Meteorites on Earth May Be From Ancient Crater on Mars

MeteoritesA crater on Mars appears to be the source of a type of meteorite widely found on Earth, scientists from the University of Oslo in Norway reported Thursday.

The meteorites, called shergottites, may have come from the 34-mile-wide (55-kilometer-wide) Mojave Crater. The results, if confirmed, would have implications for ancient volcanism on Mars—suggesting it stopped earlier in the planet’s history than some scientists believe—as well as the planet’s formation.

Martian meteorites fall to Earth after an asteroid impact blasts them off their home planet. Most of the 150 Martian meteorites found on Earth belong to one of three groups: shergottites, nakhlites, and chassignites (known as SNC meteorites). The latter two types are thought to have formed around 1.3 billion years ago, but controversy surrounds the origin of shergottites.

The study, published in Science Express, suggests that formation of the meteorites can be traced to the Mojave Crater, located in an ancient region of Mars called the Xanthe Terra. “There has been no other impact crater identified from which any of the Martian meteorites come from,” says the study’slead author Stephanie Werner.

“This research is very important for helping us interpret the geochemical data of Mars,” says Audrey Bouvier, an isotopic geochemist at Western University in Ontario, Canada, who was not involved in the study. “It has implications for the early evolution of the planet, including its formation, cooling, and the loss of its [global] magnetic field.”

To see if the meteorites came from the Mojave Crater, Werner and her colleagues compared the mineral composition of the crater—determined using Mars satellite scans—with those of three shergottites and ALH84001, a Mars meteorite not part of the SNC family. They found that the mineralogy of the crater wall outcrops matched the composition of the meteorites.

source : http://news.nationalgeographic.com/news/2014/14/140306-mars-meteorite-crater-space/





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