Geochemical competition between thermodynamics and kinetics during continental subductionzone metamorphism. The mantle transition zone controls the material and heat exchange between upper and lower mantle. Subduction zone earthquakes templates acrobat pdf 85kb apr29 08 during a lecture, have the students hold the transparency level while allowing the paper to hang downwards at any angle. Geodynamic modelling, though hampered by incomplete knowledge of rheological and mineralogical properties or by the inability to account for them. The word subduction derives from the latin verb subducere, which means pulled away from below, but metaphorically can mean to. Furthermore, plate motion models analysed in terms of subduction zone kinematics. The seismogenic zone of subduction thrust faults, in the seismogenic zone of subduction thrust faults, ed. Thorsten becker university of texas at austin geodynamics 1 subduction zone dynamics and global mantle flow 6272017. Volcanoes associated with subduction zones generally have steep sides and erupt explosively. The monash plate tectonics and geodynamics group blends people with a broad interest in the evolution of our planets tectonics and its link with the dynamics of its interiors. The paper represents the descending oceanic crust and the transparency represents the overriding plate.
Detailed studies of hp and uhp metamorphism published thus far. The role of boundary conditions in numerical models of. Supremacy of either subduction zone depends on physical parameters such as i. Metamorphic chemical geodynamics of continental subduction. The collected gpsglonass data allow us to reveal new information on the recent geodynamics of the kuril island arc. For curious kids patrice rey explains today in the conversation how mountains form. The csz is modeled from cape mendocino in california to vancouver island in british columbia.
Research focus includes tectonic and kinematics reconstructions, laboratory and computational modelling. Convection dominated midocean ridge and subduction zone simulations d. I tectonics and geodynamics grasemann, bernhard, stuwe, kurt encyclopedia of life support systems eolss oceaniccontinental subduction a deep trench is formed e. Pdf study of metamorphic suites directly representing the deep subduction of altered oceanic crust and sediments can help. Subduction zone geodynamics serge lallemand springer. Abstract the cause and geodynamic impact of flat subduction are investigated.
Summary of earth structuregeodynamics ocean leadership. A subduction zone forms when continental crust and oceanic crust collide. The role of boundary conditions in numerical models of subduction zone dynamics matthieu e. Chemical geodynamics is an integrated discipline that studies the geochemical structure and tectonic evolution of geospheres with the aim of linking tectonic processes to geochemical products in the earth system. The moho in subduction zones university of washington. The subduction zone, accordingly, is the antithesis of the midoceanic ridge. Pdf subduction is a major process that plays a firstorder role in the dynamics of the earth. The following is a list of questions compiled by merging the output of the breakout groups.
Ito and yamada, 1982 and to be the likely site of a viscosity increase hager, 1984, both of which will hamper flow across the boundary. Ikuko wada completed a doctoral degree in earth and ocean sciences at the university of victoria, bc, canada in august 2009. Develop an earth model that explains how mantle processes. The sinking of cold lithosphere into the mantle is thought by many authors to be the most important source of energy for plates driving forces. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The method adapts the mesh automatically around regions of high solution gradient, yielding enhanced resolution of the associated ow features. In the long run, how easily slabs sink through the transition zone controls how efficiently material and heat are circulated in the mantle. Seismicity and tomographic constraints from the andean margin. Investigating cascadia subduction zone geodynamics through.
Temporal and spatial relationships between protolith origin and collision type in continental subduction zones. Seismicity and tomographic constrains form the andean margin article pdf available in tectonics january 2000 with 299 reads how we measure reads. Global kinematics of tectonic plates and subduction zones since the. Outer rise earthquakes occur when normal faults oceanward of the subduction zone are activated by flexure of the plate as it bends into the subduction zone. The cascadia subduction zone extends over km along the coast of the. Plain language summary divergent double subduction dds is a potential way for closure of oceanic basins in plate tectonics, but its mechanism remains unsolved. The 2009 samoa earthquake is an example of this type of event. The sinking of cold lithosphere into the mantle is. Multiscale dynamics of the tongakermadec subduction zone. Imaging p and s attenuation in the termination region of. Geodynamics is a subfield of geophysics dealing with dynamics of the earth.
