The Mechanism of Carbon Isotope Fractionation During Thermogenic Methane Generation
GUAN Ping WU Tian-hong (School of the Earth and Space Sciences, Peking University, Beijing 100871)
Many authors, from different aspects, have modeled the carbon isotope fractionation effect during gas (methane) generation from organic matters (coals and kerogens) through different approaches. Many models about carbon isotope fractionation have been proposed. At the same time, the effects of catalysis and post-genetic process on gas carbon isotope have also been discussed. But the models can not describe carbon isotopic behavior of thermogenic methane in natural system completely, nor explain the mechanism of its fractionation perfectly. The reason is that the assumptions of the models are not completely suitable to the complexity of natural system. Furthermore, pyrolysis results are used as data source of many models. It is well known that pyrolysis has still a distance with natural process, so that the models, sometimes, can not be applied to real case successfully. To establish more perfect model with chemical kinetic approaches may be a focus in further work. And the effects of catalysis and post-genetic process on carbon isotope fractionation should also be considered.