Academic literature on the topic 'Subduction trenches'
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Journal articles on the topic "Subduction trenches"
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Geersen, Jacob, Andrea Festa, and Francesca Remitti. "Structural constraints on the subduction of mass-transport deposits in convergent margins." Geological Society, London, Special Publications 500, no. 1 (December 19, 2019): 115–28. http://dx.doi.org/10.1144/sp500-2019-174.
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AbstractThe subduction of large and heterogeneous mass-transport deposits (MTDs) is discussed to modify the structure and physical state of the plate boundary and therewith exert an influence on seismicity in convergent margins. Understanding which subduction-zone architectures and structural boundary conditions favour the subduction of MTDs, primarily deposited in oceanic trenches, is therefore highly significant. We use bathymetric and seismic reflection data from modern convergent margins to show that a large landslide volume and long runout, in concert with thin trench sediments, increase the chances for an MTD to become subducted. In regions where the plate boundary develops within the upper plate or at its base (non-accretionary margins), and in little-sedimented trenches (sediment thickness <2 km), an MTD has the highest potential to become subducted, particularly when characterized by a long runout. On the contrary, in the case of a heavily sedimented trench (sediment thickness >4 km) and short runout, an MTD will only be subducted if the thickness of subducting sediments is higher than the thickness of sediments under the MTD. The results allow identification of convergent margins where MTDs are preferentially subducted and thus potentially alter plate-boundary seismicity.
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Lemenkova, Polina. "GEBCO and ETOPO1 gridded datasets for GMT based cartographic Mapping of Hikurangi, Puysegur and Hjort Trenches, New Zealand." Acta Universitatis Lodziensis. Folia Geographica Physica, no. 19 (December 30, 2020): 7–18. http://dx.doi.org/10.18778/1427-9711.19.01.
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The study focused on the comparative analysis of the submarine geomorphology of three oceanic trenches: Hikurangi Trench (HkT), Puysegur Trench (PT) and Hjort Trench (HjT), New Zealand region, Pacific Ocean. HjT is characterized by an oblique subduction zone. Unique regional tectonic setting consist in two subduction zones: northern (Hikurangi margin) and southern (Puysegur margin), connected by oblique continental collision along the Alpine Fault, South Island. This cause variations in the geomorphic structure of the trenches. PT/HjT subduction is highly oblique (dextral) and directed southwards. Hikurangi subduction is directed northwestwards. South Island is caught in between by the “subduction scissor”. Methodology is based on GMT (The Generic Mapping Tools) for mapping, plotting and modelling. Mapping includes visualized geophysical, tectonic and geological settings of the trenches, based on sequential use of GMT modules. Data include GEBCO, ETOPO1, EGM96. Comparative histogram equalization of topographic grids (equalized, normalized, quadratic) was done by module ’grdhisteq’, automated cross-sectioning – by ’grdtrack’. Results shown that HjT has a symmetric shape form with comparative gradients on both western and eastern slopes. HkT has a trough-like flat wide bottom, steeper gradient slope on the North Island flank. PT has an asymmetric V-form with steep gradient on the eastern slopes and gentler western slope corresponding to the relatively gentle slope of a subducting plate and steeper slope of an upper one. HkT has shallower depths < 2,500 m, PT is <-6,000 m. The deepest values > 6,000 m for HjT. The surrounding relief of the HjT presents the most uneven terrain with gentle slope oceanward, and a steep slope on the eastern flank for PT, surrounded by complex submarine relief along the Macquarie Arc. Data distribution for the HkT demonstrates almost equal pattern for the depths from -600 m to ₋2,600 m. PT has a bimodal data distribution with 2 peaks: 1) -4,250 to -4,500 m (18%); 2) -2,250 to -3,000 m, < 7,5%. The second peak corresponds to the Macquarie Arc. Data distribution for HjT is classic bell-shaped with a clear peak at -3,250 to -3,500 m. The asymmetry of the trenches resulted in geomorphic shape of HkT, PT and HjT affected by geologic processes.
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Hatheway, Darwin L., and William Ellis. "Subduction Trenches as Nuclear Dumps." Science News 144, no. 5 (July 31, 1993): 67. http://dx.doi.org/10.2307/3977778.
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Plunder, Alexis, Cédric Thieulot, and Douwe J. J. van Hinsbergen. "The effect of obliquity on temperature in subduction zones: insights from 3-D numerical modeling." Solid Earth 9, no. 3 (June 14, 2018): 759–76. http://dx.doi.org/10.5194/se-9-759-2018.
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Abstract. The geotherm in subduction zones is thought to vary as a function of the subduction rate and the age of the subducting lithosphere. Along a single subduction zone the rate of subduction may strongly vary due to changes in the angle between the trench and the plate convergence vector, i.e., the subduction obliquity, due to trench curvature. We currently observe such curvature in, e.g., the Marianas, Chile and Aleutian trenches. Recently, strong along-strike variations in subduction obliquity were proposed to have caused a major temperature contrast between Cretaceous geological records of western and central Turkey. We test here whether first-order temperature variation in a subduction zone may be caused by variation in the trench geometry using simple thermo-kinematic finite-element 3-D numerical models. We prescribe the trench geometry by means of a simple mathematical function and compute the mantle flow in the mantle wedge by solving the equation of mass and momentum conservation. We then solve the energy conservation equation until steady state is reached. We analyze the results (i) in terms of mantle wedge flow with emphasis on the trench-parallel component and (ii) in terms of temperature along the plate interface by means of maps and the depth–temperature path at the interface. In our experiments, the effect of the trench curvature on the geotherm is substantial. A small obliquity yields a small but not negligible trench-parallel mantle flow, leading to differences of 30 °C along-strike of the model. Advected heat causes such temperature variations (linked to the magnitude of the trench-parallel component of velocity). With increasing obliquity, the trench-parallel component of the velocity consequently increases and the temperature variation reaches 200 °C along-strike. Finally, we discuss the implication of our simulations for the ubiquitous oblique systems that are observed on Earth and the limitations of our modeling approach. Lateral variations in plate sinking rate associated with curvature will further enhance this temperature contrast. We conclude that the synchronous metamorphic temperature contrast between central and western Turkey may well have resulted from reconstructed major variations in subduction obliquity.
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Grevemeyer, Ingo, Cesar R. Ranero, and Monika Ivandic. "Structure of oceanic crust and serpentinization at subduction trenches." Geosphere 14, no. 2 (January 12, 2018): 395–418. http://dx.doi.org/10.1130/ges01537.1.
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Bykov, V. G., and T. V. Merkulova. "THE WAVE GEODYNAMIC IMPACT OF TECTONIC PROCESSES ON THE AMURIAN PLATE." Tikhookeanskaya Geologiya 40, no. 4 (2021): 72–86. http://dx.doi.org/10.30911/0207-4028-2021-40-4-72-86.
