Figure 2. Triangular diagrams illustrating the (A) Pb- and (B) Au-rich nature of the Escanaba Trough (ET) massive sulfides relative to samples from Middle Valley (MV) or bare-rock hydrothermal systems. Other abbreviations used: TAG-Trans-Atlantic Geotraverse site; GAL- Galapagos spreading center; EPR- East Pacific Rise; END- Endeavour segment, Juan de Fuca Ridge; AX- axial seamount, Juan de Fuca Ridge; SJDF- southern Juan de Fuca Ridge; GB- Guaymas Basin. Modified from Koski et al. (1994).