Lyell Collection
Geological Society, London, Special Publications
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Grassineau, N. V.
Right arrow Articles by Nisbet, E. G.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Geological Society, London, Special Publications; 2005; v. 248; p. 195-212;
DOI: 10.1144/GSL.SP.2005.248.01.11
© 2005 Geological Society of London

Distinguishing biological from hydrothermal signatures via sulphur and carbon isotopes in Archaean mineralizations at 3.8 and 2.7 Ga

N. V. Grassineau1, P. W. U. Appel2, C. M. R. Fowler1 & E. G. Nisbet1

1 Department of Geology, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK nathalie{at}gl.rhul.ac.uk
2 Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, 1350 Copenhagen, Denmark

Carbon and sulphur isotopes have been analysed in mineralization from two Archaean greenstone belts at 3.8 Ga and 2.7 Ga, with the aim of distinguishing between the inorganic and organic processes that occurred. Despite an obvious overprinting by metamorphism (in the early belt), or hydrothermal fluids, there are convincing differences between the values of carbon and sulphur in inorganic formations and those formed by biological processes. An attempt is made to estimate the changes that occurred in the early life activities over this 1 Ga year period. Life in the Isua Greenstone Belt (3.8 Ga) was most likely present in transitory settings, probably under high temperature conditions. This was very different from the life at 2.7 Ga in the Belingwe Greenstone Belt, indicated by ranges of 38{per thousand} for {delta}34S and 37{per thousand} for {delta}13Cred. By this time, the biological sulphur and carbon cycles seem to have reached almost full operation, with the presence of well-established photosynthetic microbial mat communities.