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GEOREF RECORD

Radiation-induced defects in dickites from the El Berrocal granitic system (Spain); relation with past occurrence of natural radioelements

Thierry Allard, Philippe Ildefonse, Luis Perez del Villar, Stephanie Sorieul, Marta Pelayo, Bruno Boizot, Etienne Balan and Georges Calas
Radiation-induced defects in dickites from the El Berrocal granitic system (Spain); relation with past occurrence of natural radioelements
European Journal of Mineralogy (August 2003) 15 (4): 629-640

Abstract

This study deals with the radiation-induced defects in fracture filling clay-minerals from the El Berrocal U-deposit (Spain), which is considered as a natural analogue of a high-level nuclear waste repository in granitic rock. Mineralogical analyses shows the widespread occurrence of dickite as a secondary alteration phase, together with various amounts of associated smectite, illite, carbonates and primary minerals. Native radiation-induced defects accumulated in the dickite and smectite structure are identified by electron paramagnetic resonance spectroscopy (EPR). They are distinguished by their spectroscopic parameters and thermal stability, and can be reproduced by artificial irradiation. The dickite defects are similar to the well-characterized features in natural kaolinites, including defects stable at the scale of geological periods. Dickite can thus be used as a natural dosimeter to trace radioelement transfer in relevant geological systems. The concentration of stable defects in dickites is related to the present dose-rates, assuming dosimetry parameters from model kaolinites and several scenarii for dickite ages inferred from major tectonic events. This study demonstrates that the El Berrocal dickites correspond to different generations having recorded retention or migration events of radioelements within the whole system.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 15
Serial Issue: 4
Title: Radiation-induced defects in dickites from the El Berrocal granitic system (Spain); relation with past occurrence of natural radioelements
Affiliation: Universites Paris, Laboratoire de Mineralogie-Cristallographie de Paris, Paris, France
Pages: 629-640
Published: 200308
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 40
Accession Number: 2003-070554
Categories: Mineralogy of silicatesEngineering geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch map
N40°10'00" - N40°10'00", W04°30'00" - W04°30'00"
Secondary Affiliation: Centro de Investigaciones Energeticas, ESP, SpainEcole Polytechnique, ESP, Spain
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200321
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