Objectives :
Test the geochemistry of the fluid to be used for percolation experiments.
Description of planned work :
Batch experiments in autoclave will be performed at 150°C on powder grinded from unaltered Nojima protolith to estimate the products of alteration reactions suspected to occur in Nojima, according to WP1. Several saturating fluids will be tested. XRD analysis will be performed on the output powder to identify the products of reaction.
Once the target reactions are (…)

Objectives :
Pre-damage the Nojima and Soultz granitoids to be able to perform flow-through experiments [T2.3, T2.4]
Description of planned work :
Samples of length 20 mm and ∅ 20 mm will be pulverized using the Split Hopkinson Pressure Bars of ISTerre. This high-strain rate device records mechanical data at strain rate higher than 100/s. At high strain rate, strain localization is inhibited and several fractures developed simultaneously [1], creating a pervasive fracture network and (…)

Objectives :
Reproduce alteration in non-tectonic settings, in reference isotropic stress configuration.
Description of planned work :
Percolation experiments will be performed for several months at 180°C on the samples generated in T2.2. GM will use the ICARE flow-through laboratory. Fluids will be sampled periodically during the experiments to determine their geochemical composition, and evolution through time, allowing to perform mass balance computations.

04. Task 2-4 : Triaxial percolation experiments (Nojima+Soultz) [ISTerre]

Objectives :
Reproduce alteration in tectonic settings, under triaxial stress configuration.
Description of planned work :
Percolation experiments will be performed for several months at 180°C on the samples generated in T2.2, using the triaxial percolation cells of ISTerre, on which alteration experiments could be successfully conducted (Fig 1b). After upgrade of the device (new pumps, new stress servocontrol), monitoring will provide the high-resolution evolution of permeability and (…)

Objectives :
Measure the effect of the alteration on the petrophysical properties, in well-constrained conditions.
Description of planned work :
Prior and posterior to each experiment, X-ray CT scans and petrophysical characterization will be performed (see WP1). Mineralogical analysis of the pre and- post-mortem samples will allow to evaluate the minerals prior and posterior to the reactions of alteration, and to identify the reaction at stake in the alteration process. Acquisition (…)