Novel Thermo-Chronological Approaches of Carbonate Diagenesis Quantification (Δ47 and U/Pb): Case of the Paris Basin

We present and test here the first tandem application of two new geochemical tools, Δ47 and U-Pb, in the case of carbonate rocks of the Paris Basin. Δ47 (the carbonate clumped isotopes thermometer) allows the determination the absolute temperature and oxygen isotope composition of the fluid at the time of precipitation. U-Pb analyses by LA-SF-ICPMS allow to date carbonate crystallization directly on thin sections. In tandem these two proxies allow to access the thermo-chronological evolution of carbonate rocks and to calibrate their paragenetic sequences both in time and temperature.

Here, we validate this thermo-chronological approach using the paragenetic sequence of a well constrained carbonate reservoir unit, that host four singular and successive generations of carbonate cements formed throughout the diagenetic history in the Paris Basin.

Each cement generation has been separately characterized by both Δ47 thermometry and U/Pb dating. The obtained Δ47 temperatures compare well with the more conventional fluid inclusions micro thermometry and the thermal history deduced from both Δ47 temperature and U-Pb ages agrees with the modeled thermal history reconstructed from backstripping approach and calibrated with vitrinite reflectance data.