Hydrothermal Activity on the Southern Mid-Atlantic Ridge: Tectonically- and Volcanically-Hosted High Temperature Venting at 2-7 Degrees S
Abstract
We have conducted a systematic investigation for hydrothermal activity along the southern Mid-Atlantic Ridge, 2°30-6°50 S. Our initial approach was to use a combination of multi-beam swath mapping, deep-tow sidescan sonar imaging and water column plume-detection using MAPRs and CTD-rosette system to locate new sites of hydrothermal activity immediately south of the Romanche and Chain Fracture zones. We wanted to test whether these geologic features represent a significant barrier to gene-flow along-axis away from northern MAR vent ecosystems. During the first leg of our research cruise (RRS Charles Darwin cruise CD169, Feb-Mar 2005) we used this approach to identify two hydrothermally active regions, one in a non-transform discontinuity near 4°S and the other in a segment centre characterised by very fresh sheet-flows near 5°S. During Leg 2 we returned to the second of these areas and deployed ABE, WHOI's autonomous underwater vehicle, in a three-phase strategy to prospect for, locate, and image new hydrothermal fields. During Phase 1 two discrete target areas were located ca. 1km apart along strike within the segment centre. During Phase 2 these two areas were each mapped in detail using an SM2000 system while in situ optical back scatter, Eh, temperature, Mn and Fe(II) sensors were used to confirm the interception of buoyant hydrothermal plumes rising from the seafloor. Finally we redeployed ABE (Phase 3) to collect photo-mosaics of each of two new vent-areas whilst simultaneously sampling their buoyant plumes by CTD-rosette for TDMn, Fe and CH4 analyses.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFMOS21C..04G
- Keywords:
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- 3017 Hydrothermal systems (0450;
- 1034;
- 3616;
- 4832;
- 8135;
- 8424);
- 3035 Midocean ridge processes;
- 4832 Hydrothermal systems (0450;
- 1034;
- 3017;
- 3616;
- 8135;
- 8424);
- 8135 Hydrothermal systems (0450;
- 1034;
- 3017;
- 3616;
- 4832;
- 8424);
- 8424 Hydrothermal systems (0450;
- 1034;
- 3017;
- 3616;
- 4832;
- 8135)