Biological activities at the Archean submarine hydrothermal environments

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Hydrothermal origin of life on the Archean seafloor is becoming a popular theory, besides the idea that the evolution of early biota took place at the submarine hydrothermal environments Abundant submarine hydrothermal sediments have been found in the Archean strata and there exists possibility that remnants of early biota and chemical fossils of their ecosystem were still preserved in these sediments. The main purpose of this study is to identify the remnants of early biota and their ecosystem based on the geological and geochemical ways. In this study, detailed geological surveys were conducted in two areas : the 2.7 Ga Abitibi Greenstone Belt and 3.2 Ga Pilbara Blocks in Australia. Other samples related to Archean submarine hydrothermal activities and modern hydrothermal activities were also subjects for the chemical analyses in this study. The followings are the notable findings from this study : specific hydrothermal alterations by carbon dioxide-rich fluids and mobilization of phosphorous from oceanic crust, age specific activity of methane-related biota and their association with magmatic activity and metal enrichments in organic matter by hydrothermal reaction. New ecological energy exchange system was also found in the modern hydrothermal sediments and its links to Archean ecosystem was also proposed. These achievements were already published in the several international and domestic journals, and also reported at international conferences as invited talks. New theory of biological evolution associated with the contemporary magmatic activity is also proposed from this study.