HR: 17:30h
AN: V34B-07    [Abstracts]
TI: Preliminary Results of a Near-Bottom Integrated Seafloor and Water Column survey of Brothers volcano, Kermadec arc, Using the Autonomous Vehicle ABE
AU: * Embley, R W
EM: robert.w.embley@noaa.gov
AF: NOAA/PMEL, 2115 SE O.S.U. Dr. Newport, OR, Newport, OR 97365-5258, United States
AU: de Ronde, C
AF: GNS Science, 1 Fairway Drive Avalon 5010 PO Box 30-368, Lower Hutt, 6315, New Zealand
AU: Davy, B
AF: GNS Science, 1 Fairway Drive Avalon 5010 PO Box 30-368, Lower Hutt, 6315, New Zealand
AU: Baker, E T
AF: NOAA/PMEL, 7600 Sand Point Wy NE, Seattle, WA 98115-6349, United States
AU: Resing, J A
AF: NOAA/PMEL & JISAO-U. Washington, 7600 Sand Point Wy NE, Seattle, WA 98115-6349, United States
AU: Yoerger, D R
AF: Woods Hole Oceanographic Inst., DSL MS7 Blake Bldg, Woods Hole, MA 02543, United States
AU: Merle, S G
AF: CIMRS/Oregon St. U. & NOAA/PMEL, 2115 SE O.S.U. Dr., Newport, OR 97365-5258, United States
AU: Walker, S L
AF: NOAA/PMEL, 7600 Sand Point Wy NE, Seattle, WA 98115-6349, United States
AB: Brothers volcano, located about 310 km NE of New Zealand along the magmatic front of the Kermadec arc, is one of the best studied intraoceanic arc submarine volcanoes. Its 3.0 x 3.5 km caldera is slightly elliptical, with the long axis oriented about N320°E and has more than 300 m relief from a rim at ~1500 m to a maximum depth of 1880 m in its NW corner. Two major hydrothermal systems were discovered on it in the late 1990s, a high temperature field (up to 302°C) on the NW wall and a lower temperature gas-rich system on the summits of a pair of dacitic cones that occupy the SE half of the caldera. Although the caldera and cones were partly explored by submersibles in 2004 and 2005, the base map, made with a surface ship multibeam, was not detailed enough to understand the context of the seafloor observations. We used the autonomous vehicle ABE launched and recovered from the R/V SONNE in July-August 2007 to conduct high resolution near-bottom surveys of the caldera and its hydrothermal systems using a multibeam sonar, magnetometer, and CTD. The caldera wall, the dacite cones and part of the flat caldera rim were mapped in 96 hours of survey time over 8 dives. In addition, very detailed water column surveys at lower altitude and closer line spacing were conducted over the two most intense hydrothermal sites (i.e., the NW caldera wall and the smaller dacite cone). Although the results are preliminary, there are obvious correlations between hydrothermal activity, wall geomorphology, structural lineations, and the magnetic signature. New hydrothermal sites were discovered on the uppermost NW rim of the caldera and on the SW wall. This new map, along with the previously collected suites of fluid, mineral and seafloor observations, provides a baseline for future monitoring of Brothers' hydrothermal and volcanic activity. It will also provide a better understanding of how the long-term interplay of hydrothermal and volcanic activity affects the geomorphic evolution of submarine arc volcanoes.
UR: http://www.oceanexplorer.noaa.gov/explorations/07fire/welcome.html
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 3075 Submarine tectonics and volcanism
DE: 8185 Volcanic arcs
DE: 8424 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8135)
DE: 8440 Calderas
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting