What is the definition of metamorphism?
The correct answer and explanation is :
Definition of Metamorphism:
Metamorphism refers to the process by which rocks undergo a physical and chemical transformation due to changes in environmental conditions such as temperature, pressure, and chemical interactions. This transformation occurs without the rock melting, but rather through recrystallization and other processes that alter the mineral composition, texture, and structure of the rock. The term “metamorphism” is derived from the Greek words meta (meaning “change”) and morphosis (meaning “form” or “shape”).
Explanation:
Metamorphism occurs deep within the Earth’s crust, where temperatures and pressures are much higher than at the surface. When rocks, known as parent rocks (or protoliths), are subjected to these extreme conditions, they undergo significant physical and chemical changes. There are two main types of metamorphism: contact metamorphism and regional metamorphism.
- Contact Metamorphism: This type of metamorphism happens when rocks are heated by the intrusion of hot magma or lava. The high temperature from the magma causes minerals within the rock to recrystallize and form new minerals, without the rock melting. The transformation occurs locally, around the area where the heat is most intense. A common example is the formation of marble from limestone.
- Regional Metamorphism: This process occurs over larger areas and is typically associated with tectonic plate collisions, such as those occurring at convergent plate boundaries. In these regions, rocks are subjected to both high pressure and temperature, leading to the formation of new minerals and the reorganization of the rock’s texture. The resulting rocks, such as schist or gneiss, exhibit foliation or a layered appearance due to the alignment of minerals under pressure.
The degree of metamorphism, from low-grade to high-grade, is determined by the intensity of heat and pressure the rock experiences. Low-grade metamorphism involves relatively mild conditions, whereas high-grade metamorphism involves extreme heat and pressure, often leading to the formation of more complex and dense minerals.
Metamorphism plays a critical role in the rock cycle by transforming existing rocks into new forms, contributing to the diversity of rock types found on Earth.