Abstract
Research Highlights: > Up. Dog./Oxf. sequence is investigated for radioactive waste disposal feasibilities. > Marine carbonates suffered isotopic exchanges with meteoric water. > Modelling shows that very low W/R ratio can explain isotopic changes in clay layer. > Higher W/R ratio are needed to reach isotopic changes in carbonated layers. > Confirmed barrier property of clay layer was probably reached during early burial. - Abstract: Upper Dogger to Oxfordian Formations in the eastern part of the Paris basin (France) are currently being investigated by the French nuclear waste management agency (Andra), testing the feasibility of long-term deep nuclear waste disposal in the Callovo-Oxfordian claystones. Characterising the hydrogeological behaviour of the Callovo-Oxfordian claystones is, therefore, essential in evaluating its potential as a geological barrier. In order to evaluate and quantify water/rock interactions experienced over geological time by these Formations, bulk carbonate {delta}{sup 13}C and {delta}{sup 18}O were measured and calculations of water-rock ratios were used to explain carbonate-{delta}{sup 18}O changes. Meteoric porewater and a maximum temperature reached of about 40 deg. C were considered. The Jurassic marine carbonate {delta}{sup 13}C was preserved in the Callovo-Oxfordian claystones and in the overlying limestones (-0.28 per mille to 3.39 per mille/PDB), while the {delta}{sup
More>>
Lavastre, Veronique;
[1]
Ader, Magali;
[2]
Buschaert, Stephane;
[3]
Petit, Eddy;
Javoy, Marc
[2]
- Universite de Lyon, Universite Jean Monnet, F-42023 Saint Etienne (France); CNRS, UMR 6524, LMV, F-42023 Saint Etienne (France); Laboratoire de Geochimie des Isotopes Stables, Institut de Physique du Globe de Paris and Universite Paris 7 - UMR CNRS 7154, 4, place Jussieu, 75252 Paris cedex 05 (France)
- Laboratoire de Geochimie des Isotopes Stables, Institut de Physique du Globe de Paris and Universite Paris 7 - UMR CNRS 7154, 4, place Jussieu, 75252 Paris cedex 05 (France)
- Andra, Parc de la Croix Blanche, 7-8 rue Jean Monnet, 92 298 Chatenay-Malabry Cedex (France)
Citation Formats
Lavastre, Veronique, Ader, Magali, Buschaert, Stephane, Petit, Eddy, and Javoy, Marc.
Water circulation control on carbonate-{delta}{sup 18}O records in a low permeability clay formation and surrounding limestones: The Upper Dogger-Oxfordian sequence from the eastern Paris basin, France.
United Kingdom: N. p.,
2011.
Web.
doi:10.1016/j.apgeochem.2011.02.003.
Lavastre, Veronique, Ader, Magali, Buschaert, Stephane, Petit, Eddy, & Javoy, Marc.
Water circulation control on carbonate-{delta}{sup 18}O records in a low permeability clay formation and surrounding limestones: The Upper Dogger-Oxfordian sequence from the eastern Paris basin, France.
United Kingdom.
https://doi.org/10.1016/j.apgeochem.2011.02.003
Lavastre, Veronique, Ader, Magali, Buschaert, Stephane, Petit, Eddy, and Javoy, Marc.
2011.
"Water circulation control on carbonate-{delta}{sup 18}O records in a low permeability clay formation and surrounding limestones: The Upper Dogger-Oxfordian sequence from the eastern Paris basin, France."
United Kingdom.
https://doi.org/10.1016/j.apgeochem.2011.02.003.
@misc{etde_21593077,
title = {Water circulation control on carbonate-{delta}{sup 18}O records in a low permeability clay formation and surrounding limestones: The Upper Dogger-Oxfordian sequence from the eastern Paris basin, France}
author = {Lavastre, Veronique, Ader, Magali, Buschaert, Stephane, Petit, Eddy, and Javoy, Marc}
abstractNote = {Research Highlights: > Up. Dog./Oxf. sequence is investigated for radioactive waste disposal feasibilities. > Marine carbonates suffered isotopic exchanges with meteoric water. > Modelling shows that very low W/R ratio can explain isotopic changes in clay layer. > Higher W/R ratio are needed to reach isotopic changes in carbonated layers. > Confirmed barrier property of clay layer was probably reached during early burial. - Abstract: Upper Dogger to Oxfordian Formations in the eastern part of the Paris basin (France) are currently being investigated by the French nuclear waste management agency (Andra), testing the feasibility of long-term deep nuclear waste disposal in the Callovo-Oxfordian claystones. Characterising the hydrogeological behaviour of the Callovo-Oxfordian claystones is, therefore, essential in evaluating its potential as a geological barrier. In order to evaluate and quantify water/rock interactions experienced over geological time by these Formations, bulk carbonate {delta}{sup 13}C and {delta}{sup 18}O were measured and calculations of water-rock ratios were used to explain carbonate-{delta}{sup 18}O changes. Meteoric porewater and a maximum temperature reached of about 40 deg. C were considered. The Jurassic marine carbonate {delta}{sup 13}C was preserved in the Callovo-Oxfordian claystones and in the overlying limestones (-0.28 per mille to 3.39 per mille/PDB), while the {delta}{sup 18}O values are lower by 0-5 per mille (-6.25 per mille to -1.32 per mille/PDB). Calculations show that Upper Dogger and Oxfordian Limestone {delta}{sup 18}O data: (i)have random-like distribution through theoretical {delta}{sup 18}O-W/R