Here's why:
* Divergent Zones and Magma: Divergent zones are areas where tectonic plates move apart. This separation allows magma from the Earth's mantle to rise to the surface.
* Basaltic Magma: The magma produced at divergent zones is typically basaltic in composition. Basaltic magma is rich in magnesium and iron, and it has a relatively low silica content.
* Basalt Formation: When basaltic magma erupts and cools, it forms basalt, a dark-colored, fine-grained igneous rock.
Other Igneous Rocks at Divergent Zones:
While basalt is the most prevalent, some other igneous rocks can also be found at divergent zones, including:
* Gabbro: A coarse-grained intrusive equivalent of basalt. It forms when basaltic magma cools slowly beneath the Earth's surface.
* Rhyolite: In rare cases, divergent zones can produce rhyolitic magma, leading to the formation of rhyolite, a light-colored, fine-grained igneous rock. However, this is less common than basalt formation.
Examples:
* Mid-Ocean Ridges: These underwater mountain ranges are classic examples of divergent zones where basalt is constantly being formed.
* Continental Rifts: Areas like the East African Rift Valley also exhibit divergent plate movement, leading to the formation of basaltic rocks.
