Zircons – one of the most commonly used geochronometers – found within the Martian meteorite NWA 7533 have enabled an international team of scientists to determine the age of the Red Planet’s crust.
4.43-billion-year-old Martian meteorite NWA 7533. Image credit: Meteorites.tv.
NWA (North West Africa) 7533 was unearthed by Bedouin tribesmen in the Sahara desert. It is a highlands breccia, which sets it apart from all other Martian meteorites. A breccia contains thousands of fragments of different geological samples and is the geological equivalent of a library containing the early history of Mars.
“As it turns out the crust is very old – about 4,430 million years old, which means that everything was happening very fast in the beginning on Mars,” said Dr Alexander Nemchin from Curtin University, a team member and the second author of a paper published in the journal Nature.
“A little bit more than 100 million years after the formation of the Solar System, Mars was a fully evolved planet, with a differentiated crust and a very complex range of magmatic and atmospheric processes. This research shows that if Mars could evolve very quickly, perhaps Earth did the same.”
The meteorite is chemically similar to Martian soil analyzed by Martian Rovers, enabling the researchers to compare ancient and modern Martian crustal processes and conditions.
For instance, using NWA 7533, they can look at Martian soil properties in the lab, which has led to them to knowing why Martian soil is so sticky – it is rich in magnetic minerals.
The meteorite is depleted in the water-soluble elements sulfur, chlorine and zinc, when compared to modern Martian soil, suggesting it comes from a wetter Mars, one very different to the dry, Sahara-like conditions of today’s Mars.
“This rock would hold further clues to the impact history of Mars, and the possibility of the presence of an early biosphere,” Dr Nemchin said.
“This report is the tip of the iceberg of what the exciting continuing study of this meteorite will uncover.”
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Bibliographic information: Humayun M et al. 2013. Origin and age of the earliest Martian crust from meteorite NWA 7533. Nature 503, pp. 513–516; doi: 10.1038/nature12764
