|dc.description.abstract||The Dunbrack Pb-Cu-Zn prospect, located 5 km north of Musquodoboit Harbour and 45
km east ofHalifax, Nova Scotia, ceased operations in 1920. The Devonian
Musquodoboit Batholith hosts the minerals in a ca. 300 Ma quartz vein which occupies
the contact between the batholith and a felsic dyke. The dump from the deposit is in the
woods 50 m from Highway 327 and 200 m from the Musquodoboit river system. This
thesis attempts to evaluate whether the dump poses an environmental risk in terms of
releasing base metals. Samples of minerals, balsam fir, and lichens from the vicinity of
the dump were studied. In addition an experiment was carried out to assess the solubility
of base metals in rainwater.
Analysis of heavy mineral concentrations from a grab sample from the Dunbrack mine
dump by atomic adsorption spectrometry gave 45% Pb, 3.5% Cu, and 1 % Zn. Textural
relationships between the main sulphides give the following order of estimated relative
ages: chalcopyrite, galena, bornite, covellite, then sphalerite. Results from an experiment
involving rainwater combined with crushed dump sulphides show a drop in pH of0.81
and 0.93 pH units and an increase in the rainwater of Pb, Cu, and Zn concentrations by
factors of 100-1000.
The balsam fir and lichens in the vicinity of the dump contain anomalous concentrations
of lead, copper, zinc, and cadmium, although the only obvious stunting of the biota
occurs directly on the dump. The balsam fir lead concentrations at a distance of 60 m to
the north and east of the dump are 1.8-20 times greater than a control location.
Concentrations on the dump are 1 7 5 times higher than the control location. Other heavy
metal concentrations (Cu, Zn, and Cd) are 1.5 to 5 times greater than the control location
at a distance of 60 m from the dump, and are up to 13.5 times greater on the dump.
Lichens from the dump and surroundings are emiched 2-4.5 times in Cu, Zn, Pb, and Cd,
particularly the more sensitive species Parmelia sulcata. It is concluded that the dump
has anomalous amounts of base metals in the balsam fir and lichens surrounding the
dump, but beyond a few hundred metres from the dump it poses little risk.
Keywords: Dunbrack, dump, Musquodoboit Batholith, heavy metals, textural
relationship, biogeochemistry, pH, sulphides, balsam fir, lichens (Parmelia
sulcata, Hypogymnia physodes).||en_US