High temperature pyrrhotite and telluric iron mineralisations in western Disko, central West Greenland

Abstract

The main purpose of the summer field work was to carry out a detailed investigation of the high temperature niekeliferous pyrrhotite and tellurie iron mineralisation whieh oeeurs in the subvolcanie intrusions of the Hammers Dal Complex (Pedersen, this report, and in press), and to seareh for other occurrenees with an econornic evaluation in view. The dyke-like intrusions are mainly found in gorges in the south facing slope of the E-W trending Hammers Dal, about 10 km from the west coast of Disko. They are exposed only in the upper 400 m of the Rinks Dal Member. The depth of the intrusions was thus 400-500 m below the palaeosurfaee, marked by the weakly eontaminated basalts and more strongly eontaminated 'andesites' of the Niaqussat Member which are considered to be the extrusive equivalents of the intrusions. The magma seems to have intruded along a joint zone dipping about 70° WSW forming pipes or dyke-like bodies plunging gently NNW.