Multidisciplinary Investigations of the Galápagos Rift, 86°W to 89.5°W: 25th Anniversary of the Discovery of Hydrothermal Venting
Abstract
In May-June, 2002, a multidisciplinary expedition comprised of biologists, chemists, geologists and engineers conducted a field program on the Galápagos Rift between 86°W and 89.5°W. Objectives of the expedition included revisiting the site of one of the first-discovered low-temperature hydrothermal vents at Rose Garden (originally found in 1979), and searching for new low- and high-temperature vents along the largely unexplored western portion of the Galápagos Rift to 89.5°W. The field work was funded primarily by NOAA's Ocean Exploration Program with additional support from the National Science Foundation and Woods Hole Oceanographic Institution. A synergistic array of deep-ocean vehicles was used for the exploration program. Alvin and a new digital towed camera were used for making seafloor observations, acquiring digital imagery and collecting samples. An autonomous vehicle ABE (Autonomous Benthic Explorer), which acquired meter-scale bathymetry, near-bottom magnetics and bottom water-properties data, was utilized to explore for active hydrothermal venting. Water-column vertical casts and tow-yos with a CTD/rosette were used to explore for plumes emanating from high-temperature vents. Alvin and ABE were used to explore for the Rose Garden vent field near 86°13.5'W. Detailed bottom-water temperature maps and seafloor magnetics data, in conjunction with visual and photographic observations from Alvin and the towed camera, confirmed that the Rose Garden vent field and associated animal community no longer exists, and that prolonged high-temperature venting appears to never have occurred in this area. However, a new low-temperature vent field (which was named Rosebud) was discovered nearby at a depth of 2450 m, and was found to be developing on a fresh-looking sheet flow at a location approximately 200 m northwest of the former Rose Garden area. A second site of low-temperature hydrothermal activity, at 1670 m, was discovered on a portion of the unexplored rift near 89.5°W. This venting is the first discovered along this portion of the Galápagos Rift and it hosts a large vesicomyid (C. magnifica) clam community that covers an approximately 60 m x 60 m area. Throughout the cruise, ABE was used during night operations to provide synoptic micro-bathymetry maps, magnetics data and bottom water properties. Early each morning, these data were processed and then provided to the Alvin observers prior to that same day's dive. ABE data were occasionally combined with, or supplanted by, data from the towed camera or the CTD. A total of 9 Alvin dives, 7 ABE dives, 5 camera tows and 6 CTD tows/casts were conducted. Detailed micro-bathymetric maps and mosaics of the vent communities will be presented.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFM.T11C1255H
- Keywords:
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- 8120 Dynamics of lithosphere and mantle: general