According to new research, it is possible that chemical residues from the earliest days of our planet may have been located near the Earth’s core, and this discovery might improve our understanding of the phenomenon of plate tectonics that occurs today.
The team behind the study compares these remains with lumps of flour at the bottom of the mixture’s bowl — elements that haven’t been mixed properly over billions of years, which show up as anomalies in seismic wave readings.
We know that seismic waves slow to the point of crawling near the Earth’s core, as they pass through what is known as Extremely Low Speed Zones (ULVZs). The big question is what these regions are – and scientists now think they may have found the answer.
“This discovery changes our view of the origin and dynamics of ultra-low velocity regions,” Seismologist Surya Pachai says from the Australian National University.
“We found that this type of very low velocity region can be explained by the chemical heterogeneity that was created early in Earth’s history, and that it was still not well mixed following 4.5 billion years of convection in the mantle.”
The way seismic waves resonate through Earth’s mantle and crust gives us clues regarding its formation, but measuring it across regarding 2,900 kilometers or 1,800 miles of rock is no easy feat. To address this, the scientists used a reverse engineering approach, running hundreds of thousands of computer simulations, using a process known as Bayesian inversion.
By comparing these models with actual readings taken from under the Coral Sea between Australia and New Zealand, the team was able to narrow down the odds of what ULVZ might be made of directly above the outer core of the liquid metal.
The researchers suggest that the ULVZs might be made partly of iron oxide — we know it as rust, but it functions as a mineral deep in the mantle. It is also now possible that this part of our planet consists of several sub-layers, which was not previously suspected in these regions.
This layer may be caused by a planetary body of the size Mars Earth shattering early. This event is believed to have dumped the debris that formed the moonIt also likely created an ocean of magma, made up of rocks, gases, and crystals, which might have sank to its present location over billions of years.
“The physical properties of very low velocity regions are related to their origin, which in turn provides important information regarding the thermal and chemical state, evolution and dynamics of the Earth’s lower mantle—a key part of the convection in the mantle that drives plate tectonic movement,” Bachai says.
It is known that seismic waves slow down by up to half in the ULVZ, with the corresponding intensity rising by a third. He. She and it has been suggested That these are partially molten regions of the mantle, providing magma to volcanic hot spots at the surface (eg Iceland).
However, not all high-density areas correspond to places of frequent volcanic activity, which indicates that something else is happening. This inspired the research team to take a closer look – revealing the amazing layers that make up the ULVZs, with the help of computer modeling.
The mantle and the ULVZ at its bottom might drive the movement of tectonic plates close to the surface, which means the new research not only teaches us more regarding Earth’s birth, but also more regarding how it behaves today.
“Of all the features that we know of in the deep mantle, very low velocity regions represent what are probably the most extreme,” Geologist Michael Thorne says: from the University of Utah.
“In fact, these are some of the most extreme traits found anywhere on the planet.”
The search was published in natural earth sciences.
