HR: 0800h
AN: V41B-1391    [Abstracts]
TI: In Situ Observations of Dissolved Manganese in Hydrothermal Vent Plumes at Mariana Trough.
AU: * Okamura, K
EM: okamurak@scl.koto-u.ac.jp
AF: ICR, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Yanai, K
EM: yanai@inter3.kuicr.kyoto-u.acj.p
AF: ICR, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Sohrin, Y
EM: sohrin@scl.kyoto-u.ac.jp
AF: ICR, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Ishibashi, J
EM: ishi@geo.kyushu-u.ac.jp
AF: Kyushu University, Hakozaki, Fukuoka, 812-8581 Japan
AU: Watanabe, M
EM: mw@ori.u-tokyo.ac.jp
AF: ORI, The University of Tokyo, 1-15-1, Minamidai, Nakano, Tokyo, 164-8639 Japan
AU: Ura, T
EM: ura@iis.u-tokyo.ac.jp
AF: IIS, The University of Tokyo, 4-6-1, Komaba, Meguro, Tokyo, 153-8505 Japan
AB: We studied for hydrothermal plumes in Mariana Trough by using in situ Mn-Fe analyzers (GAMOS-II). GAMOS-II (Geochemical Anomalies MOnitoring system) is an in-situ chemical analyzer used to detect manganese and/or iron anomalies in neutrally buoyant plumes and to map distributions in bottom seawater over vent fields. During TN167 (ROV ROPOS / R/V Thomas G Thompson) cruise, GAMOS-II measurements were conducted for plume observation at the Yamanaka and Fryer sites. GAMOS-II was attached on the sampling stage of the ROPOS at dive #'777. ROPOS arrived at the bottom at 0:50, and left the bottom at 10:55. Active manganese and temperature anomalies were detected around 2:00 - 5:00 and 7:00 - 11:00, when the ROPOS passed through hydrothermally active areas. The anomaly of temperature and manganese concentration was observed coincidentally, but the relation ship is not consistently proportional. Wide variation in Mn vs. temperature ratio implies diversity between geochemical flux and heat flux depending on the type of venting in the hydrothermal sites. During KH-04-02 Leg2 (AUV r2D4 / R/V Hakuho-Maru) cruise, GAMOS-II measurements were also conducted for plume observation at NW ROTA #1 seamount. GAMOS-II was attached in the AUV r2D4 with CTD. During four successive dives, the fine structure of hydrothermal plumes changed drastically, probably reflecting temporal variation of hydrothermal activity. Continuous sampling by using GAMOS-II was also done successfully. We will also discuss about the data of this continuous sampling.
DE: 4806 Carbon cycling
DE: 4894 Instruments and techniques
DE: 1050 Marine geochemistry (4835, 4850)
DE: 1065 Trace elements (3670)
DE: 1094 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting