The mafic dykes are porphyritic to aphyric
and consist of calcic plagioclase, hornblendic amphibole or clinopyroxene +/- olivine, ilmenite, titanite and a range of secondary minerals.
The microstructure of this facies is aphyric
to porphyritic (Fig.
The Endeavour Seamount lava is highly plagioclasephyric, but all others are aphyric
to sparsely phyric (plagioclase +/- olivine, rare clinopyroxene).
The settling and flotation of cumulus crystals is also restricted to low viscosity aphyric
magmas, which would allow rapid and unimpeded vertical movements of cumulus crystals.
They present quartz and K-feldspar phenocrysts in an aphyric
matrix composed by quartz, K-feldspar(orthoclase?
This plutonic complex (cumulates, gabbros and plagiogranites) is intruded by various stages of dykes with chilled margins: 1) scarce ouralitized dolerites; 2) olivine basalts; 3) aphyric
Unit F is composed of essentially aphyric
basalt of varied petrography and chemistry, which suggests that it consists of at least two flows, although they were not distinguished in the field.
This host unit is underlain by a sequence of aphyric
andesite or latite volcanic flows which to date have not been found to host mineralization.
The mafic rocks are porphyritic to aphyric
and consist of calcic plagioclase, clinopyroxene +- olivine or hornblendic amphibole, ilmenite, titanite, and a range of secondary minerals.
The marginal zones of the dyke are aphyric
and free of xenoliths and megacrysts, both of which were concentrated in the dyke interior by flow differentiation and show varying degrees of flow alignment (Fig.
This is close to the composition of aphyric
komatiites and chilled margins of komatiitic flows.
The silicic tephra at the bottom of this unit is aphyric