2004 Fiscal Year Final Research Report Summary
Molecular paleontological research for the evolution of symbiosis of chanosynthetic biological community
| Project/Area Number |
14540437
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
OGIHARA Shigenori The University of Tokyo, Department of Earth and Planetary Science, Research Assistant, 大学院・理学系研究科, 助手 (50214044)
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| Project Period (FY) |
2002 – 2004
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| Keywords | biomarker / chemosynthetic community / methanogens / sulfate-reducing bacteria / methane seep / cold seep / carbonate rock |
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| Research Abstract |
Recent biomarker and isotopic studies indicated the participation of Archea in an anaerobic methane-oxidation (AOM) in the marine sediments. Authigenic carbonate precipitation was related to AOM which produces CO_2 and decreases pH, favoring the dissolution of carbonates rather than precipitation. Anaerobically oxidized methane produces the increase in alkalinity of carbonate and favors the precipitation of authigenic carbonates. The association of methane seepage on the sea floor and an oxidation of methane with carbonate precipitation was established on the basis of carbonate ^<13>C depletion. The cold-seep carbonates contain biomarkers suggesting the anaerobic methane-oxidation which play an important role during cold-seep carbonate precipitation. The most important diagnostic lipid compound for identifying AOM is ^<13>C depleted pentamethyleicosane (PME) and most likely crocetane Another useful compound to identify methane oxidizing Archea is ^<13>C depleted isoprenoid ether lipid or degradation product originated from ether-bound membrane lipids with an isoporenoid carbon skeleton.
Newly developed biomarker indicating AOM, especially ANME-2 (group of methanogens), is C13 and C18 isoprenoid ketone. The origin of isoprenoid ketone could be hydroxyarchaeol contained Methanosarcinaceae.
Biomarker indicating AOM was investigated from Pleistocene Koshiba formation, Recent sea-floor from Rishiri channel, five Cretaceous limestone from Hokkaido in this study. The Archeal spices related to AOM are multiple, biomarker is useful tool for distinguish AMNE-1 and ANME-2 in geological samples. The fossil chemosynthtic communities at the age of Lower Cretaceous are dominated ANME-1, and the samples from younger than Upper Cretaceous are dominated ANME-2. The combination of chemosynthetic community is evolving.
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