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Published September 2004 | public
Journal Article

Micrometer-scale porosity as a biosignature in carbonate crusts

Abstract

We formed calcite crusts in the presence and absence of the heterotrophic bacterium Desulfovibrio desulfuricans strain G20 to investigate microbial morphological signatures in fast-accreting carbonate precipitates. Submicrometer- to micrometer-sized pores (micropores) were present and ubiquitous in the G20 crusts but absent in abiotically precipitated crusts. Bacterial micropores resemble inclusions under transmitted light, but have distinct size, biological shapes and patterns (swirling or dendritic) and are distributed differently from common fluid inclusions. We observed similar porosity in both modern and ancient carbonate crusts of putative biotic origin. Our experiments support the microbial origin of micropores and help define specific criteria whereby to recognize these features as biosignatures in the rock record.

Additional Information

© 2004 Geological Society of America. Manuscript received 18 March 2004. Revised manuscript received 17 May 2004. Manuscript accepted 18 May 2004. We thank Ma Chi, George Rossman, Kenneth H. Nealson, Randall Mielke, Alicia Thompson, François Morel, Ben Weiss, and the members of the Newman lab for their help, comments, and support. The Agouron Institute (Bosak), Luce and Packard Foundations (Newman), and Spanish Ministerio de Ciencia y Tecnología (Souza-Egipsy) are acknowledged for financial support.

Additional details

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