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The analysis of data on the migration of earthquakes and slow deformations from the Indo-Eurasian collision and the Western Pacific subduction zones is given, and the wave “geodynamic impact” of these tectonic processes on the Amurian plate and surrounding structures is shown. The interaction and a relative contribution of collision and subduction to the recent geodynamics of the Amurian plate are discussed. A scheme is constructed showing localizations of the slow strain wave manifestation in the areas of central and eastern Asia. The calculations are performed aimed at revealing a transverse migration of earthquakes (M ≥ 6.5) directed from the Japan and the Kuril-Kamchatka trenches toward the Asian continent during the time period from 1960 to 2015. The migration of earthquakes along the profile crossing Hokkaido Island occurs at velocities of 15 and 23 km/yr, whereas the migration velocity from the Kuril-Kamchatka Trench via Sakhalin Island is evaluated from 20 to 40 km/yr at different depths. We focus on an insufficient study of the influence of the Western Pacific subduction on the formation of the deformation field in continental Asia.
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Fryer, Patricia, and N. Christian Smoot. "Processes of seamount subduction in the Mariana and Izu-Bonin trenches." Marine Geology 64, no. 1-2 (March 1985): 77–90. http://dx.doi.org/10.1016/0025-3227(85)90161-6.
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Shatwell, Dave. "Mesozoic Metallogenesis of Peru: A Reality Check on Geodynamic Models." SEG Discovery, no. 124 (January 1, 2021): 15–24. http://dx.doi.org/10.5382/segnews.2021-124.fea-01.
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Abstract The Andean Cordillera is generally regarded as the product of easterly subduction of oceanic lithosphere below South America since the Late Triassic, but recent syntheses have challenged this paradigm. In one model, W-dipping oceanic subduction pulls the continent west until it collides with a ribbon continent that now forms the coastal region and Western Cordillera of the Peruvian Andes. A second model involves westerly oceanic subduction until 120 to 100 Ma, without the involvement of a ribbon continent, to explain deep, subducted slabs revealed by mantle tomographic images. Both assume that “Andean-style” E-dipping subduction did not exist during the Jurassic and Early Cretaceous. Another model, also involving mantle tomography, assumes that a back-arc basin opened inboard of the trench between 145 and 100 Ma, displacing the E-dipping subduction zone offshore without changing its polarity. This article examines the implications of these hypotheses for southern Peruvian metallogenesis during the Mesozoic, when marginal basins opened and closed and were thrust eastward and then were intruded, between 110 and ~50 Ma, by a linear belt of multiple plutons known as the Coastal Batholith. The earliest mineralization in southern Peru is located on the coast and comprises major iron oxide and minor porphyry copper deposits emplaced between 180 and 110 Ma. This was followed by Cu-rich iron oxide copper-gold deposits and a large Zn-rich volcanogenic massive sulfide (VMS) deposit between 115 and 95 Ma, then minor porphyry Cu deposits at ~80 Ma. A second episode of localized VMS mineralization followed at 70 to 68 Ma, then a group of at least five giant porphyry Cu-Mo deposits in southernmost Peru formed between 62 and 53 Ma. The conventional model of Andean-style subduction, which explains many features of Mesozoic Andean metallogenesis in terms of changing plate vectors and velocities, is a poor fit with mantle tomographic anomalies that are thought to record the paleopositions of ancient trenches. A ribbon-continent model requires some plutons of the Coastal Batholith to have been separated from others by an ocean basin. West-dipping oceanic subduction does not account for Jurassic mineralization and magmatism in southern Peru. A model involving a back-arc basin that opened inboard of the existing trench, forcing E-dipping subduction to retreat offshore between 145 and 100 Ma, seems to best explain the metallogenic and tomographic data.
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Gamage, S. S. N. "Seismic Activity near the Sunda and Andaman Trenches in the Sumatra Subduction Zone." International Journal of Multidisciplinary Studies 4, no. 2 (December 28, 2017): 49. http://dx.doi.org/10.4038/ijms.v4i2.22.
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Barbot, S., and J. R. Weiss. "Connecting subduction, extension and shear localization across the Aegean Sea and Anatolia." Geophysical Journal International 226, no. 1 (February 27, 2021): 422–45. http://dx.doi.org/10.1093/gji/ggab078.
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SUMMARY The Eastern Mediterranean is the most seismically active region in Europe due to the complex interactions of the Arabian, African, and Eurasian tectonic plates. Deformation is achieved by faulting in the brittle crust, distributed flow in the viscoelastic lower-crust and mantle, and Hellenic subduction, but the long-term partitioning of these mechanisms is still unknown. We exploit an extensive suite of geodetic observations to build a kinematic model connecting strike-slip deformation, extension, subduction, and shear localization across Anatolia and the Aegean Sea by mapping the distribution of slip and strain accumulation on major active geological structures. We find that tectonic escape is facilitated by a plate-boundary-like, trans-lithospheric shear zone extending from the Gulf of Evia to the Turkish-Iranian Plateau that underlies the surface trace of the North Anatolian Fault. Additional deformation in Anatolia is taken up by a series of smaller-scale conjugate shear zones that reach the upper mantle, the largest of which is located beneath the East Anatolian Fault. Rapid north–south extension in the western part of the system, driven primarily by Hellenic Trench retreat, is accommodated by rotation and broadening of the North Anatolian mantle shear zone from the Sea of Marmara across the north Aegean Sea, and by a system of distributed transform faults and rifts including the rapidly extending Gulf of Corinth in central Greece and the active grabens of western Turkey. Africa–Eurasia convergence along the Hellenic Arc occurs at a median rate of 49.8 mm yr–1 in a largely trench-normal direction except near eastern Crete where variably oriented slip on the megathrust coincides with mixed-mode and strike-slip deformation in the overlying accretionary wedge near the Ptolemy–Pliny–Strabo trenches. Our kinematic model illustrates the competing roles the North Anatolian mantle shear zone, Hellenic Trench, overlying mantle wedge, and active crustal faults play in accommodating tectonic indentation, slab rollback and associated Aegean extension. Viscoelastic flow in the lower crust and upper mantle dominate the surface velocity field across much of Anatolia and a clear transition to megathrust-related slab pull occurs in western Turkey, the Aegean Sea and Greece. Crustal scale faults and the Hellenic wedge contribute only a minor amount to the large-scale, regional pattern of Eastern Mediterranean interseismic surface deformation.
Dissertations / Theses on the topic "Subduction trenches"
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Gonzalez, Miguel. "Nature and origin of sedimentary deposits in the Ecuador subduction trench : paleoseismological implications." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1B009/document.
