HR: 16:00h
AN: V44A-01    [Abstracts]
TI: Overview of Vent Fluid Chemistry From the Marianas Volcanic Arc
AU: * Butterfield, D A
EM: David.A.Butterfield@noaa.gov
AF: Joint Institute for the Study of the Atmosphere and Oceans, University of Washington, Seattle, WA 98195 United States
AU: Roe, K K
EM: Kevin.Roe@noaa.gov
AF: Joint Institute for the Study of the Atmosphere and Oceans, University of Washington, Seattle, WA 98195 United States
AU: Bolton, S A
EM: bolton@u.washington.edu
AF: School of Oceanography, University of Washinton, Seattle, WA 98195 United States
AU: Baross, J A
EM: jbaross@u.washington.edu
AF: School of Oceanography, University of Washinton, Seattle, WA 98195 United States
AU: Lupton, J E
EM: John.E.Lupton
AF: NOAA Pacific Marine Environmental Laboratory, 2115 SE OSU Dr, Newport, OR 97365 United States
AU: Lilley, M D
EM: illey@u.washington.edu
AF: School of Oceanography, University of Washinton, Seattle, WA 98195 United States
AU: Embley, R W
EM: Robert.W.Embley@noaa.gov
AF: NOAA Pacific Marine Environmental Laboratory, 2115 SE OSU Dr, Newport, OR 97365 United States
AU: Chadwick, W W
EM: William.W.Chadwick@noaa.gov
AF: CIMRS, Oregon State University, Newport, OR 97365 United States
AU: Resing, J A
EM: Joseph.Resing@noaa.gov
AF: Joint Institute for the Study of the Atmosphere and Oceans, University of Washington, Seattle, WA 98195 United States
AB: In March and April 2004, a research expedition on the {\it R.V.T.G. Thompason} with the ROV {\it ROPOS} investigated and sampled hydrothermal systems on six submarine volcanoes of the Marianas volcanic arc between 14.3 and 21.5 degrees N. In this two-year project sponsored by NOAA Ocean Exploration, dive targets were selected based on bathymetric and hydrothermal plume mapping conducted in 2003. Hydrothermal plume intesity and chemistry was used with success to target and sample a remarkable variety of volcanic and hydrothermal features. At NW Rota-1 submarine volcano, there is clear evidence of ongoing eruptive activity producing clouds of particulate and molten sulfur as well as mm to cm-size glassy volcanic ejecta. Fluids (34 deg C) sampled directly from an eruptive pit crater has pH of 2.0, with a high content of particulated sulfur, excess sulfate relative to seawater, and very low H2$^{s}$ content. Fluids percolating through volcaniclastic sand adjacent to the pit reached 100 deg C and had higher silica, slightly higher pH, and millimolar levels of H2$^{s}$. The chemistry of both types of fluids is indicative of input of volcanic SO$^{2}$ and disproportionation into sulfate and H2$^{s}$ (in volcaniclastic sands) and elemental sulfur (in the pit crater). Molten sulfur droplets indicate a high-temperature source at the base of the pit crater that rapidly mixes with seawater, while fluids venting through the sand remain hotter and react with volcanic glass. DNA was collected by in-situ filtration and both archaea and bacteria were amplified by PCR. Bacterial clone libraries were dominated by epsilon Proteobacteria with a high degree of relatedness to microaerophilic sulfur-, sulfide-, and hydrogen oxidizers belonging to the genera Sulfurimonas and Calderomonas. At East Diamante submarine volcano, several hydrothermal areas were found on resurgent domes within the large caldera. One of these sites hosted the only high-temperature deposits. The high volatile content of the volcanic arc environment is evident in the CO$^{2}$ and SO$^{2}$ dominated fluids sampled on the expedition. The submarine volcanoes explored were doninated by diffuse, low-temperature venting, significatly below the boiling temperature even at shallow depths.
DE: 8424 Hydrothermal systems (8135)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting