Jakarta –
Something strange is happening deep beneath our feet. Over the years, seismic studies have detected a number of anomalies occurring in the area between the Earth’s core and mantle, which are believed to be the result of processes within the mantle.
A new study, published this week in Nature, suggests that this activity may actually be related to Earth’s core.
As the authors explain in this study, the boundary between Earth and the mantle is the interface between the solid silicate mantle and the liquid metal outer core, and the structure and dynamics in this region are fundamental to understanding heat and material transfer on our planet.
Seismic imaging has allowed scientists to find fine-scale structures at the boundary between Earth’s core and mantle. This ‘anomaly’ is characterized by a difference in velocity and density compared to the normal mantle or surrounding core region.
This study specifically focuses on the Earth’s outer core which lies about 3,000 km below the surface. This region is composed of an alloy of viscous liquid iron, which has a major impact on the habitability of the Earth’s surface and the creation of its magnetic field.
Obviously, the researcher cannot access the actual core, but can conduct research under similar conditions in the laboratory, and this is what the study authors do.
“We conducted an experiment to see what happens when we combine liquid iron-hydrogen alloy with silicon under high pressure and high temperature conditions, such as those found in the outer core,” wrote one of the study’s authors, geoscientist Suyu Fu of Arizona State. University, quoted from Motherboard, Friday (17/2/2023).
“We found that silicon-rich crystals form in liquid iron or silicon-rich snow, and they are lighter than the liquid outer core, causing them to rise to the boundary between the metal core and rocky mantle, rather than sink,” he wrote.
Fu notes that this process can create silicon-rich snowdrifts that can help us understand some of the puzzling structures found at Earth’s core-mantle boundary.
“Our study sheds light on the causes of two distinct seismic wave velocity anomalies at the Earth’s core-mantle boundary, namely the ultra-slow zone on the mantle side and the core stiffness zone on the core side,” he wrote.
“While the slow zone was previously believed to be related primarily to mantle processes, our research suggests that some of it may be generated by processes occurring in the outer core. For the core rigidity zone, some researchers hypothesized that precipitation of light elements in the outer core may be responsible. We found evidence that the silicon ‘snow’ phenomenon may be behind the observed core rigidity zones,” the researchers explained.
Even under our feet, there’s still a lot we don’t know about Earth’s interior, especially its core. Just last month, scientists published a study suggesting that the Earth’s core actually briefly stopped and possibly reversed. This behavior explains a number of cyclical phenomena.
And recently, scientists discovered that there is an entire zone of Earth that lies deep beneath the surface that still eludes detection.
These new findings have implications for understanding Earth’s deep chemistry. As Fu explains, their research has revealed that some volcanic rocks found on oceanic islands, such as Hawaii, contain chemicals similar to Earth’s core.
“Our study shows that when silicon-rich crystals from the Earth’s core mix with mantle silicates to form these ultra-low velocity zones, they can provide a source of core-like chemical signatures found in volcanic rocks.”
Watch Video “Study: The Earth’s Core May Be Starting To Rotate In The Reverse Direction“
(rns/fay)
