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divergent plate boundary
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Cross-sectional diagram illustrating plate tectonics, showing oceanic and continental crust moving over the asthenosphere. It highlights divergent boundaries at oceanic ridges where crust forms, convergent boundaries at trenches with subduction zones where crust is destroyed, and a transform boundary with a fault. Features such as island arcs, rising magma, and hotspots are labeled. divergent plate boundary Diagram of the Earth showing two tectonic plates, labeled plate A and plate B, with arrows indicating their movement. Divergent and transform boundaries are marked, along with axes of plate and Earth rotation.
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divergent plate boundary

geology
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Cross-sectional diagram illustrating plate tectonics, showing oceanic and continental crust moving over the asthenosphere. It highlights divergent boundaries at oceanic ridges where crust forms, convergent boundaries at trenches with subduction zones where crust is destroyed, and a transform boundary with a fault. Features such as island arcs, rising magma, and hotspots are labeled.
crustal generation and destruction Three-dimensional diagram showing crustal generation and destruction according to the theory of plate tectonics; included are the three kinds of plate boundaries—divergent, convergent (or collision), and strike-slip (or transform).

A divergent plate boundary occurs when tectonic plates move apart from each other. This separation causes the release of pressure in the underlying mantle, leading to partial melting and the formation of magma. This basaltic magma wells up to the surface, cools, and creates new crust, making divergent margins constructive boundaries.12

When continents are involved, this process can lead to continental rifting, where fractures form and widen, eventually creating a rift valley. Over time, this can result in the separation of continental blocks and the formation of a new ocean basin with an ocean ridge at the boundary. Seafloor spreading is the term for this continuous divergence and creation of oceanic crust. Divergent boundaries are sites of volcanic activity and shallow earthquakes.12

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3 Britannica Sources
  1. plate tectonics - Continental rifting
  2. plate tectonics - Seafloor spreading
  3. plate tectonics - Island arcs

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