- Why is magma rising up through the continental crust?
- What are the factors that affect how rocks melt and crystallize?
- What causes magma to rise to the surface?
- What happens when magma becomes a solid crystal?
- How is the composition of rock added to magma?
- How does viscosity affect the composition of magma?
Why is magma rising up through the continental crust?
As the denser tectonic plate subducts, or sinks below, or the less-dense tectonic plate, hot rock from below can intrude into the cooler plate above. This process transfers heat and creates magma. Over millions of years, the magma in this subduction zone can create a series of active volcanoes known as a volcanic arc.
What are the factors that affect how rocks melt and crystallize?
The three factors that affect whether rock melts include temperature, pressure, and the presence of fluids in the rock. Rock melts when the temperature of the rock increases to above the melting point of minerals in the rock.
What causes magma to rise to the surface?
It then builds pressure, causing it to rise to the surface. Magma is made of molten rocks and minerals. It forms in the lower crust and upper mantle layers of the Earth due to movements in the mantle, changes in temperature or contact with water or carbon dioxide under the surface. These changes cause rocks in the crust to melt, forming magma.
What happens when magma becomes a solid crystal?
As minerals with lower melting points turn into liquid magma, those with higher melting points remain as solid crystals. This is known as partial melting. As magma slowly rises and cools into solid rock, it undergoes physical and chemical changes in a process called magmatic differentiation.
How is the composition of rock added to magma?
This happens via two main methods: assimilation and fractionation [ 8 ]. During assimilation, pieces of country rock with a different, often more felsic, composition are added to the magma.
How does viscosity affect the composition of magma?
Viscosity is a liquid’s resistance to flow. 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. Most felsic magma will stay deeper in the crust and will cool to form igneous intrusive rocks such as granite and granodiorite.