CIS: First Meteorite Linked to Martian Crust

[bystander]

First Meteorite Linked to Martian Crust
Carnegie Institution for Science | 2013 Jan 03

Northwest Africa (NWA) 7034
Credit: NASA/C. Agee (UNM)

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After extensive analyses by a team of scientists led by Carl Agee at the University of New Mexico, researchers have identified a new class of Martian meteorite that likely originated from Mars’s crust. It is also the only meteoritic sample dated to 2.1 billion years ago, the early era of the most recent geologic epoch on Mars, an epoch called the Amazonian. The meteorite was found to contain an order of magnitude more water than any other Martian meteorite. Researchers from the Carnegie Institution (Andrew Steele, Marilyn Fogel, Roxane Bowden, and Mihaela Glamoclija) studied carbon in the meteorite and have shown that organic carbon (macromolecular) similar to that seen in other Martian meteorites is also found in this meteorite. The research is published in the January 3, 2013, issue of Science Express.

The unique meteorite, dubbed Northwest Africa (NWA) 7034, has some similarities to, but is very different from other Martian meteorites known as SNC (for three members of the group: Shergotty, Nakhla, and Chassigny). SNC meteorites currently number 110. And so far they are the only meteoritic samples from Mars that scientists have been able to study. However, their point of origin on the Red Planet is not known. In fact, recent data from lander and orbiter missions suggest that they are a mismatch for the Martian crust.

As co-author Andrew Steele, who led the carbon analysis at the Carnegie Institution’s Geophysical Laboratory explained: “The texture of the NWA meteorite is not like any of the SNC meteorites. It is made of cemented fragments of basalt, rock that forms from rapidly cooled lava, dominated with feldspar and pyroxene, most likely from volcanic activity. This composition is common for lunar samples, but not from other Martian meteorites. This unusual meteorite’s chemistry suggests it came from the Martian crust. It is the first link thus far of any meteorite to the crust. Our carbon analysis also showed the presence of macromolecular organic carbon in feldspar grains associated with iron oxides, hinting that perhaps there is a different non-biological process at work than that explaining the presence of macromolecular carbon in other Martian meteorites.”

Lead author Agee, of the Institute of Meteoritics at the University of New Mexico, remarked: “The basaltic rock in this meteorite is consistent with the crust or upper mantle of Mars based on findings from recent Martian rovers and orbiters. Our analysis of the oxygen isotopes shows that NWA 7034 is not like any other meteorites or planetary samples. The chemistry is consistent with a surface origin and an interaction with the Martian atmosphere. The abundance of water, some 6000 parts per million, suggests that the meteorite interacted with the Martian surface some 2.1 billion years ago.”

“Perhaps most exciting, is that the high water content could mean there was an interaction of the rocks with surface water either from volcanic magma, or from fluids from impacting comets during that time,” said Steele. “It is the richest Martian meteorite geochemically and further analyses are bound to unleash more surprises.”

Unique Meteorite from Early Amazonian Mars: Water-Rich Basaltic Breccia Northwest Africa 7034 - Carl B. Agee et al

• Science (online 03 Jan 2013) DOI: 10.1126/science.1228858

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[b][color=#0000FF]Martian meteorite NWA 7034 weighs approximately 320 grams (11 ounces).[/color][/b]

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Meteorite From Mars is Water-Rich
by Nancy Atkinson on January 3, 2013

<<A 2-billion-year-old rock found in the Sahara desert has been identified as a meteorite from Mars’ crust, and it contains ten times more water than any other Martian meteorite found on Earth. It also contains organic carbon. The age of the rock, called NWA 7034, would put its origins in the early era of the most recent geologic epoch on Mars, the Amazonian epoch. While its composition is different from any previously studied Martian meteorite, NASA says it matches surface rocks and outcrops that have been studied by Mars rovers and Mars-orbiting satellites.

“The contents of this meteorite may challenge many long held notions about Martian geology,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. “These findings also present an important reference frame for the Curiosity rover as it searches for reduced organics in the minerals exposed in the bedrock of Gale Crater.”

This new class of meteorite was found in 2011 in the Sahara Desert. Designated Northwest Africa (NWA) 7034, and nicknamed “Black Beauty,” it weighs approximately 320 grams (11 ounces). Research teams from the University of New Mexico, the University of California at San Diego and the Carnegie Institution in Washington analyzed mineral and chemical composition, age, and water content.

NWA 7034 is made of cemented fragments of basalt, rock that forms from rapidly cooled lava. The fragments are primarily feldspar and pyroxene, most likely from volcanic activity.

“This Martian meteorite has everything in its composition that you’d want in order to further our understanding of the Red Planet,” said Carl Agee, leader of the analysis team and director and curator at the University of New Mexico’s Institute of Meteoritics in Albuquerque. “This unique meteorite tells us what volcanism was like on Mars 2 billion years ago. It also gives us a glimpse of ancient surface and environmental conditions on Mars that no other meteorite has ever offered.”

There are about one hundred Martian meteorites that have been collected on Earth. They were all likely blasted off the Red Planet by either an asteroid or comet impact, and then spent millions of years traveling through space before falling to Earth.

Researchers theorize the large amount of water contained in NWA 7034 may have originated from interaction of the rocks with water present in Mars’ crust. The meteorite also has a different mixture of oxygen isotopes than has been found in other Martian meteorites, which could have resulted from interaction with the Martian atmosphere.

Scientists say the age of NWA 7034 is important because it is much older than most other Martian meteorites. “We now have insight into a piece of Mars’ history at a critical time in its evolution,” said Mitch Schulte, program scientist for the Mars Exploration Program at NASA Headquarters.

Most Martian meteorites are divided into three rock types, named after three meteorites; Shergotty, Nakhla, and Chassigny. These “SNC” meteorites currently number about 110. Their point of origin on Mars is not known and recent data from lander and orbiter missions suggest they are a mismatch for the Martian crust. Although NWA 7034 has similarities to the SNC meteorites, including the presence of macromolecular organic carbon, this new meteorite has many unique characteristics.

“The texture of the NWA meteorite is not like any of the SNC meteorites,” said co-author Andrew Steele, who led the carbon analysis at the Carnegie Institution’s Geophysical Laboratory. “This is an exciting measurement in Mars and planetary science. We now have more context than ever before to understanding where they may come from.”>>