Articles | Volume 13, issue 19
https://doi.org/10.5194/bg-13-5511-2016
https://doi.org/10.5194/bg-13-5511-2016
Research article
 | 
05 Oct 2016
Research article |  | 05 Oct 2016

Linking the distribution of microbial deposits from the Great Salt Lake (Utah, USA) to tectonic and climatic processes

Anthony Bouton, Emmanuelle Vennin, Julien Boulle, Aurélie Pace, Raphaël Bourillot, Christophe Thomazo, Arnaud Brayard, Guy Désaubliaux, Tomasz Goslar, Yusuke Yokoyama, Christophe Dupraz, and Pieter T. Visscher

Abstract. The Great Salt Lake is a modern hypersaline lake, in which an extended modern and ancient microbial sedimentary system has developed. Detailed mapping based on aerial images and field observations can be used to identify non-random distribution patterns of microbial deposits, such as paleoshorelines associated with extensive polygons or fault-parallel alignments. Although it has been inferred that climatic changes controlling the lake level fluctuations explain the distribution of paleoshorelines and polygons, straight microbial deposit alignments may underline a normal fault system parallel to the Wasatch Front. This study is based on observations over a decimetre to kilometre spatial range, resulting in an integrated conceptual model for the controls on the distribution of the microbial deposits. The morphology, size and distribution of these deposits result mainly from environmental changes (i.e. seasonal to long-term water level fluctuations, particular geomorphological heritage, fault-induced processes, groundwater seepage) and have the potential to bring further insights into the reconstruction of paleoenvironments and paleoclimatic changes through time. New radiocarbon ages obtained on each microbial macrofabric described in this study improve the chronological framework and question the lake level variations that are commonly assumed.

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Short summary
The modern hypersaline Great Salt Lake shows an extended modern and ancient microbial sedimentary system. This study on aerial images and field observations discusses the non-random distribution patterns of microbial deposits along linear alignments following isobaths, polygonal geometry or straight alignments along a topographic drop-off. This particular distribution of microbial deposits brings further insights to the reconstruction of paleoenvironments and paleoclimatic changes.
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