Gold resources on Ringvassøy, Western Troms-IV: Regional geochemistry of B- and C-horizon of till

Abstract

This report establishes a link between the various methods employed in geo- chemical prospecting for gold in the lithologic and topographic regimes present on Ringvassøy; these methods are also used elsewhere in Norway. Samples of the C-horizon from 203 locations in 5 transects across the Ringvassøy Greenstone Belt, and of the B-horizon from 70 of the same sites, were analyzed for Au and 34 other elements. Comparing the results of the B- and C-horizon shows that there is little difference in the geographical distribution between these horizons. The B- and C-samples have a good success rate locating known outcrops of Au ore and of base metal sulfides. The regional scale mapping conducted by NGU over the last decades succeeds in locating the large scale gold anomalies indicated by the sub-regional and detailed investigations carried out by prospecting companies. A sub-regional approach usinf B- and C-horizon samples at regular intervals along transects is less successful with reproducing the findings of the detailed study. But this approach unveils anomalies that the sub-regional stream sediment survey did not point out. This was partly because of the lack of streams, but there were also anomalies in the transect soil sampling that were not present in the nearby stream sediments.