How Mercury formed its graphite crust and core
As the BepiColombo mission prepares to enter the final phase of its journey to Mercury, a series of studies conducted by researchers at the University of Liège and KU Leuven sheds new light on the early stages of the evolution of the planet closest to the sun. Using experimental petrology, the researchers are reconstructing in the laboratory the formation of Mercury's core, the crystallization of…
Mercury's core and graphite crust formation can be traced back to the planet's early stages of evolution. During this time, the planet experienced a magma ocean, which had a significant impact on the distribution of elements between the metallic core and the mantle. By conducting high-pressure, high-temperature experiments, researchers were able to simulate the behavior of carbon under various conditions, including the planet's extraordinarily low oxygen environment.
Under these conditions, carbon became less siderophile and instead remained in the silicate magma, where it crystallized as graphite. This graphite formation resulted in a thin crust on Mercury's surface, approximately 40-120 meters thick. The core, which makes up around 70% of Mercury's mass, contains only a few percent of light elements, primarily silicon and sulfur, rather than carbon.
These findings offer insights into the formation of other highly reduced bodies, such as proto-Mercury and certain carbon-rich exoplanets.
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