fluid inclusions were formed directly during mineral growth and provide important information about the conditions under which they were formed. This includes the pressure, temperature and the solution composition. In addition to an aqueous phase, fluid inclusions can also contain gases whose chemistry can persist for billions of years. The fluid inclusions examined in this study were trapped during crystallization of the host minerals. The fluid inclusions investigated in this study originate from the Dresser Mine in Australia. They were trapped during crystallization of the host minerals of barium sulfate (barite). The research team analyzed them extensively for their formation conditions, biosignatures and carbon isotopes.

In the course of the analyses, it turned out that they contained primordial metabolism—and thus energy sources for life. The results of Lüders’ carbon isotope analysis provided additional evidence for different carbon sources. While the gas-rich inclusions of gray barites contained traces of magmatic carbon, clear evidence of an organic origin of the carbon could be found in the fluid inclusions of black barites.

Follow-up research is possible

“The study may create a big stir,” Lüders says. Organic molecules of this type have not yet been found so far in fluid inclusions in Archean minerals. At the same time, however, he says the study is just a first step. Lüders says, “The ever-increasing sensitivity of measuring instruments will provide new tools for the study of solid and fluid micro inclusions in minerals. Measurements of bio signatures and isotope ratios are likely to become increasingly accurate in the near future.”

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