Dike

Definition

A dike is a type of igneous intrusion that forms when magma rises through pre-existing rock layers and solidifies vertically or at a steep angle. This geological feature is essential for understanding the processes that shape the Earth's crust and how different types of igneous rock are formed. Dikes can vary in thickness and length, often cutting across the layers of surrounding rock, and they play a crucial role in the classification of intrusive igneous features.

5 Must Know Facts For Your Next Test

1. Dikes are typically formed from basaltic or andesitic magma, which cools quickly as it intrudes into cooler surrounding rocks.
2. The orientation of dikes can vary widely; they may be vertical, steeply inclined, or even horizontal in some cases.
3. Dikes often contain unique mineral compositions and textures that can help geologists determine their origin and the conditions under which they formed.
4. In many regions, dikes can be observed as prominent cliffs or ridges due to differential erosion compared to the surrounding sedimentary rocks.
5. Dikes are important indicators of tectonic activity, as their formation is often associated with the movement of tectonic plates and volcanic activity.

Review Questions

• Compare and contrast dikes with sills in terms of their formation and orientation within the Earth's crust.
  • Dikes and sills are both types of igneous intrusions, but they differ in their orientation and formation processes. Dikes form when magma intrudes vertically or at a steep angle through existing rock layers, while sills form horizontally between these layers. Both features provide insights into the behavior of magma during its ascent, but their different orientations indicate varying geological conditions and tectonic settings.
• Discuss how dikes contribute to our understanding of tectonic processes and volcanic activity in a region.
  • Dikes serve as crucial evidence of tectonic processes because their formation often occurs in areas experiencing significant geological activity. The presence of dikes indicates that magma has intruded through cracks created by tectonic forces, such as plate boundaries or rifting zones. Additionally, studying the mineral composition and orientation of dikes can help geologists identify past volcanic activity, providing a clearer picture of the region's geological history.
• Evaluate the significance of dikes in the broader context of intrusive igneous features and their role in shaping Earth's crust over geological time.
  • Dikes play a vital role in shaping the Earth's crust as they represent pathways for magma to reach the surface during volcanic eruptions. Their formation contributes to the creation of diverse igneous rock formations, influencing landscape development and erosion patterns. Over geological time, dikes can help us understand past tectonic events, volcanic activity, and even resource distribution, such as minerals found within these intrusions. Their study is essential for deciphering the complex history of Earth's geological evolution.

Related terms

Sill: A sill is a horizontal or gently inclined sheet of igneous rock that forms when magma intrudes between existing rock layers.

Pluton: A pluton is a large body of intrusive igneous rock that has crystallized from molten magma deep within the Earth.

Batholith: A batholith is an enormous mass of intrusive igneous rock that forms from the cooling and solidification of large amounts of magma beneath the Earth's surface.