Figure 8From: Natural gas at thermodynamic equilibrium Implications for the origin of natural gasThe correlations between molar isotope ratios in methane, ethane, and propane in 285 gases (USGS, Table 1). Ratios are molar, calculated as described in Table 1. The lines are linear regression lines with a coefficients of correlation R2 = 0.638 for 13C2/12C2 with slope (zero intercept) = 2.028, and R2 = 0.47 for 13C3/12C3 with slope (zero intercept) = 3.055.Back to article page