what is a continental divergent boundary

Continental-continental divergent/constructive boundary In plate tectonics

, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.

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What country formed over a divergent boundary?

Iceland is on a type of tectonic plate boundary called a divergent boundary. The divergent boundary, called the Mid-Atlantic Ridge, that runs through the center of Iceland occurs because two plates, the North American Plate and the Eurasian Plate, are pulling away from each other.

What is a real life example of a divergent boundary?

What is a real life example of a divergent boundary? Divergent boundaries occur where two plates move apart from each other. This happens at the mid-ocean ridges, where seafloor spreading and volcanic activity continuously add new oceanic crust to the oceanic plates on both sides. Examples are the Mid-Atlantic Ridge and East Pacific Rise.

What feature is formed in divergent boundary on a continent?

What do divergent boundaries form?

• Ophiolites. Oceanic spreading centers or mid-ocean ridges produce oceanic crust and a unique type of rock section called ophiolites.
• Hydrothermal Vents – Black Smokers. As magma is brought toward the surface at mid-ocean ridges, hydrothermal vents transport superheated, mineral rich water to the ocean floor.
• Extreme Biological Environments. ...

Where can you find a divergent continental plate boundary?

Unlike convergent boundaries, divergence occurs between only oceanic or only continental plates, not one of each. The vast majority of divergent boundaries are found in the ocean, where they were not mapped or understood until the mid-to-late 20th century. In divergent zones, the plates are pulled, and not pushed, apart.

What is an example of a continental to continental divergent boundary?

The East African Rift is a continental divergent boundary in East Africa.

What are 2 examples of divergent boundaries?

Visit the Interactive Plate Boundary Map to explore satellite images of divergent boundaries between oceanic plates. Two locations are marked: 1) the Mid-Atlantic Ridge exposed above sea level on the island of Iceland, and 2) the Mid-Atlantic Ridge between North America and Africa.

What are 3 things that are formed at a divergent boundary?

Most divergent plate boundaries are underwater and form submarine mountain ranges called oceanic spreading ridges. While the process of forming these mountain ranges is volcanic, volcanoes and earthquakes along oceanic spreading ridges are not as violent as they are at convergent plate boundaries.

What places have divergent boundaries?

Well known ocean ridges include the Mid Atlantic Ridge, the East Pacific Rise, the Juan de Fuca Ridge, and the Galapagos Rise. Within continents, divergent margins produce rift valleys such as the Red Sea and East African Rifts; and the lesser known West Antarctic Rift.

What is an example of a divergent plate?

A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earth's mantle to the surface, solidifying to create new oceanic crust. The Mid-Atlantic Ridge is an example of divergent plate boundaries.

What is a famous divergent boundary?

Perhaps the best known of the divergent boundaries is the Mid-Atlantic Ridge. This submerged mountain range, which extends from the Arctic Ocean to beyond the southern tip of Africa, is but one segment of the global mid-ocean ridge system that encircles the Earth.

What is the example of convergent boundary?

Examples. The collision between the Eurasian Plate and the Indian Plate that is forming the Himalayas. Subduction of the northern part of the Pacific Plate and the NW North American Plate that is forming the Aleutian Islands. Subduction of the Nazca Plate beneath the South American Plate to form the Andes.

What happens when 2 continental plates diverge?

When two continental plates diverge, a valleylike rift develops. This rift is a dropped zone where the plates are pulling apart. As the crust widens and thins, valleys form in and around the area, as do volcanoes, which may become increasingly active.

What are the effects of continental rifting?

The same continental rifting processes that form the high-elevation valleys and mountain ranges of the Basin and Range Province and Rio Grande Rift also result in earthquakes and volcanic activity. As the lithosphere pulls apart and thins, the underlying, hot asthenosphere rises and expands like a hot-air balloon, elevating the entire region. The drop in pressure on the shallow asthenosphere makes it start to melt. Some of the liquid rock (magma) makes it to the surface and forms lava flows, shield volcanoes, cinder cones, and other volcanic features.

What causes valley floors to drop down along fault lines in the Basin and Range Province?

