| dc.description |
The first investigation by submersible of high‐temperature black smoker vents in the Atlantic Ocean was made with the ALVIN submersible as part of a cruise of the research vessel Atlantis II between May 16 and June 18, 1986. The site, near 26°08′N, 44°49′W, in the rift valley of the Mid‐Atlantic Ridge, was discovered 1 year ago (Eos, October 1, 1985, p. 682) by multiple surface ship methods. The vent mound is about 250 m in diameter and rises 50 m from a water depth of 3670 m. The site is at the juncture between the base of the east wall of the rift valley and the rift floor within the Trans‐Atlantic Geotraverse (TAG) Hydrothermal Field (see “Black smokers, massive sulphides, and vent biota at the Mid‐Atlantic Ridge” by P. Rona et al., in Nature, vol. 321, p . 33, 1986). The mound appears to be a constructional feature built primarily of massive sulfides. A sequence of venting phenomena with increasing fluid temperatures, including shimmering water, white smokers, blue‐white smokers, and black smokers, was encountered from the edge to the center of the mound. A group of black smokers situated at the center of the mound vented such a large, dense, black cloud of metallic particles that visibility was partially obscured, consequently limiting access by the submersible. |
