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Geomicrobial Processes and Diversity in Ultra-High Pressure Metamorphic Rocks and Deep Fluids from Chinese Continental Scientific Deep Drilling

Zhang, Gengxin
http://rave.ohiolink.edu/etdc/view?acc_num=miami1165003593

Abstract Details

2006, Doctor of Philosophy, Miami University, Geology and Environmental Earth Science.
This dissertation investigates the microbial communities and microbe-mineral interactions in ultra-high pressure metamorphic rocks and deep fluids from the Chinese Continental Scientific Drilling (CCSD) project by using geochemical, mineralogical, cultivation and molecular microbiology methods. The drilling site is located in the eastern part of the Dabie-Sulu ultra high-pressure metamorphic (UHPM) orogenic belt at the convergent plate boundary between the Sino-Korean and Yangtze Plates. This integrated approach conclusively demonstrates that microbes can survive in the deep continental subsurface (down to 3350 m) and they play important roles in mineral transformations and elemental cycling. The first half of this study focuses on geochemical conditions and diversity and metabolic functions of microbial community. Characterization of SSU rRNA genes indicated that the bacterial clone sequences shifted form a Proteobacteria-dominated community to a Firmicutes-dominated one with increased depth. From the ground surface to 2030 m, most clone sequences were related to nitrate reducers, with a saline, alkaline, and cold habitat. From 2290 to 3350 m most sequences were closely related to anaerobic, thermophilic, halophilic or alkaliphilic bacteria. The archaeal diversity was low. Most archaeal sequences from the ground surface to 3350m were not related to known cultivated species, but to environmental clone sequences recovered from subsurface marine environments. An important contribution of this research is an enrichment of a thermophilic (optimal temperature of 68°C) organism from 2450m with an ability to reduce Fe(III) and oxidize Fe(II) under different conditions. This enriched organism was capable of reducing Fe(III) in aqueous form and in the structure of clay minerals and iron oxides at acidic pH. This organism was also capable of oxidizing Fe(II) in aqueous form and in the structure of pyrite and siderite. The second half of this dissertation focuses on microbe-mineral interactions by using enriched and isolated cultures to react with clay and iron oxide minerals. Mesophilic and thermophilic iron-reducing bacteria were incubated with lactate as the electron donor and structural Fe(III) in solid minerals as the sole electron acceptor. Extensive mineral reaction took place. One important such reaction was the smectite to illite reaction promoted by mesophilic and thermophilic metal reducing bacteria. This particular reaction highlights the significant role of iron-reducing bacteria in promoting the smectite to illite reaction at high temperature.
Hailiang Dong (Advisor)
216 p.
Geochemistry; Geology
Fe; Drilling Fluids; Nontronite; illite; smectite; microbial

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Citations

  • Zhang, G. (2006). Geomicrobial Processes and Diversity in Ultra-High Pressure Metamorphic Rocks and Deep Fluids from Chinese Continental Scientific Deep Drilling [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1165003593

    APA Style (7th edition)

  • Zhang, Gengxin. Geomicrobial Processes and Diversity in Ultra-High Pressure Metamorphic Rocks and Deep Fluids from Chinese Continental Scientific Deep Drilling. 2006. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1165003593.

    MLA Style (8th edition)

  • Zhang, Gengxin. "Geomicrobial Processes and Diversity in Ultra-High Pressure Metamorphic Rocks and Deep Fluids from Chinese Continental Scientific Deep Drilling." Doctoral dissertation, Miami University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1165003593

    Chicago Manual of Style (17th edition)

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This open access ETD is published by Miami University and OhioLINK.