Seafloor spreading that creates crust slowed 35%, growing mountains may be driving it: Study

What is the News?

According to a study that analyzed data from the last 19 million years, seafloor spreading rates have slowed down by roughly 35% globally.

What is Sea Floor Spreading?

Seafloor spreading is a geological process that creates crusts, the outermost shell of Earth. 

In this process, new oceanic crust forms continuously along rifts thousands of miles long on the seafloor driven by plate tectonics. 

As subduction pulls old crust down, rifts open up like fissures in an effusive volcano, drawing hot crust toward the surface. Once at the surface, the crust begins to cool and gets pushed away from the rift, replaced by hotter, younger crust.

Determining the rate of this process is crucial because seafloor spreading influences sea level and the carbon cycle.

For example, faster rates mean more volcanic activity, which injects greenhouse gases into the atmosphere.

How did the researchers find out the seafloor spreading rate?

Researchers studied magnetic records for 18 of the world’s largest spreading ridges using seafloor ages and their areas to calculate how much ocean crust each ridge has produced over the last 19 million years. 

What did the researchers find out?

The seafloor is spreading at rates of around 140 millimetres per year, this is down from around 200 millimetres per year just 15 million years ago in some places.  

But not all ridges moved alike: Some sped up while others almost slowed down. The effects were particularly pronounced at ridges along the eastern Pacific. Some ridges in the region were roughly 100 millimetres per year slower compared to 19 million years ago, lowering the world’s average.

Why has the sea floor’s spreading rate slowed down?

Growing mountains might be one of the factors driving the slowdown.

The other factor might be changes in mantle convection. Mantle convection transports heat from the earth’s interior to the surface. 

Source: This post is based on the article “Seafloor spreading that creates crust slowed 35%, growing mountains may be driving it: Study” published in Down To Earth on 22nd April 2022