Table 2. Metal content of hydrothermal mineral samples recovered 

 from the TAG site at the Mid-Atlantic Ridge (Thompson et al. 

 1985, 1988) and the NESCA and SESCA sites in the Escanaba 



Trough of the southern Gorda Ridge (Fig. 6; Koski et al. 

 1988). 



TAG Hydrothermal Field, Mid-Atlantic Ridge Escanaba Trough, Gorda Ridge 

 Metal 



(wt. %) Manganese Oxides Massive Sulfides Massive Sulfides Barite Crusts 



0.1-42.6 



16.3-43.2 



< 0.01 



< 0.01-0.25 < 7.6 < 14 



0.03-21.6 < 43 < 17 



< 5-285 < 700 < 390 

 0.8-16.4 < 2 



1 Scott et al. 1974, Thompson et al . 1985 



2 Rona et al . 1986, Thompson et al. 1988, Hannington et al. 1988 



3 Koski et al. 1988, Table 3 



14 



