HR: 0800h
AN: V51A-1462    [Abstracts]
TI: An outline of the interdisciplinary survey on a new type intra-plate volcanism -
AU: * Abe, N
EM: abenatsu@jamstec.go.jp
AF: IFREE, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Hirano, N
EM: nhirano@geo.titech.ac.jp
AF: Tokyo Inst. Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AU: Fujiwara, T
EM: toshi@jamstec.go.jp
AF: IFREE, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Machida, S
EM: machida@ori.u-tokyo.ac.jp
AF: ORI, Univ. Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo, 164-8639
AU: Araki, E
EM: araki@jamstec.go.jp
AF: IFREE, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Araki, E
EM: araki@jamstec.go.jp
AF: ORI, Univ. Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo, 164-8639
AU: Baba, K
EM: kbaba@eri.u-tokyo.ac.jp
AF: ERI, Univ. Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Ichiki, M
EM: ichiki@jamstec.go.jp
AF: IFREE, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Nakanishi, M
EM: nakanisi@earth.s.chiba-u.ac.jp
AF: Chiba Univ., 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522 Japan
AU: Ogawa, Y
EM: yogawa@arsia.geo.tsukuba.ac.jp
AF: Univ. Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8572 Japan
AU: Sugioka, H
EM: hikari@jamstec.go.jp
AF: IFREE, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Suyehiro, K
EM: suyehiro@jamstec.go.jp
AF: IFREE, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Ishii, T
EM: ishii@ori.u-tokyo.ac.jp
AF: ORI, Univ. Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo, 164-8639
AU: Suzuki, T
EM: takahiro7211@yahoo.co.jp
AF: Univ. Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8572 Japan
AU: Takahashi, A
EM: ayu@eps.s.u-tokyo.ac.jp
AF: Univ. Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan
AU: Takahashi, E
EM: etakahas@geo.titech.ac.jp
AF: Tokyo Inst. Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AU: Yamamoto, J
EM: jyama@bep.vgs.kyoto-u.ac.jp
AF: Inst. Geotherm. Sci., Kyoto Univ., Noguchibaru, Beppu, 874-0903 Japan
AU: Onboard Scientists, K K
EM:
AF: JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AB: Several very young volcanoes (< 1 Ma) were discovered on the Early Cretaceous (~135 Ma) NW Pacific Plate. They are very small knolls on the abyssal plane (~ 6000 m water depth) and erupted strong to moderate alkaline basalt, generally including deep-seated xenoliths. This volcanic field is far from any trenches and also spreading centers, therefore these are classified as a kind of intra-oceanic plate volcanism. In this area, however, there are neither any hotspots nor large igneous province previous reported. Therefore, this volcanic activity is not adequate for any existence volcanic models on the earth. Then, we named this special volcanism Petit Spot. To understand this petit spot volcanism, we've been taking interdisciplinary surveys. The main results of these surveys using JAMSTEC four cruises (KR03-07, KR04-08, YK05-06 and KR05-10) and shore-based research are listed below. 1) Volcanic rocks were sampled from three small knolls by dredges and submersible dives. They are highly vesicular, and generally include peridotite xenoliths and peridotitic xenocrysts. 2) Terrestrial Heat Flow was measured at two points with piston coring on the pelagic sediments. 3) Seabeam mapping shows there are a lot of small knolls assumed young volcanoes. The arrangement and the size of the knolls imply that this volcanic field is a monogenic volcanic cluster, which are often observed in the intra-continental plate. 4) Single Channel Seismic (SCS) Reflection survey profiles suggest that main body of the young volcano exists between pelagic sediment and oceanic basement. 5) Magnetotelluric soundings (MT) experiment using ocean bottom electromagnetometers (OBEM) implies the maximum electric conductivity observed around 100-130 km depth. In addition to these results, some seismic activities (M3 - 5) were observed in this area by world network of seismic stations for this quarter century. As a whole, petit spot volcanism is quite unique and highly remarkable phenomenon.
DE: 1645 Solid Earth (1225)
DE: 1749 Volcanology, geochemistry, and petrology
DE: 4200 OCEANOGRAPHY: GENERAL
DE: 5480 Volcanism (6063, 8148, 8450)
DE: 7280 Volcano seismology (8419)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005