Highly Altered Organic Matter on Earth: Biosignature Relevance

Abstract

On earth, organic matter of biological origin is subjected to various alteration processes, dominated by oxidation and thermal metamorphism due to deep burial, typically a result of plate-tectonic processes. Other alteration processes unrelated to the oxidizing atmosphere and plate tectonics include impact metamorphism, irradiation and thermal degradation of dissolved organic species. The implications of these transformation processes as observed on earth for the use of carbon forms as biosignatures on other planetary bodies are discussed. Carbon minerals, such as graphite and diamond, are potential biosignatures, their major advantage being a high degree of stability.