Carbon and oxygen isotope values of bulk carbonates for Castellas Fault zone and D19 fault zones, La Fare anticline (SE France).

Carbon and oxygen isotope values of bulk carbonates for Castellas Fault zone and D19 fault zones, La Fare anticline (SE France).

B: bulk measurement; M: micrite value; C1, C3, C4, and C5: cement isotopic value; FR: fault rock isotopic value.

To determine stable carbon and oxygen isotopes (13C and 18O), 204 microsamples (< 5 mg) were drilled, 194 of them were micro-drilled from polished thin sections with an 80 μm diameter micro-sampler (Merkantec Micromill) at VU 15 Amsterdam (the Netherlands). We micro-sampled bulk rocks (57), sparitic cements (101), fault rocks (9) and micrite (27). The bulk rock values are related to a nonselective sampling giving information on the whole-rock isotopic values. These values do not capture the signature of isolated cement (Swart, 2015). Carbon and oxygen isotopic values were acquired with Thermo Finnigan DeltaCmass spectrometer equipped with a GasBench preparation device at VU Amsterdam. The internationally used standard IAEA-603, with official values of +2.46‰for 13C and -2:37‰for 18O, is 25 measured as a control standard. The standard deviation (SD) of the measurements is, respectively, < 0:1‰ and < 0:2‰ for 13C and 18O. Ten whole-rock samples were analyzed using a GasBench II connected to a Thermo Fisher Delta V Plus mass spectrometer at the FAU University (Erlangen, 30 Germany). Measurements were calibrated by assigning 13C values of +1:95‰ to NBS19 and -47:3‰ to IAEA-CO9 and 18O values of -2:20‰ to NBS19. All values are reported
in per mil relative to V-PDB.