The detailed study of the diagenetic signature (diagenetic time sequence and geochemical composition) of syntectonic cements of the hydrofractured chalks in the Omey area allowed to demonstrate that (1) hydrofracturing affected a water saturated aquifer where the temperature was below 50 degrees C, (2) the interstitial fluids of the diagenetic environment was meteoric, (3) the diagenetic system closed gradually with respect to the liquid phase, due to the diagenetic evolution of the chalk, (4) during hydrofracturing, the temporal evolution of the oxidation-reduction potential of the diagenetic environment controlled the speciation of Mn and Ce, (5) the diagenetic time sequence of the cements represents a sensitive record of the tectonic control of the deformation of the aquifer.