Here is one interesting new research about the nearest planet to the sun, Mercury.
As reported in the NCSU website, a new paper published at the Geophysical Research Letters journal suggests that most volcanic activity on Mercury–a planet located at about thirty-six million miles from the sun–most likely ended about 3.5 billion years ago. These findings, scientists say, could give them more insight into the geological evolution of the planet, and what happens when rocky planets contract and cool in general.
The team, with planetary geologist and NC State assistant professor, Paul Byrne, explains that there are two types of volcanic activity on rocky planets: explosive and effusive. Explosive volcanic activity is a violent event similar to the Mount Pinatubo eruption in the Philippines in 1991, and the Mount Saint Helens in 1980, and effusive volcanism refers to widespread lava flows that slowly pour out over a landscape. Effusive, the team adds, is believed to be a key process in rocky planets’ crust formation.
Determining the ages of effusive volcanic deposits can give scientists a hold on a planet’s geological history. For example, effusive volcanism is still active on Earth today, but on Mars, it stopped a few million years ago. On Venus, it ended a few hundred million years ago.
Exploring the last volcanic activity on Mercury
By using the data from the NASA MESSENGER mission, the team was able to determine when the effusive volcanic activity ended on Mercury.
We all know that scientists have no physical samples from the planet which could be used for radiometric dating, so they used photographs of Mercury’s surface, and used crater size-frequency analysis, in which the number and size of craters are placed into established mathematical models. It allowed them to calculate absolute ages for effusive volcanic deposits on Mercury.
Their analysis has shown that Mercury’s major volcanic activity stopped at around 3.5 billion years ago, the earliest in the inner solar system.
Byrne says there is a huge geological difference between our planet, Mars and Venus, and Mercury. The smallest planet in our solar system has a much smaller mantle–where radioactive decay produces heat–compared to those on its neighbors. Mercury began to contract, and the crust sealed off any conduits that magma could use to reach the surface.
The research is titled ‘Widespread effusive volcanism on Mercury likely ended by about 3.5 Ga.’ It is accessible online via the AGU Publications website.