Chapter

Earliest Life on Earth: Habitats, Environments and Methods of Detection

pp 51-78

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Archaean Hydrothermal Systems in the Barberton Greenstone Belt and Their Significance as a Habitat for Early Life

  • Axel HofmannAffiliated withPalaeoproterozoic Mineralization Research Group, Department of Geology, University of Johannesburg Email author 

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Abstract

Hydrothermal systems have played an important role in shaping the 3.54–3.23 Ga volcano-sedimentary succession of the Barberton greenstone belt. Evidence for relatively low-temperature (≤150°C) seafloor hydrothermal activity is widely recorded in extensive silicification of volcanic and sedimentary rocks, leaching of elements commonly mobile during water-rock interaction, and extensive hydraulic fracturing. Evidence for the presence of high-temperature hydrothermal vents is scarce and restricted to a massive sulphide deposit near the top of the succession. Many of the zones affected by seafloor alteration are spatially associated with traces of early life, such as carbonaceous matter and bioalteration features. Diffuse venting of low-temperature hydrothermal fluids was a widespread phenomenon on the Palaeoarchaean seafloor, making it an ideal habitat for hyperthermophiles and the possible birthplace of life during earlier times.

Keywords

Barberton greenstone belt Archaean Hydrothermal activity Seafloor alteration Silicification