We appreciate the discussion by Clauer et al. on our article (Yun et al., 2010) on dating petroleum emplacement by illite 40Ar/39Ar laser stepwise heating. Their major comment is “… discuss especially the fact that the authors discarded 39Ar recoil, followed by an evaluation of its impact on the results and the interpretations,” (Clauer et al., 2011, p. 2107). In an illite 40Ar/39Ar stepwise heating experiment, the sample is heated step by step from low to high laser outputs (or from low to high temperatures), which makes different minerals in the illite sample release their gases separately. Compared with a mixture K-Ar age of an illite sample, its 40Ar/39Ar age spectrum by laser stepwise heating technique can better constrain the petroleum emplacement age and reveal the detrital K-feldspar age. High-precision 40Ar/39Ar stepwise heating on illite samples has many superiors to their K-Ar dating despite the 39Ar recoil. The specially designed apparatus for organic gas purification is of crucial importance for us to obtain credible illite 40Ar/39Ar age results.

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