The dabiesulu orogenic belt of eastcentral china has long been a type location for the study of geodynamic processes associated with ultrahighpressure uhp tectonics. The maximum deformation stress accumulates in the southern and northern parts of the study area, while a long fading transition process of postseismic motions is observed in the central segment of the kuril arc as a result of the 20062007 great simushir. Sequestration and subduction of deepsea carbonate in the global ocean since the early cretaceous. Displacement of the sea floor caused by this event generated a sixmeter tsunami in nearby samoa. Her dissertation research focused on the depth extent of mechanical decoupling between the subducting slab and the overlying mantle and its effect on mantle wedge flow and the thermal structure. Study of metamorphic suites directly representing the deep subduction of altered oceanic crust and sediments can help elucidate the geochemical evolution of the forearctosubarc slabmantle interface, the nature of slabderived fluids added to arc lava source regions, and the chemical changes in subducting rocks potentially contributing to the geochemical heterogeneity of the deeper mantle. Sinking of the oceanic lithosphere sediments, crust, mantle, by contrast of density between the cold and old lithosphere and the hot asthenospheric mantle wedge, is the strongest force but not the only one needed to drive plate motion and is the dominant mode of mantle convection. Buitera,b, susan ellisc a centre for geodynamics, geological survey of norway ngu, leiv eirikssons vei 39, 7491 trondheim, norway.
Subduction zone igneous activity formed most ore deposits and. The cause and geodynamic impact of flat subduction are investigated. Metamorphic chemical geodynamics in continental subduction zones. What experiments, observations, or activities are likely to. Each of the papers collected in the present volume is primarily concerned with one of these topics. The maximum deformation stress accumulates in the southern and northern parts of the study area, while a long fading transition process of postseismic motions is observed in the central segment of the kuril arc as a result of the 20062007 great simushir earthquakes of m w 8. The 2004 sumatra earthquake and other great earthquakes giancarlo scalera ingv istituto nazionale di geo.
Shallow subduction zone earthquakes and their tsunamigenic. Covers most recent developments in subduction zone dynamics. Geodynamics subduction through the mantle transition. Subduction processes in oceanicoceanic plate convergence also result in the formation. The upperlower mantle boundary has long been realized to coincide with an endothermic phase transition ringwood, 1975. Much of our understanding of the worlds most enigmatic processes in.
How can the cnd be enhanced to better address this science. As the plate sinks deeper, it can reach depths of 50 to 100 miles 80160 kilometers were it is so hot that the crust releases fluids. Double subduction is a geodynamic process in which two plates following each other are synchronously subducted. The approach utilizes an automatic, unstructured mesh generator and a. A complete timedependent model for the cascadia subduction zone, including m 8. Cascadia subduction zone csz were discussed and debated at a march 2829, 2006 pacific northwest workshop for the usgs national seismic hazard maps. What other approaches could be combined with the observatory elements to better address the science questions across the range of spatialtemporal scales. Pdf chemical geodynamics of continental subductionzone. The study of uhp metamorphism and continental deep subduction has greatly promoted the development of solid earth sciences in china. Tectonics and geodynamics encyclopedia of life support. Physics of the earth and planetary interiors dynamics of double. Perry 2016, the thermal effect of fluid circulation in the. Geodynamics subduction through the mantle transition zone.
