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Igneous rocks are formed through the cooling and solidification of magma or lava. They are a key component of Earth’s crust and are especially prevalent along tectonic plate boundaries. Understanding their distribution helps in studying geological processes and plate movements worldwide.
Types of Igneous Rocks
Igneous rocks are classified into two main types based on their formation process: intrusive and extrusive. Intrusive rocks, such as granite, form beneath the Earth’s surface, while extrusive rocks, like basalt, solidify on the surface.
Igneous Rocks at Divergent Boundaries
At divergent boundaries, tectonic plates move apart, allowing magma to rise and create new crust. This process results in the formation of extensive basaltic lava flows and gabbroic intrusions. Mid-ocean ridges are prominent examples where these rocks are abundant.
Igneous Rocks at Convergent Boundaries
Convergent boundaries involve plates colliding, often leading to subduction zones. Here, magma generated from subducted oceanic crust rises to form volcanic arcs composed mainly of andesite and rhyolite. These regions are associated with active volcanoes and complex geological activity.
Global Distribution of Igneous Rocks
- Mid-ocean ridges in the Atlantic and Pacific Oceans
- Volcanic arcs in the Pacific Ring of Fire
- Continental rift zones in Africa and East Africa
- Subduction zones along the Pacific Plate margins