Oceancontinent convergence when oceanic crust converges with continental crust, the denser oceanic plate plunges beneath the continental plate. Plate tectonics processes and landforms at plate margins. The himalayas in south central asia are an example of a continent continent convergent plate boundary. Destructive plate margins occur where continental and oceanic plates meet or two continental plates collide. Which of the following sea s was formed when subduction jum. This margin can be found on land as well as in the centre of oceans. A passive margin is the transition between oceanic and continental lithosphere that is not an. Those are continent continent, continent ocean, and ocean ocean. As the plates converge, friction occurs between them. Whereas subduction recycling of oceanic lithosphere is one of the central themes of plate tectonics, the recycling of continental lithosphere appears to be far more complicated and less well. First of all, let us clarify that a continental margin is a boundary between a continental plate composed of generally ancient, thick and relatively low density continental crust composed of granitic, sedimentary and metamorphic rocks and an oc.
Because there is no collision or subduction taking place, tectonic activity is. This is where the oceanic crust converges with another oceanic crust. On the accompanying map, large destructive earthquakes that affect land are most likely at locations. Describe where destructive margins are located in europe and the pacific ocean. When friction is overcome and strain is released, the gps receiver will snap back toward its original position. What do we find at convergent subduction zones ocean.
Oceanocean convergent plate boundaries learn that subduction of the older, denser oceanic crust leads to the formation of a volcanic island arc and accompanying earthquakes. Convergent plate boundaries are locations where lithospheric plates are moving towards one another. This process, called subduction, occurs at the oceanic trenches. Subduction of one of the oceanic plates occurs because one plate is likely to be older and denser than the other. Oceancontinent convergent plate boundaries read earth. Pdf tectonic interactions between india and arabia since the.
Typically this is the result of a collision of some kind either two continents colliding. The continent ocean boundary cob or continent ocean transition is the boundary between continental crust and oceanic crust on a passive margin. Regional tectonic map of the arabiaindiaeurasia collision zone, with. Active margins are found on the edge of a continent where subduction occurs. Numerical simulations of an oceancontinent convergent system. The volcanic activity the subduction causes leads to the formation of a chain of volcanic islands known as an island arc.
Convergent margins are among the worlds most seismogenic zones, and are characterized by progressively deeper earthquakes as one proceeds from trench to backarc region at most convergent margins, these earthquake foci define a dipping plane the wadatibenioff zone, or wbz which corresponds to a fault zone between subducting oceanic. Subductiondriven recycling of continental margin lithosphere. Jan 04, 2017 first of all, let us clarify that a continental margin is a boundary between a continental plate composed of generally ancient, thick and relatively low density continental crust composed of granitic, sedimentary and metamorphic rocks and an oc. In the future, as the atlantic continues to widen due to sea floor spreading in the centre, the ocean continent boundaries will eventually become subduction zones with new convergent destructive margins being formed. The destructive nature of subduction erosion poses challenges to fully understanding the evolution of erosive convergent margins that are critical to understanding crustal recycling and seismogenesis. Influence of subduction geometry and mantle wedge hydration on crustal recycling may 2010 geochemistry geophysics geosystems 115.
The plates are locked and the overlying plate is forced back. The marginal sea and the continental shelf basins, mainly. The thinner oceanic plate sinks beneath the continental plate, forming an ocean trench and subduction zone. Chapter 3 geology 111 with susan harris at central carolina. Carbonate limestone dominated passive margin continental shelf. Examples in the world another example of the oceaniccontinental convergent boudaries is the washingtonoregon coastline of the us. You need to understand this concept, open up your text book, look at the cross sections and it will become clear. Ocean continent convergence when oceanic crust converges with continental crust, the denser oceanic plate plunges beneath the continental plate. Gps can record the movement of the leading edge of the overlying continental plate in a subduction zone. This is an active margin, where subduction and transverse faulting are taking place. The continental margin is a major zone of the ocean floor. The interaction of the subduction zone and the asthenosphere of the mantle generates the melts that rise to feed the volcanism typical of island arcs and active continental margins. The edge of an oceanic plate is shown sinking subducting under a continental plate, because of gravity.
