques en plomb (206Pb/204Pb de 18,51 à 19,04, 207Pb/204Pb de 15,59 à 15,63, et 208Pb/204Pb de 38,67 à 39,15). Les éléments majeurs de la plupart des échantillons primitifs (MgO > 5 % en poids) sont comparables à ceux des fusions partielles à faible degré (4-9%) d'une lherzolite à grenat et spinelle avec des rapports grenat:spinelle de 40:60 à 20:80. Les résultats obtenus par géothermobarométrie clinopyroxène-liquide indiquent une variété de réservoirs magmatiques, allant de niveaux profonds (79-60 km) à des niveaux moins profonds (2 km). Les rapports isotopiques de Sr, Nd, Pb et Hf, ainsi que les profils similaires d'éléments traces incompatibles normalisés par la chondrite et par le manteau primitif, ainsi que les estimations thermobarométriques sur les cristaux d'olivine, de clinopyroxène et d'amphibole, suggèrent que la source mantellique est une source asthénosphérique enrichie et que de la croûte continentale a été mélangée au cours du processus de différenciation. Les données sont cohérentes avec la fusion partielle d'un manteau sous-continental à grenat modifié par subduction et les interactions avec un manteau à spinelle pendant l'ascension magmatique. La phase magmatique éocène pourrait avoir été déclenchée par une remontée de l'Asthénosphère liée au début de la subduction à pendage sud du bassin transcaucasien. L'ascension magmatique a probablement été facilitée par des failles décrochantes trans-lithosphériques mises en évidence par les données paléomagnétiques. Le passage d'une composante magmatique calco-alcaline à une composante magmatique plus alcaline avec le temps, du sud au nord du massif de Talysh, suggère un raidissement de la plaque en réponse à un retournement à l'Éocène supérieur. Après cette période, le volcanisme s'est arrêté dans le Talysh Sud et a considérablement diminué dans le massif du Talysh Nord, où il a évolué vers un magmatisme de type adakitique au cours du Miocène supérieur et du QuaternaireThe Cenozoic magmatism of the Central Tethyan orogenic belt, which links the tectonic zones of Iran, the South Armenian Block (lesser Caucasus), and Turkey, remains a topic of debate. This research focuses on the thick geological succession of high-K calc-alkaline shoshonitic volcanic rocks exposed in the Talysh Massif, part of the Alborz magmatic belt, northwestern Iran. The aim of this study is to investigate the relatively unstudied volcanic rocks of the Talysh Massif to better constrain the geodynamic setting of magmatism during regional convergence. A comprehensive study including new field data, mineral chemistry, bulk-rock major and trace element geochemistry, isotope composition (Sr, Nd, Pb, Hf), geochronology 40Ar-39Ar, and zircon U-Pb. We classify them as olivine, clinopyroxene-phyric basalts, clinopyroxene-phyric basalts, amphibole-phyric basalts, tephrites, trachy-andesites, and pyroclastic rocks. They contain multiple crystal populations, including phenocrysts, antecrysts, and xenocrysts: olivine, clinopyroxene, amphibole, and re-equilibrium phlogopite, along with complex oscillatory and reverse zoning, sieve textures, and resorption textures, which suggests that the magmas stalled and differentiated in the crust prior to eruption. Olivine-clinopyroxene-phyric samples in the southern part of the study area exhibit olivine phenocrysts chemically balanced with their host rock, with a slight zoning from high-Mg# cores (Mg# = 90) to rims (Mg# = 80). Furthermore, the amphiboles, biotite 40Ar-39Ar ages of basalts, and zircon U-Pb ages of pyroclastic rocks indicate that volcanic activity took place for ~ 10 Myr (between 49 and 38 Myr). Enrichment in LILE and depletion in Nb, Ta, and Ti are characteristics of the Talysh lavas, which exhibit arc geochemical features. They have isotopic compositions that vary, for 87Sr/86Sr (i) from 0.7045 to 0.7066, for ɛNd(i) from ~-2.2 to +1.7, and ɛHf(i) from -2.5 to +3.6. The rocks have radiogenic lead 206Pb/204Pb ratios from 18.51 to 19.04, 207Pb/204Pb from 15.59 to 15.63, and 208Pb/204Pb from 38.67 to 39.15. The major elements of most primitive samples (MgO > 5 wt%) are comparable to those of melts obtained from low-degree (4–9%) partial melting of a spinel-garnet lherzolite with garnet:spinel ratios of 40:60 to 20:80. The results obtained from clinopyroxene-liquid geothermobarometry indicate a variety of magma reservoirs, ranging