The Kraemer Island macrodyke that is exclusively exposed on Kraemer Island about 7 km west
of the Skaergaard Intrusion belongs to a regional dyke swarm termed the ‘Skaergaard-like dykes’ (or FG-1
dykes). Weakly modally layered olivine gabbros dominate the exposed parts of the intrusion that has a
width of 650 m to 1000 m. Plagioclase (core An68±2) and Ca-rich pyroxene (core Mg no. 79±1) grains are
normally zoned, whereas olivine grains (Fo50–65) are homogeneous. Calculated mineral–magma equilibria,
based on experimentally determined Mg–Fe magma–olivine and magma–clinopyroxene partition coefficients,
suggest that the observed olivine and clinopyroxene compositions in the gabbros cannot have
formed from a common parental magma. The unzoned nature of olivine grains and their iron-rich com-positions
relative to clinopyroxene suggest post-cumulus Mg–Fe exchange between olivine and interstitial
melt. A gabbroic pegmatite is developed in the centre of the intrusion along its entire exposed 5 km strike
length. Here, mineral zonation is limited and compositions are similar to rims of cumulus minerals in the
enveloping olivine gabbros. The pegmatite could therefore represent interstitial melt mobilized from gabbroic
cumulates that later accumulated and crystallized at its present stratigraphic location. Cumulus
olivines in the gabbros are close to equilibrium with Ca-rich pyroxene in the pegmatite. This is interpreted
as reflecting interstitial melt mobility during the late stages of solidification of the macrodyke. Chilled
margins are well preserved at the intrusion margins and are rich in Fe (14–15.3% FeOTOT), Ti (3–3.3%
TiO2) and light rare-earth elements ([La/Sm]N = 1.2–1.3), similar to magmas well represented in the overlying
sequence of contemporaneous High-Ti Series flood basalts. It is therefore likely that extensive wall-rock
melting adjacent to the macrodyke reflects continuous feeding of the overlying flood basalts through
the Kraemer Island macrodyke.