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La sédimentation marine récente dans les fosses de subduction est caractérisée par l'interstratification de sédiments hémipélagiques et de turbidites localement intercalées avec les coulées de débris, qui peuvent résulter de la destabilisation des pentes continentales par de tremblements de terre. La marge d’Equateur est constituée par une forte érosion tectonique qui contribue à la formation d'une fosse profonde remplie d'une suite complexe de faciès sédimentaires. La sédimentation par écoulements gravitaires est omniprésente le long de la marge et les faciès vont de dépôts de transport de masse d'épaisseur métriques latéralement continus à des turbidites d'épaisseur centimétriques isolées intercalées avec des couches d'hémipélagites, de volcanoclastiques et de téphras. Nous présentons l'interprétation de la bathymétrie, des profils sismiques à haute résolution et des données pétrophysiques des carottes sédimentaires. L'objectif de cette étude est de décrire la complexité morphologique à la frontière équatorienne de la plaque de Nazca où un ensemble d'aspérités marines profondes ont subducté à différentes échelles, et ses conséquences sur la distribution latérale des sédiments dans les différents sous-bassins. La marge équatorienne comprend trois segments géomorphologiques: Le segment nord, situé au nord de la crête Carnegie, est caractérisé par une large (5-10 km) et profonde fosse (3800-4000 m), une pente continentale ravinée et une plate-forme (10-40 km de large) avec subsidence active. Le segment central en face de la crête de Carnégie montre une fosse étroite (0-5 km de large) et peu profonde (3100-3700 m), la pente escarpée et ravinée, sans canyons, et plateau continental étroit de 15 à 40 km de large caractérisé par des zones d'affaissement et de soulèvement actifs. Enfin, le segment sud, situé au sud de la crête Carnegie, présente une large (5-10 km) et profonde fosse (4000-4700 m), une pente continentale pauvre en sédiments avec des systèmes de canyons bien définis et une large plate-forme de subsidence (20-50 km). La dynamique sédimentaire le long de la marge est évaluée par l'analyse de 15 carottes sédimentaires dont la description visuelle, les photographies à haute résolution, l'imagerie par rayons X, les données XRF et les propriétés pétrophysiques conduisent à l'identification de 11 faciès sédimentaires caractérisant 7 processus sédimentaires: dépôts de turbidite, hémipélagites, téphras, dépôts de coulées de débris, homogénites, des slumps et des dépôts de carbonate de ooze. Les âges des dépôts sont définis par la datation au radiocarbone des sédiments hémipélagites. Les âges vont de 500 à 48000 ans BP. Les profils sismiques à haute résolution permettent de définir 3 echo-faciès: transparent, stratifiés et chaotiques. Le facies transparent est principalement associé aux dépôts d'homogénites, le facies stratifié est associé aux dépôts interstratifiés turbiditique-hémipélagique et le facies chaotique est associé à des dépôts gravitaires grossiers. Le remplissage de la fosse représente un enregistrement lacunaire mais important de l'histoire de la marge de subduction. De grandes coulées de débris se déplaçant vers l'est dans les deux séquences inférieures du remplissage de la fosse sont initiées le long de la paroi extérieure de la fosse, le long de grandes failles normales dues à la flexion de la plaque océanique subductante. Les sédiments de la séquence supérieure du remplissage qui nappent la fosse sont plus largement fournis par la paroi interne de la fosse mais avec un fort contrôle de la ride de Carnegie. En conséquence, la profondeur, la fréquence, l'épaisseur, la composition et la disposition latérale des dépôts sédimentaires varient grandement entre le nord et le sud. Les grands méga-lits simples, les slumps, les coulées de débris et les homogénites sont situés dans les segments nord et sud. Ils sont déclenchés par de grands escarpements de failles régionales, dans le NordRecent deep marine sedimentation in subduction trenches is characterized by the inter-stratification of hemipelagic and turbidite sediments locally interbedded with debris flow, which can result from continental slope shaking triggered by earthquakes. The active margin of Ecuador comprises tectonic erosion that contributes to the formation of a deep trench filled by a complex suite of sedimentary facies. Gravity flow sedimentation is ubiquitous along the margin and facies range from laterally continuous m-thick mass transport deposits to isolated cm-thick turbidites intercalated with hemipelagite, volcanoclastics and tephra. In this study we show interpretation of swath bathymetry, high-resolution seismic profiles and petrophysical data from cores. The objective is to describe the morphologic complexity on the Ecuadorian border of the Nazca plate where a set of deep marine asperities is subducting at different scales, and their consequences on the distribution of sediments in the different sub-basins. Ecuadorian margin comprises three geomorphological segments: The northern segment, northward of the Carnegie Ridge, is characterized by a wide (5-10 km) and deep trench (3800 – 4000 m), a gentler gullied continental slope and a shelf (10-40 km wide) with active subsidence. The central segment facing the Carnegie Ridge, is strongly influenced by the subduction of the Carnegie ridge which induces a narrow (0–5 km wide) and shallow trench (3100 – 3700 m depth), a steep and gullied slope with no canyons and a 15–40 km wide shelf characterized by areas with active subsidence and uplift. Finally, the southern segment, southward of the Carnegie Ridge, presents a wide (5–10 km) and deep (4000–4700 m) trench, a starved continental slope with well-defined canyon systems and a wide subsiding shelf (20–50 km). The sedimentary dynamics along the margin is evaluated by the analysis of 15 cores. Visual description, high-resolution photographs, X-Ray imagery, XRF data and petrophysical properties led to the identification of 11 sedimentary facies that characterize seven sedimentary processes: turbidites, hemipelagites, tephras, debris flows, homogenites, slumps, and ooze carbonate deposits. Age of the deposits is defined by radiocarbon age dating of hemipelagic sediments. Ages range from 500 to 48,000 years BP. High-resolution seismic profiles allow definition of three echo-facies: transparent, layered and chaotic. Transparent echo-facies is mainly associated to homogenite deposits, layered echo-facies is associated to the turbiditic-hemipelagic interbedded deposits and chaotic echo-facies is associated to reworked gravity flow deposits. The trench fill represents a lacunar but important record of the subduction margin history. Large eastward debris flows in the lower two sequences of the trench fill are provided by the trench outer wall as a results of slope failures along normal faults due to the downward bending of the oceanic plate. The sediment of the upper sequence of the trench fill draping the trench floor, are largely provided by the inner trench wall strongly controlled by the Carnegie Ridge. As a result, depth, frequency, thickness, composition and lateral disposition of the deposits vary greatly from those at north and south. The large, simple mega-beds like slump, debris flows and homogenites are located at the northern and southern segments. They were triggered by large regional faults in the North and enhanced by the activity of sets of splay faults in the South overhanging the seafloor at the slope toe. Small-size, fluid rich events were triggered by subduction of isolated seamounts at the edges of the Carnegie Ridge due to frequent but small destabilizations of an inner trench wall preconditioned by the impacts of successive seamounts. Sets of partly volcanoclastic turbidites in central segment might have been triggered by the complex interaction of slope and continental shelf deformation by seamount subduction
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Maiti, Tannistha. "3D trench-parallel flow in the subduction region and correlation with seismic anisotropy direction." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/44192.
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The motivation of this study is to understand the seismic anisotropy observations from various subduction regions of the world. In subduction zone backarcs both trench-parallel and trench-normal seismic anisotropy, or fast wave polarization direction of shear wave, are observed. In the mantle the general assumption is that seismic anisotropy is caused by Lattice Preferred Orientation (LPO) of olivine minerals and that the direction of anisotropy is an indicator of the direction of mantle flow. The complex pattern of seismic anisotropy observations suggests that the flow geometry in the vicinity of subduction zones differs at different subduction zones with some subduction zones having trench perpendicular flow, consistent with corner flow in the mantle wedge while other subduction zones have trench parallel flow, consistent with a mode of flow where material from the mantle wedge flows around the edges of the slab. It should be noted that the direction of LPO orientation can also be modified by the presence or absence of water, pressure, and temperature in the mantle and that it is possible that the difference in anisotropy observations reflects a difference in water content or thermal structure of back arcs. The aim of this study is to test whether the flow geometry of mantle in numerical subduction calculations can influence the direction of seismic anisotropy and if we parameters that control the pattern of flow can be identified. In this study we explicitly assume that seismic anisotropy occurs only due to plastic and dynamic re-crystallization of mantle mineral forming LPO. To approach the problem two different models are formulated. In one of the models the trench evolves self-consistently, with no prescribed artificial zones of weakness. The self-consistent model has a sticky-air layer at the top of the model domain that mimics a â free-surface.â The other model has the same initial conditions but a trench-migration velocity boundary condition is imposed to the model. The mantle flow pattern for the self-consistent model is consistent with the 2D corner flow with no flow around the trench and no trench migration. However when the trench-migration velocity boundary condition is imposed, 3D flow around the mantle is observed. The stress field from these simulations are used to calculated instantaneous strain axis directions which correlate with LPO directions. The LPO orientations are measured from the models showing that the seismic-anisotropy direction is primarily trench-perpendicular for both models. Because the models have different flow patterns, the trench-perpendicular anisotropy alignment that is calculated for both the models is a bit puzzling. It could be that factors such as high temperature and non-linear rheology cause the LPO direction to align trench perpendicular in both the cases. It can also be possible that the 3D vertical flow is not strong enough to cause change in orientation of the LPO direction. From the present study it can be concluded that by looking at the LPO direction nature of mantle flow might not be predicted. This suggests that in addition to flow direction other factors such as the presence of water in mantle wedge, pressure, and high temperature due to viscous coupling modify the seismic anisotropy directions.Master of Science
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Alsaif, Manar. "Upper plate deformation in retreating subduction zones." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTG026.