curves and (ii)suggest that water/rock ratios (0.08-0.4) needed to explain {delta}{sup 18}O changes are higher by a factor of about 2-20 compared to the present-day water/rock ratio. These features indicate advection in both aquifers. According to the history of the Paris basin, this hydrogeological behaviour could have been effective since Jurassic/Cretaceous transition times. Inversely, the carbonate-{delta}{sup 18}O content trends observed for the Callovo-Oxfordian data show that changes were controlled by post-depositional fluid-rock interaction with water/rock ratio (0.02-0.15) similar to the present-day porewater/rock ratio. The 130 m thick Callovo-Oxfordian claystone appears remarkably homogenous regarding its hydrogeological properties. This study suggests an initial marine porewater replacement by meteoric water only after porosity was reduced to its present value, thus demonstrating that the Callovo-Oxfordian clay has mainly been isolated from advective meteoric water circulation. Only the upper 20 m of the Callovo-Oxfordian claystone Formation underwent heterogeneous water-rock exchange (W/R from 0.01 to 0.3), probably as a result of its mineralogical heterogeneity and proximity to the advective Oxfordian Limestone aquifer. This study of carbonate-{delta}{sup 18}O confirms the hydrogeological barrier properties of the Callovo-Oxfordian clay and suggests that it has been a natural hydrological barrier since the earliest times of its diagenesis.}
doi = {10.1016/j.apgeochem.2011.02.003}
journal = []
issue = {5}
volume = {26}
place = {United Kingdom}
year = {2011}
month = {May}
}
title = {Water circulation control on carbonate-{delta}{sup 18}O records in a low permeability clay formation and surrounding limestones: The Upper Dogger-Oxfordian sequence from the eastern Paris basin, France}
author = {Lavastre, Veronique, Ader, Magali, Buschaert, Stephane, Petit, Eddy, and Javoy, Marc}
abstractNote = {Research Highlights: > Up. Dog./Oxf. sequence is investigated for radioactive waste disposal feasibilities. > Marine carbonates suffered isotopic exchanges with meteoric water. > Modelling shows that very low W/R ratio can explain isotopic changes in clay layer. > Higher W/R ratio are needed to reach isotopic changes in carbonated layers. > Confirmed barrier property of clay layer was probably reached during early burial. - Abstract: Upper Dogger to Oxfordian Formations in the eastern part of the Paris basin (France) are currently being investigated by the French nuclear waste management agency (Andra), testing the feasibility of long-term deep nuclear waste disposal in the Callovo-Oxfordian claystones. Characterising the hydrogeological behaviour of the Callovo-Oxfordian claystones is, therefore, essential in evaluating its potential as a geological barrier. In order to evaluate and quantify water/rock interactions experienced over geological time by these Formations, bulk carbonate {delta}{sup 13}C and {delta}{sup 18}O were measured and calculations of water-rock ratios were used to explain carbonate-{delta}{sup 18}O changes. Meteoric porewater and a maximum temperature reached of about 40 deg. C were considered. The Jurassic marine carbonate {delta}{sup 13}C was preserved in the Callovo-Oxfordian claystones and in the overlying limestones (-0.28 per mille to 3.39 per mille/PDB), while the {delta}{sup 18}O values are lower by 0-5 per mille (-6.25 per mille to -1.32 per mille/PDB). Calculations show that Upper Dogger and Oxfordian Limestone {delta}{sup 18}O data: (i)have random-like distribution through theoretical {delta}{sup 18}O-W/R curves and (ii)suggest that water/rock ratios (0.08-0.4) needed to explain {delta}{sup 18}O changes are higher by a factor of about 2-20 compared to the present-day water/rock ratio. These features indicate advection in both aquifers. According to the history of the Paris basin, this hydrogeological behaviour could have been effective since Jurassic/Cretaceous transition times. Inversely, the carbonate-{delta}{sup 18}O content trends observed for the Callovo-Oxfordian data show that changes were controlled by post-depositional fluid-rock interaction with water/rock ratio (0.02-0.15) similar to the present-day porewater/rock ratio. The 130 m thick Callovo-Oxfordian claystone appears remarkably homogenous regarding its hydrogeological properties. This study suggests an initial marine porewater replacement by meteoric water only after porosity was reduced to its present value, thus demonstrating that the Callovo-Oxfordian clay has mainly been isolated from advective meteoric water circulation. Only the upper 20 m of the Callovo-Oxfordian claystone Formation underwent heterogeneous water-rock exchange (W/R from 0.01 to 0.3), probably as a result of its mineralogical heterogeneity and proximity to the advective Oxfordian Limestone aquifer. This study of carbonate-{delta}{sup 18}O confirms the hydrogeological barrier properties of the Callovo-Oxfordian clay and suggests that it has been a natural hydrological barrier since the earliest times of its diagenesis.}
doi = {10.1016/j.apgeochem.2011.02.003}
journal = []
issue = {5}
volume = {26}
place = {United Kingdom}
year = {2011}
month = {May}
}