Abstract:

In order to understand the component and origin of gases from gashydrate drillhole (ZK1) in Wuli permafrost zone, QinghaiTibetan Plateau, the gas components and the carbon isotopes of headspace gas samples and resolving gas samples from hole ZK1 and its adjacent drillholes and gas samples from lake water are analyzed. At the same time, the carbon isotopes of carbonate rocks from cores are also analyzed. The results show that more than 98% natural gas is composed of carbon dioxide with a little hydrocarbon gas(mainly methane),the main maximum values of δ13CCO2 are between-4‰ and-6‰(VPDB), the main maximum values of δ13CCH4 from a few richmethane samples are between -3238‰ and -2782‰(VPDB), while the mean value of δ13CCaCO3 is -387‰(VPDB).Integrated with regional geology, it could be drawn a conclusion that the CO2 of Wuli permafrost zone is mainly of volcanic mantle type, which is related with strong tectonic movement and magma activities.

Key words: carbon dioxide, Wuli permafrost zone, QinghaiTibetan Plateau