Over four billion years ago, the Red Planet may have been red hot. A 4.45-billion-year-old grain of the mineral zircon in a Martian meteorite found in the Sahara Desert in 2011 indicates Mars may have been home to boiling hot hydrothermal systems similar to Earth's volcanoes. The findings are detailed in a study published November 22 in the journal Science Advances.
The team analyzed meteorites from a large space rock designated as NWA7034 or "Black Beauty." While all Martian meteorites have clues about the planet's geologic history, most of them are igneous rocks like those found on Earth and others are mantle rocks.
"What makes Black Beauty so special is that it's a sample of regolith from the surface, which is similar to soil," Aaron Cavosie, a study co-author and a planetary scientist from the Space Science and Technology Centre at Curtin University in Australia, tells Popular Science. "It contains hundreds of rock and mineral fragments from lots of different sources on Mars."
Roughly 20 meteorites have been found here on Earth that are all believed to have been chipped off of Mars during the impact event that hurled the original Black Beauty stone down to Earth. The tiny grain of zircon within the meteorite was first described in a 2022 study. It provided scientists with an early record of crust formation on Mars, but also preserved the damage caused by earlier impacts by meteorites.
"The Black Beauty meteorites offer an extraordinary buffet of clues that help to fill in the geological puzzle of Mars," says Cavosie.
In the new study, Cavosie and the team decided to take a closer look at the grain of Martian zircon, focusing on the trace elements within the space rock for clues about the early history of Mars. They used nano-scale geochemistry and found elemental evidence of hot water on Mars about 4.45 billion years ago. On Earth, these types of systems were essential to the development of life and water was key during the earliest parts of crust formation.
Nanoscale imaging and spectroscopy helped the team identify the element patterns in the zircon. These include iron, sodium, yttrium, and aluminum.
"We could tell by the patterns of how the Fe [Iron], Al [Aluminum], and Na [sodium] are found inside the zircon that they were incorporated into the grain as it grew, like layers in an onion," Cavosie says.
[Related: Meteorite found in a drawer in 1929 contains ancient evidence of liquid water on Mars.]
On Earth, the only zircons that have patterns like these form in magmatic-hydrothermal systems. These form when water is heated by a "volcanic plumbing system." This system of hot boiling water then moves through rocks, taking these trace elements with them. The team believes that these elements were added as the zircon formed 4.45 billion years ago. This suggests that water was present during early magma-filled days on Mars. Other studies found that Earth's moon also used to be full of magma.
"When we did the follow-up trace element study, and found that the martian zircon looks very similar to zircons from the Olympic Dam hydrothermal ore deposit in South Australia, we were very surprised, and even more excited," says Cavosie. "It not only meant finding evidence for magmatic-hydrothermal systems on early Mars, but it also gave us an idea about what kinds of environments they form in from an Earth perspective."