Clays and Clay Minerals, Vol. 60, No. 5, 484–495, 2012.
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Authors
Kim, Jin-wook
Kogure, Toshihiro
Yang, Kiho
Kim, Sang-tae
Jang, Young-nam
Baik, Hion-suck
Geesey, Gill
Issue Date
2012
Type
Article
Language
Keywords
Periodicals , Geology , Calcium Carbonate Precipitate , Carbon Isotope , Cyanobacterial Mat , Electron Energy Loss Spectroscopy , Focused Ion Beam , Transmission Electron Microscopy
Alternative Title
The Characterization Of Caco3 In A Geothermal Environment: A Sem/tem-eels Study
Abstract
Mineralization of microbial biomass is a common phenomenon in geothermal habitats, but knowledge of the structure of the minerals formed in these environments is limited. A combination of spectroscopic, microscopic, and stable isotopic methods, as well as the chemical analysis of spring water, were employed in the present study to characterize calcium carbonate minerals deposited in filamentous cyanobacterial mats in different locations of La Duke hot spring, a circumneutral thermal feature near the north entrance of Yellowstone National Park, Montana, USA. Calcite was the primary crystalline mineral phase associated with biofilm-containing deposits closest to the source of the spring and the suspended microbial biomass in a pool further from the source. The carbonate minerals at all sites occurred as aggregated granules, ~2 mm in diameter, in close association with the microbial biomass. Only in the deposits closest to the source were the granules organized as laminated structures interspersed with microbial biomass. The calcium carbonate grains contained two distinct regions: a dense monolithic calcite core and a porous dendritic periphery containing organic matter (OM). Electron energy loss spectroscopy (EELS) indicated that the voids were infilled with OM and carbonates. The EELS technique was employed to distinguish the source of carbon in the organic matter and carbonate mixture. The studies of carbon isotope compositions of the calcium carbonates and the saturation indices for calcite in the spring waters suggest that processes (abiotic vs. biotic) controlling the carbonate formation may vary among the sampling sites.
Description
gsccm60505-kim.pdf -- 3,714 KB
Citation
Clays and Clay Minerals, Vol. 60, No. 5, 484–495, 2012.
Publisher
The Clay Minerals Society
License
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