Destructive plate margin at convergence of oceanic and. On active margins, such as the western part of the north american plate, the north american continent roughly coincides with the plate boundary. It is constantly being recycled into the mantle, only to. Destructive margins oceaniccontinental mr rudge geography. Trenches associated with subduction zones act as sediment traps. A divergent plate boundary is most likely associated with an. Exploring geology with connect plus 1semester access card 3rd edition edit edition. The collision of tectonic plates can result in earthquakes, volcanoes, the formation of mountains, and other geological events.
Subduction erosion along the middle america convergent margin. As an oceanic plate descends to hotter depths beneath the overriding plate, it is heated and releases water. Where in the oceans is the newest ocean crust found. The ocean floor is some of the youngest pieces of the crust we have. Subduction zones are convergent destructive margins. If theyre subducting you get crust entering the mantle and being recycled and volcanos being created.
Continent continent convergent plate boundaries are not zones of subduction in the normal sense. The plates are locked together and periodically overcome the friction causing the leading edge of the overlying plate to surge back, lifting a wall of water producting a tsunami. Williams and others published ocean subduction find, read and cite all the research you need on researchgate. The nazca plate and the south american plate forming the andes along the west coast of south america. Which of the following seas was formed when subduction. The resulting magma is less dense than the surrounding rock, so it rises up toward the surface. An example of subduction is the pacific plate subducting under the north america plate. Subductionrelated offscraping created the central rangehengchun peninsulahengchun ridge accretionary complex and the luzon arc and forearc basin fig. If the area shown in this figure is 240 kilometers wide, and the oldest crest is 4 million years old, what was the approximate rate of seafloor spreading across this ridge.
The east and west sides of the atlantic are good examples at present. At which type of plate margin would you expect to find black smokers. This happens because the oceanic plate is denser heavier than the continental plate. When an oceanic plate converges with a continental plate, it is always.
Ocean ocean convergent plate boundaries learn that subduction of the older, denser oceanic crust leads to the formation of a volcanic island arc and accompanying earthquakes. Which one of the following mountain ranges have been formed by continental collision at a convergent plate margin. The process going on with convergent plates are that two plates are colliding or subducting depending on the crust. Chapter 3 geology 111 with susan harris at central. This movie was created to show the formation of cretaceous rocks in california, including the sierra nevada granite batholiths, great valley sediments, and the franciscan formation accretionary wedge, but it applies in a general way to many oceancontinent subduction. Subduction zones have a lot of intense earthquakes and volcanic eruptions. Describe where destructive margins are located in europe. There are no plate boundaries now, but a subduction zone will form along the western coast of the continent, and the eastern part of the continent will be rifted away. The continental margin consists of three features continental rise.
Feb 05, 2009 this is a good distance from the passive margins of north american continent or the european continent. Is any part of panama in south america or is all of panama in north america. Divergent plate boundarypassive continental margins geology. On this map, identify which letter is over the pacific ocean. In a sense, subduction zones are the opposite of divergent boundaries, areas where material rises up from the mantle and plates are moving apart. Oceancontinent subduction, animation illustrates the geologic processes commonly found at oceancontinent subduction zones. Most commonly found in oceans, the plate type is oceanic on both sides and upon moving apart a gap is left, which is immediately filled with magma that rises up from the mantle. From convergent plate margin to arccontinent collision. At each one there are distinctive landforms and events that characterise them. Subduction zones, island arcs and active continental margins. Did the character of subduction change at the end of the.
Earthquakes at the margins of ocean crust show a pattern of progressively deeper foci plural of focus further toward the continent and away from the ocean plate. Continental crustal material is generally too light to be subducted to great depth. The identification of continent ocean boundaries is important in the definition of plate boundaries at the time of breakup when trying to reconstruct the geometry and position of ancient continents e. In addition, essential clues on the evolution of subduction zones that culminated in the thrusting of. Pdf numerical simulations of an oceancontinent convergent. Instead, the two continents collide with each other, folding, thrust faulting, and building upward into a high, wide mountain range. The ccop forms in the upper plate of this subduction zone, behind the arc, at ca. Changes in the ratio of ttg to calcalkaline granitoids after 2. Whats the difference between an active and passive continental margin. Where two plates move toward each other a oceanic continental. The atlantic and gulf coasts show the classic form of a passive continental margin.
