This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The evolutionary histories of Earth and Mercury differ fundamentally. The smallest planet, closest to the sun, likely began cooling early on, much like a setting pudding: As early as about 1 billion years after its formation, Mercury's volcanic activity came to a halt, and a solid, continuous "rock skin" formed on the planet's surface.
Earth's crust, on the other hand, is still in motion: Volcanism and plate tectonics are constantly stirring up the "Earth pudding." Exactly what Mercury's unique volcanic past looked like and how it shaped its current appearance remain unclear. However, researchers can gain important clues from the composition of its surface. In a new study, researchers from the Max Planck Institute for Solar System Research in Germany and the Universities of Münster and Göttingen, also in Germany, have determined the proportion of silicon dioxide on Mercury's surface with greater accuracy than ever before.
Their findings are published in the journal Planetary Research. The study reveals a surprise: With a mass fraction of about 37%, silicon dioxide on Mercury is up to 25% less abundant than previously thought. On Earth, however, the compound consisting of one silicon atom and two oxygen atoms is virtually ubiquitous: in its pure form as sand and in large quantities in all volcanic rocks, such as basalt, andesite and granite, which contain up to 75% silicon dioxide.
"Our findings suggest that the volcanic rocks on Mercury formed from mantle material that had melted at greater depths than previously assumed," said Christian Renggli, lead author of the new study and head of the "Experimental Laboratory Magma Ocean" research group at the MPS. Silicon dioxide gradually accumulates in the molten mantle of a young planet—that is, the layer beneath the solidified crust. This is because, as the mantle cools, the first rocks to form extract comparatively little silicon dioxide from the melt.
The hot lava that wells up to the surface therefore becomes increasingly rich in silicon dioxide over time. If this compound is present in small amounts on the surface, it indicates high temperatures in the interior. It is also possible that Mercury once had more silicon dioxide in its crust but gradually lost its oxygen.
It is difficult to make statements about the surface composition of Mercury. No lander has ever touched down on its surface; there are no rock samples from there. Researchers therefore have no choice but to infer its composition from remote sensing data—that is, from telescopes on Earth or from space probes.
Extract — continue reading at the source.
