European scientists examined liquid basalt at record high pressures and temperatures to better understand how our planet evolved billions of years ago.
Their results, reported in the journal Nature, suggest molten magma once formed an ocean within the Earth’s mantle, comprising two layers of fluid separated by a crystalline layer.
Scientists agree that Earth formed around 4.5 billion years ago, at which time much of the planet was molten. As it cooled, Earth’s crust was formed. The team is keen to pin down how the planet’s core and crust took shape and how its volcanic activity developed.
The discovery supports current theories of how and when our planet evolved.
To recreate conditions at the Earth’s core, the scientists placed basalt under pressures equivalent to almost one billion times that of Earth’s atmosphere and temperatures above 2,000 degrees Celsius.
They found that at high pressure, silicon atoms in the basalt change the way in which they form bonds, which results in a denser magma.
Their findings help pinpoint how magma behaves deep in the Earth and is a missing piece in the puzzle of how Earth’s core formed.
“Modern labs make it possible for scientists to recreate conditions deep in the Earth’s core, and give us valuable insight into how materials behave at such extremes. This helps us build on what we already know about how Earth formed,” said study lead author Dr Chrystele Sanloup from the University of Edinburgh.
Bibliographic information: Chrystèle Sanloup et al. 2013. Structural change in molten basalt at deep mantle conditions. Nature 503, 104–107; doi: 10.1038/nature12668
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