Comparative EPMA and μ-XRF methods for mapping micro-scale distribution of iodine in biocarbonates of the Callovian–Oxfordian clayey formation at Bure, Eastern part of the Paris Basin
A pluridisciplinary approach was used to define iodine immobilization mechanisms by biocarbonates in a natural marine carbonate-bearing clayey formation. For this purpose, different techniques of observation (optical microscope, scanning electron microscope (SEM), cathodoluminescence (CL)) and of an...
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Published in | Physics and Chemistry of the Earth. Parts A/B/C Vol. 35; no. 6; pp. 271 - 277 |
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Main Authors | , , , , , , , , , , |
Format | Journal Article Conference Proceeding |
Language | English |
Published |
Elsevier Ltd
2010
Elsevier [2002-....] RSC |
Subjects | |
Online Access | Get full text |
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Summary: | A pluridisciplinary approach was used to define iodine immobilization mechanisms by biocarbonates in a natural marine carbonate-bearing clayey formation. For this purpose, different techniques of observation (optical microscope, scanning electron microscope (SEM), cathodoluminescence (CL)) and of analyses (infrared spectrometry (IR), electron microprobe (EPMA), spatially resolved synchrotron-based X-ray fluorescence (μ-XRF) and X-ray diffraction (μ-XRD)) were performed on two entire and centimeter-sized carbonate shells of the Callovian–Oxfordian (160
Ma) clayey formation from the ANDRA (French Radioactive Waste Management Agency) Underground Research Laboratory (Meuse/Haute Marne, France), in the Eastern part of the Paris Basin. Combined (SEM, CL, IR and μ-XRD) data indicates that the biostructure of the Rhynchonella shell is relatively well-preserved but bio-aragonite slowly transforms into calcite, whereas the bivalve shell is entirely recrystallized into diagenetic calcite and celestite. EPMA and μ-XRF data show bioaccumulation of iodine in carbonate shells, confirming previous work on present-day mollusks. EPMA analyses give evidence of iodine content up to 1200
ppm in the preserved Rhynchonella shell and up to 2000
ppm in recrystallized bivalve shell. μ-XRF elemental mapping shows that iodine is more homogeneously distributed in bio-calcite of the Rhynchonella shell than in recrystallized calcite of the bivalve shell, suggesting a loss of iodine during re-crystallization processes, but not a total exclusion of iodine from the carbonate structure. Combined EPMA data and μ-XRF elemental maps do not give evidence of any correlation between the iodine location and the distribution of other elements. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1474-7065 1873-5193 |
DOI: | 10.1016/j.pce.2010.04.003 |