from deep levels (79–60 km) to shallower levels (2 km). The isotopic ratios of Sr, Nd, Pb, and Hf, as well as the similar chondrite-normalized REE and primitive-mantle-normalized incompatible trace element patterns along thermobarometry estimates on olivine, clinopyroxene, and amphibole crystals, suggests that the mantle source is an enriched asthenospheric source, and that continental crust was mixed in during the differentiation process. The data are consistent with the partial melting of a garnet-bearing subduction-modified subcontinental mantle and interactions with a spinel-bearing mantle during magmatic ascent. This magmatic flare-up could have been triggered by an asthenosphere upwelling related to the onset of south-dipping subduction of the Transcaucasus basin. Asthenosphere flow and magmatic ascent were likely facilitated by trans-lithospheric strike-slip faults and block rotations highlighted by paleomagnetic data. A transition from calc-alkaline towards a more alkaline magmatic component with time, from south to north of the Talysh massif, suggests a slab steepening in response to roll-back in the Late Eocene. After this period, volcanism stopped in the South Talysh and significantly decreased in the North Talysh massif, where it evolved into an adakitic-type magmatism during the Late Miocene and Quaternary
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Shaw, Beth. « Active tectonics of the Hellenic subduction zone ». Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608877.
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Rowland, Andrea Jane. « Numerical modelling of subduction zone magmatism ». Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266491.
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Daniel, Andrew John. « The geodynamics of spreading centre subduction in southern Chile ». Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320503.
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Audet, Pascal. « Seismic and mechanical attributes of lithospheric deformation and subduction in western Canada ». Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2435.
Texte intégralRésumé :
Convergent continental margins are regions of intense deformation caused by the interaction of oceanic plates with continents. The spatial extent of deformation is broadly commensurate with the specific time scale of the causative phenomenon. For example, subduction-related short-term deformation is limited to <200 km from the margin, whereas long-term plate convergence cause deformation over ∼1000 km landward. Deformation is thus manifested in multiple ways, with attributes depending on the scale of measurement. In this thesis we investigate the use of two geophysical approaches in the study of deformation: 1) The analysis of potential-field anomalies to derive estimates of the elastic thickness (Te) of the lithosphere, and 2) The structural study of past and present subduction systems using seismic observations and modelling. Both approaches involve the development of appropriate methodologies for data analysis and modelling, and their application to the western Canadian landmass. Our findings are summarized as follows: 1) We develop a wavelet-based technique to map variations in Te and its anisotropy; 2) We show how a step-wise transition in Te and its anisotropy from the Cordillera to the Craton is a major factor influencing lithospheric deformation; 3) We implement a waveform modelling tool that includes the effects of structural heterogeneity and anisotropy for teleseismic applications, and use it to model the signature of a fossil subduction zone in a Paleoproterozoic terrane; 4) We use teleseismic recordings to map slab edge morphology in northern Cascadia and show how slab window tectonism and slab stretching led to the creation of the oceanic Explorer plate; 5) We use seismic signals from the subducting oceanic crust to calculate elevated Poisson’s ratio and infer high pore-fluid pressures and a low-permeability plate boundary within the forearc region of northern Cascadia.
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Liodas, Nathaniel Thomas. « Gneiss dome development & ; transcurrent tectonics in the Archean : example of the Pukaskwa batholith and Hemlo shear zone, Superior Province, Canada ». OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/753.
