Geomarkers versus Biomarkers: Paleoenvironmental and Astrobiological Significance

摘要

A fundamental problem related to the paleoenvironmental study of early Earth rocks and minerals, and astrobiological exploration of planetary materials (e.g., asteroidal and Mars meteorites, Martian rocks) is not only recognizing and quantifying carbon-related compounds that may be present but also differentiating those molecules formed abiotically from those generated by extinct or extant life. Only through the combination of biomarkers and geomarkers will we be able to understand the global framework. Whereas, biological markers or "biomarkers" are molecular fossils (1), there is not a clear and official definition of the term "geomarker," and it has been ambiguously used to refer to different topics, not always following a formal concept. Biomarkers are defined as "complex organic compounds, which originated from formerly living organisms and which are composed of carbon, hydrogen, and other elements. Abiotic organic compounds are not biomarkers per se because they do not originate from biosynthesis" (1).