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La surface de la Terre est en permanence remodelée par les mouvements des plaques tectoniques, dont le moteur principal est la subduction, i.e. le plongement de plaques océaniques dans le manteau profond. Les fosses océaniques de subduction constituent également des limites de plaques mobiles, et les observations montrent que, sur des échelles de temps géologiques de plusieurs millions d’années, ces fosses reculent (vers la plaque plongeante) ou avancent (vers la plaque chevauchante/supérieure). Historiquement, le retrait de la fosse a été associé à une extension de la plaque supérieure au-dessus du panneau plongeant. Cependant, les zones de subduction sur Terre montrent plusieurs exemples de fosses en recul associées à des contraintes compressives. Cette thèse étudie la déformation (arrière-arc) de la plaque supérieure pour une subduction en retrait. Trois approches ont été utilisées : des modèles numériques explorant les processus physiques mis en jeu à grande échelle, des profils sismiques en mer Égée centrale permettant d’étudier la répartition des failles à l’échelle du bassin, et des observations de terrain pour caractériser l’évolution temporelle de la déformation de la plaque supérieure en mer Égée centrale. Les modèles thermo-mécaniques à grande échelle reproduisent une déformation visqueuse de la plaque supérieure, et permettent d’analyser les relations entre traction du slab, recul du slab, retrait de la fosse et déformation de la plaque supérieure, à des échelles allant de 100 à 1000 km. Ils montrent que des courants dans le manteau asthénosphérique sous les plaques (vers 100-200 km de profondeur) peuvent contrôler à la fois le mouvement relatif de la fosse et la déformation de la plaque supérieure. Cette dernière dépend également des conditions mécaniques aux limites: si la plaque est libre de bouger, sa déformation sera plutôt compressive ; mais une plaque fixe sera en extension. Ce dernier cas est comparable à la région de la mer Égée, une plaque supérieure montrant de l’extension et associée à une zone de subduction étroite en retrait. Les structures extensives associées ont été analysées grâce à l’observation sur le terrain et à l’étude de profils sismiques, révélant des failles normales, obliques et décrochantes synchrones. Cela est interprété comme résultant de la combinaison de contraintes extensives associées au recul de la fosse et de contraintes décrochantes associées à l’extrusion d’un bloc voisin. La rotation et le recul de la fosse réactivent d’anciennes failles normales dans un mode oblique-extensif, et engendrent des nouvelles failles purement normales. Les données suggèrent également un changement récent de l’état de contrainte mécanique dans la plaque, qui pourrait être dû à une déchirure du panneau plongeant côté Ouest. En sus, l’accélération du recul de la fosse et l’intensification de l’extension de la plaque supérieure expliquent probablement le flux de chaleur élevé en mer Égée, ce qui rend l’énergie géothermique potentiellement exploitable dans cette zone. Une évaluation de l’apport de la modélisation tectonique pour prédire le potentiel géothermique est finalement présentée comme perspective de l’application des recherches en géodynamique, s’appuyant sur l’exemple de la plaque supérieure égéenne amincieThe Earth’s surface is constantly reshaped by the tectonic plate motion, which is mainly driven by subduction of plates into the deeper mantle. Subduction trenches are also mobile plate boundaries, and are observed to retreat towards the subducting plate or advance towards the upper plate over geological time. Trench retreat has been historically thought to cause extension in the upper plate above the subducting slab. However, natural subduction systems show several examples of retreating trenches that are associated with upper-plate compression. This thesis explores upper plate (back-arc) deformation in retreating subduction systems. Three techniques are used: large-scale numerical models addressing physical processes; seismic profiles in the Central Aegean addressing basin-scale fault patterns; and field-scale observations clarifying fault kinematics in the Central Aegean. The large-scale thermo-mechanical models deal with viscous deformation of the upper plate, and investigate the relationship between slab pull, slab rollback, trench retreat and upper plate deformation at scales of 100 to 1000 km. They show that asthenosphere flows below the plates (100-200 km depth) can control both trench retreat and upper plate deformation. The type of deformation in the upper plate also depends on the plate’s far-field conditions: if the plate is free to move, deformation tends to be compressive, but a fixed upper plate shows extension. The latter is comparable to the Aegean region, an upper plate exhibiting extension above a narrow, retreating subduction zone. Related extensional structures in the central Aegean have been analysed from seismic and field data, revealing co-existing normal, oblique and strike slip faults. These features reflect a combination of rollback-related extension and extrusion-related strike slip activity. Resulting block rotation and trench retreat re-activate inherited normal faults in oblique-normal slip, while new pure-normal faults are created. We also infer a recent change in stress state possibly related to the slab tear on the western side of the Hellenic slab. Additionally, accelerated trench retreat and upper plate extension are the cause of the Aegean’s high surface heat flow, which makes it potentially suitable for geothermal energy production. As a final perspective on the application of geodynamic research, an assessment of the role of tectonic modelling in predicting geothermal energy potential is presented, using the stretched Aegean upper plate as an example
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Magni, Valentina <1984>. "Numerical models of trench migration for lateral heterogeneous subducting plates." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4280/.
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The aim of this Thesis is to investigate the effect of heterogeneities within the subducting plate on the dynamics of subduction. In particular, I study the motion of the trench for oceanic and continental subduction, first, separately, and, then, together in the same system to understand how they interact. The understanding of these features is fundamental to reconstruct the evolution of complex subduction zones, such as the Central Mediterranean.
For this purpose, I developed 2D and 3D numerical models of oceanic and continental subduction where the rheological, geometrical and compositional properties of the plates are varied. In these models, the trench and the overriding plate move self-consistently as a function of the dynamics of the system.
