AsianScientist (Aug. 12, 2016) – Researchers in Japan have provided insights into how Earth-type planets form when giant asteroids collide. The study was published in Science Advances.
According to Professor Toshimori Sekine from Hiroshima University, who is the first author of the paper, collisions at these extreme temperatures and pressures created Earth and may have also formed the mantles of other ‘Super Earth’ planets.
These powerful collisions between asteroids cause chemical reactions within the giant rocks. Many of these rocks contain forsterite, a mineral that makes up much of the matter in space. Forsterite, known to scientists as Mg2SiO4, is a combination of magnesium, silicon and oxygen and is the most abundant constituent of Earth’s mantle, the layer between the surface crust and molten core.
The research team successfully measured the melting of forsterite and replicated the extreme collision conditions that can turn minerals into magma. The latter was previously a challenge for scientists to accomplish.
Using a technique called laser shock, Sekine’s team irradiated a block of forsterite with a high-powered laser. This technique put the forsterite crystals under pressures between approximately 250 and 970 Giga Pascals (GPa). For comparison, the pressure at the center of Earth is estimated to be 360 GPa.
The energy of the laser beam caused the target’s molecules to abruptly expand, and the inertia of this expansion generated a shock wave. The energy from the shock wave created light and heat, the latter of which melted the forsterite.
Earlier research had connected magnesium oxide, one of the minerals that is formed from forsterite, to the reactions necessary for a planet to develop a magnetic field that persists for a long geological time, such as the magnetic field of Earth.
With these new details of forsterite’s melting behavior, researchers may be able to predict how minerals separate into different layers of magma and which minerals may be close enough to react with each other.
The article can be found at: Sekine et al. (2016) Shock Compression Response of Forsterite Above 250 GPa.
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Source: Hiroshima University; Photo: Pixabay.
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