Ancient Water-rich Meteorite Linked to Martian Crust

NWA 7034, nick­named “Black Beauty,” could shed light on the Red Planet’s past. Photo credit Carl Agee.

While the Mars’ Rovers con­tinue to scour the sur­face of the Red Planet snap­ping pic­tures, zap­ping rocks and look­ing at any other clues about its com­po­si­tion, researchers at the Uni­ver­sity of New Mexico’s Insti­tute of Mete­orit­ics have made what could be a once in a life­time dis­cov­ery right here on Earth involv­ing a rock deliv­ered by an inter­plan­e­tary free-ride from Mars.

Led by Carl Agee, direc­tor and cura­tor, Uni­ver­sity of New Mexico’s Insti­tute of Mete­orit­ics in Albu­querque, a team of researchers, includ­ing groups at UC San Diego and the Carnegie Insti­tu­tion, have iden­ti­fied a new class of Mar­t­ian mete­orite that fell to Earth and likely orig­i­nated from the planet’s crust and sur­face environment.

The mete­orite, North­west Africa (NWA) 7034, nick­named “Black Beauty,” is nearly 320 grams in weight and was found in the Saha­ran Desert in 2011. Now after more than a year of inten­sive study, Agee’s assem­bled team has deter­mined that the mete­orite formed 2.1 bil­lion years ago, the early era of the most recent geo­logic epoch on Mars called the Ama­zon­ian. Addi­tion­ally, the mete­orite, found to con­tain an order of mag­ni­tude more water (10x’s) than any other Mar­t­ian mete­orite, is a nearly per­fect match for sur­face rocks and out­crops that NASA’s mis­sions have stud­ied by remote sensing.

The research, sup­ported by NASA’s Cos­mo­chem­istry Pro­gram and Astro­bi­ol­ogy Insti­tute, the New Mex­ico Space Grant Con­sor­tium and the National Sci­ence Foun­da­tion, was pub­lished in the Jan­u­ary 3, 2013 issue of Sci­ence Express.

“This mete­orite is unlike any­thing I’ve ever seen before,” said Agee, who is also a pro­fes­sor in the Depart­ment of Earth and Plan­e­tary Sci­ences at UNM and an expert in the field who has spent much of his career study­ing mete­orites. “It’s a com­pletely new type of Mar­t­ian mete­orite. It has every­thing in its com­po­si­tion that you’d want in order to fur­ther our under­stand­ing of the Red Planet. This unique Mar­t­ian mete­orite tells us what vol­can­ism was like 2 bil­lion years ago, but it also gives us a glimpse of ancient sur­face and envi­ron­men­tal con­di­tions on Mars that no other mete­orite has offered.”

Researchers from the Insti­tute of Mete­orit­ics and Depart­ment of Earth and Plan­e­tary Sci­ences, includ­ing Fran­cis McCub­bin, Karen Ziegler, Vic­tor Polyak, Zachary Sharp, Yemane Asmerom, and grad­u­ate stu­dents Nicole Wil­son and Stephen Elardo, per­formed microbeam and x-ray analy­sis of min­er­als, water analy­sis, sta­ble iso­tope analy­sis, and age-dating in labs at UNM.

At UCSD, oxy­gen iso­topes of water and car­bon diox­ide were done by Mor­gan Nunn, Mark Thiemens, Robina Sha­heen and Zhisheng Zhang.

At the Carnegie Insti­tu­tion, researchers Andrew Steele, Mar­i­lyn Fogel, Rox­ane Bow­den and Mihaela Glam­o­clija, stud­ied car­bon in the mete­orite and dis­cov­ered that organic car­bon (macro­mol­e­c­u­lar) sim­i­lar to that seen in other Mar­t­ian mete­orites is also found in this meteorite.

“This mete­orite, made of brec­ciated vol­canic rock, is con­sis­tent with the com­po­si­tion of sur­face rocks on Mars ana­lyzed by Mar­t­ian rovers and orbiters,” said Agee. “But, our analy­sis of the oxy­gen iso­topes, oxy­gen atoms with dif­fer­ent num­bers of neu­trons, shows that NWA 7034 is not like any other mete­orites or plan­e­tary sam­ples. The chem­istry is con­sis­tent with sur­face rocks that have inter­acted with the Mar­t­ian atmos­phere, an idea that had been hypoth­e­sized by ear­lier stud­ies. The abun­dance of water, some 6,000 parts per mil­lion, sug­gests that the mete­orite inter­acted with Mar­t­ian sur­face– or ground-water 2.1 bil­lion years ago.”

The unique mete­orite 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. So far, they are the only mete­oritic sam­ples from Mars that sci­en­tists have been able to study in Earth-based lab­o­ra­to­ries. How­ever, their point of ori­gin on the Red Planet is uncer­tain. In fact, recent data from lan­der and orbiter mis­sions sug­gest that they are a mis­match for the Mar­t­ian crust.

“The tex­ture of the NWA mete­orite is not like any of the SNC mete­orites,” explained Steele, who led the car­bon analy­sis at the Carnegie Institution’s Geo­phys­i­cal Lab­o­ra­tory. “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.”

The mete­orite will undoubt­edly pro­vide addi­tional clues about Mars’ warm, wet past and its present cold, dry state as researchers at UNM and oth­ers con­tinue to exam­ine the rare rock.

“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.”

“For me per­son­ally, this is a once in a career dis­cov­ery. You try to do high qual­ity sci­ence, you do good work, per­se­vere, but once in a while, you just get lucky.” said Agee.

Media con­tact: Steve Carr, (505) 277‑1821; email: scarr@unm.edu