The effect of continental subduction on trench migration is largely investigated. Results from a parametric study showed that despite different rheological properties of the plates, all models with a uniform continental crust share the same kinematic behaviour: the trench starts to advance once the continent arrives at the subduction zone. Hence, the advancing mode in continental collision scenarios is at least partly driven by an intrinsic feature of the system. Moreover, the presence of a weak lower crust within the continental plate can lead to the occurrence of delamination. Indeed, by changing the viscosity of the lower crust, both delamination and slab detachment can occur. Delamination is favoured by a low viscosity value of the lower crust, because this makes the mechanical decoupling easier between crust and lithospheric mantle. These features are observed both in 2D and 3D models, but the numerical results of the 3D models also showed that the rheology of the continental crust has a very strong effect on the dynamics of the whole system, since it influences not only the continental part of plate but also the oceanic sides.
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Kelly, Robyn K. "Subduction dynamics at the middle America trench : new constraints from swath bathymetry, multichannel seismic data, and ¹⁰Be." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/59656.
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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, and the Woods Hole Oceanographic Institution), September 2003.Includes bibliographical references.
The cosmogenic radionuclide ¹⁰Be is a unique tracer of shallow sediment subduction in volcanic arcs. The range in ¹⁰Be enrichment in the Central American Volcanic Arc between Guatemala and Costa Rica is not controlled by variations in ¹⁰Be concentrations in subducting sediment seaward of the Middle America Trench. Sedimentary ¹⁰Be is correlated negatively with ¹⁴³ND/¹⁴⁴Nd, illustrating that ¹⁰Be concentrations varied both between and within cores due to mixing between terrigenous clay and volcanic ash endmember components. This mixing behavior was determined to be a function of grain size controls on ¹⁰Be concentrations. A negative correlation of bulk sedimentary ¹⁰Be concentrations with median grain size and a positive correlation with the proportion of the sediment grains that were <32 [mu]m in diameter demonstrated that high concentrations of ¹⁰Be in fine-grained, terrigenous sediments were diluted by larger grained volcanogenic material. The sharp decrease in ¹⁰Be enrichment in the Central American Volcanic Arc between southeastern Nicaragua and northwestern Costa Rica correlates with changes in fault structure in the subducting Cocos plate. Offshore of Nicaragua, extensional faults associated with plate bending have throw equal to or greater than the overlying subducting sediment thickness. These faults enable efficient subduction of the entire sediment package by preventing relocation of the d6collement within the downgoing sediments.
(cont.) Offshore of Costa Rica, the reduction of fault relief results in basement faults that do not penetrate the overlying sediment. A conceptual model is proposed in which the absence of significant basement roughness allows the d6collement to descend into the subducting sediment column, leading to subsequent underplating and therefore removal of the bulk of the sediment layer that contains ¹⁰Be. Basement fault relief was linearly related to plate curvature and trench depth. The systematic shoaling of the plate from southeastern Nicaragua to northwestern Costa Rica is not explained by changes in plate age for this region. Instead, it is hypothesized that the flexural shape of the plate offshore of southeastern Nicaragua and northwestern Costa Rica represents a lateral response to a buoyant load caused by the thick crust and elevated thermal regime in the Cocos plate offshore of southeastern Costa Rica.
by Robyn K. Kelly.
Ph.D.
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Ghosh, Abhijit. "Earthquake Frequency-Magnitude Distribution and Interface Locking at the Middle America Subduction Zone near Nicoya Peninsula, Costa Rica." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16288.
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Subduction zone megathrusts produce the majority of the world's largest earthquakes. To understand the processes that control seismicity here, it is important to improve our knowledge on the subduction interface characteristics and its spatial variations. Nicoya Peninsula, Costa Rica, extends the continental landmass ~50 km towards the trench, making it a very suitable place to study interface activity from right on the top of the seismogenic zone of the Middle America Subduction Zone (MASZ). We contribute to and utilize an earthquake catalog of 8765 analyst-picked events to determine the spatial variability in the earthquake frequency-magnitude distribution (FMD) in this region. After initial detection, magnitude determination and location, the events are precisely relocated using a locally derived 3-D seismic compressional and shear wave velocity model (DeShon et al., 2006). After restricting the dataset to events nearest the interface and with low formal error (horizontal location error < 5 km), we retain a subset of 3226 events that best resolves interface activity.
Beneath Nicoya, we determine the spatial variability and mean FMD of the interface, and focus on the relative relationship of small-to-large earthquakes, termed b-value. Across the region, the overall b-value (1.18 ± 0.04) is higher than the global average (b~1), and much larger than the global subduction zone average (b~0.6). Significant variation in b-value is observed along the active plate interface. A well resolved zone of lower b is observed at and offshore central Nicoya coast, in a previously determined locked patch using deformation observed from Global Positioning System (GPS). Conversely, high b-values prevail over the subducted portion of the Fisher ridge, which likely ruptured in the 1990 Gulf of Nicoya Mw 7.0 earthquake. Observed regions of low b-value approximately corresponds to more strongly-locked segments of the subduction interface resulting in higher differential stress, which may be released in the next large interface earthquake in this part of the MASZ. Across the region the b-value is found to vary inversely with the degree of interface locking. Thus, it is proposed that if sufficient data exist, spatial b-value mapping can be used as a proxy to determine interface locking. This method is especially useful along the subduction megathrust, which is generally offshore making geodetic measurements difficult.
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Johnson, Julie A. "A Geochemical Study of Crustal Plutonic Rocks from the Southern Mariana Trench Forearc: Relationship to Volcanic Rocks Erupted during Subduction Initiation." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1249.
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Two suites of intermediate-felsic plutonic rocks were recovered by dredges RD63 and RD64 (R/V KK81-06-26) from the northern wall of the Mariana trench near Guam, which is located in the southern part of the Izu-Bonin-Mariana (IBM) island arc system. The locations of the dredges are significant as the area contains volcanic rocks (forearc basalts and boninites) that have been pivotal in explaining processes that occur when one lithospheric plate initially begins to subduct beneath another. The plutonic rocks have been classified based on petrologic and geochemical analyses, which provides insight to their origin and evolution in context of the surrounding Mariana trench.
Based on whole rock geochemistry, these rocks (SiO2: 49-78 wt%) have island arc trace element signatures (Ba, Sr, Rb enrichment, Nb-Ta negative anomalies, U/Th enrichment), consistent with the adjacent IBM volcanics. Depletion of rare earth elements (REEs) relative to primitive mantle and excess Zr and Hf compared to the middle REEs indicate that the source of the plutonic rocks is similar to boninites and transitional boninites. Early IBM volcanic rocks define isotopic fields (Sr, Pb, Nd and Hf-isotopes) that represent different aspects of the subduction process (e.g., sediment influence, mantle provenance). The southern Mariana plutonic rocks overlap these fields, but show a clear distinction between RD63 and RD64. Modeling of the REEs, Zr and Hf shows that the plutonic suites formed via melting of boninite crust or by crystallization from a boninite-like magma rather than other sources that are found in the IBM system.
The data presented support the hypothesis that the plutonic rocks from RD63 and RD64 are products of subduction initiation and are likely pieces of middle crust in the forearc exposed at the surface by faulting and serpentine mudvolcanoes. Their existence shows that intermediate-felsic crust may form very early in the history of an intra-oceanic island arc system. Plutonic rocks with similar formation histories may exist in obducted suprasubduction zone ophiolites and would be evidence that felsic-intermediate forearc plutonics are eventually accreted to the continents.
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Pedley, Katherine Louise. "Modelling Submarine Landscape Evolution in Response to Subduction Processes, Northern Hikurangi Margin, New Zealand." Thesis, University of Canterbury. Geological Sciences, 2010. http://hdl.handle.net/10092/4648.