Texte intégralRésumé :
Archean greenstone belts typically form narrow sheared basins separating bulbous tonalo-trondjhemo-granodioritic (TTG) batholiths. The role played by gravity in the development of such dome-and-keel structures is a key question in Archean tectonics. The Pukaskwa batholith - Hemlo shear zone (HSZ) is a representative example of the dome-and-keel structures that are common in Archean terrains. This region has received considerable attention because the HSZ hosts several major gold deposits that are currently being mined. Late dextral strike-slip kinematics of the HSZ are well recorded by abundant strain markers in greenstone rocks, whereas the quartzofeldspathic coarse-grained rocks of the Pukaskwa batholith bear no macroscopically visible fabric. The goal of this study is to understand the structural history of this greenstone belt-batholith system. The Pukaskwa batholith is a heterogeneous assemblage of TTG gneisses bounded by the Hemlo greenstone belt to the north. The density of the Pukaskwa batholith rocks (density = 2700 kg/m3) is on average less than that of the Hemlo greenstone rocks (density = 3000 kg/m3). Since Archean geotherms were considered higher than modern equivalents, the effective viscosity of the TTG rocks might have been sufficiently low to allow their diapiric ascent through denser greenstone rocks. Alternatively, the emplacement of the TTG batholith might have been driven primarily by transpressive tectonics. The anisotropy of magnetic susceptibility (AMS) provides valuable information on the internal fabric of the Pukaskwa batholith. This study provides the kinematic information needed to support either the diapiric or the transpressive tectonic model. AMS recorded east-west trending prolate and plano-linear fabrics across the northern section along the contact, suggesting that transpressional forces from the Hemlo shear zone affected the emplacement of the Pukaskwa batholith. Away from the contact, fabrics are generally flattened, indicative of doming through diapiric processes. Also, in order to fully evaluate the diapiric hypothesis, it is necessary to obtain reliable data on rock densities across the Pukaskwa batholith. The density of about 360 representative specimens from the Pukaskwa batholith has been measured and will constitute a valuable database for future gravimetric investigations by mining companies. The significant degree of correlation between high-field magnetic susceptibility and density in the Pukaskwa batholith should be taken into account in geophysical exploration in Archean terrains, only as a proxy for iron content.
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Fujihara, Satoru. « Thermal state beneath the Japanese Islands and its implication to tectonics of subduction zone ». 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149561.
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Medema, Guy Frederick. « Juan de Fuca subducting plate geometry and intraslab seismicity / ». Thesis, Connect to this title online ; UW restricted, 2006. http://hdl.handle.net/1773/6828.
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Schellart, Wouter Pieter. « Subduction rollback, arc formation and back-arc extension ». Monash University, School of Geosciences, 2003. http://arrow.monash.edu.au/hdl/1959.1/9485.
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Seebeck, Hannu Christian. « Normal Faulting, Volcanism And Fluid Flow, Hikurangi Subduction Plate Boundary, New Zealand ». Thesis, University of Canterbury. Geological Sciences, 2013. http://hdl.handle.net/10092/8884.
Texte intégralRésumé :
This thesis investigates normal faulting and its influence on fluid flow over a wide range of spatial and temporal scales using tunnel engineering geological logs, outcrop, surface fault traces, earthquakes, gravity, and volcanic ages. These data have been used to investigate the impact of faults on fluid flow (chapter 2), the geometry and kinematics of the Taupo Rift (chapter 3), the hydration and dehydration of the subducting Pacific plate and its influence on the Taupo Volcanic Zone (chapter 4), the migration of arc volcanism across the North Island over the 16 Myr and the associated changes in slab geometry (chapter 5) and the Pacific-Australia relative plate motion vectors since 38 Ma and their implications for arc volcanism and deformation along the Hikurangi margin (chapter 6). The results for each of these five chapters are presented in
the five paragraphs below.
Tunnels excavated along the margins of the southern Taupo Rift at depths < 500 m provide data on the spatial relationships between faulting and ground water flow. The geometry and hydraulic properties of fault-zones for Mesozoic basement and Miocene strata vary by several orders of magnitude approximating power-law distributions with the dimensions of these zones dependent on many factors including displacement, hostrock type and fault geometries. Despite fault-zones accounting for a small proportion of the total sample length (≤ 15%), localised flow of ground water into the tunnels occurs almost exclusively (≥ 91%) within, and immediately adjacent to, these zones. The spatial distribution and rate of flow from fault-zones are highly variable with typically ≤ 50% of fault-zones in any given orientation flowing. The entire basement dataset shows that 81% of the flow-rate occurs from fault-zones ≥ 10 m wide, with a third of the total flow-rate originating from a single fault-zone (i.e. the golden fracture). The higher flow rates for the largest faults are interpreted to arise because these structures are the most connected to other faults and to the ground surface.
