Question

What is the regional metamorphism in the formation of metamorphic rock

Answer 1

Regional metamorphism is the transformation of existing rocks into metamorphic rocks due to heat and pressure over a wide area, often related to tectonic events like mountain building. It results in a predictable pattern of rock grades based on proximity to the collision center, and these rocks can be exposed on the surface through erosion.

Step-by-step explanation:

Regional metamorphism refers to the process by which existing rocks within the Earth's crust are transformed into metamorphic rocks due to a combination of heat and pressure over a wide area, usually related to tectonic processes such as mountain building. This type of metamorphism often produces a predictable sequence of rocks known as the Barrovian sequence, where the grade of metamorphism increases towards the center of the tectonic collision. Metamorphic rocks can be brought to the surface by erosion, where the overlying, less metamorphosed rocks are worn away, revealing the deeper, more highly metamorphosed rock layers. Examples of metamorphic rocks and the processes by which pressure, temperature, or fluids transform them include the alteration of shale into slate, limestone into marble, and the presence of certain minerals like mica in schist or garnet in gneiss depending on the initial composition of the rocks and the conditions they are subjected to.

Answer 2

Typically rocks formed by regional metamorphism have experienced deviatoric stress producing foliations. Rock types such as slate, phyllite, schist, gneiss and granulite are typical of regional metamorphism.
Low-grade metamorphism takes place at temperatures between about 200 to 320oC, and relatively low pressure. Low grade metamorphic rocks are generally characterized by an abundance of hydrous minerals. With increasing grade of metamorphism, the hydrous minerals begin to react with other minerals and/or break down to less hydrous minerals.