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Published July 2003 | public
Journal Article

Microbial nucleation of calcium carbonate in the Precambrian

Abstract

Microbial sulfate reduction is thought to stimulate carbonate precipitation in modern stromatolites, yet whether this metabolism was important in shaping Precambrian stromatolites is unknown. Here we use geochemical modeling to suggest that the influence of sulfate reduction on the saturation index of calcite (SI) is negligible when seawater is in equilibrium with high pCO_2, as is thought for the Precambrian. Our laboratory experiments with heterotrophic bacteria in a medium mimicking Precambrian seawater chemistry show that even if sulfate reduction does not significantly change the SI, the presence of bacteria stimulates calcite precipitation over sterile controls by effectively increasing the SI over a pH range from 7.3 to 7.8. Under our experimental conditions, dead cells stimulate in situ carbonate precipitation equally, if not more, than active sulfate-reducing bacteria. Heterogeneous nucleation of calcite by microbial cell material appears to be the driving mechanism that explains this phenomenon.

Additional Information

© 2003 Geological Society of America. Manuscript received 27 February 2003; Revised manuscript received 31 March 2003; Manuscript accepted 2 April 2003. We thank Janet Hering, George Rossman, Elisabeth Arredondo, Ma Chi, the members of the Newman laboratory, and our reviewers for their valuable comments. Financial support from the Packard Foundation, the Luce Foundation, and the Agouron Institute is gratefully acknowledged.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023