石英
粘土矿物
沉积物
地质学
矿物学
沉积岩
潮间带
硅藻
地球化学
地貌学
海洋学
古生物学
作者
Thibault Duteil,Raphaël Bourillot,Brian Grégoire,Maxime Virolle,Benjamin Brigaud,J. Nouet,Olivier Braissant,Éric Portier,Hugues Féniès,Patricia Patrier,Étienne Gontier,Isabelle Svahn,Pieter T. Visscher
出处
期刊:Geology
[Geological Society of America]
日期:2020-06-19
卷期号:48 (10): 1012-1017
被引量:28
摘要
Abstract In sedimentary environments, clay and sand are segregated by hydrodynamic processes. Yet, clay coats, thin clay envelopes lining sand grains, are abundant in modern and ancient coastal sedimentary deposits. Here, we present laboratory experiments in which we produced clay-coated quartz sands similar to those observed in modern and ancient estuarine sands. These coats were produced at ambient temperature by mixing exopolymeric substances (EPS) derived from intertidal diatom biofilms with clay minerals and quartz reference materials. The imaging of sediment-EPS mixes using cryo–scanning electron microscopy and atomic force microscopy demonstrated that EPS form organic bridges between clay and quartz. The physicochemical properties of the EPS were characterized independently through wet chemical assays and Fourier transform infrared spectroscopy. The results indicated that several EPS components (e.g., proteins, polysaccharides) had a potential to complex with quartz and clay. Our findings provide novel insights in the importance of biofilms in the aggregation of clay and sand. Detrital coats from ancient estuarine sandstones show textural similarities to the experimental clay-EPS complexes and could be considered as biosignatures of biofilm development and EPS production in past environments.
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