A comparative study on microbial mediated mineralization in Kamchatka hot springs and the Pearl River Delta sedimentary environments
Materials deposited in low-temperature environments are characterized by their small particle size. The activity of microorganisms in aqueous sedimentary environments may have effective impacts on the geochemical parameters, which consequently change the original mineralogical records. The character...
| Main Authors: | , |
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
The University of Hong Kong (Pokfulam, Hong Kong)
2014
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| Subjects: | |
| Online Access: | https://doi.org/10.5353/th_b5295514 http://hdl.handle.net/10722/202362 |
| Summary: | Materials deposited in low-temperature environments are characterized by their small particle size. The activity of microorganisms in aqueous sedimentary environments may have effective impacts on the geochemical parameters, which consequently change the original mineralogical records. The characterization of the fine environmental materials, especially those related to the microbial mediation is usually overlooked, but is essential for studies in the field of environmental microbiology or records of environmental change. The Kamchatka volcanic hot springs have been extensively studied for their microbiology because of their unique geological setting and applications to our understanding of life in the extreme environment. In those hot springs, minerals commonly appear with various morphologies. The hot springs have been existed for 40,000 years. Authigenic minerals, such as clay minerals, silica, sulfur, sulfide, and sulfate were characterized. Two types of silica and silicified biota were observed. Elemental sulfur crystals were observed although they are thermodynamically unstable. Pyrite and gypsum showed high diversities in morphologies and crystal sizes. Single forms of pyrite crystals included: cube, pyritohedron, octahedron, and sphericities. Prismatic, prismatic pseudo-hexagonal, fibrous, tubular, lenticular and twinned gypsum crystals were observed. The co-existence of diverse crystal habits of gypsum implies a long-term interaction between hot spring geochemistry and the metabolisms of the microbial community. The morphology of gypsum in hot springs was compared with that of gypsum with hydrothermal genesis in Lower Cambrian black shale. The crystallization of gypsum in the black shale of the Lower Cambrian, which shows similar but less varied morphology, was influenced by post-depositional hydrothermal fluids. I suggest that the high diversities of the morphology and crystal size of gypsum in those hot springs represent the continuous mediation of microorganism, which could be used as mineral ... |
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