Abstract
Plume-ridge interaction in the Reykjanes Ridge and Iceland region
is graphically demonstrated by several V-shaped ridges surrounding
the spreading axis, indicating mantle flow away from Iceland. It
also has significant geochemical effects. Regionally, incompatible
element concentrations increase northwards coinciding with decreasing
depth and increasing crustal thickness, depth of melting and proximity
to Iceland. Major and trace element data show that isolated magma
bodies feed individual volcanic systems along the ridge. Fractionation
within these systems increases towards 60-61degreesN, where it coincides
with the intersection of a V-shaped ridge, thicker crust and more
abundant seamounts. Trace element, Nd and Sr isotopic data reveal
dynamic melting and mixing within a southward-thinning, heterogeneous
mantle wedge beneath the Reykjanes Ridge. Melting is variable and
locally enhanced at 58degreesN, 59degreesN, 60degreesN and 61degreesN.
A total of six mantle components are identified. Some are specific
to Iceland whereas others are found only beneath the ridge axis.
The geographical distribution of these components reflects their
origin within the deep upper and lower mantle and subsequent translation
by plume outflow along the entire length of the ridge.
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