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Dioritic-gabbroic massifs
Within the study area some units of diorite to gabbroic rocks occur (Figure 4-1). Some of
them are situated inside the area that has been surveyed with both gravity and helicopterborne
geophysics. Outcropping mafic units, together with unexposed “probable diorite to
gabbro complexes” indicated geophysically, have been checked in field regarding their
electrical conductivity, as revealed from the multi-frequency EM data (Figure 5-6). In a few
cases a slightly increased conductivity can be found to be, at least partly, associated with
these mafic complexes. However, by comparing these conductive areas with the digital
elevation model it is obvious that most of the anomalies, if not all, are associated with
topographic depressions in the terrain. In depressions and low-land areas the conductivity
is normally higher because of the increased soil cover and/or increased fracturing in the
underlying bedrock, although an increased weathering due to the occurenc of sulphide
minerals in the bedrock can not be excluded.The general conclusion is that the anomalies
studied here are not related to any near surface sulphide mineralisation associated with
dioritic to gabbroic rocks.
Figure 5-6. Map showing the electrical conductivity of possible dioritic-gabbroic complexes in the
Simpevarp area. In the background the out-of-phase component of the coaxial 7001 Hz EM-system
is shown where yellowish to greenish colours indicate increased conductivity. Conductors are
found at the borders of the possible mafic complexes and where the digital elevation model oftenly
shows topographic depressions.
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