HR: 1330h
AN: B12A-0747 INVITED     [PDF]
TI: Endeavour Segment, Juan de Fuca Ridge, Integrated Studies Site (ISS) Update and Opportunities
AU: * Butterfield & RIDGE Community, D
EM: butterfield@pmel.noaa.gov
AF: JISAO, University of Washington and NOAA/PMEL, Seattle, WA 98115 United States
AB: The Ridge 2000 (R2K) Integrated Studies bull's eye on the Juan de Fuca Ridge is focused on the Main Endeavour hydrothermal field, located on the central portion of the Endeavour Segment. This vent field is one of the most vigorously venting systems along the global mid-ocean ridge spreading network, hosting at least 18 large sulfide structures that contains more than100 smokers. Prior to a magmatic event in 2000 some of the edifices had been venting 380C, volatile-rich fluids with extremely low chlorinities for a decade. In addition to the Main Endeavour Field there are four other known high temperature vent fields spaced approximately 2 kilometers apart along the segment (with hints of more) and abundant areas of diffuse flow, both nearby and distal to the high temperature venting. Diffuse flow from the structures and from a variety of basaltic-hosted sites provides rich habitats abundant with microbial and macrofaunal communities. There are well-developed gradients in volatile concentrations along axis that may reflect influence from a sedimentary source to the north, and high chlorinity fluids vent from the most southern (Mothra) and northern fields (Sasquatch). Twenty years of research have laid a firm base for the 5-year plans of R2K at this site, which include examining the response of this segment to perturbations induced by tectonic and magmatic events, identification of the reservoirs, fluxes, and feedbacks of mass and energy at this site, and predictive modeling coupled with field observations. Since designation as an IS site, high-resolution bathymetric mapping (EM300) and an extensive multi-channel seismic survey have been conducted along the entire segment. Smaller focused areas have also been mapped at meter resolution by SM2000 sonar. Intense field programs in 2003 established the first in-situ seismic array along a mid-ocean ridge, which includes installation of a buried broadband seismometer and 7 short-period seismometers emplaced within basaltic bedrock along the flanks of the segment and within the axial valley. It is anticipated that this network will be in place for many years. In addition to monitoring seismic activity, in-situ fluid samplers have been deployed in two of the vent fields for a year, temperature monitoring devices are installed in three of the 5 fields, and two high-temperature prototype incubators were emplaced in the walls of active sulfide chimneys for long-term monitoring and sampling of microbial communities. Discrete fluid sampling in four of the five fields, and sampling of microbial and macrofaunal communities were also conducted. To examine the transfer of fluid and heat along the axial valley, a fence of current meters and up-looking acoustic current profilers were installed that bound the Main Endeavour Field. Data collected with these instruments will be coupled to intense water column surveys by ABE in 2004. An overview of the site is presented here.
UR: http://Ridge2000.bio.psu.edu
DE: 0400 Biogeosciences
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3015 Heat flow (benthic) and hydrothermal processes
DE: 3035 Midocean ridge processes
SC: Biogeosciences [B]
MN: 2003 Fall Meeting