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7 de mar. de 2024 · There are many different types of plate boundaries. For example, sections of Earth’s crust can come together and collide (a “convergent” plate boundary), spread apart (a “divergent” plate boundary), or slide past one another (a “transform” plate boundary).
Spreading rates vary considerably, from 1 cm/y to 3 cm/y in the Atlantic, to between 6 cm/y and 10 cm/y in the Pacific. Some of the processes taking place in this setting include (Figure 4.26): Melted rock (magma) from the mantle rising up to fill the voids left by divergence of the two plates.
Rates of motions of the major plates range from less than 1 cm/y to over 10 cm/y. The Pacific Plate is the fastest, followed by the Australian and Nazca Plates. The North American Plate is one of the slowest, averaging around 1 cm/y in the south up to almost 4 cm/y in the north.
There are three kinds of plate tectonic boundaries: divergent, convergent, and transform plate boundaries.
- Divergent Boundaries
- Convergent Boundaries
- Transform Boundaries
- Plate-boundary Zones
- Rates of Motion
Divergent boundaries occur along spreading centers where plates are movingapart and new crust is created by magma pushing up from the mantle. Picturetwo giant conveyor belts, facing each other but slowly moving in oppositedirections as they transport newly formed oceanic crust away from the ridgecrest. Perhaps the best known of the divergent bounda...
The size of the Earth has not changed significantly during the past 600million years, and very likely not since shortly after its formation 4.6billion years ago. The Earth's unchanging size implies that the crust mustbe destroyed at about the same rate as it is being created, as Harry Hesssurmised. Such destruction (recycling) of crust takes place ...
The zone between two plates sliding horizontally past one another is calleda transform-fault boundary, or simply a transform boundary. Theconcept of transform faults originated with Canadian geophysicist J. TuzoWilson, who proposed that these large faults or fracture zonesconnecttwo spreading centers (divergent plate boundaries) or, less commonly, ...
Not all plate boundaries are as simple as the main types discussed above.In some regions, the boundaries are not well defined because the plate-movementdeformation occurring there extends over a broad belt (called a plate-boundaryzone). One of these zones marks the Mediterranean-Alpine region betweenthe Eurasian and African Plates, within which sev...
We can measure how fast tectonic plates are moving today, but how do scientistsknow what the rates of plate movement have been over geologic time? Theoceans hold one of the key pieces to the puzzle. Because the ocean-floormagnetic striping records the flip-flops in the Earth's magnetic field,scientists, knowing the approximate duration of the rever...
A spreading center is a linear area where new crust forms where two crustal plates are moving apart, such as along a mid-oceanic ridge. Spreading centers are typically seismically active regions in ocean basins and may be regions of active or frequent volcanism (Figure 4.7).
Boundaries between the plates are of three types: divergent (i.e., moving apart), convergent (i.e., moving together), and transform (moving side by side). Before we talk about processes at plate boundaries, it’s important to point out that there are never gaps between plates.
