Experimental evidence of microbially catalyzed smectite-illite reaction at high pressure and high temperature; analogy in the Nankai Trough

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Author(s): Koo, Tae-hee; Park, Hanbeom; Morono, Yuki; Inagaki, Fumio; Kim, Jinwook
Author Affiliation(s): Primary:
Yonsei University, Seoul, South Korea
Japan Agency for Marine-Earth Science and Technology, Japan
Volume Title: AGU 2018 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2018; American Geophysical Union 2018 fall meeting, Washington, DC, Dec. 10-14, 2018. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Microbial Fe-reduction in smectite structure plays a significant role in illitization accompanying with the structural/chemical modification of smectite closely linked to the petrophysical properties of sediment, elemental cycles, fault behavior, and deep biosphere. The present study demonstrates evidence of microbially catalyzed S-I reaction at high pressure and high temperature (55 MPa and 80-140°C) to analogy in the modern mudstone of Nankai Trough. The sediment of lower Shikoku basin (660-855 mbsf) from the Site C0023 (32022.0018' N, 134057.9844' E) which was conducted by Expedition 370 of International Ocean Discovery Program (IODP), was incubated at various temperature (80, 95, 110, 125, and 140°C) to examine the changes in mineralogy, particularly structural/geochemical modification in smectite and illite. The X-ray diffraction profiles showed a modification in intensity of d001 peak of smectite as well as a detection of mixed layer (I/S) in 2θ=9.84° that may indicate the S-I reaction has been progressed by microbial respiration and/or thermal diagenetic process. Additionally, changes in Al/Si ratio, K contents and oxidation state of structural Fe of smectite and illite were measured by transmission electron microscopy with energy dispersive X-ray spectroscopy and electron energy loss spectroscopy to determine the progress in illitzation at nano-scale. Furthermore, Al, Si, and Fe concentration in supernatant was measured to verify the dissolution of clay mineral. The detail evidences to reveal the microbially catalyzed S-I reaction in deep subseafloor environment will be discussed.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 07 Marine Geology and Oceanography; Expedition 370; Geochemistry; IODP Site C0023; International Ocean Discovery Program; Marine sediments; Nankai Trough; North Pacific; Northwest Pacific; Pacific Ocean; Sediments; Tectonics; West Pacific
Coordinates: N322200 N322200 E1345759 E1345759
Record ID: 2019032004
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