Preservation of Biological Information in Thermal Spring Deposits: Developing a Strategy for the Search for Fossil Life on Mars
| Autor: | M. R. Walter, David J. Des Marais |
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| Rok vydání: | 1993 |
| Předmět: |
Geological Phenomena
Hot Temperature Extraterrestrial Environment Earth Planet Earth science Carbonates Mars Fresh Water Volcanic Eruptions Cyanobacteria Life on Mars Spring (hydrology) Thermal Environmental Microbiology geography geography.geographical_feature_category Bacteria Fossils Paleontology Geology Astronomy and Astrophysics Mars Exploration Program Silicon Dioxide Fresh water Space and Planetary Science Extraterrestrial life Mineral Waters |
| Zdroj: | Icarus. 101:129-143 |
| ISSN: | 0019-1035 |
| DOI: | 10.1006/icar.1993.1011 |
| Popis: | Current interpretations of the early history of Mars suggest many similarities with the early Earth and therefore raise the possibility that the Archean and Proterozoic history of life on Earth could have a counterpart on Mars. Terrestrial experience suggests that, with techniques that can be employed remotely, ancient springs, including thermal springs, could well yield important information. By delivering water and various dissolved species to the sunlit surface of Mars, springs very likely created an environment suitable for life, which could have been difficult, if not impossible, to attain elsewhere. The chemical and temperature gradients associated with thermal springs sort organisms into sharply delineated, distinctive and different communities, and so diverse organisms are concentrated into relatively small areas in a predictable and informative fashion. A wide range of metabolic strategies are concentrated into small areas, thus furnishing a useful and representative sampling of the existing biota. Mineral-charged springwaters frequently deposit chemical precipitates of silica and/or carbonate which incorporate microorganisms and preserve them as fossils. The juxtaposition of stream valley headwaters with volcanoes and impact craters on Mars strongly implies that subsurface heating of groundwater created thermal springs. On Earth, thermal springs create distinctive geomorphic features and chemical signatures which can be detected by remote sensing. Spring deposits can be quite different chemically from adjacent rocks. Individual springs can be hundreds of meters wide, and complexes of springs occupy areas up to several kilometers wide. Benthic microbial mats and the resultant stromatolites occupy a large fraction of the available area. The relatively high densities of fossils and microbial mat fabrics within these deposits make them highly prospective in any search for morphological evidence of life, and there are examples of microbial fossils in spring deposits as old as 300 Myr. |
| Databáze: | OpenAIRE |
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