What geological events occur at plate boundaries?
Excellent answer given.Transform Plate BoundaryI grew up near one of the most famous plate boundaries in the world, a transform boundary, which separates the Pacific plate from the North American plate. We have experienced, since I was born, over 1,320,000 earthquakes (all sizes, mostly small quakes) that have occurred in and around this plate boundary - one of the most seismically active areas of the world (and a great place to study geology, seismology, vulcanology, plate tectonics, geomorphology, petrology, paleontology, mineralogy, geophysics, and so many more disciplines).Convergent Plate BoundaryConvergent plate boundaries, such as the Indian plate and Eurasian plate boundary, have produced (and are still producing) the Himalayas and the uplifted Tibetan plateau; other convergent plate boundaries, between continental plates (Eurasian, North American, and South American) and oceanic plates (Pacific and other minor plates, such as the Juan de Fuca, the Cocos, the Philippine Sea plates) causes the oceanic plates to dive under the continental plate, giving many deep quakes, tsunamis, volcanic arcs (e.g. the infamous Ring of Fire, which consists of 452 volcanos, active and dormant). Subduction rates vary greatly, depending on the speed of encroachment of the overriding plate, the speed of the nearest seafloor spreading zone, and so forth.Divergent Plate BoundaryA divergent plate boundary is essentially the seam between plates (oceanic or continental) where new magma / lava is introduced and where the plates that are either side of that seam are augmented. Rates of spreading varies, from 3 cm/yr at the Mid-Atlantic Ridge to 14 cm/yr at the East Pacific Rise (spreading rates at the EPR were as high as 20 cm/yr). The Rift Valley of East Africa is another spreading zone, which is slowly ripping Africa into two sections, moving at between 6–7 mm/yr.Map courtesy of WikimediaIn an estimated 10 million years, the lithosphere will rupture, the Somalian plate will break off, and a new ocean basin will form.The interplay of the various types of Plate boundaries gives us the surface features that we have come to know. In a slow dance, the surface is always changing, with some plate boundaries building up, others tearing down, and others still grinding away.[1]Footnotes[1] East African Rift - Wikipedia
Divergent boundaries are mostly seen in oceanic crust. Why?
I think this is not due to particular factor (reason) or it only favors ocenic crust.Since it is due to magma convection i.e an internal process not an external surface process so magma convection do not depend on the nature of the surface i.e oceanic or land.Since after 200 million year and also depending on the rate of movement of the great rift.It will be definitely became a mid oceanic ridge…Iam saying this because as the rift progress the thickness of the great rift valley will also increase and a time will come when a giant sea and then occean will be formed from this rift.As we know mid altantic ridge is a mid oceanic ridge but there was a time when it was a part of Gondwana land and at the time of origin it was definitely started as a rift but now it is mid oceanic ridge…We can also say that only in the early stage of divergence it will be conveniental while as time passes and as it mature it will became oceanic.Go Green…
Why does subduction occur at an oceanic-oceanic plate boundary, but not at a continental-continental boundary?
The plate that is subducted in an oceanic-oceanic convergent boundary is the older one. Because it is older, it is more dense. Because it is more dense, then it is the one that is subducted. In continental-continental plate boundaries, the plates involved are essentially the same density. Since continental crust is more buoyant, or less dense, than oceanic crust, one plate does not easily override the other. Instead, the plates crumple as they plow into one another, and a very high mountain range is created. This is a special type of convergent boundary called a collisional boundary. EDIT: For Mike: The lithospheric plates are not of the same age because the ocean floor is constantly renewing itself due to sea floor spreading. This process does not affect the age of continental plates. Older oceanic plates are more dense due to being colder, accumulation of sediment and compaction.
How do the 3 main types of plate boundaries compare and contrast?
The three types of plate boundaries are Convergent, Divergent and Transform.The convergent plate boundary is when two plates move towards each other. In this case it has three possibilities:An oceanic-continental convergent: In this case the the oceanic plate goes beneath the continental in a subduction zone. And due to this process, the continental crust crumples and forms mountains.An oceanic-oceanic convergent: Here the denser plate goes beneath the other in a subduction zone.A continental-continental convergent: And in this case the thickness of the crust doubles as the convergent makes mountains.The divergent plate boundary is when two plates move away from each other. This type of plate boundaries happens between the same plate type, this way it has two possibilities:An oceanic-oceanic divergent: In this case when two plates goes apart, the magma from the mantle goes up to fill the gap that the separation made.A continental-continental divergent: And here it’s characterized by rift valleys.The third and last type is the transform plate boundary. And this one happens when two plates slide along each other horizontally.
What are the different types of plate tectonic boundaries?
1. Divergent Boundary: A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, lava spews from long fissures and geysers spurt superheated water. Frequent earthquakes strike along the rift. Beneath the rift, magma—molten rock—rises from the mantle. It oozes up into the gap and hardens into solid rock, forming new crust on the torn edges of the plates. Magma from the mantle solidifies into basalt, a dark, dense rock that underlies the ocean floor. Thus at divergent boundaries, oceanic crust, made of basalt, is created.2. Convergent Boundary : When two plates come together, it is known as a convergent boundary. The impact of the two colliding plates buckles the edge of one or both plates up into a rugged mountain range, and sometimes bends the other down into a deep seafloor trench. A chain of volcanoes often forms parallel to the boundary, to the mountain range, and to the trench. Powerful earthquakes shake a wide area on both sides of the boundary. If one of the colliding plates is topped with oceanic crust, it is forced down into the mantle where it begins to melt. Magma rises into and through the other plate, solidifying into new crust. Magma formed from melting plates solidifies into granite, a light colored, low-density rock that makes up the continents. Thus at convergent boundaries, continental crust, made of granite, is created, and oceanic crust is destroyed.3. Transform plate boundary : Two plates sliding past each other forms a transform plate boundary. Natural or human-made structures that cross a transform boundary are offset—split into pieces and carried in opposite directions. Rocks that line the boundary are pulverized as the plates grind along, creating a linear fault valley or undersea canyon. As the plates alternately jam and jump against each other, earthquakes rattle through a wide boundary zone. In contrast to convergent and divergent boundaries, no magma is formed. Thus, crust is cracked and broken at transform margins, but is not created or destroyed.
Describe the three types of tectonic plate boundaries and motion that occurs at each type of boundaries?
Divergent plate boundaries (mid ocean ridges). Plates are moving away from each other and new ocean floor is being created Convergent plate boundaries (subduction zones) Plates are moving towards each other, with one plate being pulled/pushed down into the athenosphere Transform Boundaries (transform fault) Plates are sliding past each other.
Convergent Boundary and Subduction?
They are the same, except "Subduction" is a specific process. Technically a Convergent boundary can be Transform for a portion of its history, but that is a semantic argument and may not even truly be real in actual nature.