USGS1965
Sedimentary iron and heavy-metal deposits of undetermined size have been found in the middle of the Red Sea some 2000 meters below the surface of the sea. This discovery has been made from the Research Vessel Atlantis II , which is still at sea engaged in a series of oceanographic investigations which ultimately will end in November 1965, after the ship has circumnavigated the globe. The discovery is significant because the environment and the processes controlling deposition of heavy metals are observable and appear to be still active. The environment of the deposits can be breiefly described as an isolated sub-marine pool of brine having a pH as low as 5.3, a temperature of 56° c. and a salt content of about 310 grams per liter (at 20° c). Shipboard oxygen determinations and the indicated presence of H 2 S, divalent iron and divalent manganese in the water suggest that the environment is anaerobic. This hot, dense brine is trapped in a local depression of the Red Sea median valley. (Atlantis II Deep). The iron deposits, consisting largely of hydrous iron oxides, are found in the same depression. Brines from the Discovery Deep (21° 17 1 N, 38° 02'E) (1), a few miles southwest of the Atlantis II Deep (21°21 1 N, 38 ° 04'E), have a pH of 6.2 and a temperature of 44.7° c, and are also associated with iron-bearing sedirnents. The Discovery and Atlantis II brine pools both extend about 150 meters above the bottom. A few miles south of the: Discovery Deep another depression of greater depth has been reported (2) containing essentially normal Red Sea water. Deeps several hundred miles to the north (Sta. 540) and south (Sta. 545) were investigated and contained no brine. One of these (Sta. 545) is known to contain normal sediments.