Ground check of airborne geophysical anomalies and regional rust zones in Inglefield Land, North-West Greenland

Field work was carried out in 1995 over the Precambrian crystalline basement in lnglefield Land as a follow-up on an airborne geophysical survey the previous year. This report covers the geological field checks of selected geophysical anomalies and rust zones. The strongest magnetic anomaly in lnglefield Land, located near Minturn Elv (Map 1 ), is only betrayed by an abundance of magnetite float. A thin layer of magnetite was observed in nearby outcrop of a mafic-ultramafic complex, and modelling of the geophysical data suggests that such layers may reach thicknesses of 200-300 m.

Among numerous electromagnetic (EM) anomalies, 24 high priority targets were geologically checked during helicopter stops. The anomalies are often covered by surficial deposits. Outcropping miner~lisation consisted of disseminated to semi-massive iron sulphides hosted in a silicious, often graphitic, gneiss.

Rust zones several kilometres long are common in central and north-east lnglefield Land. They are reflected as regional EM anomalies and consist of siliceous gneiss with disseminated to massive pyrrhotite, minor pyrite and traces of chalcopyrite. The highest analytical values from the sampled regional rust zones are 294 ppb Au, 4216 ppm Cu and 2935 ppm Zn. Other minor sulphide mineralisation returned up to 1188 ppb Au -and 1.3% Cu.

It is concluded that the best mineral potential in lnglefield Land is for copper and gold. In addition, the area has a significant potential for magmatic magnetite occurrences.