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The SNC Meteorites Are From MarsThe thirteen SNC meteorites are all igneous rocks, either basalts or basaltic cumulates. They are inferred to be from Mars, based on direct comparison with martian materials and on consistency with inferences about Mars. Most telling is that the SNC meteorites contain traces of gas which is very similar in elemental and isotopic compositions to the modem Martian atmosphere as measured by Viking. The martian atmosphere appears to be unique in the solar system, so its presence in the SNCs is accepted as virtually unequivocal proof that they formed on Mars. Independent of this link, the SNC meteorites must be from a planet with a significant atmosphere because they contain several abundant gas components, some of which carry large isotopic fractionations characteristic of atmospheric processing. The chemical compositions of the SNC meteorites are also consistent with data from in situ analyses of martian soils and rocks, and are quite different from compositions of other meteorites, rocks from the Earth, and rocks from the Moon. The range of formation ages for the SNC meteorites, 4.5 Ga to 0. 18 Ga, is consistent with the varied ages of the Martian surface (based on its cratering record) and inconsistent with surface ages on any other solar system body. The extreme chemical fractionations in the SNC meteorites suggest complex internal processes on a large planet, which is inconsistent with an asteroidal origin. Some SNCs were altered by aqueous solutions at greater than 0.7 Ga, consistent with the recent presence of liquid groundwater in Mars inferred independently from the geology of its surface. There seems little likelihood that the SNCs are not from Mars. If they were from another planetary body, it would have to be substantially identical to Mars as it now is understood.
Document ID
20000085942
Acquisition Source
Johnson Space Center
Document Type
Abstract
Authors
Treiman, Allan H.
(Lunar and Planetary Inst. Houston, TX United States)
Gleason, James D.
(Ecole Normale Superieure Lyon, France)
Bogard, Donald D.
(NASA Johnson Space Center Houston, TX United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Astrophysics
Funding Number(s)
PROJECT: RTOP 344-31-00-05
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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