The Earth’s geomagnetic field is created by charged particles moving with the flow of molten rock rising away from a heated. The core is thought to be about a billion years old, though some studies have found that the resulting magnetic field dates back as far as 4 billion years ago. All this opposing figures have only added to the mystery of the magnetic field’s actual age. But, a new evidence could finally provide the breakthrough needed to give us some answers.
The formation of tiny crystals of quartz far beneath our feet may be the answer to accurately modelling the buoyancy of our planet’s deep molten rock according to a research by Kei Hirose from the Tokyo Institute of Technology in Japan.
The mismatch between the age we think our planet’s core is and the age of its magnetic field, or the New Core Paradox, occurs in part because of how heat from the inner core forces currents of gooey rock up toward the crust from the outer core.
Computer models created in 2012 suggest that heat is generated in the inner core’s iron at 150 watts per meter per kelvin. This happens too rapidly to have triggered convection currents in the surrounding molten rock.
Although other solutions to the paradox have tried to offer other ways Earth’s core could have generated heat, Hirose chose to analyze the core’s chemistry beyond its iron.
“In the past, most research on iron alloys in the core has focused only on the iron and a single alloy,” says Hirose. “But in these experiments we decided to combine two different alloys containing silicon and oxygen, which we strongly believe exist in the core.” In order to try understanding how these elements might form alloys and other compounds under these given conditions, Hirose and his team squeezed microscopic amounts of iron, silicon, and oxygen to core-like pressure by using precision-cut diamonds.
The next thing they do is using layers to hit the samples in order to reach temperatures of up to 4,000 degrees Celsius, and this caused some of the material to melt, and other parts to crystalize into quartz.
Those results suggest that the slow rise and fall of molten rock in a young Earth was helped along by quartz pulling silicon and oxygen from the mixture billions of years ago.
“This result proved important for understanding the energetics and evolution of the core,” says team member John Hernlund. ”We were excited because our calculations showed that crystallisation of silicon dioxide crystals from the core could provide an immense new energy source for powering the Earth’s magnetic field.”
But the geophysicist from the California Institute of Technology in Pasadena, David Stevenson presented a different idea.However, arguing that magnesium oxide would be more likely to precipitate out of the molten solution before silicon dioxide.
Hirose and his team agreed magnesium oxide is more likely, but that the temperatures inside a new Earth would require much hotter temperatures for magnesium to reside in the core.
At the end, in both of these cases, the fact remains that the more we know about chemistry’s role in the formation of the geomagnetic field, the more we can understand when Earth created it.