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The steep forearc slope along the northern sector of the obliquely convergent Hikurangi subduction zone is characteristic of non-accretionary and tectonically eroding continental margins, with reduced sediment supply in the trench relative to further south, and the presence of seamount relief on the Hikurangi Plateau. These seamounts influence the subduction process and the structurally-driven geomorphic development of the over-riding margin of the Australian Plate frontal wedge.
The Poverty Indentation represents an unusual, especially challenging and therefore exciting location to investigate the tectonic and eustatic effects on this sedimentary system because of: (i) the geometry and obliquity of the subducting seamounts; (ii) the influence of multiple repeated seamount impacts; (iii) the effects of structurally-driven over-steeping and associated widespread occurrence of gravitational collapse and mass movements; and (iv) the development of a large canyon system down the axis of the indentation. High quality bathymetric and backscatter images of the Poverty Indentation submarine re-entrant across the northern part of the Hikurangi margin were obtained by scientists from the National Institute of Water and Atmospheric Research (NIWA) (Lewis, 2001) using a SIMRAD EM300 multibeam swath-mapping system, hull-mounted on NIWA’s research vessel Tangaroa. The entire accretionary slope of the re-entrant was mapped, at depths ranging from 100 to 3500 metres. The level of seafloor morphologic resolution is comparable with some of the most detailed Digital Elevation Maps (DEM) onshore. The detailed digital swath images are complemented by the availability of excellent high-quality processed multi-channel seismic reflection data, single channel high-resolution 3.5 kHz seismic reflection data, as well as core samples. Combined, these data support this study of the complex interactions of tectonic deformation with slope sedimentary processes and slope submarine geomorphic evolution at a convergent margin.
The origin of the Poverty Indentation, on the inboard trench-slope at the transition from the northern to central sectors of the Hikurangi margin, is attributed to multiple seamount impacts over the last c. 2 Myr period. This has been accompanied by canyon incision, thrust fault propagation into the trench fill, and numerous large-scale gravitational collapse structures with multiple debris flow and avalanche deposits ranging in down-slope length from a few hundred metres to more than 40 km. The indentation is directly offshore of the Waipaoa River which is currently estimated to have a high sediment yield into the marine system. The indentation is recognised as the “Sink” for sediments derived from the Waipaoa River catchment, one of two target river systems chosen for the US National Science Foundation (NSF)-funded MARGINS “Source-to-Sink” initiative. The Poverty Canyon stretches 70 km from the continental shelf edge directly offshore from the Waipaoa to the trench floor, incising into the axis of the indentation. The sediment delivered to the margin from the Waipaoa catchment and elsewhere during sea-level high-stands, including the Holocene, has remained largely trapped in a large depocentre on the Poverty shelf, while during low-stand cycles, sediment bypassed the shelf to develop a prograding clinoform sequence out onto the upper slope. The formation of the indentation and the development of the upper branches of the Poverty Canyon system have led to the progressive removal of a substantial part of this prograding wedge by mass movements and gully incision. Sediment has also accumulated in the head of the Poverty Canyon and episodic mass flows contribute significantly to continued modification of the indentation by driving canyon incision and triggering instability in the adjacent slopes.
Prograding clinoforms lying seaward of active faults beneath the shelf, and overlying a buried inactive thrust system beneath the upper slope, reveal a history of deformation accompanied by the creation of accommodation space. There is some more recent activity on shelf faults (i.e. Lachlan Fault) and at the transition into the lower margin, but reduced (~2 %) or no evidence of recent deformation for the majority of the upper to mid-slope. This is in contrast to current activity (approximately 24 to 47% shortening) across the lower slope and frontal wedge regions of the indentation. The middle to lower Poverty Canyon represents a structural transition zone within the indentation coincident with the indentation axis. The lower to mid-slope south of the canyon conforms more closely to a classic accretionary slope deformation style with a series of east-facing thrust-propagated asymmetric anticlines separated by early-stage slope basins. North of the canyon system, sediment starvation and seamount impact has resulted in frontal tectonic erosion associated with the development of an over-steepened lower to mid-slope margin, fault reactivation and structural inversion and over-printing.
Evidence points to at least three main seamount subduction events within the Poverty Indentation, each with different margin responses:
i) older substantial seamount impact that drove the first-order perturbation in the margin, since approximately ~1-2 Ma
ii) subducted seamount(s) now beneath Pantin and Paritu Ridge complexes, initially impacting on the margin approximately ~0.5 Ma, and
iii) incipient seamount subduction of the Puke Seamount at the current deformation front.
The overall geometry and geomorphology of the wider indentation appears to conform to the geometry accompanying the structure observed in sandbox models after the seamount has passed completely through the deformation front. The main morphological features correlating with sandbox models include: i) the axial re-entrant down which the Poverty Canyon now incises; ii) the re-establishment of an accretionary wedge to the south of the indentation axis, accompanied by out-stepping, deformation front propagation into the trench fill sequence, particularly towards the mouth of the canyon; iii) the linear north margin of the indentation with respect to the more arcuate shape of the southern accretionary wedge; and, iv) the set of faults cutting obliquely across the deformation front near the mouth of the canyon. Many of the observed structural and geomorphic features of the Poverty Indentation also correlate well both with other sediment-rich convergent margins where seamount subduction is prevalent particularly the Nankai and Sumatra margins, and the sediment-starved Costa Rican margin. While submarine canyon systems are certainly present on other convergent margins undergoing seamount subduction there appears to be no other documented shelf to trench extending canyon system developing in the axis of such a re-entrant, as is dominating the Poverty Indentation.
Ongoing modification of the Indentation appears to be driven by: i) continued smaller seamount impacts at the deformation front, and currently subducting beneath the mid-lower slope, ii) low and high sea-level stands accompanied by variations on sediment flux from the continental shelf, iii) over-steepening of the deformation front and mass movement, particularly from the shelf edge and upper slope.
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Lallemand, Serge. "La fosse du japon : contexte geodynamique et effets de la subduction d'asperites sur la tectogenese de la marge (programme kaiko)." Orléans, 1987. http://www.theses.fr/1987ORLE2039.
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On presente dans un premier temps, la chronologie et les modalites d'ouverture de la mer du japon et de ses differents bassins. Ils se sont ouverts en pull-apart le long de deux zones de cisaillement ou resultent du blocage du mouvement le long de la faille est-coreenne ou encore d'extension arriere-arc liee a la subduction pacifique. Ceci constitue le contexte geodynamique de la marge pacifique au niveau de la fosse du japon. On observe ensduite la subduction des asperites de la croute oceanique telles que horsts, grabens de la plaque plongeante, anciennes failles reactivees on volcans sous-marins. Le modele du prisme de coulomb semble s'appliquer parfaitement au passage d'un volcan sous une marge
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Lin, Tzu-Chi, and 林姿綺. "Tsunami and shaking simulations of potential large subduction zone earthquake along the southernmost Ryukyu Trench." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/07460846568235360946.