Continental rifting causes valleys floors to drop down along fault lines in the Basin and Range Province. Snake Valley, Tucson Basin and Death Valley are the basins, while the Snake Range, Rincon Mountains, Tucson Mountains and Panamint Mountains are the adjacent ranges.

Why does magma become rich in silica?

The magma becomes enriched in silica because high-silica minerals tend to melt first. Some of the lava that initially pours out at continental rift zones is thus thick and pasty, cooling to light-colored rocks (rhyolite and dacite), and steep-sided lava domes and composite volcanoes.

What is the topography of the Rio Grande Rift?

The high elevations (brown shading) and rugged topography of the Basin and Range Province and Rio Grande Rift, which are actively forming can be seen in the shaded relief map, below. The Keweenwan Rift has sedimentary and volcanic rock layers similar to those found in the active rifts, but its topography is subdued because it formed over a billion years ago.

What is the topography of the Basin and Range Province and Rio Grande Rift?

The topography of the Basin and Range Province and Rio Grande Rift reveals the full range of characteristics of a continental rift zone. First, much of the region—particularly the northern portion—is well above sea level.

What is the basin and range province?

The Basin and Range Province is thus a high-elevation region that includes all of Nevada and portions of Wyoming, Utah, California, and Arizona, and extends into southern Oregon, Idaho, and Montana.

Which crust sticks up above sea level?

Continental crust is thick and buoyant, and therefore sticks up above sea level.

What is a divergent boundary?

In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.

Where do divergent plates form?

Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges. Divergent boundaries also form volcanic islands, which occur when the plates move apart to produce gaps that magma rises to fill. Current research indicates that complex convection within the Earth's mantle allows material to rise to the base ...

What type of boundary can create massive fault zones in the oceanic ridge system?

Divergent boundaries can create massive fault zones in the oceanic ridge system. Spreading is generally not uniform, so where spreading rates of adjacent ridge blocks are different, massive transform faults occur. These are the fracture zones, many bearing names, that are a major source of submarine earthquakes.

How far away do tectonic plates move?

Over millions of years, tectonic plates may move many hundreds of kilometers away from both sides of a divergent plate boundary. Because of this, rocks closest to a boundary are younger than rocks further away on the same plate.

Who discovered the link between magnetic banding and polar reversals?

Scientists had been studying polar reversals and the link was made by Lawrence W. Morley, Frederick John Vine and Drummond Hoyle Matthews in the Morley–Vine–Matthews hypothesis. The magnetic banding directly corresponds with the Earth's polar reversals.

What evidence supports the seafloor spreading hypothesis?

It is at mid-ocean ridges that one of the key pieces of evidence forcing acceptance of the seafloor spreading hypothesis was found. Airborne geomagnetic surveys showed a strange pattern of symmetrical magnetic reversals on opposite sides of ridge centers. The pattern was far too regular to be coincidental as the widths of the opposing bands were too closely matched. Scientists had been studying polar reversals and the link was made by Lawrence W. Morley, Frederick John Vine and Drummond Hoyle Matthews in the Morley–Vine–Matthews hypothesis. The magnetic banding directly corresponds with the Earth's polar reversals. This was confirmed by measuring the ages of the rocks within each band. The banding furnishes a map in time and space of both spreading rate and polar reversals.

What is a Divergent Boundary?

You've just boiled an egg and are removing the shell. Suddenly; it slips from your hand and hits the floor with a crack. You pick it up to find the whole surface littered with lines and breaks. While nobody has ever dropped the Earth (as far as we know!), the cracked surface of the egg is just like the Earth's crust. While it might seem solid enough, it is actually broken into sections called tectonic plates. These plates float on a sea of hot magma. This magma is solid but becomes a liquid when it reaches the surface through volcanoes.

What are the three types of divergent plate boundaries?

False, because the correct statement is: There are three types of divergent plate boundaries, namely continental-continental, oceanic-continental, and oceanic-oceanic.

What makes a continental plate?

Continental plates are indeed above sea level, but again, what makes a plate officially continental is the presence of felsic or granitic rock. Most divergent boundaries in the world today are between two oceanic plates.

What is an oceanic plate?

