Geochemistry and14C dating of groundwaters from Jurassic aquifers of North Aquitaine Basin (France)

摘要: Twenty-seven samples from a confined Lower-Middle Jurassic aquifer and an unconfined Oxfordian of the North Aquitaine Basin (France) have been analysed for their major elements, Br−,18O,2H,13C and14C contents. Hydrochemistry indicates (1) dissolution carbonate anhydrite near recharge zone (2) dilution saline water derived seawater/halite mixing in deeper part aquifer. The is also visible δ18O vs Cl− diagram which two different groups appear: recent waters old indicating process between fresh groundwaters. composition likely to be 34,100±11,200 ppm Cl, 70±20 Br more than −3.5±07‰ SMOW in18O.13C contents indicate C exchange with CaCO3 matrix groundwaters participation organic matter deep aquifer. Residence times area outcrop correspond Holocene Late Pleistocene periods. depletion stable isotopes 10 15,000 y B.P. show late glacial period infiltration After distance about km aquifer, the14C activities are 0 pmc showing presence ‘old’