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Patterns of metal distribution in hypersaline microbialites during early diagenesis; implications for the fossil record

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doi: 10.1111/gbi.12218
Authors:Sforna, Marie C.; Daye, M.; Philippot, P.; Somogyi, A.; Zuilen, M. A.; Medjoubi, K.; Gérard, E.; Jamme, F.; Dupraz, C.; Braissant, O.; Glunk, C.; Visscher, P. T.
Author Affiliations:Primary:
Universite Paris Diderot, Institut de Physique du Globe de Paris, Paris, France
Stockholm University, Sweden
University of Basel, Switzerland
Societe Suisse des Explosifs, Switzerland
University of Connecticut, United States
Volume Title:Geobiology
Source:Geobiology, 15(2), p.259-279. Publisher: Wiley, Oxford, United Kingdom. ISSN: 1472-4677
Publication Date:2017
Note:In English. 109 refs.; illus., incl. 1 table, sketch maps
Summary:The use of metals as biosignatures in the fossil stromatolite record requires understanding of the processes controlling the initial metal(loid) incorporation and diagenetic preservation in living microbialites. Here, we report the distribution of metals and the organic fraction within the lithifying microbialite of the hypersaline Big Pond Lake (Bahamas). Using synchrotron-based X-ray microfluorescence, confocal, and biphoton microscopies at different scales (cm-µm) in combination with traditional geochemical analyses, we show that the initial cation sorption at the surface of an active microbialite is governed by passive binding to the organic matrix, resulting in a homogeneous metal distribution. During early diagenesis, the metabolic activity in deeper microbialite layers slows down and the distribution of the metals becomes progressively heterogeneous, resulting from remobilization and concentration as metal(loid)-enriched sulfides, which are aligned with the lamination of the microbialite. In addition, we were able to identify globules containing significant Mn, Cu, Zn, and As enrichments potentially produced through microbial activity. The similarity of the metal(loid) distributions observed in the Big Pond microbialite to those observed in the Archean stromatolites of Tumbiana provides the foundation for a conceptual model of the evolution of the metal distribution through initial growth, early diagenesis, and fossilization of a microbialite, with a potential application to the fossil record. Abstract Copyright (2017), John Wiley & Sons, Ltd.
Subjects:Archean; Biogenic structures; Biologic evolution; Carbonate rocks; Diagenesis; Distribution; Electrodes; Fossil record; Fossilization; Hypersaline environment; Laminations; Limestone; Metabolism; Metals; Microbialite; Patterns; Planar bedding structures; Precambrian; Pyrite; Raman spectroscopy; Sedimentary rocks; Sedimentary structures; Spectroscopy; Stromatolites; Sulfides; X-ray analysis; X-ray fluorescence; Bahamas; Caribbean region; West Indies; Big Pond Lake
Coordinates:N240000 N240000 W0760000 W0760000
Record ID:794442-6
Copyright Information:GeoRef, Copyright 2021 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom
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