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Abstract

The use of stable carbon and nitrogen isotopes in hydrocarbon exploration and active magmatic and/or hydrothermal systems (e. g. black smoker, volcanic and geothermal fields) is widely applied and provides important information about the sources and isotopic compositions of natural gases. However, no information about the composition, origin and fate of migrated gases can be obtained in unexplored hydrocarbon provinces or commercially dry fields due to the lack of gas tests during drilling. The same holds true for fossil magmatic and hydrothermal ore-forming systems. In such frontier areas gas-bearing fluid inclusions hosted in minerals can provide pointers to past gas migration and the origin of gases. A new analytical method for simultaneous measurements of stable isotope ratios of nitrogen (N2), methane (CH4), and carbon dioxide (CO2) in natural gas mixtures released by crushing of fluid inclusions in minerals was developed at the GFZ. Isotopic studies of fluid inclusion gases using this on-line method have been performed so far with regard to the origin of gases in hydrocarbon- and ore-forming systems. These studies have demonstrated the applicability and importance of the developed method in the field of Geo Resources research.