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碩士國立臺灣大學
地質科學研究所
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During the last century, many big earthquakes with magnitude larger than 9 had occurred along the subduction zones. For example, the 1960 Chile earthquake (M9.5), the 2004 Sumatra-Andaman earthquake (M9.3), and the 2011 Tohoku earthquake (M9.0). In this study, we focus on the southernmost Ryukyu Trench which is extremely close to northern Taiwan. Interseismic GPS data in northeast Taiwan shows a pattern of strain accumulation suggests that the maximum likely magnitude of a potential future large earthquake in this area is probably about moment magnitude 8.7. In order to evaluate the influence of the potential megathrust event, we consider a 3-D fault plane along this portion of subduction zone at depths shallower than 50 km. We apply the interseismic GPS data to invert the source slip pattern on the subducting fault plane. In addition, several source rupture scenarios with different characterized slip patterns are considered to simulate the ground shaking based on 3-D spectral-element method. We analyze ShakeMap and ShakeMovie from the simulation results to evaluate the influence over the island between different source models. A dispersive tsunami propagation simulation is also carried out to evaluate the maximum tsunami wave height along the coastal areas of Taiwan due to coseismic seafloor deformation of different source models. From the results of all rupture scenarios, the peak ground acceleration larger than 1g can be observed in many areas even though the rupture occurs off northeastern coast of Taiwan. The tsunami simulation results show that the sea level raised significantly along the eastern coast, especially in the offshore area of Ilan where tsunami high can over 20 meters. The results of this numerical simulation study can provide a physically based information of megathrust earthquake scenario for the emergency response agency to take the appropriate action before the really big one happens.
Books on the topic "Subduction trenches"
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Kelly, Robyn K. Subduction dynamics at the middle America trench: New constraints from swath bathymetry, multichannel seismic data, and ¹⁰Be. Cambridge, Mass: Massachusetts Institute of Technology, 2003.
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Tregoning, Paul. GPS measurements in the Australian and Indonesian regions, 1989-1993: Studies of the Java Trench subduction zone, the Sunda Strait and the Australian Plate. Sydney: School of Geomatic Engineering, University of New South Wales, 1996.
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Gurūpu, Kaikō II Kenkyū, ed. Nihon shūhen no kaikō: 6000m no shinkaitei e no tabi : shashinshū = 6000 meters deep : a trip to the Japanese trenches ; photographic records of the Nautile Dives in the Japanese subduction zones. Tōkyō: Tōkyō Daigaku Shuppankai, 1987.
Find full textBook chapters on the topic "Subduction trenches"
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Seno, Tetsuzo, and Takashi Takano. "Seismotectonics at the Trench-Trench-Trench Triple Junction off Central Honshu." In Subduction Zones Part II, 27–40. Basel: Birkhäuser Basel, 1989. http://dx.doi.org/10.1007/978-3-0348-9140-0_3.
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Ruff, Larry J. "Do Trench Sediments Affect Great Earthquake Occurrence in Subduction Zones?" In Subduction Zones Part II, 263–82. Basel: Birkhäuser Basel, 1989. http://dx.doi.org/10.1007/978-3-0348-9140-0_9.
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Seno, Tetsuzo, and Yoshiko Yamanaka. "Double Seismic Zones, Compressional Deep Trench-Outer Rise Events, and Superplumes." In Subduction Top to Bottom, 347–55. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm096p0347.
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Bilek, Susan L., and Thorne Lay. "Comparison of Depth Dependent Fault Zone Properties in the Japan Trench and Middle America Trench." In Seismogenic and Tsunamigenic Processes in Shallow Subduction Zones, 433–56. Basel: Birkhäuser Basel, 1999. http://dx.doi.org/10.1007/978-3-0348-8679-6_3.
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Shaw, Beth. "The AD 365 Earthquake: Large Tsunamigenic Earthquakes in the Hellenic Trench." In 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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Shipley, Thomas H., and Gregory F. Moore. "Sediment Accretion and Subduction in the Middle America Trench." In Formation of Active Ocean Margins, 221–55. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-4720-7_10.
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Ogawa, Yujiro. "Erosional Subduction Zone in the Northern Japan Trench: Review of Submersible Dive Reports." In Accretionary Prisms and Convergent Margin Tectonics in the Northwest Pacific Basin, 39–52. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-8885-7_2.
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Verstappen, Herman Th. "Volcanic Islands." In The Physical Geography of Southeast Asia. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780199248025.003.0020.
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Volcanism is of widespread occurrence in the tectonically active zones of Southeast Asia. It is a dominant feature in many (particularly smaller) islands where other landform types are absent or scarce. The geographic distribution, major landform types, exogenous and endogenous processes, resources, and hazards of southeast Asian volcanic environments are discussed, first in general terms, and thereafter by using the examples of two typical volcanic islands, Bali and Lombok (Indonesia), which also illustrate the interaction between tectonism and volcanism in this part of the world. The distribution pattern of volcanism in Southeast Asia is related to plate tectonics, as discussed in Chapter 1. Three major plates dominate the region: the Eurasian, Indo-Australian, and Pacific, each of which is composed of several sub-plates. They meet at a triple point situated south of the Bird’s Head of Papua. Volcanism develops where, at some distance from the deep sea trenches that mark subduction zones, the subducting material melts and the magma rises to the surface. Volcanic geanticlinal belts, known as volcanic arcs and stretching parallel to the subduction zones, are thus formed. The arcs are often affected by transcurrent or compartmental faulting, and their roofs may collapse in places. The activity of individual volcanoes comes to an end when the magma chambers concerned are emptied or become inactive otherwise. Volcanism becomes extinct in (part of ) a volcanic arc when subduction abates. It may shift in position with changes in the configurations of the related subduction zone and plates. The plates, subduction zones, and the location of the volcanoes in Southeast Asia are shown in Figure 1.1. All volcanoes discussed in this chapter are Quaternary volcanoes in the sense that the oldest and most eroded ones ended their activity in the Lower Quaternary. The volcanism is of the intermediate andesite–basaltic Circum-Pacific suite, but locally more acidic rocks (rhyolites, dacites, etc.) occur. Neogene volcanic materials, intercalated with marine strata, are common, particularly in the flanks of the volcanic arcs of the region. Volcanic rocks, dating from Cretaceous and older geological periods and related to Pre-Tertiary subduction patterns, occur in Peninsular Malaysia, Borneo, and other areas outside the present arcs.
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Molnar, Peter. "4. Subduction of oceanic lithosphere." In Plate Tectonics: A Very Short Introduction, 53–76. Oxford University Press, 2015. http://dx.doi.org/10.1093/actrade/9780198728269.003.0004.
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‘Subduction of oceanic lithosphere’ begins with the notion that for the Earth not to expand, the sum total of new lithosphere made at a spreading centre (or mid-ocean ridge) must be matched by the removal, by subduction, of an equal amount of lithosphere elsewhere. The subduction process is asymmetric: one plate will slide beneath the other at island arcs and continental margins like the Andes of South America. Before it plunges beneath the island arc, the subducting plate of lithosphere bends down gently to cause a deep-sea trench. The subducting plate slides beneath the region between the trench and volcanoes, commonly in large earthquakes, and plunges to great depth, pulled down by gravity acting on the dense slab of subducted lithosphere. Water carried to depth by the subducting plate lowers the melting temperature of the adjacent rock and enables volcanoes to form.
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Boniface, Nelson, and Tatsuki Tsujimori. "New tectonic model and division of the Ubendian-Usagaran Belt, Tanzania: A review and in-situ dating of eclogites." In Plate Tectonics, Ophiolites, and Societal Significance of Geology: A Celebration of the Career of Eldridge Moores. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2552(08).
