What type of magma is associated with spreading center volcanism?

What type of magma is associated with spreading center volcanism?

Either way, this is how the oceanic plates are created. The lava produced at the spreading centers is basalt, and is usually abbreviated MORB (for Mid-Ocean Ridge Basalt). MORB is by far the most common rock type on the Earth’s surface, as the entire ocean floor consists of it.

What happens at spreading center?

Spreading centers occur where two plates are moving away from each other, and deep cracks are opened through the crust. This lengthening of the crust allows magma from the upper mantle to rise to the surface and cool, commonly forming basalt. An excellent example is the Mid-Atlantic Ridge.

Why does melting occur at spreading ridges?

Melting is a primary means by which the earth cools: sea- floor spreading brings hot mantle from depth to the colder sur- face. As mantle ascends beneath the mid-ocean ridge, less and less rock lies above it, so large pressure changes occur, which leads to melting.

What type of volcanoes are formed at spreading centers?

Shield volcanoes are common at spreading centers or intraplate hot spots. The lava that creates shield volcanoes is fluid and flows easily and creates the shield shape. Shield volcanoes are built by many layers over time and the layers are usually of very similar composition.

What causes the melting in divergent plate boundaries?

At divergent plate boundaries hot mantle rock rises into the space where the plates are moving apart. The rock is under lower pressure; this lowers the melting temperature of the rock and so it melts.

What drives melting at subduction zones?

In a subduction zone (like the Cascades or the Andes), where an oceanic plate slides down under another plate, that downgoing slab releases its water as it heats up. That water then rises up into the mantle above it, causing it to melt at a lower temperature and, bam!

Which of the following explains a spreading center volcanism?

Spreading center volcanism occurs at the site of mid-oceanic ridges, where two plates diverge from one another. The rise of this hot mantle provides thermal buoyancy to the ridge area and this is the reason that they stand as high ridges in the center of ocean basins.

What type of melting occurs at subduction zones?

Volatile-driven melting
Volatile-driven melting happens at all subduction zones. The melt is generally formed at the point when the slab gets to a certain depth (the depth at which the pressure becomes high enough to force out the water). Pencast of a plot in Pressure-Temperature space for volatile-driven melting!

How do volcanoes form at a spreading center?

Spreading center volcanism occurs at the site of mid-oceanic ridges, where two plates diverge from one another. As the plates are pulled apart, hot asthenosphere rises upward to fill voids of the extended lithosphere.

What type of geologic formation can volcanoes create?

Craters form as the result of explosive eruptive activity at a volcanic vent where rock, magma, and other material is ejected leaving a conical void.

Where does spreading-center volcanism occur in the world?

Spreading-center volcanism occurs at rift-zones, where two plates are moving apart from each other. Most commonly this is the case at mid-oceanic ridges, where two oceanic plates move apart. The (developing) boundary between two spreading continental plates is known as a continental rift.

How are mantle and crustal processes related to volcanism?

The mantle and crustal processes that take place in areas of volcanism are illustrated in Figure 4.4. At a spreading ridge, hot mantle rock moves slowly upward by convection (cm/year), and within about 60 km of the surface, partial melting starts because of decompression.

How is volcanism related to continental rifting?

Volcanism in northwestern B.C. (Figures 4.5 and 4.6) is related to continental rifting. This area is not at a divergent or convergent boundary, and there is no evidence of an underlying mantle plume.

How does magma contribute to the melting of the crust?

There it contributes to partial melting of crustal rock, and thus it assimilates much more felsic material. That magma, now intermediate in composition, continues to rise and assimilate crustal material; in the upper part of the crust, it accumulates into plutons.