The structural geometry and kinematics of rifting is constrained by earthquake focal mechanisms and by geological slip and fault mapping. Comparison of present day geometry and kinematics of normal faulting in the Taupo Rift (α=76-84°) with intra-arc rifting in the Taranaki Basin and southern Havre Trough show, that for at least the last 4 Myr, the slab and the associated changes in its geometry have exerted a first-order control on the location, geometry, and extension direction of intra-arc rifting in the North Island. Second-order features of rifting in the central North Island include a clockwise ~20° northwards change in the strike of normal faults and trend of the extension direction. In the southern rift normal faults are parallel to, and potentially reactivate, Mesozoic basement fabric (e.g., faults and bedding). By contrast, in the northern rift faults diverge from basement fabric by up to 55° where focal mechanisms
indicate that extension is achieved by oblique to right-lateral strike-slip along basement fabric and dip-slip on rift faults.
Hydration and dehydration of the subducting Pacific plate is elucidated by earthquake densities and focal mechanisms within the slab. The hydration of the subducting plate varies spatially and is an important determinant for the location of arc volcanism in the overriding plate. The location and high volcanic productivity of the TVZ can be linked to the subduction water cycle, where hydration and subsequent dehydration of the subducting oceanic lithosphere is primarily accomplished by normal-faulting earthquakes. The anomalously high heat flow and volcanic productivity of the TVZ is spatially associated with high rates of seismicity in the underlying slab mantle at depths of 130-210 km which can be tracked back to high rates of deeply penetrating shallow intraplate seismicity at the trench in proximity to oceanic fluids. Dehydration of the slab mantle correlates with the location and productivity of active North Island volcanic centres, indicating this volcanism is controlled by fluids fluxing from the subducting plate.
The ages and locations of arc volcanoes provide constraints on the migration of volcanism across the North Island over the last 20 Myr. Arc-front volcanoes have migrated southeast by 150 km in the last 8 Ma (185 km since 16 Ma) sub-parallel to the present active arc. Migration of the arc is interpreted to mainly reflect slab steepening and rollback. The strike of the Pacific plate beneath the North Island, imaged by Benioff zone seismicity (50-200 km) and positive mantle velocity anomalies (200-600 km) is parallel to the northeast trend of arc-front volcanism. Arc parallelism since 16 Ma is consistent with the view that the subducting plate beneath the North Island has not
rotated clockwise about vertical axes which is in contrast to overriding plate vertical-axis rotations of ≥ 30º. Acceleration of arc-front migration rates (~4 mm/yr to ~18 mm/yr), eruption of high Mg# andesites, increasing eruption frequency and size, and
uplift of the over-riding plate indicate an increase in the hydration, temperature, and size of the mantle wedge beneath the central North Island from ~7 Ma.
Seafloor spreading data in conjunction with GPlates have been used to generate relative plate motion vectors across the Hikurangi margin since 38 Ma. Tracking the southern and down-dip limits of the seismically imaged Pacific slab beneath the New Zealand indicates arc volcanism in Northland from ~23 Ma and the Taranaki Basin between ~20 and 11 Ma requires Pacific plate subduction from at (or beyond) the northern North Island continental margin from at least 38 Ma to the present. Pacific plate motion in a west dipping subduction model shows a minimum horizontal transport distance of 285 km preceding the initiation of arc volcanism along the Northland-arc normal to the motion vector, a distance more than sufficient for self-sustaining
subduction to occur. Arc-normal convergence rates along the Hikurangi margin doubled from 11 to 23 mm/yr between 20 and 16 Ma, increasing again by approximately a third between 8 and 6 Ma. This latest increase in arc-normal rates coincided with changes in relative plate motions along the entire SW Pacific plate boundary and steepening/rollback of the Pacific plate.
