According to a new analysis of the Lafayette Meteorite, minerals within it formed in the presence of water 742 million years ago.
It’s a real breakthrough in the dating of aqueous minerals on Mars, and suggests that, sometimes, Mars might still be a little damp.
We do not think there was abundant liquid water on the surface of Mars at this time.
One of the materials in question is a type of rock called iddingsite, which forms from volcanic basalt in the presence of liquid water.
The Lafayette Meteorite contains iddingsite, which itself fortuitously contains inclusions of argon.
More and more evidence points to the fact that Mars was once wet and sloshy, covered in lakes and oceans that lapped at shorelines and left behind sediments that are currently being examined by robots rolling across the now-dusty Mars.
They had water. We know it was. Figuring out where it went, how it happened, and when it happened is a little more difficult. A meteorite that was ejected from Mars 11 million years ago and then traveled to Earth provides us with a significant hint, however, that liquid water existed on Mars less than a billion years ago.
A recent analysis of the Lafayette Meteorite indicates that minerals in it were formed 742 million years ago when water was present. It represents a significant advance in the dating of Martian aqueous minerals and raises the possibility that the planet may occasionally still be somewhat damp.
“Dating these minerals can therefore tell us when there was liquid water at or near the surface of Mars in the planet’s geologic past,” says Marissa Tremblay, a geochemist at Purdue University in the United States.
These minerals were discovered to have formed 742 million years ago when we dated them in the Martian meteorite Lafayette. We don’t believe that there was a lot of liquid water on Mars’ surface at this time. Rather, we believe that the water originated from the melting of permafrost, a type of nearby subsurface ice, which was brought on by magmatic activity that still happens occasionally on Mars today. “.”.
Iddingsite, a kind of rock that is formed from volcanic basalt in the presence of liquid water, is one of the materials. Oddly, iddingsite, which is found in the Lafayette Meteorite, also has argon inclusions.
Although dating minerals can be a little challenging, as technology develops, we’ve been becoming increasingly proficient at it. Argon isotopes can be subjected to a process known as radiometric dating, which provides an accurate record of the element’s formation time. Although potassium decays radioactively to produce argon, a single sample of the isotope argon-40 can still be dated in the absence of potassium.
This is because the amount of potassium that was initially present determines how much of the lighter isotope argon-39 is produced when argon-40 is irradiated in a nuclear reactor. Since potassium decays at a known rate, scientists can determine how long it has been since the rock formed by using the argon-39 that is produced as a stand-in for potassium.
This method was applied to a small sample of the Lafayette meteorite to determine the duration since the formation of iddingsite by the interaction of rock and water.
Rocks can also change if they are ejected from Mars during an impact event, fly through the Solar System, and then crash into Earth through its atmosphere, getting heated as they go. The scientists were able to simulate and take into consideration the temperature variations that the meteorite encountered during its lengthy journey, as well as ascertain whether or not they would have affected the sample’s apparent age.
Tremblay explains, “The impact that ejected the Lafayette Meteorite from Mars, the heating Lafayette received during the 11 million years it was floating out in space, or the heating Lafayette experienced when it fell to Earth and burned up a little bit in Earth’s atmosphere could have all had an impact on the [estimated] age.”.
We were able to show, however, that none of these factors had an impact on Lafayette’s age of aqueous alteration. “,”.
New limitations on the known date of moisture on Mars are imposed by the results. Additionally, the team discovered that the new date aligns with a time when Mars’ volcanic activity is at its highest. A lot more is happening inside the planet than its naive exterior would imply, according to recent observations made by the Mars InSight lander, even though such activity seems to be much quieter now.
The findings, however, have ramifications beyond our comprehension of Mars. The methods used by the team have the potential to help us understand the Solar System more broadly, including the long-standing and urgent question of how Earth obtained its water billions of years ago.
“To determine when liquid water might have existed, we have shown a reliable method to date alteration minerals in meteorites that can be applied to other meteorites and planetary bodies,” says Tremblay.
