Aeromagnetic study of the continental crust of northeast Greenland

Abstract

A reconnaissance‐type aeromagnetic survey of northeast Greenland was undertaken by the Alfred Wegener Institute for Polar and Marine Research between 1993 and 1996. These data were compiled in a regional magnetic anomaly map at 3700 m altitude, covering the Caledonian orogen of east Greenland and parts of the Precambrian shield of north Greenland. The survey area was divided into regions with distinct magnetic anomalies. The interpretation of the magnetic anomalies is based on comparison with exposed geological structures and is locally supported by in situ measurements of magnetic susceptibilities. Middle Proterozoic magmatic rocks determine the magnetic character of the Precambrian shield of north Greenland. Rifting and downfaulting of the Precambrian basement at its northern and eastern margin are reflected by gradients in the magnetic field. The Caledonian fold belt of east Greenland could be subdivided into a northern only weakly magnetic part, where pervasive Caledonian reworking probably demagnetized the crust, and a southern part, where isolated positive anomalies occur. Magnetite survived Caledonian metamorphism in these areas. The sensitivity of magnetite to Caledonian metamorphism was recognized in several places in the Caledonides of east Greenland. This observation might be useful in determining the much debated degree of Caledonian reworking of the crystalline complexes of east Greenland.