Livres sur le sujet "Transcurrent and subduction tectonics"
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1952-, Ruff Larry J., et Kanamori H. 1936-, dir. Subduction zones. Basel : Birkhäuser, 1988.
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Serge, Lallemand, et Funicello Francesca, dir. Subduction zone geodynamics. Berlin : Springer, 2009.
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Shaw, Beth. Active tectonics of the Hellenic subduction zone. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-20804-1.
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Shaw, Beth. Active tectonics of the Hellenic subduction zone. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012.
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E, Wells Ray, et Geological Survey (U.S.), dir. Cascadia : Regional lithospheric studies of the Pacific Northwest. [Menlo Park, CA] : U.S. Dept. of the Interior, U.S. Geological Survey, 1993.
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L, Smellie J., et Geological Society of London, dir. Volcanism association with extension at consuming plate margins. London : Geological Society, 1998.
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H, Dixon Timothy, et Moore J. Casey 1945-, dir. The seismogenic zone of subduction thrust faults. New York : Columbia University Press, 2007.
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Renata, Dmowska, et Ekström Göran, dir. Shallow subduction zones : Seismicity, mechanics, and seismic potential. Basel : Birkhäuser Verlag, 1993.
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C, Zoback Mary Lou, et Geological Survey (U.S.), dir. Wellbore breakout analysis for determining tectonic stress orientations in Washington State. Menlo Park, Calif : U.S. Dept. of the Interior, U.S. Geological Survey, 1992.
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United States. National Aeronautics and Space Administration., dir. Mantle dynamics and geodesy. [Washington, DC : National Aeronautics and Space Administration, 1990.
Trouver le texte intégralChapitres de livres sur le sujet "Transcurrent and subduction tectonics"
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Frisch, Wolfgang, Martin Meschede et Ronald Blakey. « Subduction zones, island arcs and active continental margins ». Dans Plate Tectonics, 91–122. Berlin, Heidelberg : Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-76504-2_7.
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Ruff, Larry J., Jeffrey W. Given, Chris O. Sanders et Christine M. Sperber. « Large Earthquakes in the Macquarie Ridge Complex : Transitional Tectonics and Subduction Initiation ». Dans Subduction Zones Part II, 71–129. Basel : Birkhäuser Basel, 1989. http://dx.doi.org/10.1007/978-3-0348-9140-0_5.
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Konishi, Kenji. « Coral Reefs and Present-Day Collision-Subduction Tectonics ». Dans Formation of Active Ocean Margins, 875–90. Dordrecht : Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-4720-7_39.
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Shaw, Beth. « Introduction ». Dans Active tectonics of the Hellenic subduction zone, 1–5. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-20804-1_1.
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Shaw, Beth. « Kinematic GPS River Profiles from Crete ». Dans Active tectonics of the Hellenic subduction zone, 167–69. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-20804-1_10.
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Shaw, Beth. « The AD 365 Earthquake : Large Tsunamigenic Earthquakes in the Hellenic Trench ». Dans Active tectonics of the Hellenic subduction zone, 7–28. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-20804-1_2.
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Shaw, Beth. « Earthquakes in the Eastern Mediterranean ». Dans Active tectonics of the Hellenic subduction zone, 29–66. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-20804-1_3.
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Shaw, Beth. « Radiometric Dating of Uplifted Marine Fauna in Crete and Central Greece ». Dans Active tectonics of the Hellenic subduction zone, 67–88. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-20804-1_4.
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Shaw, Beth. « Geomorphology ». Dans Active tectonics of the Hellenic subduction zone, 89–111. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-20804-1_5.
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Shaw, Beth. « Conclusions ». Dans Active tectonics of the Hellenic subduction zone, 113–15. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-20804-1_6.
Texte intégralActes de conférences sur le sujet "Transcurrent and subduction tectonics"
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Valentino, David, et Jeffrey Chiarenzelli. « SHAWINIGAN SUBDUCTION AND TRANSCURRENT ASSEMBLY OF THE ADIRONDACK MASSIF, NEW YORK ». Dans 53rd Annual GSA Northeastern Section Meeting - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018ne-310601.
