Published on: April 26, 2022
According to a study that analyzed data from the last 19 million years, Seafloor spreading rates have slowed down by roughly 35% globally
WHAT DID THE STUDY SAY
- Researchers selected 18 of the world’s largest spreading ridges (mid-ocean ridges)
- By studying magnetic records in the rocks on the oceanic crust, they calculated how much oceanic crust had formed over the last 19 million years. Basalt rocks on the oceanic crust contain magnetic properties
- Their magnetism is influenced by the Earth’s magnetic field when the magma reaches the surface and begins cooling to form the crust
- Records are incomplete because the crusts get destroyed at subduction zones
- Subduction zone is a point where two tectonic plates collide, causing one of them to sink into the Earth’s mantle beneath the other plate
REASONS BEHIND THE DECLINE OF SEAFLOOR SPREADING
- Growing mountains on the continents might be one of the factors driving the slowdown (as it causes resistance to seafloor spreading)
- Natural consequence of a ‘mature’ stage of supercontinent breakup and dispersal
- Changes in mantle convection could also be playing a role as mantle convection transports heat from the earth’s interior to the surface.
WHAT IS SEAFLOOR SPREADING?
- The seafloor spreading hypothesis was proposed by the American geophysicist Harry H. Hess in 1960.
- Seafloor spreading is the process of magma welling up in the rift as the old crust pulls itself in opposite directions. Cold seawater cools the magma, creating a new crust.
- The upward movement and eventual cooling of this magma has created high ridges on the ocean floor over millions of years.
- However, the seafloor is destroyed in subduction zones, where oceanic crust slides under continents and sinks back into the mantle, and is reforged at seafloor spreading ridges.