Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Geological Magazine

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by FURNES, H. Articles by SHI, L. Search for Related Content GeoRef GeoRef Citation

Bio-signatures in metabasaltic glass of a Caledonian ophiolite, West Norway

HARALD FURNES^*,, KARLIS MUEHLENBACHS, TERJE TORSVIK, OLE TUMYR^* and LANG SHI^¶

^* Geological Institute, University of Bergen, Allegt. 41, 5007 Bergen, Norway
Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
Department of Microbiology, University of Bergen, Jahnebk. 5, 5007 Bergen, Norway
^¶ 3505 Ste. Famille, Apt. 100, Montreal, Quebec H2X 2L3, Canada

Author for correspondence: Harald.Furnes{at}geo.uib.no

Evidence of bioalteration of natural basaltic rocks, presently receiving much attention, has so far been restricted to in situ oceanic crust and ophiolites in which fresh glass is still present. Here we present evidence of preserved bio-signatures in the chilled margin of pillow lavas of an old (443 Ma) ophiolite that has suffered pervasive lower greenschist facies metamorphism and deformation. X-ray mapping of initial alteration zones shows the remains of organic carbon associated with highly-concentrated Fe and S. Bioproduction of CO₂ is further reflected in the low ¹³C values of calcite extracted from pillow rims, compatible with microbe-induced fractionation during oxidation of organic matter. We attribute these effects to growth of sulphate-reducing bacteria at the early stage of ophiolite formation. During energy metabolism these bacteria reduce sulphate to H₂S and oxidize organic matter to CO₂. Hydrogen sulphide will eventually react with iron and form pyrite, and carbon dioxide is precipitated as calcium carbonate. The results of this study may thus trigger the search for bio-signatures in glassy volcanic rocks of any age.

Key Words: Caledonides • ophiolite • pillow lava • biogenic effects • stable isotopes

This article has been cited by other articles:

				N. McLoughlin, H. Furnes, N.R. Banerjee, K. Muehlenbachs, and H. Staudigel Ichnotaxonomy of microbial trace fossils in volcanic glass Journal of the Geological Society, January 1, 2009; 166(1): 159 - 169. [Abstract] [Full Text] [PDF]

				M. E. Sanz-Montero, J. P. Rodriguez-Aranda, and C. Perez-Soba Microbial weathering of Fe-rich phyllosilicates and formation of pyrite in the dolomite precipitating environment of a Miocene lacustrine system European Journal of Mineralogy, January 1, 2009; 21(1): 163 - 175. [Abstract] [Full Text] [PDF]

				H. Furnes and K. Muehlenbachs Bioalteration recorded in ophiolitic pillow lavas Geological Society, London, Special Publications, January 1, 2003; 218(1): 415 - 426. [Abstract] [PDF]