Divergent plate boundaries, caused by the shifting of the Earth's tectonic plates, create igneous rocks as the plates move. The rocks are formed by cooling magma, and their specific type depends on the minerals available in the area.
What are Divergent Boundaries?
DIvergent plate boundaries are areas in the Earth's crust where two of the tectonic plates are moving away from each other. This motion opens deep cracks in the crust, allowing magma to seep through and rise to the surface. This magma leakage creates types of rock that are common at divergent boundaries, but relatively rare elsewhere.
Type of Rock
The main type of rock found at divergent plate boundaries is igneous. These rocks are formed when magma cools and becomes solid, either above or below ground. They are rich in elements including silicon, aluminium, sodium, potassium, calcium and iron, and make up about 95 percent of the upper part of the Earth's crust. More than 700 types of igneous rock have been identified.
Most rocks formed at divergent boundaries are categorized as malefic igneous rocks, which are dark-colored due to their high magnesium and iron content. This category includes basalt, gabbro and peridotites, which are often found at these boundaries.
Divergent plate boundaries are usually found at mid-ocean ridges, such as those in the Gulf of California and in the mid-Atlantic Ridge. There is also a divergent boundary in the East African rift zone and one in the Dead Sea rift valley, on land.
About the Author
From 2006 through 2009, Rebecca Jernigan wrote and edited articles for Laurin Publishing, where she was published in "Photonics Spectra," "BioPhotonics" and "Europhotonics" magazines. She has experience in fields ranging from ophthalmology to photonics, and holds a master's degree in publishing as well as degrees in psychology, English and Spanish.