Geological structure and indicators of hydrothermal ore-bearing activity at the junction of the southern rift segment and the Doldrums Transform Fracture Zone, Central Atlantic

Ultra-depleted melt refertilization of mantle peridotites in a large intra-transform domain (Doldrums Fracture Zone; 7–8°N, Mid Atlantic Ridge)

“…These values are inconsistent with the average degree of melting inferred from the basalts physically associated to the DFZ-N residual peridotites (Fig. 1c; Skolotnev et al, 1991) that show Na8 values ranging from 2.7 to 3.4, corresponding to an average degree of melting from 7 to 12% of a DM source (calculated from the parameterization of Klein and Langmuir, 1987). We note, however, that the use of sp Cr# as melting indicator relies on two main assumptions:…”

“…Nonetheless, minor and trace elements data from some basalts in the region are reported in the cruise report of Expeditions S06 and S09 (Skolotnev et al, 1991). These preliminary data indicate that the basalts spatially associated with the ITR peridotites have a N-MORB-type geochemical signature.…”