%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Bouchez, C.
%A Deschamps, Pierre
%A Goncalves, J.
%A Hamelin, Bruno
%A Sylvestre, Florence
%A Doumnang, J.C.
%A Nour, A.M.
%A Goni, I.B.
%A Favreau, Guillaume
%A Genthon, Pierre
%A Seidel, J.L.
%T Investigation of Cl-36 distribution : towards a new estimation of groundwater residence times in the confined aquifer of the LCB ?
%B 11th Applied isotope geochemistery conference AIG-11
%D 2015
%E Millot, R.
%E Negrel, P.
%L fdi:010065222
%G ENG
%J Procedia Earth and Planetary Science
%@ 1878-5220
%K DATATION ; EAU SOUTERRAINE ; AQUIFERE ; NAPPE ; METHODOLOGIE ; CHIMIE DE L'EAU ; GEOCHIMIE ; CHLORE ; CHLORURE ; PUITS ; ECHANTILLONNAGE ; PALEOENVIRONNEMENT
%K TRACEUR ; PALEOHYDROLOGIE ; CONTINENTAL TERMINAL
%K TCHAD ; TCHAD LAC ; NIGER ; NIGERIA ; ZONE SAHELIENNE
%M ISI:000360103500036
%P 147-150
%R 10.1016/j.proeps.2015.07.035
%U https://www.documentation.ird.fr/hor/fdi:010065222
%> https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers15-09/010065222.pdf
%V 13
%W Horizon (IRD)
%X 36Cl measurements in groundwaters of the deep confined aquifer of the Lake Chad Basin (LCB) were performed in order to constrain groundwater geochemical ages and residence times. Twenty-seven wells were sampled in Nigeria, Niger and Chad in the southern parts of the large (700 000 km2) multilayered aquifer of the LCB. 36Cl/Cl values range between 11±1.10-15 to 148±8.10-15 at/at. The highest ratios are observed near the recharge zone of the Nigerian part of the Continental Terminal aquifer, while the lowest ones are found in wells located near the southern fringe of the present-day lake Chad. Chloride concentrations are low (below 100 mg/l) and not correlated to the 36Cl/Cl values, indicating negligible dissolution of evaporites in most samples. Reliable 36Cl ages can be calculated along the different flow paths investigated, suggesting residence times of the deep groundwaters larger than 300 000 years. These results are consistent with new AMS-14C data below the detection limit but are in contradiction with previous 14C data obtained in the area.
%B International Symposium on Applied Isotope Geochemistry
%8 2015/09/21-25
%$ 064GEOCHI ; 062MECEAU04