Giant collisions with moon-sized objects explain the presence of gold and platinum in the Earth’s mantle

“Previous simulations of impacting objects penetrating the Earth’s mantle have shown that only small portions of the planetary metal core are available for uptake by the Earth’s mantle, while most of these metals – including HSEs – are rapidly discharged to the Earth’s core,” he said. Marchi, who authored the paper Proceedings of the National Academy of Sciences (PNAS) Description of new results.

This leads us to the question: How did the Earth get some of its precious metals? “We have developed new simulations to try to explain the mixture of minerals and rock materials in the present mantle.”

The new simulation examined how a partially molten zone beneath the impact’s magma ocean could stop the descent of planetary minerals into the Earth’s core.

“To achieve this, we modeled the mixing of a colliding planet with mantle material in three liquid phases: solid silicate minerals, molten silicate magma, and liquid mineral,” said Dr. Jun Kurinaga, lead author of the paper from the university Yale.

“The fast dynamics of such a three-phase system, combined with the long-term mixing provided by convection in the mantle, allows HSEs from planets to persist in the mantle.”

When the metals reach the partially molten zone below, the metal will quickly penetrate through the melt, and then slowly sink to the bottom of the mantle. During this process the molten mantle solidifies, trapping the metal. This occurs when convection dominates, where heat from the Earth’s core causes a very slow creeping movement of material in the solid mantle, and the resulting currents carry the heat from the Earth’s interior to the planet’s surface.

“Mantle transport refers to the process of warm mantle material rising and cold material sinking,” Korenaga said. “The mantle is almost entirely solid, although, over long geological timescales, it behaves as an elastic and highly viscous fluid, mixing and redistributing mantle materials, including HSEs accumulated by large collisions that occurred billions of years ago.”