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Geofluids
Volume 2018 (2018), Article ID 1606753, 20 pages
https://doi.org/10.1155/2018/1606753
Research Article

A Deep Alteration and Oxidation Profile in a Shallow Clay Aquitard: Example of the Tégulines Clay, East Paris Basin, France

1BRGM, BP36009, 45060 Orléans Cedex 2, France
2ANDRA, 1-7 rue Jean-Monnet, 92298 Châtenay-Malabry Cedex, France
3UMR 7327 Institut des Sciences de la Terre d’Orléans (ISTO), Université d’Orléans-CNRS/INSU-BRGM, Orléans, France
4Energy Geoscience Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
5ERM, Bâtiment B8, 7 rue Albert Turpain, 86000 Poitiers, France
6CIEMAT, Departamento de Medio Ambiente, 28040 Madrid, Spain
7Center for Advanced Marine Core Research, Kochi University, B200 Monobe, Nankoku 783-8502, Japan
8Institut de Physique du Globe de Paris (IPGP), Paris, France

Correspondence should be addressed to Catherine Lerouge; rf.mgrb@eguorel.c

Received 12 June 2017; Revised 23 September 2017; Accepted 11 December 2017; Published 23 January 2018

Academic Editor: Douglas K. Solomon

Copyright © 2018 Catherine Lerouge et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The oxidation profile of a surficial clay aquitard was studied on a 35-meter borecore from the Albian Tégulines Clay near Brienne-le-Château (Paris Basin, France). Mineralogical, geochemical, and petrophysical data showed evidences of gradual oxidation taking place down to a depth of 20 m. Below 20 m, the clay material was nonplastic and nonfractured, and it inherited reduced redox conditions from bacterial sulfate reduction that occurred after sediment deposition. Above 20 m, the clay material was plastic. Up to a depth of 10-11 m, only rare yellowish aggregates of glauconite attested to limited oxidation, and pore water chemistry was unmodified. The 5–11 m depth interval was characterized by intensive pyrite oxidation, calcite dissolution, and formation of sulfate and iron hydroxide minerals. The upper 2-3 m was ochrous and entirely oxidized. These mineralogical changes were mirrored with pore water chemistry modifications such as an increase of alkalinity and sulfate concentration in the upper part of the profile. The presence of siderite at ~11 m evinced the reactivity of Fe(II) in the structure of clay minerals with dioxygen from meteoric waters that infiltrated into the Tégulines Clay through vertical fractures.