Exploration of the deep coalbed biosphere (IODP Expedition 337)

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doi: 10.1180/minmag.2013.077.5.9
Author(s): Inagaki, Fumio; Hinrichs, Kai-Uwe; Kubo, Yusuke
Integrated Ocean Drilling Program, Expedition 337 Scientists
Author Affiliation(s): Primary:
Japan Agency for Marine-Earth Science and Technology, Submarine Resources Research Project, Nankoku, Japan
University of Bremen, Germany
Volume Title: Goldschmidt abstracts 2013
Source: Mineralogical Magazine, 77(5), p.1356; Goldschmidt 2013, Florence, Italy, Aug. 25-30, 2013. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0026-461X
Note: In English
Summary: Integrated Ocean Drilling Program (IODP) Expedition 337 was the first expedition dedicated to subseafloor microbiology that used riser drilling technology [1]. IODP drill Site C0020 is located in a forearc basin formed by the subduction of the Pacific plate off the Shimokita Peninsula at a water depth of 1,180 m. Seismic profiles suggested the presence of deep, coal-bearing horizons at ∼2 km subseafloor depth. Our primary objectives during Expedition 337 were to study the relationship between the deep microbial biosphere and the subseafloor coalbed and to explore the limits of life in horizons deeper than ever probed before by scientific ocean drilling. Among the questions that guided our research strategy was: Do deeply buried hydrocarbon reservoirs such as coalbeds act as geobiological reactors that sustain subsurface life by releasing nutrients and carbon substrates? To address this question and other objectives, we penetrated a 2,466 m deep sedimentary sequence with a series of coal layers at ∼2 km below the seafloor. Hole C0020A is currently the deepest hole in the history of scientific ocean drilling [1]. During Expedition 337, over 1,700 microbiological and biogeochemical samples have successfully been obtained, for which rigorous contamination controls enable differentiation of contaminants from indigenous microbial communities. We conducted gas chemistry and isotopic analyses using a new mud-gas monitoring laboratory during riser-drilling operation [1], which provided the first indication of biologically mediated CO2 reduction to methane at the 2 km-deep coalbed layers. The numbers of microbial cells are generally less than 103 cells cm-3; however, increase of biomass was observed at the coal layers. Potential rates of organoclastic sulfate reduction are elevated in coalbed-bearing strata.
Year of Publication: 2013
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; Biochemistry; Biosphere; Carbon dioxide; Coal; Drilling; Expedition 337; Geochemistry; Integrated Ocean Drilling Program; Sedimentary rocks
Coordinates: N411035 N411036 E1421202 E1421201
Record ID: 2014009362
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