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Moerdyk, David. « DID SUBDUCTION PLATE TECTONICS START WITH A BANG ? » Dans GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-296292.
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Waldron, John W. F., et Michael C. Rygel. « Extension, shortening, and salt tectonics at a Paleozoic transcurrent plate boundary : Cumberland Basin, Nova Scotia ». Dans SEG Technical Program Expanded Abstracts 2008. Society of Exploration Geophysicists, 2008. http://dx.doi.org/10.1190/1.3063918.
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Zhu, Ren-Zhi. « The nature and influence of magmatism during transcurrent tectonics : geochemical perspectives on geophysical constraints in Western Yunnan ». Dans Goldschmidt2023. France : European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.16646.
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Greene, H. Gary, Vaughn Barrie et Brian J. Todd. « THE SKIPJACK ISLAND FAULT ZONE - AN ACTIVE TRANSCURRENT STRUCTURE WITHIN THE UPPER PLATE OF THE CASCADIA SUBDUCTION COMPLEX ». Dans GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-297426.
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Seyler, Caroline, James Kirkpatrick, Alexis Licht, Dana Šilerová et Christine Regalla. « EVIDENCE FOR SUBDUCTION ALONG THE LEECH RIVER FAULT AND IMPLICATIONS FOR CORDILLERAN TECTONICS ». Dans GSA 2020 Connects Online. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020am-355976.
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Penniston-Dorland, Sarah, Kayleigh M. Harvey, Matthew J. Kohn, Philip M. Piccoli, Stephanie Walker, Paul G. Starr et Ethan Baxter. « GOING DEEPER – INSIGHTS INTO THE TECTONICS OF SUBDUCTION ZONES FROM THE CATALINA SCHIST (CA) ». Dans GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-364591.
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Wang, Lu, Wei Hu, Timothy Kusky, Wenbing Ning, Tao Chen et Bo Huang. « Evidence for deep subduction reveals modern-style plate tectonics operated in the late Archean ». Dans Goldschmidt2023. France : European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.17933.
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Liu, Kang, Yigang Li, Yanyun Nan, Hongguang Li et Jingping Wang. « Exploration on the relationship between earthquake-triggered landslides and tectonics in the Himalayan Subduction Zone ». Dans International Conference on Remote Sensing, Mapping, and Geographic Systems (RSMG 2023), sous la direction de Feiyue Mao, Chunmei Wang et Zhaowu Yu. SPIE, 2023. http://dx.doi.org/10.1117/12.3010307.
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ПРОКОПЬЕВ А, В., Б. ЕРШОВА В, В. ШМАНЯК А et К. ХУДОЛЕЙ А. « MAGMATISM AND TECTONICS OF THE NORTHEAST OF THE OCTOBER REVOLUTION ISLAND (SEVERNAYA ZEMLYA ARCHIPELAGO) ». Dans ГЕОЛОГИЯ И МИНЕРАЛЬНО-СЫРЬЕВЫЕ РЕСУРСЫ СЕВЕРО-ВОСТОКА РОССИИ 2024, 375–78. Crossref, 2024. http://dx.doi.org/10.53954/9785604990100_375.
Texte intégralRésumé :
In the northeastern part of October Revolution Island (Kara terrane), supra-subduction subvolcanic and volcaniclastic rocks are described. Their Ordovician-Early Devonian isotope age (U-Pb, SHRIMP II, zircon and baddeleyite) and tectonic structure have been established. Volcaniclastic rocks yielded age at 463±3 Ma. Subvolcanic granite porphyry dated at 461-472 Ma while basalts, basaltic lava breccias and dolerite sills yielded ages at 467±16 Ma. Chemical data suggest that, the studied rocks could be formed on the active continental margin of the Ordovician-Silurian in age. Deformed rocks are intruded by Late Silurian to Early Devonian dolerite dikes (407±1, 416±1.5 Ma). A comparison is made with coeval magmatic rocks of the southern and southeastern parts of October Revolution Island.
