Abstract:
Muriel Pacton et al., Geological Institute, ETH-Zürich, Rämistrasse 101, 8092 Zürich, Switzerland. Posted online 27 April 2012; doi: 10.1130/G32846.1.
Muriel Pacton et al., Geological Institute, ETH-Zürich, Rämistrasse 101, 8092 Zürich, Switzerland. Posted online 27 April 2012; doi: 10.1130/G32846.1.
Going nano: A new step toward understanding the processes governing freshwater ooid formation
Boulder, CO | Posted on April 30th, 2012
Ooids are well-rounded sand grains composed of a nucleus encompassed by poorly to well-developed concentric micritic laminae. Results presented here by Muriel Pacton and colleagues challenge the standard hypothesis that ooids are indicators of turbulent hydrodynamic conditions by showing microbes as the main agent in ooid cortex formation in a quiescent environment. Pacton and colleagues combine cutting-edge techniques (i.e., NanoSIMS ion mapping, scanning electron microscopy imaging and analysis, and secondary ion mass spectrometry delta-13C and delta-18O isotopic analyses) to identify the microbial metabolism involved in ooid cortex formation. The combined elemental mapping and stable isotope study of freshwater ooids indicate that lamina formation is the result of the mineralization of organic substances produced by photosynthetic microbes. This study illustrates the importance of physico-chemical conditions versus organo-mineralization in determining the distribution, abundance, and cortical mineralogy of oolitic sands throughout the Phanerozoic stratigraphic record of carbonate accumulation. These new data further highlight the advantage of using a nano-scale approach to better discern between the various biotic and abiotic processes linked to carbonate precipitation.
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Contacts:
Kea Giles
Copyright © Geological Society of America
Fonte: Nanotechnology Now
