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Where two plates are being stretched apart.
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The divergent motion and creation of oceanic crust caused by rising magma along divergent plate boundaries, evidence includes:
- Deep ocean floor show basaltic oceanic crust and overlying sediment which become progressively younger as the mid-ocean ridge is approached, and the sediment cover is thinner near the ridge. Second,the rock making up the ocean floor is considerably younger than the
- continent. This confirms that older ocean crust has been reabsorbed in
- ocean trench systems.
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Linear Sea
Water in an oceanic trench?
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Oceanic Lithosphere Layers
Oceanic lithosphere consists mainly of: Mafic Crust and Ultramafic Mantle, and is denser than continental lithosphere.
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General term for an underwater mountain system that consists of various mountain ranges (chains), typically having a valley known as a rift running along its spine, formed by plate tectonics.
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Volcanoes are generally found where tectonic plates are diverging or converging. Mid-Atlantic Ridge, Pacific Ring of Fire
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Boundary where two plates are forced into eachother
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3 Types of Convergent Boundaries
- Oceanic to Continental-oceanic plate is subducted due to the fact that it is more dense, which can cause volcanos and mountain building
- Oceanic to Oceanic-subduction, causing underwater volcanoes to form
- Continental to Continental-two continental plates collide, neither subducts into the mantle, the
- crust is thickened, and mountain ranges are formed from the thickening
- and uplift
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The process by which an oceanic plate is driven beneath another plate into the mantle along a convergent boundary
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formed from sediments that are accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust
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A type of archipelago composed of a chain of volcanoes which alignment is arc-shaped, and which are situated parallel and close to a boundary between two converging tectonic plates
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Geologic features, submarine basins associated with island arcs and subduction zones, result from tensional forces caused by oceanic trench rollback and the collapse of the edge of the continent
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- A depression in the sea floor located between an accretionary wedge and a
- volcanic arc in a subduction zone, and lined with trapped sediment.
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In an Andestic magma contains 52–63% silica, the lava is of intermediate composition.These "andesitic" volcanoes generally only occur above subduction zones. Andesitic lava is typically formed at convergent boundary margins of tectonic plates
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Obduction occurs where a fragment of continental crust is caught in a subduction zone with resulting overthrusting of oceanic mafic and ultramafic rocks from the mantle onto the continental crust creating an ophiolite.
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- a section of the Earth's oceanic crust and
- the underlying upper mantle that has been uplifted and exposed above sea
- level and placed on the continental crust
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A deep long depression in the sea floor making the surfaceof a subduction zone
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Beginning of an accretion event which is a process by which material is added to a tectonic plate or a landmass. This material may be sediment, volcanic arcs, seamounts or other igneous features
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A suture is structural geology in a major fault zone through an orogen or mountain range.
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A portion of a plate added to a larger block of crust
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Any small lithospheric plate.
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Lithology, age, fossils, and paleomagnetic orientation of a suspect terrane may differ from its host continent.
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Active Continental Margins
Passive Continental Margins
Leading Edge Margins
Trailing Edge Margins
Place where the edge of a continent coincides with a plate boundary, West vs. East Coast of the US
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- Fold Mountains (Folded Mountains):
- when two plates collide head on
- Faultblock Mountains(BlockMountains):
- form when faults or cracks in the earth's crust force some materials or blocks of rock up and others down
- DomeMountains:
- are the result of a great amount of melted rock (magma) pushing its way up under the earth crust. Without
- actually erupting onto the surface, the magma pushes up overlaying rock layers
- VolcanicMountains:
- formed when molten rock (magma) deep within the earth, erupts, and piles upon the surface
- Plateau Mountains:
- mountains are formed by erosion. Plateaus are large flat areas next to folded mountains
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- A geological fault (a form of strike-slip fault) found in mid-ocean
- ridges in which displacement undergoes a sudden change in direction
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Complex or Folded Mountain
- Folded, or complex, mountains are created by intense compressional forces that fold, fault, and metamorphose the rocks,
- resulting in many of the world's biggest mountain belts, such as the
- Himalayas
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Causes landforms and rocks to be disrupted, creating features that geologists can uses to interpret the forces that made them
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Causes rocks to crumple and buckle, reverse faults are found in areas of compression
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Reverse and Thrust Faults
A fault along which one side is moved up and over the otherside as a result of compression
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Extension
Stretching that occurs in response to stresses directed away from eachother
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A fault that drops down one side down relative to the other as a result of extension
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Forces causing two bodies of rock or other materials to move past eachother
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Strike Slip Fault or Transform Fault
Fault with lateral motion, also a transform fault
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A combination of compression and transform motion
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A combination of extension and transform motion
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Deformation refers to the changes in volume or shape of a body of rock
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