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A Reduced Organic Carbon Component in Martian Basalts

Science  13 Jul 2012:
Vol. 337, Issue 6091, pp. 212-215
DOI: 10.1126/science.1220715

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Abiotic Martian Organics

Understanding the sources and the formation mechanisms of organic carbon compounds on Mars has implications for our understanding of the martian carbon cycle. Steele et al. (p. 212, published online 24 May) present measurements of organic material in 11 martian meteorites, including the Tissint meteorite, which fell in the Moroccan desert in July 2011. Ten of the meteorites contain complex hydrocarbons encased within igneous minerals. The results imply that the organics formed as the magma melt crystallized and are thus of abiotic origin.

Abstract

The source and nature of carbon on Mars have been a subject of intense speculation. We report the results of confocal Raman imaging spectroscopy on 11 martian meteorites, spanning about 4.2 billion years of martian history. Ten of the meteorites contain abiotic macromolecular carbon (MMC) phases detected in association with small oxide grains included within high-temperature minerals. Polycyclic aromatic hydrocarbons were detected along with MMC phases in Dar al Gani 476. The association of organic carbon within magmatic minerals indicates that martian magmas favored precipitation of reduced carbon species during crystallization. The ubiquitous distribution of abiotic organic carbon in martian igneous rocks is important for understanding the martian carbon cycle and has implications for future missions to detect possible past martian life.

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