Geophysical and geological investigations for graphite on Senja and in Kvæfjord, Troms county, northern Norway

Abstract

As a part of the MINN project (Minerals in Northern Norway) helicopter-borne geophysical surveys were performed on Senja and in Kvæfjord. Electromagnetic data from these surveys showed up anomalies that could be caused by large graphite mineralisation. Geophysical and geological ground follow-up work were performed at seven locations on Senja and two in Kvæfjord.Previously known graphite at Hesten, Vardfjellet and Bukken and new discoveries at Litjkollen (Bukken), Grunnvåg and Skarsvåg on Senja, were mapped in detail using ground based electric and electromagnetic geophysical methods. The length of the possible graphite mineralisation was from 1 to 2 km in all areas. The thickness perpendicular to strike and dip varies from a few metres to tens and even hundreds of metres. Geological mapping confirmed graphite of interesting quality in most of the areas. The area Skarsvåg had low total carbon content in surface exposures, and the sulphur content was relatively high. However, electric measurements indicate graphite of better quality deeper than 20 m. In all areas on Senja, analysis of thin sections shows flake graphite of same quality as mined at Trælen in western Senja, and as in Vesterålen where a beneficiation test was successful. All areas are intensively folded and some of them faulted. More detailed ground geophysics and deeper core drilling are recommended in the areas called Hesten, Vardfjellet, Bukken, Grunnvåg and Skarsvåg.