Elephant Moraine A79001 Martian meteorite, Elephant Moraine, Victoria Land, Eastern Antarctica, Antarcticai

Regional Level Types
Elephant Moraine A79001 Martian meteorite	Meteorite Fall Location
Elephant Moraine	- not defined -
Victoria Land	Region
Eastern Antarctica	Region
Antarctica	Continent

Martian basalt: Shergottite, Olivine-phyric
Found, 1979; 7.942 kg

Found on the Elephant Moraine icefield of Antarctica, the moderately large Elephant Moraine A790001 stone (usually, 'EETA79001') soon became a highly studied meteorite. With its interior largely protected by a largely intact fusion crust, its similarities to the very unusual and highly shocked Shergotty fall of 1865 drew immediate attention. Closer attention revealed a further and intriguing complexity — EETA79001 is a rare example of a meteorite co-dominated by two distinct silicate lithologies in contact with each other. The somewhat subordinate 'lithology B' is marked by the clinopyroxene-maskelynite intergrowth (~70 & 15-20 vol%, resp.) which characterizes Shergotty and other basaltic shergottites. The slightly predominant 'lithology A' contains these phases in somewhat different proportions — but it also contains an admixture of conspicuous olivine, orthopyroxene, and chromite crystals. These 'megacrysts' appear to represent earlier stages in the melts which have produced the 100+ Martian shergottites now known. We document some of the mineralogical findings below. However, the most dramatic finding was the identification of gases within some small dark glassy clasts (aka, 'Lithology C'). In 1984 Becker & Pepin discovered that these EETA79001 gases were virtually identical to those found in the Martian atmosphere by the Viking Lander. EETA79001 was demonstrably a rock from Mars! Similar findings were subsequently established for additional shergottites and other members of the SNC clan.

A number of studies EETA79001 studies have focused on unraveling the igneous processes and shock events which have helped to shaped the minerals and phases of Elephant Moraine A79001 on the planet Mars and, perhaps, during additional collisions during their journeys to Earth. There is, however, another related mineralogical story of great interest. Carbonates and sulfates have been found within the meteorite. Some of these phases have been produced by terrestrial weathering. However, there is also direct isotopic evidence that these phases were produced by aqueous alterations occurring on Mars as well as on earth. The more, there is an evidence showing that this meteorite also contains perchlorate, chlorate, and nitrate anions in its bulk composition.


Isotopic 'ages' for EETA79001 have been somewhat difficult to interpret, but the basic mineral components appear to have been produced by Martian lava less than 200 million years ago. EETA79001 has an unusually young cosmic ray exposure age of less than a million years. EETA79001 is the 6th most massive of 151 Martian meteorites listed at the Meteoritical Bulletin Database (as of early June 2015). Sixteen of these meteorites have been further sub-classified as 'Olivine-phyric Shergottites' at the Martian Meteorite Compendium sponsored by the Johnson Space Center.

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