Response of soil C- and O-horizon and terrestrial moss samples to various lithological units and mineralization in southern Norway

This study was conducted to determine which sample material provides the most reliable signal for geochemical exploration under Norwegian conditions. A 100-km long transect was placed over two mineral deposits in southern Norway; the Nordli Mo deposit with surfaces exposure of molybdenite (MoS2) and a sandstone-hosted Pb mineralization with surface exposures of sphalerite. At each of 41 sampling sites, soil C- and O-horizon samples and terrestrial moss (Hylocomium splendens) were collected. All samples were analysed for 53 chemical elements following an aqua regia extraction. The Pb deposit is indicated by all three sample materials by anomalous high consentratons of Pb, especially by the C-horizon. The Mo deposit is indicated by more than one anomalous high Mo value in both O- and C-horizon but is not indicated by any clear anomaly in moss. The general mineraliation area of the two deposits is detected on a regional scale using low sample density. However, to exactly localise the mineralization and to define drill targets, a sample density >10 sites/km(2) would be required. Though high Pb concentrations in moss are usually interpreted as being due to anthropogenic activities, results presented here demonstrate that locally moss reacts strongly to the presence of Pb mineralization.