As mantle ascends beneath the mid-ocean ridge, less and less rock lies above it,
so large pressure changes occur
, which leads to melting. The melt is less dense than the solid, and rises to the surface to form the oceanic crust.
What type of magma is mafic?
Mafic magmas are
low in silica and contain more dark, magnesium and iron rich mafic
minerals, such as olivine and pyroxene. … Viscosity determines what the magma will do. Mafic magma is not viscous and will flow easily to the surface. Felsic magma is viscous and does not flow easily.
Which type of melting is responsible for mafic magmas at mid-ocean ridges and why?
Answer: At mid-ocean ridges, underlying hot asthenosphere
Does partial melting result in predominantly mafic or felsic magma Why?
most rocks melt by partial melting–felsic minerals melt at lower temperatures than mafic minerals, partial melting
produces magma more felsic than the source
.
What other melting process produces magma in an oceanic ridge?
Diverging Plate Boundaries
Decompression melting
could result, generating magmas that intrude and erupt at the oceanic ridges to create new oceanic crust. Iceland is one of the few areas where the resulting magmatism has been voluminous enough to built the oceanic ridge above sea level.
What type of melting occurs at mid-ocean ridges?
Decompression
.
Decompression melting
occurs at mid-ocean ridges. When two plates move apart, they create a space that can be filled by hot rock that rises buoyantly from below.
What are some examples of mid-ocean ridges?
Mid-ocean ridges are typically half a mile to six miles wide and over a mile underwater. Two of the most well-known mid-ocean ridges are
the Mid-Atlantic Ridge and the East Pacific Rise
. As you might guess, most of the Mid-Atlantic Ridge is in the Atlantic, and most of the East Pacific Rise is in the Pacific.
What are the three main components of magma?
Magma and lava contain three components:
melt, solids, and volatiles
. The melt is made of ions from minerals that have liquefied. The solids are made of crystallized minerals floating in the liquid melt.
Which component of magma is the highest and lowest in value?
Felsic magma
has the highest silica content of all magma types, between 65-70%. As a result, felsic magma also has the highest gas content and viscosity, and lowest mean temperatures, between 650
o
and 800
o
Celsius (1202
o
and 1472
o
Fahrenheit).
Which magma has the highest viscosity?
The magma that has the highest viscosity is
rhyolitic magma
.
Why can we find so many different types of magmas?
Why are there so many different types of magmas?
Because it depends on the source, how it interacts with its surroundings (assimilation)
, and whether crystals sink as they form (partial melting and magma mixing).
Why the resulting magma is mafic?
Answer:
At mid-ocean ridges, underlying hot asthenosphere rises from below
. Decompression melting occurs in these peridotites at shallow depths as they rise, resulting in mafic magmas.
Why do all magmas create dominantly silicate minerals upon cooling?
Why do all magmas create dominantly silicate minerals upon cooling? …
Si and O are the least abundant elements in the magma. Si and O are the most abundant elements in the magma
. Al and Si are the least abundant elements in the magma.
What are the four main factors involved in the formation of magma?
the formation of magma are
temperature, pressure, water content, and mineral content
.
Why does magma come out of mid oceanic ridges?
Mid-ocean ridges are considered the planet’s largest magmatic system. At divergent plate boundaries, magma is
generated by decompression melting of upwelling mantle
. Melts are focused as they ascend through the upper mantle and lower crust and collect beneath the ridge axis in elongate melt lenses.
Why does melting occur at spreading centers quizlet?
Why does melting occur at spreading centers?
Pressure decreases as mantle rises upward
.
