Breccia

Definition

Breccia is a type of rock composed of angular, broken fragments of minerals or rocks cemented together by a fine-grained matrix. It is typically formed through processes such as tectonic activity, weathering, or impact events, and is commonly associated with the formation of impact craters on planetary surfaces.

5 Must Know Facts For Your Next Test

1. Breccia is a common feature of impact craters, formed by the high-energy impact and subsequent collapse of the crater walls.
2. The angular fragments in breccia are typically derived from the target material, such as bedrock or sedimentary layers, that has been shattered and displaced by the impact.
3. Breccia can also contain fragments of the impactor, such as meteorite or asteroid material, which can provide valuable information about the composition and origin of the impacting body.
4. The matrix that binds the angular fragments in breccia can be composed of a variety of materials, including fine-grained rock, mineral grains, or even impact-generated melt.
5. Breccia can exhibit a range of textures and colors, depending on the composition of the fragments and the nature of the cementing matrix.

Review Questions

• Explain how the formation of breccia is related to the impact crater process.
  • The formation of breccia is closely tied to the impact crater process. When a meteorite, asteroid, or comet strikes the surface of a planet or moon, the high-energy impact shatters and displaces the target material, creating angular fragments that become cemented together by a fine-grained matrix. This breccia is a common feature found within the crater itself, as well as in the ejecta deposits surrounding the crater. The specific characteristics of the breccia, such as the size and composition of the fragments, can provide valuable information about the impact event and the nature of the target material.
• Describe the different types of breccia that can be found in association with impact craters.
  • In addition to the general breccia formed by the impact process, there are several specific types of breccia that can be found in association with impact craters. Suevite, for example, is a type of breccia that contains glass fragments and mineral grains that have been melted or altered by the high temperatures and pressures of the impact event. Other types of breccia may contain a higher proportion of impactor material, such as meteorite or asteroid fragments, which can provide insights into the composition and origin of the impacting body. The specific characteristics of the breccia can vary depending on the nature of the impact, the target material, and the post-impact processes that have affected the crater.
• Analyze how the study of breccia can contribute to our understanding of impact crater formation and the broader geological history of a planetary body.
  • The study of breccia found in and around impact craters can provide valuable insights into the formation and evolution of these geological features. By analyzing the composition, texture, and distribution of the breccia, scientists can gain information about the nature of the impacting body, the physical and chemical processes involved in crater formation, and the broader geological history of the planetary surface. For example, the presence of certain mineral or rock fragments in the breccia can indicate the composition of the target material, while the degree of melting or alteration of these fragments can reveal the intensity of the impact event. Additionally, the distribution and characteristics of the breccia can help researchers reconstruct the complex sequence of events that occurred during and after the impact, ultimately contributing to a more comprehensive understanding of the impact crater formation process and its role in shaping the geological landscape of a planetary body.

Related terms

Impact Crater: An impact crater is a circular depression formed in the surface of a planet, moon, or other solid body as a result of the high-velocity impact of a smaller body, such as a meteorite, asteroid, or comet.

Ejecta: Ejecta refers to the material that is thrown out or expelled from an impact crater during the formation process, including fragments of the impactor and the target material.

Suevite: Suevite is a type of breccia that contains glass fragments and mineral grains that have been melted or altered by the high temperatures and pressures associated with an impact event.