Rn. Taylor et al., PETROGRAPHIC AND GEOCHEMICAL VARIATION ALONG THE REYKJANES-RIDGE, 57-DEGREES-N-59-DEGREES-N, Journal of the Geological Society, 152, 1995, pp. 1031-1037
High-density sampling of the neo-volcanic zone along the Reykjanes Rid
ge has been used to test the relationship between bathymetric features
and geochemistry. The axial region has short wavelength features whic
h correspond to elongate, en-echelon volcanic ridges. These ridges sit
atop intermediate wavelength features, termed swells and troughs. A b
road correspondence is found between the sections containing more frac
tionated samples and the intermediate wavelength swells. Conversely, t
he troughs are dominated by more primitive lavas. This suggests that s
wells represent areas of greater melt dux, resulting in thicker crust
and hence generally more fractionation. Progressively higher concentra
tions of incompatible elements are found northwards along the ridge, w
ith increases occurring as a series of steps that do not correlate wit
h short or intermediate wavelength bathymetric features. The northward
increase in ratios such as Nb/Zr suggests that sections of the ridge
are fed by similar aggregate melt fractions, and that melt fractions b
ecome slightly smaller northwards. Changes or consistency in ratio, pa
rticularly Rb/Nb, cannot be explained by progressively greater northwa
rd incorporation of a component from the Icelandic plume mantle.