Late cretaceous subduction initiation on the eastern margin. Subduction does still occur because one plate is highly likely to be slightly olderdenser than the other. Observe an animation of volcanism at a subduction zone. The presence of hot, waterrich liquids causes the overlying rock to begin melting. When continental and oceanic plates collide, the thinner and more dense oceanic. Nov 26, 2016 the continental margins of the pacific ocean are narrower than those of the atlantic and are not covered with thick layers of sediment.
The volcanic activity the subduction causes the same as in oceaniccontinental destructive margins leads to the formation of a chain of volcanic islands like the mariana islands. Post120 ma magmatism in the great arc occurs above a westdipping subduction zone. The continental shelf is the shallow, flooded edge of the continent. The convergence of two oceanic plates represents the simplest type of destructive plate boundary and exemplifies most of the features associated with the destruction of oceanic lithosphere. The plate collisions that occur in these areas can produce earthquakes, volcanic activity, and crustal deformation.
In the future, as the atlantic continues to widen due to sea floor spreading in the centre, the oceancontinent boundaries will eventually become subduction zones with new convergent destructive margins being formed. Oceaniccontinental convergencevaried subduction angles depending on density, therefore it depends on lithologymineralogy and temperaturefor example, subduction below the peruchile region has a very low angle due to proximity to ocean spreading center. The answer is simple midocean ridges are divergent constructive margins. Plate tectonics plate boundaries 2 convergent destructive margins where two plates move toward each other a. In continentocean subduction boundaries, this sediment is deposited in the ocean. A convergent plate boundary is a location where two tectonic plates are moving toward each other, often causing one plate to slide below the other in a process known as subduction. It separates the thin oceanic crust from the thick continental crust.
Coastal plains are often dominated by fluvial processes, while the continental shelf is dominated by deltaic and longshore current processes. Nov 12, 2014 whereas subduction recycling of oceanic lithosphere is one of the central themes of plate tectonics, the recycling of continental lithosphere appears to be far more complicated and less well. Late cretaceous subduction initiation on the eastern. The subduction zone iswhere two tectonic lithospheric plates come together, one subducting diving beneath the other. Covers convergent plate boundaries where an oceanic plate meets a continental plate. Continental lithosphere lies at a higher surface elevation than oceanic lithosphere because of its lower overall density. When an oceanic plate converges with a continental plate, it is always the ocean plate that subducts beneath the continental plate. The processes occurring here are that the plates are being pulled apart in a pattern of divergence. How did these ocean features and continental margins form. The nankai subduction zone, a site of great earthquakes and a relatively shallow. The south china sea continental shelf developed after collapse of the west pacific subducting margin. In an active continental margin, the boundary between the continent and the ocean is.
Mar 19, 2020 a convergent plate boundary is a location where two tectonic plates are moving toward each other, often causing one plate to slide below the other in a process known as subduction. Destructive, constructive and conservative plate margins bbc. Dec 14, 2008 in a sense, subduction zones are the opposite of divergent boundaries, areas where material rises up from the mantle and plates are moving apart. After a full day of talks and posters on the subject, approximately 125 scientists continued with a nankai subduction zone town meeting on december 15, 2000 at the san francisco american geophysical union meeting, cosponsored by intermargins and u. Daniela mata, jonathan perez, chris valdez,adrian sosa real life examples references good afternoon ladies and gentlemen. Cenozoic plate tectonics and basin evolution in indonesia.
506 682 241 522 556 664 324 1051 357 716 627 689 906 596 570 541 841 23 1103 519 1304 28 1232 215 1256 1027 545 885 856 570 733