Oceanic plates are, unsurprisingly, plates below sea level and under the oceans. But the 'oceans' part isn't actually what makes it an oceanic plate because there are some exceptions to this rule. Instead, it's more about the plate's composition. Oceanic plates are composed of mafic or basaltic rock.

What is the mid Atlantic ridge?

The mid-Atlantic ridge is an example of a divergent boundary, where the Eurasian Plate that covers all of Europe separates from the North American Plate. This underwater mountain range is constantly growing as new crust is formed. Further up that same boundary, it passes through Iceland. There it forms characteristics of a continental divergence, and a rift is forming on the island. Eventually, Iceland will break into two separate islands, with sea in between.

When will the two plates break apart?

Sometime in the next ten million years, the two plates will finally rupture and separate, creating a new ocean in between. Lesson Summary. The Earth's crust is split into sections called tectonic plates. Divergent boundaries are where two of those plates are moving away from each other.

When one continental and one oceanic plate diverge, there can be features of both?

When one continental and one oceanic plate diverge, there can be features of both. It is more a matter of whether the boundary itself lies over an ocean or land than whether the plates are continental or oceanic.

Where are divergent boundaries found?

The vast majority of divergent boundaries are found in the ocean, where they were not mapped or understood until the mid-to-late 20th century.

Which oceans are examples of continental divergence?

A much better example of how continental divergence creates oceans is easy to see in the South Atlantic Ocean . There, the precise fit between South America and Africa testifies to the fact that they were once integrated with a larger continent.

Why do ridges have steeper sides?

Slow-spreading ridges like the Mid-Atlantic Ridge have steeper-sloping sides because it takes less distance for their new lithosphere to cool. They have relatively little magma production so that the ridge crest can develop a deep dropped-down block, a rift valley, at its center.

Why is the fresh seafloor higher than the older lithosphere?

At oceanic divergent boundaries, new lithosphere is born hot and cools over millions of years. As it cools it shrinks, thus the fresh seafloor stands higher than the older lithosphere on either side. This is why divergent zones take the form of long, wide swells running along the ocean floor: mid-ocean ridges. The ridges are only a few kilometers high but hundreds wide.

What did the study of mid ocean ridges help establish?

The study of mid-ocean ridges helped establish the theory of plate tectonics in the 1960s. Geomagnetic mapping showed large, alternating "magnetic stripes" in the seafloor, a result of Earth's ever-changing paleomagnetism. These stripes mirrored each other on both sides of divergent boundaries, giving geologists irrefutable evidence of seafloor spreading.

What is the slope of a ridge?

The ridges are only a few kilometers high but hundreds wide. The slope on the flanks of a ridge means that diverging plates get an assist from gravity, a force called "ridge push" that, together with slab pull, accounts for most of the energy driving the plates. On the crest of each ridge is a line of volcanic activity.

What happens to the hot mantle rock in divergent zones?

In divergent zones, this pulling motion uncovers the hot deep mantle rock of the asthenosphere. As the pressure eases on the deep rocks, they respond by melting, even though their temperature may not change.

What is the effect of a plate capped by thick continental crust?

As a plate capped by thick continental crust pulls apart, the crust thins and elevates a broad region. These forces result in long mountain ranges, intervening valleys (basins) and volcanic activity characteristic of the Basin and Range Province and Rio Grande Rift. Ancient continental rifting formed similar rocks and geological structures in the Keweenawan Rift of the upper midcontinent region.

What has happened to the North American continent?

Throughout its existence the North American continent has been subjected to forces trying to rip it apart, sometimes successfully. The landscapes of several National Park Service sites reveal divergent plate boundary processes that have resulted in continental rift zones and passive continental margins.

Which crust sticks up above sea level?

Continental crust is thick and buoyant, and therefore sticks up above sea level.

Why does the ocean basin sink below sea level?

The ocean basin sinks below sea level because the crust is thinner and more dense, and therefore less buoyant.

What are the effects of continental rifting?

