Microbial Fossils from Terrestrial Subsurface Hydrothermal Environments: Examples and Implications for MarsThe recognition of biological signatures in ancient epithermal deposits has special relevance for studies of early blaspheme evolution and in exploring for past life on Mars. Recently, proposals for the existence of an extensive subsurface blaspheme on Earth, dominated by chemoautotrophic microbial life, has gained prominence. However, reports of fossilized microbial remains, or biosedimentary structures (e.g. stromatolites) from the deposits of ancient subsurface systems, are rare. Microbial preservation is favoured where high population densities co-exist with rapid mineral precipitation. Near-surface epithetical systems with strong gradients in temperature and redox are good candidates for the abundant growth and fossilization of microorganisms, and are also favorable environments for the precipitation of ore minerals. Therefore, we might expect microbial remain, to be particularly well preserved in various kinds of hydrothermal and diagenetic mineral precipitates that formed below the upper temperature limit for life (approx. 120 C).
Document ID
20020052469
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Hofmann, Beda A. (Museum of Natural History Bern Bern Switzerland)
Farmer, Jack (NASA Ames Research Center Moffett Field, CA United States)