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Can Small amounts of water lower partial melting temperatures in silicate rocks?
Yes, small amounts of water can lower the partial melting temperatures of silicate rocks by promoting the breaking of chemical bonds and reducing the viscosity of the rock. This can lead to increased melting and magma formation at lower temperatures compared to dry conditions.
What does most magma forms from?
Most magma forms from the partial melting of Earth's mantle rocks. As these rocks are subjected to high temperatures and pressures in the mantle, certain minerals melt at different temperatures, leading to the formation of magma.
Describe the composition and temperature of the mantle?
The mantle is composed mainly of silicate minerals rich in magnesium and iron. It has an average temperature of about 1300-3300 degrees Celsius, with the highest temperatures near the core-mantle boundary. The mantle is predominantly solid, but some regions can undergo partial melting to form magma.
The process by which different minerals melt at different temperatures is called?
Fractional crystallization is the process where different minerals melt at different temperatures. This process occurs during the cooling of magma or lava, where minerals crystallize and separate based on their melting points.
Most basaltic magmas are believed to form by partial melting of granite in the lower crust and upper mantle?
Basaltic magmas are typically formed by partial melting of the upper mantle, specifically the mantle wedge above subduction zones. This process occurs at high temperatures and low pressures, resulting in the generation of magma rich in iron and magnesium. The melting of granite in the lower crust is less common but can also give rise to basaltic magmas through processes such as assimilation and fractional crystallization.
Can Small amounts of water lower partial melting temperatures in silicate rocks?
Yes, small amounts of water can lower the partial melting temperatures of silicate rocks by promoting the breaking of chemical bonds and reducing the viscosity of the rock. This can lead to increased melting and magma formation at lower temperatures compared to dry conditions.
What does most magma forms from?
Most magma forms from the partial melting of Earth's mantle rocks. As these rocks are subjected to high temperatures and pressures in the mantle, certain minerals melt at different temperatures, leading to the formation of magma.
Describe the composition and temperature of the mantle?
The mantle is composed mainly of silicate minerals rich in magnesium and iron. It has an average temperature of about 1300-3300 degrees Celsius, with the highest temperatures near the core-mantle boundary. The mantle is predominantly solid, but some regions can undergo partial melting to form magma.
What is responsible for the partial melting of peridotite?
In the mantle, temperatures range between 500 to 900 °C (932 to 1,652 °F) at the upper boundary with the crust; to over 4,000 °C (7,230 °F) at the boundary with the core.Although the higher temperatures far exceed the melting points of the mantle rocks at the surface (about 1200 °C for representative peridotite), the mantle is almost exclusively solid. The enormous lithostatic pressure exerted on the mantle prevents melting, because the temperature at which melting begins (the solidus) increases with pressure.
The process by which different minerals melt at different temperatures is called?
Fractional crystallization is the process where different minerals melt at different temperatures. This process occurs during the cooling of magma or lava, where minerals crystallize and separate based on their melting points.
What is the parent rock of migmatite?
The parent rock of migmatite is typically a metamorphic rock like gneiss or schist that has undergone partial melting due to high temperatures and pressures. This partial melting results in the formation of a mixed rock composed of both igneous and metamorphic features.
When magma forms by partial melting which are the first mineral pairs that melt first?
When magma forms by partial melting, the first minerals to melt are typically those with lower melting points, such as olivine and pyroxene. These minerals are rich in iron and magnesium and tend to crystallize at higher temperatures. As melting progresses, other minerals like amphibole and biotite may also begin to melt, contributing to the composition of the resulting magma. This selective melting is influenced by the mineral's chemistry and the temperature and pressure conditions present in the Earth's crust.
What rocks would exhibit evidence of partial melting?
Rocks such as migmatites, which are a mixture of igneous and metamorphic rock formed through partial melting, would exhibit evidence of this process. Additionally, some granites and gneisses can show signs of partial melting due to the presence of melt pockets or segregated mineral assemblages.
What is the mantle made up of melted rock called?
The mantle is primarily composed of solid rock, but it contains regions of partially melted rock known as "magma." This magma can form due to high temperatures and pressures within the Earth, leading to partial melting of the mantle's silicate minerals. When magma rises to the surface, it can lead to volcanic activity. The mantle plays a crucial role in the geological processes of the Earth, including plate tectonics.
How the composition of the melted material in magma changes as it cools. how is the partial melting the opposite of fractional crystallization?
As magma cools, the composition of the solidifying minerals changes due to the crystallization of different minerals at varying temperatures, leading to a more silica-rich residual melt. Partial melting occurs when specific minerals in the rock melt at lower temperatures, producing a melt with a different composition than the original rock. In contrast, fractional crystallization involves the sequential crystallization of minerals from a melt, resulting in a solid that is compositionally different from the remaining liquid. While partial melting creates a melt enriched in certain elements, fractional crystallization depletes the melt of those same elements as they are incorporated into the forming crystals.
Would pressure play a role in partial melting?
In so far as pressure affects the melting point of substances, the answer is yes.
What causes partial melting?
Partial melting occurs when only a portion of a rock melts due to an increase in temperature or a decrease in pressure. This melting can be triggered by the addition of heat from nearby magma, the lowering of the melting point by the presence of volatiles like water, or by the decompression of rocks as they rise towards the surface through tectonic processes.
