Seafloor spreading, a geological phenomenon affecting the Earth’s tectonic plates, has experienced a significant slowdown recently. This conclusion is based on a study that analyzed data from the past 19 million years and found that seafloor spreading rates have decreased by roughly 35% globally. This article will explore the concept of seafloor spreading, its impact on Earth’s geography, and potential reasons for its notable decline.
Study Highlights
The researchers involved in this study selected 18 of the world’s largest spreading ridges. These geographical features are chains of mountains or hills that form a continuous elevated crest over an extended distance. By studying magnetic records in the rocks on the oceanic crust, the team calculated the amount of oceanic crust that had formed over the past 19 million years.
However, data is not comprehensive as crusts are often destroyed at subduction zones, places where two tectonic plates collide, causing one to sink into the Earth’s mantle beneath the other plate. The fierceness of these collisions erases magnetic records over time.
Understanding Seafloor Spreading
First proposed by American geophysicist Harry H. Hess in 1960, the concept of seafloor spreading revolves around magma. The process begins when magma wells up in a rift as the old crust pulls apart. This upward movement and eventual cooling create high ridges on the ocean floor over millions of years.
However, these newly formed seafloors are not eternal. They often get destroyed in subduction zones, where they slide under continents and sink back into the mantle. Surprisingly, this seemingly destructive process gives birth to new seafloors at spreading ridges. The East Pacific Rise, located on the divergent boundary of several tectonic plates, is a major site for seafloor spreading.
Why is Seafloor Spreading Slowing Down?
One possible reason for the decline in seafloor spreading is the growth of mountains on continents, which might be causing resistance. This theory dates back 200 million years ago when Pangea, a massive supercontinent, began to split into pieces. At that time, continents were relatively flat and free from any major plate collisions or mountain chains.
However, as Pangea broke apart, new ocean basins formed and the now fragmented continents began colliding into each other. This mature stage of supercontinent breakup and dispersal could be causing resistance to seafloor spreading. Changes in mantle convection, which transports heat from the earth’s interior to the surface, could be another factor affecting spreading rates.
The Impact of Seafloor Spreading
This slowing down of seafloor spreading can influence sea level and the carbon cycle. An increased rate of seafloor spreading results in the inflation of the ridge due to the speedy formation of hot, young lithosphere. As this lithosphere moves away from the ridge at a faster pace before cooling and contracting, the sea level rises.
Additionally, seafloor spreading influences the carbon cycle. Higher spreading rates mean more volcanic activity, which subsequently releases greenhouse gases into the atmosphere. Therefore, a slowdown in seafloor spreading could have significant implications for our planet, impacting everything from sea levels to climate change.