Evidence for variability of magmatic processes and upper mantle heterogeneity in the axial region of the Mid-Atlantic Ridge near 22° and 36° N

摘要: Abstract Basalt samples at 36°N (FAMOUS area) and 22°N (leg 45 leg 46 of D.S.D.P.) are compared with particular reference to their trace element concentrations. The results interpreted in terms variability magmatic processes compositional heterogeneity the upper mantle material. It is shown that concentrations elements such as nickel, chromium cobalt, which have high partition coefficients, do not vary significantly either residue or liquid a result varying degrees partial melting. large variations Ni Cr, together narrow range variation Co oceanic basalts provide valuable constraints for models fractional crystallization. hygromagmaphile (low coefficient elements) ratios two these function initial values source material, melting lesser extent crystallization processes. When generated through melting, it likely solid should be treated (previous melting) fertile sources same both sites 395 396 almost symmetric relation ridge. compositionally different. These (at 36°N) can considered original different constituting areas residues an homogeneous mantle.