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A laboratory model of abiotic peloid formation

Bosak, T. and Souza-Egipsy, V. and Newman, D. K. (2004) A laboratory model of abiotic peloid formation. Geobiology, 2 (3). pp. 189-198. ISSN 1472-4677.

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Peloids are rounded grains of micritic calcite whose origin has been attributed to various biological and abiotic mechanisms. To constrain abiotic parameters that favour the formation of peloids, we precipitated calcite crusts in the absence of microorganisms. Clotted opaque fabrics that formed during the initial stages of the experiment consisted of ∼ 10 μ M peloids, while compact clear sparitic crusts precipitated in subsequent stages. The increasing supersaturation of the solution in time is responsible for this morphological succession. Initially, peloids form by the radial growth of spar crystals around a small number of nuclei. As the supersaturation increases, more spar crystals nucleate and aggregate nonradially into compact crusts. Rounded clotted precipitates are a consequence of the growth in suspension and geopetal settling, and isopachous crusts grow in the absence of these processes. Although peloids are commonly assumed to have a microbial origin, our results show that very similar morphologies can be created by purely abiotic mechanisms. Thus, the biological origin of rounded micritic calcite grains in the rock record must be verified against the abiotic null-hypothesis in each specific case.

Item Type:Article
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Newman, D. K.0000-0003-1647-1918
Additional Information:© 2004 Blackwell Publishing Ltd. Issue published online: 29 September 2004; Article first published online: 29 September 2004; Received 02 May 2004; accepted 30 July 2004. We want to thank Ma Chi, Alicia Thompson and Randall Mielke for technical assistance, Frank Corsetti, Adam Maloof, Ben Weiss, Dawn Sumner, Kenneth H. Nealson, three anonymous reviewers and Kurt Konhauser for helpful comments. The Agouron Institute, the Packard and the Luce Foundations and Spanish Ministerio de Ciencia y Tecnología are acknowledged for financial support.
Funding AgencyGrant Number
Agouron InstituteUNSPECIFIED
Packard FoundationUNSPECIFIED
Luce FoundationUNSPECIFIED
Spanish Ministerio de Ciencia y TecnologíaUNSPECIFIED
Issue or Number:3
Record Number:CaltechAUTHORS:20130424-104406541
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Official Citation:BOSAK, T., SOUZA-EGIPSY, V. and NEWMAN, D. K. (2004), A laboratory model of abiotic peloid formation. Geobiology, 2: 189–198. doi: 10.1111/j.1472-4677.2004.00031.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38092
Deposited By: Jason Perez
Deposited On:24 Apr 2013 21:09
Last Modified:03 Oct 2019 04:54

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