HR: 0800h
AN: V41B-1387    [Abstracts]
TI: Sulfur Isotope Geochemistry of Mariana Arc Hydrothermal Systems
AU: * Miyabe, S
EM: miyabe@misasa.okayama-u.ac.jp
AF: Institute for Study of the Earth's Interior, Okayama University, Misasa, Tottori, 682-0193 Japan
AU: Butterfield, D A
EM: David.A.Butterfield@noaa.gov
AF: Pacific Marine Environmental Laboratory, NOAA, 7600 Sand Point Way NE , Seattle, WA 98115 United States
AU: Roe, K K
EM: kevin.roe@noaa.gov
AF: Pacific Marine Environmental Laboratory, NOAA, 7600 Sand Point Way NE , Seattle, WA 98115 United States
AU: Ishibashi, J
EM: ishi@geo.kyushu-u.ac.jp
AF: Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University, Hakozaki, Fukuoka, 812-8581 Japan
AU: Embley, R W
EM: robert.w.embley@noaa.gov
AF: Pacific Marine Environmental Laboratory, NOAA, Hatfield Marine Science Centre, 2115 SE Marine Science Drive, Newport, OR 97365-5258 United States
AU: Chiba, H
EM: hchiba@cc.okayama-u.ac.jp
AF: Department of Earth Science, Faculty of Science, Okayama University, Tsushima, Okayama, 700-8530 Japan
AU: Nakamura, K
EM: koichi.nakamura@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, 305-8561 Japan
AB: Sulfur isotope measurments were performed on H$_{2}$S and SO$_{4}$ in hydrothermal fluids together with elemental sulfur precipitates collected from newly discovered active hydrothermal systems in Mariana Arc. These samples were collected during R/V Thomas G Thompson cruise with ROPOS at March 2004, conducted under Submarine Ring of Fire 2004 project. We report sulfur isotope systematics of these hydrothermal fluids comparing with those from TOTO cauldron in southern Mariana Arc previously studied. The venting fluids from some Mariana Arc hydrothermal systems have remarkably low \delta $^{34}$S(H$_{2}$S) values (-5.9 to -10.0\permil for NW Rota, -3.0 to -6.9\permil for NW Eifuku, -5.5\permil for Kasuga 2) as well as TOTO ( -3.8\permil). Compared with mid-oceanic ridge hydrothermal fluids showing \delta $^{34}$S of -2.3 to + 7.3\permil, these low values suggests that the Mariana Arc and TOTO caldera hydrothermal systems are distinctive in terms of production mechanisms of hydrogen sulfide or source of sulfur. At NW Rota Pit, we found that, venting fluid has higher sulfate concentration (35.4mM) and slightly lower\delta $^{34}$S value (19.0\permil) than ambient seawater (28mM, 21.0\permil). We also confirmed existence of sulfur spherules (\delta $^{34}$S =-5.1\permil). These results suggest disproportionation reaction of the exsolved SO$_{2}$ from a magma body is a predominant mechanism of sulfur species of the hydrothermal system. Extremely low pH of the fluid agrees with production of sulfuric acid by disproportionation.
UR: http://oceanexplorer.noaa.gov/explorations/04fire/welcome.html
DE: 9355 Pacific Ocean
DE: 8135 Hydrothermal systems (8424)
DE: 4870 Stable isotopes
DE: 1724 Ocean sciences
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting