Summary
A NASA-funded study dates the Martian meteorite Teghaza 001 to more than 4.1 billion years ago. Its minerals also record alteration by water around that time, offering a rare sample of ancient Martian crust.
A NASA-funded study dates the Martian meteorite Teghaza 001 to more than 4.1 billion years ago, placing it among the oldest known pieces of Mars found on Earth. The mineral analysis also indicates that water altered the rock around 4.1 billion years ago, after it had formed.
The researchers’ initial characterization, published in Science, makes Teghaza 001 a rare sample of ancient Martian crust. Its minerals preserve clues to how that crust formed and how it later interacted with water beneath the planet’s surface.
Dating a rare Martian sample
The nearly 800-gram meteorite was found in the Sahara in 2022 and named for the salt plain in Mali where it was discovered. Researchers at the University of New Mexico identified it as Martian by matching its oxygen-isotope signature to those of other Martian meteorites. Oxygen isotopes act as geochemical fingerprints that can help distinguish material from different planetary bodies.
The NASA Jet Propulsion Laboratory team examined the rock’s unusual textures and minerals, including zircon crystals. Zircons can preserve clues about a rock’s formation and help geologists determine its age. The team used an in-situ rubidium-strontium dating method to analyse individual mineral grains on the surface of a piece smaller than a fingernail. Unlike a bulk-analysis method that dissolves an entire sample, this approach leaves most of a scarce meteorite available for later research.
The dating indicates that water altered Teghaza 001 around 4.1 billion years ago. The researchers infer that the rock itself formed earlier. The meteorite is one of three of the most ancient Martian meteorites found on Earth, according to NASA.
Clues to Mars’ early crust
Teghaza 001 stands out from other ancient Martian meteorites for its texture and mix of igneous, or volcanic, minerals. Together, those minerals provide evidence about crust formed as magma cooled and subsequently changed through interaction with subsurface water. The meteorite’s mineralogy also matches observations of Mars’ cratered southern highlands made by NASA’s Mars Reconnaissance Orbiter.
Researchers have identified 13 locations on Mars whose observed mineralogy and chemistry match the meteorite. Those matches narrow the possibilities, but its exact place of origin on Mars is not known.
Teghaza 001 is one of roughly 435 meteorites identified as coming from Mars. Such rocks were blasted off the planet by impacts before eventually reaching Earth. Its age and varied minerals give researchers an unusually informative sample for studying early Martian geology. Further work on the meteorite could help scientists investigate how rocks and water interacted as Mars’ surface and crust developed.