January 4th, 2013 by James Ayre
An entirely new ‘class’ of Martian meteorite, that likely originates from the crust on Mars, has been identified by researchers at the University of New Mexico.
So far, this is the only sample that we have of a meteorite dated to around 2.1 billion years ago, which dates to a Martian epoch named the Amazonian. The most interesting part of the meteorite though is that it contains “an order of magnitude more water than any other Martian meteorite.”
The researchers investigated the “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 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.”
The new research was just published January 3rd 2013, in Science Express.
Source: Carnegie Institution
Image Credits: Carl Agee, University of New Mexico; Wikimedia: Creative Commons Attribution-Share Alike 2.0 Generic license
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