Figure 4: Sensitivity of the model to small variations of each parameter.

(a) The Δ36SCAS versus Δ33SCAS diagram and (b) the Δ33SCAS versus δ34SCAS diagram. Changes in Fin/Fout of ±5% (green line), in 1,000ln(34α) of ±7‰ (grey line) and in 33β of ±0.3‰ are tested. The blue line corresponds to the best-fit model and the dashed to the straight line passing through the data. This figure highlights the high sensitivity of the model to all considered parameters (that is, Fin/Fout, 34α and 33β). Based on duplicate and triplicate analyses, uncertainties of Δ33S and Δ36S values by the SF6 technique are estimated at 0.01‰ and 0.2‰ in 2σ, respectively.