Metamorphism

Definition

Metamorphism is the process by which existing rocks undergo changes in mineralogy, texture, and chemical composition due to heat, pressure, and chemically active fluids. This transformative process is essential in understanding the rock cycle as it links igneous, sedimentary, and metamorphic rocks while also playing a vital role in Earth's dynamic systems. Through metamorphism, minerals can become more stable under different environmental conditions, influencing both the geological landscape and the availability of resources.

5 Must Know Facts For Your Next Test

1. Metamorphism can create valuable minerals like graphite, talc, and certain gemstones, significantly impacting economic geology.
2. The degree of metamorphism can vary widely, from low-grade metamorphism, which occurs at relatively low temperatures and pressures, to high-grade metamorphism, involving extreme conditions.
3. The presence of fluids during metamorphism can facilitate chemical reactions and enhance the formation of new minerals.
4. Metamorphic rocks are classified based on texture and mineral composition into foliated (layered) and non-foliated types.
5. Understanding metamorphism is critical for interpreting Earth's history and the processes that shape its crust over geological time.

Review Questions

• How does metamorphism connect different types of rocks in the rock cycle?
  • Metamorphism serves as a bridge between the three main rock types: igneous, sedimentary, and metamorphic. When igneous or sedimentary rocks experience intense heat and pressure, they can transform into metamorphic rocks. This process highlights how dynamic Earth’s systems are interconnected, as the continual recycling of materials leads to the formation of new rock types over geological time.
• Discuss the economic implications of metamorphism on mineral resources.
  • Metamorphism plays a significant role in the formation of economically important minerals such as marble (from limestone) and schist (from shale). These metamorphic rocks are not only utilized in construction but also serve as sources for various industrial minerals. Understanding metamorphic processes helps in exploring and extracting these valuable resources efficiently.
• Evaluate how different types of metamorphism affect rock properties and stability under geological conditions.
  • Different types of metamorphism, such as regional and contact metamorphism, influence the physical properties of rocks in distinct ways. Regional metamorphism typically results in foliation due to directional pressure, enhancing the strength of the rock. In contrast, contact metamorphism usually creates non-foliated rocks where temperature is the dominant factor. The changes in texture and mineral composition affect how these rocks respond to stress and strain in tectonic settings, which is critical for understanding rock deformation processes.

Related terms

Parent Rock:

The original rock from which a metamorphic rock forms; it can be an igneous, sedimentary, or another metamorphic rock.

Regional Metamorphism: A type of metamorphism that occurs over large areas under high pressure and temperature, often associated with tectonic plate boundaries.

Contact Metamorphism:

Metamorphism that occurs when rocks are heated by nearby molten magma or lava, resulting in localized changes in mineralogy.