HR: 0800h
AN: V41B-1377    [Abstracts]
TI: Temporal Variations in Flow Velocity and Temperature of Hydrothermal Fluids at Suiyo Seamount, Izu-Ogasawara Arc, Western Pacific
AU: * Tanaka, A
EM: akiko-tanaka@aist.go.jp
AF: Geological Survey of Japan, AIST, AIST Tsukuba Central 7, 1-1-1 Higashi, Tsukuba, 305-8567 Japan
AU: Urabe, T
EM: urabe@eps.s.u-tokyo.ac.jp
AF: Dept. of Earth & Planetary Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
AU: Schultz, A
EM: adam@coas.oregonstate.edu
AF: Oregon State University, 104 COAS Admin Building, Corvallis, OR 97331-5503 United States
AB: The Suiyo Seamount on the volcanic front of the Izu-Bonin (Ogasawara) Arc, western Pacific is a dacitic volcano. There is a hydrothermal field on the floor of the caldera at a depth of 1380 m, where high-temperature fluid is venting through the sediments. A high-temperature hydrothermal system at the Suiyo Seamount has been drilled in June 2001 and in August 2002 using a tethered, submarine rock-drill system (BMS; Benthic Multi-coring System). The BMS produced 10 cores/holes with average depth of 5 meters. Six holes show fluid discharge with temperatures ranging from 9$^{o}$C to 308$^{o}$C. We deployed two Medusa/Gemini (MG) systems on top of cased seafloor boreholes and two Mini-Medusa (MM) systems at areas of warm diffusive flow sites of Suiyo Seamount in August 2002 for about two weeks. These systems are members of the Medusa series of deep sea fluid monitoring systems. The MG and MM systems have been designed for installations directly atop a cased borehole drilled into the seafloor and on the diffuse seafloor, respectively. All data shows strong correlation between fluid temperatures and seawater temperatures. Four systems are located at distances of several tens of meters; however, both synchronized and anti- synchronized temperature fluctuations are frequently observed. The fluid velocities show strong positive correlation with those of temperatures in cases of MG on top of cased seafloor boreholes. It suggests that the fluid is driven by buoyancy through the cased seafloor borehole. However, they show negative correlation in cases of MM on diffusive flow areas. The most prominent feature of all data is the strong semi-diurnal oscillation. This research is funded by Ministry of Education, Science and Technology through Special Coordination Fund "Archaean Park" project.
DE: 8424 Hydrothermal systems (8135)
DE: 8135 Hydrothermal systems (8424)
DE: 3015 Heat flow (benthic) and hydrothermal processes
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting