Question

Identify the correct statements: regarding Regional Metamorphism,

1. It involves recrystallization due to deformation.
2. It is caused by tectonic shearing.
3. It requires only high pressure, while temperature remains constant.

• A. 2 only
• B. 1, 2
• C. All
• D. 1 only

Answer 1

Answer:

B. 1, 2

Regional Metamorphism

• Regional metamorphism is a type of metamorphism that occurs over large areas, typically associated with mountain building processes (orogeny).
• It is characterized by changes in rocks due to high pressure and intermediate to high temperatures.
• Recrystallization and the development of new minerals occur as a result of the intense pressure and heat, often leading to the formation of foliated metamorphic rocks like slate, phyllite, schist, and gneiss.
• Tectonic shearing is a significant factor in regional metamorphism, where large blocks of the Earth's crust are forced past each other, generating immense pressures and stresses. This differential stress plays a crucial role in deforming and transforming the rocks.
• Statement 1 is correct: Regional metamorphism involves recrystallization due to deformation, which is driven by tectonic forces.
• Statement 2 is correct: It is indeed caused by tectonic shearing and compressional stresses associated with plate tectonics.
• Statement 3 is incorrect: Regional metamorphism requires both high pressure and high temperature. While pressure is a key driver, temperature also increases significantly with depth and proximity to magmatic activity, facilitating the chemical and mineralogical changes in the rocks. It does not occur with constant temperature.
• Examples of regions that have undergone extensive regional metamorphism include the Himalayas, the Alps, and the Appalachian Mountains.