What is the definition of metamorphism?
The correct answer and explanation is :
Definition of Metamorphism:
Metamorphism is the process by which the mineral composition, texture, and structure of a rock are altered by changes in temperature, pressure, or the presence of chemically active fluids, typically occurring deep within the Earth’s crust.
Explanation:
Metamorphism occurs when pre-existing rocks, known as protoliths, undergo significant changes due to environmental conditions such as increased temperature, pressure, and/or chemically active fluids. These conditions occur deep within the Earth’s crust, where the heat and pressure are much greater than those at the Earth’s surface.
The primary agents responsible for metamorphism are heat, pressure, and chemically reactive fluids. Heat plays a critical role because it provides the energy necessary for the chemical reactions that alter the minerals in the rock. The heat often comes from the Earth’s internal heat sources, such as the decay of radioactive elements in the mantle and crust. As the temperature increases, existing minerals may break down and recombine into new minerals that are more stable under the higher temperature conditions.
Pressure, particularly in the form of differential pressure (uneven pressure from different directions), is also a key factor. This pressure causes the minerals in the rock to reorient themselves, resulting in the formation of foliation (layering) in some metamorphic rocks. This can cause significant physical changes, such as the flattening or stretching of mineral grains.
Chemically active fluids, like water and gases, often interact with the minerals in the rock. These fluids can facilitate the movement of ions between minerals, leading to the formation of new minerals or changes in the rock’s composition.
Metamorphism can lead to the creation of a variety of metamorphic rocks, such as slate, schist, and marble, depending on the intensity of the heat and pressure and the original composition of the protolith. The process can occur over millions of years and is typically associated with tectonic activity, such as subduction zones, mountain-building events, and continental collisions.