Metamorphic rock

Definition

Metamorphic rock is a type of rock that has been transformed from its original form due to changes in temperature, pressure, and the presence of chemically active fluids. This process, known as metamorphism, alters the mineral composition and texture of the rock, resulting in new types of rocks that exhibit unique features. These rocks play a vital role in understanding Earth's geological history and the dynamic processes that shape its structure and composition.

5 Must Know Facts For Your Next Test

1. Metamorphic rocks can be classified into two main categories: foliated and non-foliated, depending on the alignment of minerals within the rock.
2. Common examples of metamorphic rocks include schist, gneiss, marble, and slate, each having unique properties based on their parent rocks and metamorphic conditions.
3. The process of metamorphism can occur over millions of years and often requires high pressures and temperatures found deep within Earth's crust.
4. Metamorphic rocks are important indicators of tectonic activity since they often form in regions where plates converge or collide.
5. These rocks can undergo further changes and eventually become sedimentary or igneous rocks through the rock cycle, illustrating the dynamic nature of Earth's materials.

Review Questions

• How do metamorphic rocks differ from igneous and sedimentary rocks in terms of their formation processes?
  • Metamorphic rocks differ significantly from igneous and sedimentary rocks due to their formation process. While igneous rocks originate from the cooling and solidification of molten magma or lava, sedimentary rocks form from the accumulation of particles and organic material. Metamorphic rocks arise when existing rocks undergo metamorphism, which involves changes in temperature and pressure that alter their mineral structure and composition without melting them. This highlights how each type of rock represents a different part of the geological cycle.
• Discuss how the classification of metamorphic rocks into foliated and non-foliated varieties relates to their formation environment.
  • The classification of metamorphic rocks into foliated and non-foliated varieties is closely tied to their formation environment. Foliated metamorphic rocks, such as schist and gneiss, develop under directional pressure which causes minerals to align parallel to each other, giving them a layered appearance. In contrast, non-foliated metamorphic rocks like marble form under conditions where pressure is applied equally in all directions or when the original rock lacks a significant amount of layering. This distinction indicates how differing environmental conditions influence the physical characteristics of the resulting metamorphic rock.
• Evaluate the role of metamorphic rocks in understanding Earth's geological history and tectonic processes.
  • Metamorphic rocks play a crucial role in understanding Earth's geological history and tectonic processes by providing evidence of past environmental conditions and plate interactions. The presence of specific metamorphic minerals can indicate high-pressure environments typical of subduction zones or areas affected by continental collision. Additionally, studying these rocks helps geologists decipher past tectonic events that shaped regions over millions of years. Through this evaluation, metamorphic rocks serve as key indicators for reconstructing historical geological scenarios and understanding ongoing Earth dynamics.

Related terms

Igneous rock: Igneous rock is formed from the solidification of molten material called magma or lava, and it is one of the three main types of rocks, alongside sedimentary and metamorphic.

Sedimentary rock: Sedimentary rock is formed through the accumulation and cementation of mineral and organic particles, often in layers, and it provides insights into past environments.

Metamorphism: Metamorphism is the process by which existing rocks are altered due to changes in temperature, pressure, and chemical conditions, resulting in metamorphic rocks.