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The characterization of CaCO (sub 3) in a geothermal environment; a SEM/TEM-EELS study

Jin-Wook Kim, Toshihiro Kogure, Kiho Yang, Sang-Tae Kim, Young-Nam Jang, Hion-Suck Baik and Gill Geesey
The characterization of CaCO (sub 3) in a geothermal environment; a SEM/TEM-EELS study
Clays and Clay Minerals (October 2012) 60 (5): 484-495


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, approximately 2 mu m 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.

ISSN: 0009-8604
EISSN: 1552-8367
Serial Title: Clays and Clay Minerals
Serial Volume: 60
Serial Issue: 5
Title: The characterization of CaCO (sub 3) in a geothermal environment; a SEM/TEM-EELS study
Affiliation: Yonsei University, Department of Earth System Sciences, Seoul, South Korea
Pages: 484-495
Published: 201210
Text Language: English
Publisher: Clay Minerals Society, Chantilly, VA, United States
References: 46
Accession Number: 2013-009612
Categories: Isotope geochemistrySedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, 4 plates
N45°01'55" - N45°01'55", W110°42'21" - W110°42'21"
Secondary Affiliation: University of Tokyo, JPN, JapanMcMaster University, KOR, South KoreaKorea Institute of Geoscience and Mineral Resources, KOR, South KoreaKorea Basic Science Institute, KOR, South KoreaMontana State University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, Copyright, Clay Minerals Society. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201307
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