Pdf subduction zones are where sediments, oceanic crust, and mantle lithosphere return to and reequilibrate with earths mantle. Metamorphic chemical geodynamics in continental subduction. Such collisional orogens are characterized by foldandthrust belts, regional metamorphism, igneous activities, exhumation of highgrade and ultrahighpressure rocks and. Importantly, circulation models with an improved representation of convergent margins will help to close the gap between regional and global approaches to subduction, and to better understand the potential role of the overriding plate. They are known to have a very important role in modulating climate on earth, and are believed to have played an essential part in making the earths surface habitable, a role that extends to presentday. Subduction zone geodynamics, seismic tomography and anisotropy, great subduction zone earthquakes, seismogenic zone characterization, continental and ridge subduction processes. The thrust convergence rate on the trench as calculated from gps wallace et al. The seismic expression of both forms is linked to the nature of a landward dipping, lowvelocity zone lvz that has been detected in a. Mapping the growth of seafloor carbonates in deep time. A figure showing the oceanic plate sliding beneath the continental plate. Jul 11, 2017 thorsten becker university of texas at austin geodynamics 1 subduction zone dynamics and global mantle flow 6272017. The word subduction derives from the latin verb subducere, which means pulled away from below, but metaphorically can mean to lose footing or remove secretly. It was primarily focused on mantle geochemistry, with an emphasis on geochemical recycling in oceanic subduction zones.
Shallow subduction zone earthquakes and their tsunamigenic potential j. Aspect, like other geodynamics codes that solve the stokes equation, assumes that the. We first calculate the timedependent probability only for the m 8. Thermomechanically coupled subduction modelling with aspect. The multiscale nature of dynamics within the earth is easily seen in the observed geoid and bathymetry in the region surrounding the tongakermadec subduction zone. Subduction zone, oceanic trench area marginal to a continent in which, according to the theory of plate tectonics, older and denser seafloor underthrusts the continental mass, dragging downward into the earths upper mantle the accumulated trench sediments. Kanamori seismological laboratory, caltech, pasadena, ca 91125,usa. Pdf subduction zones are where sediments, oceanic crust, and mantle. Subduction is a major process that plays a firstorder role in the dynamics of the earth. Subduction zone volcanism volcano world oregon state.
Earthquake hypocenter data image two morphologic highs in the subducting nazca plate which correlate with the positions of subducted oceanic plateaus. The continental crust is thicker and more buoyant than the oceanic crust so the oceanic crust subducts beneath the continental crust. The seismic expression of both forms is linked to the nature of a landward dipping, lowvelocity zone lvz that has been detected in a majority of subduction zones about the. He 2016, modeled temperatures and fluid source distributions for the mexican subduction zone. The northern south island marks the transition between the hikurangi subduction zone which forms the southern end of the kermadec subduction zone and the dextral alpine fault and southern alps in central south island, which are associated with oblique continental collision fig. The observed geoid is dominated by a very longwavelength 5000 km increase in geoid height, from east to west and south to north 40100 m. Subduction zones are ubiquitous features on earth, and an integral part of plate tectonics.
Buitera,b, susan ellisc a centre for geodynamics, geological survey of norway ngu, leiv eirikssons vei 39, 7491 trondheim, norway b physics of geological processes, university of oslo, po 1072 blindern, 0316 oslo, norway c gns science, po box 30368, lower hutt, new zealand. Mar 14, 2018 in the long run, how easily slabs sink through the transition zone controls how efficiently material and heat are circulated in the mantle. Pdf metamorphic chemical geodynamics of subduction zones. First, the 1500 km long peru flat slab segment is examined. The study of uhp metamorphism and continental deepsubduction has greatly promoted the development of solid earth sciences in china. Find materials for this course in the pages linked along the left. Recent geodynamics of the kuril subduction zone springerlink. Her research at whoi focused on 1 the sharp transition in seismic attenuation in the forearc mantle wedge due to nonlinear mantle wedge flow wada et al. Twenty years of subduction zone science geological society of. Citescore values are based on citation counts in a given year e. It applies physics, chemistry and mathematics to the understanding of how mantle convection leads to plate tectonics and geologic phenomena such as seafloor spreading, mountain building, volcanoes, earthquakes, faulting and so on. Subduction zones produce volcanic arcs, curving chains of steepsided volcanoes, for example the aleutian islands in alaska. Metamorphic chemical geodynamics of subduction zones. Subduction zones are interior expressions of earths 55,000 km of convergent plate margins and are the geodynamic system that builds island.
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