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ABSTRACT Records of high-pressure/low-temperature (HP-LT) metamorphic interfaces are not common in Precambrian orogens. It should be noted that the association of HP-LT metamorphic interfaces and strongly deformed ocean plate stratigraphy that form accretionary prisms between trenches and magmatic arcs are recognized as hallmark signatures of modern plate tectonics. In East Africa (Tanzania), the Paleoproterozoic Ubendian-Usagaran Belt records a HP-LT metamorphic interface that we consider as a centerpiece in reviewing the description of tectonic units of the Ubendian-Usagaran Belt and defining a new tectonic model. Our new U-Pb zircon age and the interpretations from existing data reveal an age between 1920 and 1890 Ma from the kyanite bearing eclogites. This establishment adds to the information of already known HP-LT metamorphic events at 2000 Ma, 1890–1860 Ma, and 590–520 Ma from the Ubendian-Usagaran Belt. Arc–back-arc signatures from eclogites imply that their mafic protoliths were probably eroded from arc basalt above a subduction zone and were channeled into a subduction zone as mélanges and got metamorphosed. The Ubendian-Usagaran events also record rifting, arc and back-arc magmatism, collisional, and hydrothermal events that preceded or followed HP-LT tectonic events. Our new tectonic subdivision of the Ubendian Belt is described as: (1) the western Ubendian Corridor, mainly composed of two Proterozoic suture zones (subduction at 2000, 1920–1890, Ma and 590–500 Ma) in the Ufipa and Nyika Terranes; (2) the central Ubendian Corridor, predominated by metamorphosed mafic-ultramafic rocks in the Ubende, Mbozi, and Upangwa Terranes that include the 1890–1860 Ma eclogites with mid-ocean ridge basalt affinity in the Ubende Terrane; and (3) the eastern Ubendian Corridor (the Katuma and Lupa Terranes), characterized by reworked Archean crust.
Conference papers on the topic "Subduction trenches"
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Aurelio, Mario, Kristine Joy Taguibao, Edmundo Vargas, Maria Visitacion Palattao, Rolando Reyes, Carl Nohay, Roy Anthony Luna, and Alfonso Singayan. "Geological Criteria for Site Selection of an LILW Radioactive Waste Repository in the Philippines." In ASME 2013 15th International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icem2013-96127.
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In the selection of sites for disposal facilities involving low- and intermediate-level radioactive waste (LILW), International Atomic Energy Agency (IAEA) recommendations require that “the region in which the site is located shall be such that significant tectonic and surface processes are not expected to occur with an intensity that would compromise the required isolation capability of the repository”. Evaluating the appropriateness of a site therefore requires a deep understanding of the geological and tectonic setting of the area. The Philippines sits in a tectonically active region frequented by earthquakes and volcanic activity. Its highly variable morphology coupled with its location along the typhoon corridor in the west Pacific region subjects the country to surface processes often manifested in the form of landslides. The Philippine LILW near surface repository project site is located on the north eastern sector of the Island of Luzon in northern Philippines. This island is surrounded by active subduction trenches; to the east by the East Luzon Trough and to the west by the Manila Trench. The island is also traversed by several branches of the Philippine Fault System. The Philippine LILW repository project is located more than 100 km away from any of these major active fault systems. In the near field, the project site is located less than 10 km from a minor fault (Dummon River Fault) and more than 40 km away from a volcanic edifice (Mt. Caguas). This paper presents an analysis of the potential hazards that these active tectonic features may pose to the project site. The assessment of such geologic hazards is imperative in the characterization of the site and a crucial input in the design and safety assessment of the repository.
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Fujimoto, H., S. Miura, A. Sweeney, M. Ito, Y. Osada, and T. Kanazawa. "GPS/acoustic seafloor positioning experiment in the subduction zone of the Japan Trench." In Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492). IEEE, 2003. http://dx.doi.org/10.1109/oceans.2003.178411.
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Tian, Jianwei, Zhe Liu, and Luchuan Ren. "The Seismic Hazard Estimate of the Manila Trench Subduction Zone based on the Generalized Pareto Distribution." In 7th Annual Meeting of Risk Analysis Council of China Association for Disaster Prevention (RAC-2016). Paris, France: Atlantis Press, 2016. http://dx.doi.org/10.2991/rac-16.2016.114.
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Wang, Genhou, Xiao Liang, Jinhan Gao, and Guoli Yuan. "Middle–Late Triassic trench-slope basin in Central Qiangtang, Tibet: Records of subduction-accretion process of the Paleo-Tethys Ocean." In 15th International Congress of the Brazilian Geophysical Society & EXPOGEF, Rio de Janeiro, Brazil, 31 July-3 August 2017. Brazilian Geophysical Society, 2017. http://dx.doi.org/10.1190/sbgf2017-323.
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Lucero, Angela C., Glenn A. Spinelli, and Jiangheng He. "THE THERMAL EFFECTS OF PLATE-BENDING-RELATED THICKENING OF THE OCEANIC CRUSTAL AQUIFER IN THE JAPAN TRENCH AND NANKAI TROUGH SUBDUCTION ZONES." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-304298.
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Bustinza, Juan A., Ricardo J. Rocca, Marcelo E. Zeballos, and Roberto E. Terzariol. "Rerouting of a Pipeline due to Landslide Reactivation in an Andean Valley." In ASME 2013 International Pipeline Geotechnical Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ipg2013-1960.
Full textAbstract:
The bi-national pipeline Loma de la Lata (Argentina)-Talcahuano (Chile) belonging to Gas del Pacifico, crosses the Andes at Latitude 37.1° South (Buta Mallin pass), following the Lileo river valley. In the region, there are large ancient landslides within an area of about 50 km2, which have been attributed to Holocene glaciations and seismic activity. In the winter of 2005, when snow limited the access to the area, it was found a pressure loss, that later was attributed to a landslide in a sector of the south bank of the valley. The adiabatic expansion generated a considerable volume of frozen soil around the pipe. The following summer it was studied the characteristics of the sliding and analyzed different solutions of the affected section. The geotechnical study showed details of the slipped area and its relationships with ancient landslides. It was found by comparative analysis of aerial photographs that an old slide about 1 km3 was not fully reactivated. The general morphology has remained unchanged at least in the last 50 years, when the oldest aerial photography was taken. As additional verification, it was found that a small set of cascading ponds located in the slipped mass, has remained stable at that time, bearing the influence of the great 1960 Mw = 9.6 Valdivia earthquake. It was identified tension cracks delimiting the slipped area that was a modest portion of the historical landslide. Geotechnical parameters were estimated by back analysis of the land involved and it could establish a model for sliding mass process. A general analysis of long-term stability took into account the influence of distant earthquakes such as the subduction zone, which has a recurrence of about 100 years and other local seismic sources. Prior to define the most appropriate solution, a 250 meters long trench was dug preventively releasing the pipeline from the terrain to avoid new deformations. Among the solutions considered were the construction of an absorption system with movement monitoring, or the relocation of the trace on the opposite bank of the river. It was decided to adopt the latter solution due to the difficulty of ensuring the stability of the terrain and the inaccessibility during the winter. It implied an additional river crossing and consequently, the need to monitor the stability of the channel to the river erosion.