Distribution and isotopic signatures of archaeal lipid biomarkers associated with gas hydrate occurrences on the northern Cascadia margin

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doi: 10.1016/j.chemgeo.2013.02.003
Author(s): Kaneko, Masanori; Naraoka, Hiroshi; Takano, Yoshinori; Ohkouchi, Naohiko
Author Affiliation(s): Primary:
Kyushu University, Department of Earth and Planetary Sciences, Fukuoka, Japan
Other:
Japan Agency for Marine-Earth Science and Technology, Japan
Volume Title: Chemical Geology
Source: Chemical Geology, Vol.343, p.76-84. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0009-2541 CODEN: CHGEAD
Note: In English. Includes appendices. 87 refs.; illus., incl. 2 tables, sketch map
Summary: We have investigated the distributions and carbon isotopic compositions of archaeal membrane lipids in gas-hydrate-bearing sediments collected from the northern Cascadia Margin offshore from Vancouver Island (Sites U1327 and U1328) by the R/V JOIDES Resolution during IODP Expedition 311. Archaeal lipid biomarkers, including glycerol dialkyl glycerol tetraethers (GDGTs), tend to become abundant below 100 mbsf (meters below sea floor). Tricyclic biphytane (BP[3]; which is a robust biomarker derived from GDGT), crenarchaeol, and other BPs exhibit δ13C values of ca. -20 ppm, and become abundant between 130 and 230 mbsf at Site U1328. In this depth range, concentrations of ammonium and phosphate in interstitial waters also increase, suggesting that a larger population and higher activity of heterotrophic community consisting of crenarchaeota and other archaea decompose the sedimentary organic matter, thereby liberating ammonium and phosphate. Such crenarchaeotic activity can produce other metabolic products such as molecular hydrogen by fermentation of organic matter during diagenesis. Furthermore, near the organic matter decomposition zone (130 to 230 mbsf), a probable methanogen biomarker (13C-depleted BP[1] with δ13C values as low as -48.8 ppm) becomes abundant, indicating that methanogens utilize these diagenetic products. The molecular and isotopic distributions of archaeal lipid biomarkers indicate that the archaeal community plays an important role in the biogeochemical cycles of deep-sea sediments, including both methanogenesis and nutrient recycling. Abstract Copyright (2013) Elsevier, B.V.
Year of Publication: 2013
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Aliphatic hydrocarbons; Alkanes; Archaea; Biochemistry; Biomarkers; C-13/C-12; Carbon; Cascadia subduction zone; Chemical composition; Chromatograms; Diagenesis; East Pacific; Expedition 311; Gas chromatograms; Gas hydrates; Hydrocarbons; IODP Site U1327; IODP Site U1328; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; Lipids; Marine sediments; Mass spectra; Methane; Molecular structure; North Pacific; Northeast Pacific; Organic compounds; Pacific Ocean; Sediments; Spectra; Stable isotopes
Coordinates: N484000 N484000 W1265100 W1265100
N484200 N484200 W1265200 W1265200
Record ID: 2013048160
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands