Abstract

This paper reports on the results of three weeks of investigations in the Mellemfjord-Eqaluit area of south-west Disko, carried out in the summer of 1974. Very little has been published on the geology in this area: Steenstrup (1882, 1883, 1900) described the area briefly and concentrated on native iron bearing lavas, from which samples were petrographically decribed by Lorenzen (1882), Nicolau (1900), and Pauly (1969), who also communicated results from an unpublished field report by W. Fisch. The purpose of the present investigation was threefold, namely the study ofthe youngest exposed voicanic rocks on Disko, the study of native iron bearing voicanic rocks and the study of the structure of the coast area which is of interest for the interpretation of the off-shore geology.

Highlights

  • This paper reports on the results of three weeks of investigations in the Mellemfjord-Eqaluit area of south-west Disko, carried out in the summer of 1974

  • The large size of the phenocrysts, together with evidence from scattered sediment-derived xenocrysts indicates that this lava type evolved in high level magma reservoirs during stagnating eruptive conditions

  • The Nordfjord member vo1canism was characterized by upwelling through the crust of feldsparphyric tholeiitic melts slightly more mafic than the Rinks Dal member basalts

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Summary

Introduction

This paper reports on the results of three weeks of investigations in the Mellemfjord-Eqaluit area of south-west Disko, carried out in the summer of 1974. About 800 m of feldsparphyrie plateau basalts belonging to the upper part of the Rinks Dal member are exposed within the area and appear as a monotonous sequenee of typieally 20-25 m thiek brownish aa lavas, someof whieh may be very voluminous. A volcanie neek feeding Rinks Dal member basalts has been loealized on the inner part of the south eoast of Nordfjord. It seems that upwelling from depth of the basalts oeeurred over large areas. Eross-bedded Rinks Dal member pillow breeeias in the Godhavn area indieate outpouring of sueh basalts both from the east and the w.est of the N-S trending, extensive water-filled depressions found east ofthe Disko gneiss ridge. Samples analysed from dredges more than 70 km south of Disko by Clarke (1975) are eompositionally identieal to Rinks Dal member basalts

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Summary
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