Mid-ocean ridge process Flashcards
What happens first?
Plate Divergence: Mid-ocean ridges form at divergent plate boundaries, where tectonic plates are moving away from each other. This movement creates a gap or rift between the plates.
What happens second?
Upwelling of Mantle Material: As the plates move apart, the underlying asthenosphere, which is a semi-fluid layer of the Earth’s mantle, rises to fill the gap. This upwelling of hot mantle material provides the necessary heat and magma for mid-ocean ridge formation.
What happens third?
Magma Generation: As the asthenosphere rises, it undergoes decompression melting. The reduction in pressure causes the mantle rock to melt, forming magma. This magma is enriched in basaltic composition.
What happens fourth?
Magma Injection: The newly formed magma accumulates beneath the rift zone, creating a magma chamber. As the pressure builds up, the magma seeks pathways to reach the surface.
What happens fifth?
Volcanic Activity: The magma eventually finds cracks or fissures in the overlying lithosphere and erupts onto the seafloor. It forms lava flows that cool and solidify, creating new oceanic crust. This process is known as seafloor spreading. The erupted lava is mostly basalt, which is dark and dense.
What happens sixth?
Crustal Spreading: As new magma continues to rise and erupt, it pushes the existing oceanic crust away from the ridge axis in both directions. This leads to the continuous formation of new oceanic crust, causing the ridge to grow in length.
What happens seventh?
Faulting and Rift Valley Formation: The movement of the plates at the mid-ocean ridge can create faults and fractures in the crust. These faults often form a central rift valley along the ridge axis. The rift valley is characterized by steep walls and a down-dropped central block.
What happens last?
Hydrothermal Venting: Mid-ocean ridges are associated with hydrothermal vent systems. Seawater infiltrates through cracks and fractures in the crust, gets heated by the underlying magma chamber, and rises back to the seafloor as hydrothermal vents. These vents support unique ecosystems and mineral deposits
