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Evidence for biological activity in mineralization of secondary sulphate deposits in a basaltic environment: implications for the search for life in the Martian subsurface

Published online by Cambridge University Press:  24 July 2013

C. Doc Richardson ,
Nancy W. Hinman  and
Jill R. Scott
C. Doc Richardson
Affiliation:
Geosciences Department, University of Montana, Missoula, 32 Campus Drive #1296, Missoula, MT 59812, USA
Nancy W. Hinman
Affiliation:
Geosciences Department, University of Montana, Missoula, 32 Campus Drive #1296, Missoula, MT 59812, USA
Jill R. Scott
Affiliation:
Chemical and Radiation Measurement, Idaho National Laboratory, 1765 North Yellowstone Hwy, Idaho Falls, ID 83415-2208, USA e-mail: Jill.Scott@inl.gov
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Abstract

Evidence of microbial activity associated with mineralization of secondary Na-sulphate minerals (thenardite, mirabilite) in the basaltic subsurface of Craters of the Moon National Monument (COM), Idaho were examined by scanning electron microscopy, X-ray diffraction, laser desorption Fourier transform ion cyclotron resonance mass spectrometry (LD-FTICR-MS), Fourier transform infrared spectroscopy (FTIR) and isotope ratio mass spectrometry. Peaks suggestive of bio/organic compounds were observed in the secondary Na-sulphate deposits by LD-FTICR-MS. FTIR provided additional evidence for the presence of bio/organic compounds. Sulphur fractionation was explored to assist in determining if microbes may play a role in oxidizing sulphur. The presence of bio/organic compounds associated with Na-sulphate deposits, along with the necessity of oxidizing reduced sulphur to sulphate, suggests that biological activity may be involved in the formation of these secondary minerals. The secondary Na-sulphate minerals probably form from the overlying basalt through leached sodium ions and sulphate ions produced by bio-oxidation of Fe-sulphide minerals. Since the COM basalts are one of the most comparable terrestrial analogues for their Martian counterparts, the occurrence of biological activity in the formation of sulphate minerals at COM has direct implications for the search for life on Mars. In addition, the presence of caves on Mars suggests the importance of these environments as possible locations for growth and preservation of microbial activity. Therefore, understanding the physiochemical pathways of abiotic and biotic mineralization in the COM subsurface and similar basaltic settings has direct implications for the search for extinct or extant life on Mars.

Keywords

bio/organic compoundsCraters of the Moon National MonumentFTICR-MSFTIRMarsSEMsulphur isotopesThenarditeXRD
Type
Research Article
Information
International Journal of Astrobiology , Volume 12 , Issue 4 , October 2013 , pp. 357 - 368
Copyright
Copyright © Cambridge University Press 2013 

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