HR: 0800h
AN: T31A-0476    [Abstracts]
TI: High-Resolution Micro-Bathymetry Mapping in the Lau Basin: Examples From the Tui Malila and Mariner Vent Sites
AU: Ferrini, V
EM: vferrini@whoi.edu
AF: Woods Hole Oceanographic Institution, Woods Hole, Woods Hole, MA 02543 United States
AU: Sterling, A
EM: akel@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, 1680 East West Road, Honolulu, HI 96822 United States
AU: Martinez, F
EM: martinez@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, 1680 East West Road, Honolulu, HI 96822 United States
AU: Tivey, M K
EM: mktivey@whoi.edu
AF: Woods Hole Oceanographic Institution, Woods Hole, Woods Hole, MA 02543 United States
AU: Mottl, M
EM: mmottl@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, 1680 East West Road, Honolulu, HI 96822 United States
AU: * Kim, S
EM: skim@mlml.calstate.edu
AF: Moss Landing Marine Laboratories, The California State University, 8272 Moss Landing Road, Moss Landing, CA 95039 United States
AB: High-resolution SM2000 (200 kHz) multibeam sonar data were collected at six vent areas on the Lau Basin spreading center in April 2005. Data were acquired during near-bottom surveys conducted with the ROV Jason II at altitudes ranging from 5 to 20 m. High altitude (20 m) bathymetric surveys were complemented by near-bottom visual surveys, which provided ground-truth observations of the seafloor. Combined with Doppler and Long Baseline (LBL) Navigation, these bathymetry data provide sub-meter resolution of seafloor features, and reveal individual vent structures, faults and fissures. We present bathymetry data from two sites located 22 km apart, which are geologically and biologically distinct and exhibit contrasts in venting styles and biota. The Mariner vent field contains massive vent structures, many of which are taller than 25 m, with active venting from their bases and sides. Fluids exit as vigorous, high-temperature (< 363°C) black smoker fluids through chalcopyrite-lined conduits, and as less focused flow from porous beehive structures. Inactive structures are friable and are composed of iron- and copper-oxides. There was little evidence of faulting or fracture at the vent field, but we note the presence of collapsed volcanic dome structures. The vent fauna at Mariner is very limited; only Bythograeid and Galatheid crabs, and one Brisingid Seastar, were found. Tui Malila, by contrast, is characterized by shorter and wider branched vent structures with coalesced spires, the tops of which were actively venting. There is extensive faulting and fracture at this site, as well as a number of large flanges and areas of diffuse flow. At Tui Malila fluids exit tall structures through chalcopyrite- and zinc-lined conduits (at temperatures < 312°C), from beneath flanges, and directly from andesite. Hydrothermal breccias are also present. Tui Malila hosts a more typical vent community, with greater abundances of both Bythograeid and Galatheid crabs, mostly within 4 m of the vent field. Ifremeria Nautilei and Bathymodiolus Brevior were prolific within 2 m of the vent field, and sponges and anemones abundant from 4 to 32 m away.
DE: 1034 Hydrothermal systems (0450, 3017, 3616, 4832, 8135, 8424)
DE: 3035 Midocean ridge processes
DE: 3080 Submergence instruments: ROV, AUV, submersibles
SC: Tectonophysics [T]
MN: Fall Meeting 2005