Résumé
In the district of Provins, the characteristics of chalk diagenesis (physico-chemistry, structure and mineralogy) are quite well known. We try in this paper to discuss some constraints on convective circulation which are eventually at the origin of this diagenesis. For this, we first give the general thermal and hydraulic settings of such circulations. Then, we view the possibility of forced as well as of thermally induced convection. For a forced system, a reasonable order of magnitude of inferred flux is 1 cm/year. For thermoconvection, the parameters appear to be under-critical but thermoconvection cannot be excluded. Assuming a vertical velocity of 1 cm/y and a geochemical system at equilibrium with pure calcite results in porosity variations of 0.015% per My. This figure is strongly dependent of the assumed geochemical system.