A spectroscopic method for identifying terrestrial biocarbonates and application to Mars

✍ Scribed by A. Blanco; V. Orofino; M. D’Elia; S. Fonti; A. Mastandrea; A. Guido; F. Russo

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 697 KB
• Volume: 213
• Category: Article
• ISSN: 0019-1035
• DOI: 10.1016/j.icarus.2011.03.027

✦ Synopsis

Searching for traces of extinct and/or extant life on Mars is one of the major objectives for remote-sensing and in situ exploration of the planet. In previous laboratory works we have investigated the infrared spectral modifications induced by thermal processing on different carbonate samples, in the form of fresh shells and fossils of different ages, whose biotic origin is easily recognizable. The goal was to discriminate them from their abiotic counterparts. In general, it is difficult to identify biotic signatures, especially when the organisms inducing the carbonate precipitation have low fossilization potential (i.e. microbes, bacteria, archaea). A wide variety of microorganisms are implicated in carbonate genesis, and their direct characterization is very difficult to evaluate by traditional methods, both in ancient sedimentary systems and even in recent environments.

In the present work we apply our analysis to problematic carbonate samples, in which there is no clear evidence of controlled or induced biomineralization. This analysis indicates a very likely biotic origin of the aragonite samples under study, in agreement with the conclusion previously reported by Guido et al. (2007) who followed a completely different approach based on a complex set of sedimentary, petrographic, geochemical and biochemical analyses. We show that our method is reliable for discriminating between biotic and abiotic carbonates, and therefore it is a powerful tool in the search for life on Mars in the next generation of space missions to the planet.