Rapports d'organisations sur le sujet "Transcurrent and subduction tectonics"
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Harris, L. B., P. Adiban et E. Gloaguen. The role of enigmatic deep crustal and upper mantle structures on Au and magmatic Ni-Cu-PGE-Cr mineralization in the Superior Province. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328984.
Texte intégralRésumé :
Aeromagnetic and ground gravity data for the Canadian Superior Province, filtered to extract long wavelength components and converted to pseudo-gravity, highlight deep, N-S trending regional-scale, rectilinear faults and margins to discrete, competent mafic or felsic granulite blocks (i.e. at high angles to most regional mapped structures and sub-province boundaries) with little to no surface expression that are spatially associated with lode ('orogenic') Au and Ni-Cu-PGE-Cr occurrences. Statistical and machine learning analysis of the Red Lake-Stormy Lake region in the W Superior Province confirms visual inspection for a greater correlation between Au deposits and these deep N-S structures than with mapped surface to upper crustal, generally E-W trending, faults and shear zones. Porphyry Au, Ni, Mo and U-Th showings are also located above these deep transverse faults. Several well defined concentric circular to elliptical structures identified in the Oxford Stull and Island Lake domains along the S boundary of the N Superior proto-craton, intersected by N- to NNW striking extensional fractures and/or faults that transect the W Superior Province, again with little to no direct surface or upper crustal expression, are spatially associated with magmatic Ni-Cu-PGE-Cr and related mineralization and Au occurrences. The McFaulds Lake greenstone belt, aka. 'Ring of Fire', constitutes only a small, crescent-shaped belt within one of these concentric features above which 2736-2733 Ma mafic-ultramafic intrusions bodies were intruded. The Big Trout Lake igneous complex that hosts Cr-Pt-Pd-Rh mineralization west of the Ring of Fire lies within a smaller concentrically ringed feature at depth and, near the Ontario-Manitoba border, the Lingman Lake Au deposit, numerous Au occurrences and minor Ni showings, are similarly located on concentric structures. Preliminary magnetotelluric (MT) interpretations suggest that these concentric structures appear to also have an expression in the subcontinental lithospheric mantle (SCLM) and that lithospheric mantle resistivity features trend N-S as well as E-W. With diameters between ca. 90 km to 185 km, elliptical structures are similar in size and internal geometry to coronae on Venus which geomorphological, radar, and gravity interpretations suggest formed above mantle upwellings. Emplacement of mafic-ultramafic bodies hosting Ni-Cr-PGE mineralization along these ringlike structures at their intersection with coeval deep transverse, ca. N-S faults (viz. phi structures), along with their location along the margin to the N Superior proto-craton, are consistent with secondary mantle upwellings portrayed in numerical models of a mantle plume beneath a craton with a deep lithospheric keel within a regional N-S compressional regime. Early, regional ca. N-S faults in the W Superior were reactivated as dilatational antithetic (secondary Riedel/R') sinistral shears during dextral transpression and as extensional fractures and/or normal faults during N-S shortening. The Kapuskasing structural zone or uplift likely represents Proterozoic reactivation of a similar deep transverse structure. Preservation of discrete faults in the deep crust beneath zones of distributed Neoarchean dextral transcurrent to transpressional shear zones in the present-day upper crust suggests a 'millefeuille' lithospheric strength profile, with competent SCLM, mid- to deep, and upper crustal layers. Mechanically strong deep crustal felsic and mafic granulite layers are attributed to dehydration and melt extraction. Intra-crustal decoupling along a ductile décollement in the W Superior led to the preservation of early-formed deep structures that acted as conduits for magma transport into the overlying crust and focussed hydrothermal fluid flow during regional deformation. Increase in the thickness of semi-brittle layers in the lower crust during regional metamorphism would result in an increase in fracturing and faulting in the lower crust, facilitating hydrothermal and carbonic fluid flow in pathways linking SCLM to the upper crust, a factor explaining the late timing for most orogenic Au. Results provide an important new dataset for regional prospectively mapping, especially with machine learning, and exploration targeting for Au and Ni-Cr-Cu-PGE mineralization. Results also furnish evidence for parautochthonous development of the S Superior Province during plume-related rifting and cannot be explained by conventional subduction and arc-accretion models.