2007 Fiscal Year Final Research Report Summary
Understanding of the new type volcanism on the 130 m. y. -old Cretaceous Pacific Plate
| Project/Area Number |
17340136
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
ABE Natsue Japan Agency for Marine-Earth Science and Technology, Institute for Research on Earth Evolution (IFREE), Scientist (80302933)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIWARA Toshiya Institute for Research on Earth Evolution (IFREE), 地球内部変動研究センター, Technical Scientist (30359129)
SUGIOKA Hiroko Institute for Research on Earth Evolution (IFREE), 地球内部変動研究センター, Technical Scientist (00359184)
BABA Kiyoshi Earthquake Researth Institute, University Tokyo, 地震研究所, Assistant Professor (70371721)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Peitit Spot / Oceanic Lithosphere / Asthenosphere / Outer Rise Earthquake / Heat Flow / BBOBS / OBEM / Mantle xenoliths |
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| Research Abstract |
Petit-spot is a young volcanic field(<1 Ma) discovered on the Early Cretaceous(〜130 Ma) northwestern Pacific Plate. The volcanoes belong to petit-spot are very small knolls on the abyssal plane(〜6000 m water depth) and erupted strong to moderate alkaline basalt, generally including deep-seated xenoliths. The volcanic field is far 600 km away from the Japan Trench, any spreading centers and any hotspots. Therefore, the volcanic activity is not adequate for any existence volcanic models on Earth. In order to understand this petit spot volcanism, we've been taking multidisciplinary surveys. The main results for three years' research including the cruises using JAMSTEC R/V YOKOSUKA and KAIREI(YK05-06, KR05-10, KR06-03, KR07-06, KR07-07 and YK07-15) and shore-based research were listed below.
FY2005 : Two other small knolls were discovered as the petit-spot volcanoes with SHINKAI 6500 submersible, and alkaline basalt samples were collected from the knolls. Several acoustic explorations on the petit-spot knolls and NW Pacific area with a single channel streamer(SCS). Five Ocean Bottom Electro-Magnetometers(OBEMs) were deployed and recovered around the volcanic field. The crustal heat flow measurements were taken using with Miniaturized temperature data loggers.
FY2006 : Multinarrow-beam bathymetry mapping and SCS acoustic explorations were taken in the petit-spot volcanic field and surrounding area.
FY2007 : Three broad band ocean bottom seismometers(BBOBSs) and three OBEMs were deployed in the volcanic field to observe the intraplate seismicity and the melt supply process in the upper mantle. Several mantle xenoliths included petit-spot alkaline basalts were sampled during SHINKAI 6500 dives. In addition to this, another petit-spot volcanic field was discovered on the outer rise near the Japan Trench.
These results were published on both international and domestic journals, presented at scientific meetings and press releases.
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