Hunt and Ross 



was used to define the water structure, position other equipment in certain 

 water levels and to test other areas of the Red Sea for high temperature waters. 

 No other areas tested contained anomalously hot water. 



The highest water temperature measured was 56°C. This was from 

 below a depth of 2040 meters in the ATLANTIS II Deep. This water had a 

 "salinity" of about 317^^ . The "salinity" was determined by a Schleicher- 

 Bradshaw salinometer on samples diluted by volume with distilled water. 

 Salinity values so determined assume that the brine water has the same relative 

 proportion of salts as normal sea water. This assumption is not correct. A 

 better estimate of salinity is total solids by evaporation to dryness at 200°C, 

 which for the 56°C water is about 255^^ (F.T. Manheim, personal 

 communication). The 56°C water of the ATLANTIS II Deep is overlain by a 

 layer of 44°C water (total solids about 131^). This 44°C water grades into 

 normal 22°C Red Sea bottom water. The 44°C and 56°C water generally 

 have oxygen values of 0. 1 ml/l or less. 



The DISCOVERY Deep has water with a temperature of 44.7°C 

 below a depth of 2038 m, which is overlain in some instances by a layer of 

 36°C water. This 44.7° water has a salinity similar to the 56°C water of the 

 ATLANTIS II Deep. 



The CHAIN Deep has a maximum temperature of 34 °C and a 

 "salinity" of about 74^^ . Its deepest part was not sampled. 



Continuous seismic reflection profiles have not been fully analyzed 

 at present. Field observations suggest considerable rifting and faulting in and 

 adjacent to the brine areas. Using a recording bandwidth of 37.5 to 150 Hz 

 some reflections were obtained from the hot brine water in the ATLANTIS II 

 and DISCOVERY Deeps (no records were made in the CHAIN Deep area). 

 These reflections apparently are due to density differences between the hot 

 brine water and the overlying Red Sea water. 



All gravity observations, bathymetry and navigation data were 

 processed while at sea, and the results computed and plotted on line by the 

 shipboard IBM 1710 computer. A gravity anomaly of about + 120 mllligals 

 is observed In the hot brine area. However, this value is within the range 

 normally observed in the rift valley. A magnetic anomaly of - 650 gammas 

 was observed over the ATLANTIS II Deep, and an anomaly of + 350 gammas 

 was observed over the DISCOVERY Deep. The large magnetic gradient 

 between these areas may be due to higher sub-surface temperatures In the 

 ATLANTIS II Deep. 



Temperature gradients in the sediments, as determined by heat flow 

 measurements, were 10 to 20 times the world average of 1°C per 16 meters. 



103 



