Ancient zircon minerals from Mars reveal the elusive internal structure of the red planet

[Judi Lynn]

Date:
November 17, 2020
Source:
University of Copenhagen The Faculty of Health and Medical Sciences
Summary:
Analysis of an ancient meteorite from Mars suggests that the mineral zircon may be abundant on the surface of the red planet. By determining the age and hafnium isotope composition of these zircons, researchers have shown that a population of these crystals were sourced from the deep interior of Mars. If the researchers are correct, it means that the young zircons contain information about the deep, inaccessible interior of Mars, which provides insights into the internal structure of the planet.


The uranium-bearing mineral zircon is an abundant constituent of Earth's continental crust, providing information about the age and origin of the continents and large geological features such as mountain chains and giant volcanoes. But unlike Earth, Mars's crust is not evolved and is compositionally similar to the crust found under the Earth's oceans, where zircon is rare. Therefore, zircon is not expected to be a common mineral on Mars.

"We were quite surprised and excited when we found so many zircons in this martian meteorite. Zircon are incredible durable crystals that can be dated and preserve information that tell us about their origins. Having access to so many zircons is like opening a time window into the geologic history of planet," describes Professor Martin Bizzarro from the GLOBE Institute, who led the study.

The team investigated the ancient Martian meteorite NWA 7533, dubbed "Black Beauty," which was discovered in the desert of Morocco in 2011. After crushing 15 grams of this rock, they extracted about 60 zircons. By age-dating the zircons, they found that the majority of crystals date back to about 4.5 billion years ago, namely the very beginning of the planet's life. But they also made an unexpected discovery: some of the zircons defined much younger ages, ranging from about 1500 million years down to 300 million years.

"These young ages were a great surprise," says Bizzarro. "The Black Beauty meteorite is believed to come from the southern hemisphere of Mars, which does not have any young volcanic terrains. The only possible source for these young zircons is the Tharsis volcanic province located in the northern hemisphere of the planet, which contains large volcanoes that were recently active," Martin Bizzarro adds.

More:
https://www.sciencedaily.com/releases/2020/11/201117113057.htm

[NNadir]

1. Thank you for directing our attention to this paper.

This Thanksgiving, I'm thankful for your overviews of trends in science.

You're the best.