Anisotropy of elastic, magnetic and microstructural properties of the Callovo-Oxfordian shales (Meuse)

The purpose of this study was to investigate the anisotropic behaviour of the Callovo-Oxfordian shales in laboratory experiments, and relate this anisotropy to microstructural features analysed using different imaging techniques. The starting material was a 31 cm long core with diameter 10 em retrieved at 460 meters depth in well EST204 of the future French Underground Research Laboratory site in the Meuse/Haute-Marne region. The core axis is clearly perpendicular to the bedding, but it is important to notice that we have no indication of the core azimuth with respect to the local geographic coordinates. A total number of 17 small cylindrical samples with diameter 25 mm and length 22.5 mm were cored in three orthogonal directions from the original core: 9 of them were cored in the vertical direction parallel to the big core axis, 4 in the bedding plane in a direction defined arbitrarily as the North-South direction, and 4 in the bedding plane in the corresponding East-West a direction. All our conclusions on the directional properties of the studied material are relative to the arbitrary reference frame linked to the big core sample. (authors)