Investigation of polymetallic mineralisation in Lower Devonian volcanics near Alva, central Scotland

The subsurface characteristics of three known
occurrences of fracture-controlled mineralisation
in the Lower Devonian Ochil Volcanic Formation
near Alva, central Scotland, were tested by shallow
boreholes. Target structures were intersected by
each borehole, but they contain only minor
amounts of baryte and geochemical enrichments of
copper, arsenic and uranium. Differential fracturing
within the variegated volcanic sequence and
enhanced brecciation at fault intersections are
principal controls. Earlier silver-cobalt mineralisation
appears to have been followed by copperbarium
mineralisation. The andesitic rocks of the
volcanic pile represent a suitable source for the
metals.