What is the role of heat and pressure to metamorphism?
Metamorphism occurs because some minerals are stable only under certain conditions of pressure and temperature. When pressure and temperature change, chemical reactions occur to cause the minerals in the rock to change to an assemblage that is stable at the new pressure and temperature conditions.
What are two sources of heat and pressure that cause metamorphism?
AGENTS OF METAMORPHIC CHANGE Heat sources include magma, geothermal heat, and friction along faults. Pressure sources include the weight of overlying rocks deep in the earth. Shear pressure in fault zones can metamorphose rocks at shallower depths.
What are the two types of metamorphic?
There are two major kinds of metamorphism: regional and contact. Regional metamorphism. Most metamorphic rocks are the result of regional metamorphism (also called dynamothermal metamorphism). These rocks were typically exposed to tectonic forces and associated high pressures and temperatures.
What is the highest metamorphic grade?
Gneiss
Is phyllite a high grade metamorphic rock?
The various types of foliated metamorphic rocks, listed in order of the grade or intensity of metamorphism and the type of foliation are slate, phyllite, schist, and gneiss (Figure 7.8)….7.2 Classification of Metamorphic Rocks.
| Mudrock | |
| Very Low Grade | slate |
| Low Grade | phyllite |
| Medium Grade | schist |
| High Grade | gneiss |
What is the metamorphic grade?
Metamorphic grade refers to the range of metamorphic change a rock undergoes, progressing from low (little metamorphic change) grade to high (significant metamorphic change) grade. These index minerals also provide important clues to a rock’s sedimentary protolith and the metamorphic conditions that created it.
How is metamorphic grade determined?
metamorphism. (Metamorphic grades refer to the degree and intensity of the metamorphism: they are determined by the pressure and temperatures to which the rock has been subjected.) Such areas are generally referred to as metamorphic core complexes.
What are high grade metamorphic rocks?
Slate, schist, and gneiss are three common foliated metamorphic rocks. Schist and gneiss are produced by medium to high grade metamorphism. In some cases gneisses are produced by higher grade metamorphism than schists.
What does high and low metamorphic grade mean?
Metamorphic grade refers to the range of metamorphic change a rock undergoes, progressing from low (little metamorphic change) grade to high (significant metamorphic change) grade. Low-grade metamorphism begins at temperatures and pressures just above sedimentary rock conditions.