The same continental rifting processes that form the high-elevation valleys and mountain ranges of the Basin and Range Province and Rio Grande Rift also result in earthquakes and volcanic activity. As the lithosphere pulls apart and thins, the underlying, hot asthenosphere rises and expands like a hot-air balloon, elevating the entire region. The drop in pressure on the shallow asthenosphere makes it start to melt. Some of the liquid rock (magma) makes it to the surface and forms lava flows, shield volcanoes, cinder cones, and other volcanic features.

What happens when tectonic plates move away from one another?

The underlying asthenosphere rises and expands like a hot-air balloon, elevating a broad region . If the plate is capped by thick continental crust, the resulting continental rift zone rises high above sea level.

What is the rift zone?

Where tectonic plates move away from one another the lithosphere thins. The underlying asthenosphere rises and expands like a hot-air balloon, elevating a broad region. If the plate is capped by thick continental crust, the resulting continental rift zone rises high above sea level. The Basin and Range Province is thus a high-elevation region that includes all of Nevada and portions of Wyoming, Utah, California, and Arizona, and extends into southern Oregon, Idaho, and Montana. It is similar to the East African Rift, where volcanic materials and sedimentary layers deposited by rivers and lakes partially fill rift valleys. Prominent planar surfaces (fault escarpments) along range fronts are evidence that the region continues to rip apart—erosion would smooth them out if the fault movement stopped. The Rio Grande Rift is an arm of the Basin and Range Province extending across westernmost Texas, New Mexico, and southern Colorado. Earthquakes, fault-block mountains, and volcanism at Guadalupe Mountains National Park and Bandelier and White Sands national monuments are consequences of the ongoing continental rifting.

Why does magma become rich in silica?

The magma becomes enriched in silica because high-silica minerals tend to melt first. Some of the lava that initially pours out at continental rift zones is thus thick and pasty, cooling to light-colored rocks (rhyolite and dacite), and steep-sided lava domes and composite volcanoes.

What is the topography of the Basin and Range Province and Rio Grande Rift?

The topography of the Basin and Range Province and Rio Grande Rift reveals the full range of characteristics of a continental rift zone. First, much of the region—particularly the northern portion—is well above sea level.

Which crust sticks up above sea level?

Continental crust is thick and buoyant, and therefore sticks up above sea level.

What is the thick crust of North America?

Like other continents, North America has thick crust, compared to the thin crust beneath the adjacent Atlantic and Pacific oceans. In the western part of the continent, divergent plate boundary forces are beginning to rip the continent apart, forming the Basin and Range Province and its adjacent eastern arm, known as the Rio Grande Rift.

What is the difference between a divergent and a mid-ocean ridge?

When a divergent boundary occurs between two oceanic plates a mid-ocean ridge. This is where new oceanic lithosphere forms. Mid-ocean ridges are also called spreading centers because of the way the plates spread apart.

What happens to the continents when rifting continues?

If rifting continues, the continent splits into two pieces and a narrow ocean basin forms as seafloor spreading takes place. As the edges of the continents move away from the heat associated with active spreading , the thinned continental crust cools and drops in elevation, eventually dropping below sea level.

What happens when plates move apart?

As the plates move apart, an opening is created which allows the asthenosphere to rise toward the surface to fill that space. As the plates pull apart, the load on the asthenosphere decreases which decreases the pressure in the asthenosphere and leads to decompression melting.

What happens to the seafloor during continental rifting?

If continental rifting progresses it can lead to seafloor spreading and the formation of a new ocean basin. The initial stage of continental rifting commonly includes broad uplift of the surface as mantle-derived magma ascends into crust. That magma can melt parts of the continental crust which produces additional magma.

Why are mid ocean ridges elevated above the seafloor?

Mid-ocean ridges are elevated above the surrounding seafloor because they consist of hotter, less dense materials and the underlying asthenosphere is thinner and bulging right beneath the ridges. The elevation of the seafloor decreases away from the ridge because the rock cools and contracts.

Overview

Description

At divergent boundaries, two plates move away from each other and the space that this creates is filled with new crustal material sourced from molten magma that forms below. The origin of new divergent boundaries at triple junctions is sometimes thought to be associated with the phenomenon known as hotspots. Here, exceedingly large convective cells bring very large quantities of hot asthenospheric material near the surface, and the kinetic energy is thought to b…

Examples

Other plate boundary types

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