Research Team

Past Students

Drew Drummond, BSc Honours

  • Graduation year: 2017
  • Project Title: Textural and Geochemical Analysis of the Lower Proterozoic, Kerry Road Volcanogenic Massive Sulphide Deposit, Loch Maree Group, Gairloch, NW Scotland
  • Supervisor: Dr. Jonathan Cloutier
    • Abstract: The Kerry Road volcanogenic massive sulphide (VMS) deposit (500,000 tonnes grading at 1.242% Cu, 3.464% Zn and 0.015% Pb) is a metamorphosed Besshi type (mafic-siliciclastic) VMS deposit hosted within the Lower Proterozoic Loch Maree Group (c. 2.0 Ga) in the northwest of Scotland. This metamorphosed deposit is hosted within an intensely deformed, low-amphibolite facies supracrustal sequence of metavolcanics (amphibolites) and metasediments (quartz mica schist).

The sulphide mineralisation typically consisted of pyrite and pyrrhotite with subordinate chalcopyrite and sphalerite. Four types of sulphide mineralisation textures are present (1) disseminated (2) vein (3) durchbewegung and (4) semi-massive to massive. Prolonged low-amphibolite facies metamorphism associated with Laxfordian deformation caused a remobilisation and deformation of sphalerite, chalcopyrite and pyrhhotite due to ductile flow. Maximum temperature was not high enough for pyrite to cross the brittle-ductile boundary and thus pyrite displayed brittle deformation characteristics. The pyrite underwent mechanical reworking and was rounded, fractured and transported as it was carried by the remobilised sulphide varieties during ductile remobilisation. Sulphide remobilisation provides a low-amphibolite facies constraint for pressure-temperature conditions experienced by the deposit.

Low-amphibolite metamorphism overprints any associated VMS alteration in the surrounding host rock. Microprobe analysis of amphibole composition was used to record systematic variation in chemical composition associated with VMS alteration. Mg- and Si- limited ferrotschermakite amphibole composition (Ca1.6(Mg0.03,Fe2.44)Al2.6Si5.93O22(OH)2) is the dominant Kerry Road amphibole composition, but closer to the deposit the composition becomes more Mg- and Si- rich and displays an actinolite composition (Ca1.7(Mg3.9,Fe1.1Si7.94O22(OH)2). Thus variation in amphibole geochemistry could be used as a vector in the Loch Maree Group or other VMS mineralisation regions as an indicator for proximity to VMS mineralisation. Immobile element systematics of amphibolite sequences surrounding the Kerry Road deposit displayed a tholeiitic chemical signature and fit with an island-arc tholeiite tectonic setting. The VMS Besshi type classification and the geochemistry of the surrounding metavolcanic amphibolites agree with the subduction-accretion model of Park et al. (2001) for the origin of the Loch Maree Group.

Clare Crossan, BSc Honours

  • Graduation year: 2017
  • Project Title: Mine waste mineralogy and trace element distribution of sulphides associated with the Parys Mountain VMS deposit, Wales
  • Supervisor: Dr. Jonathan Cloutier

    • Abstract: Trace element distribution is essential to understanding the effects mine waste piles have on the environment. The non-economically viable rock extracted during the mining process is abandoned, and these piles allow the dissolution of sulphides to occur due to interaction with the atmosphere and hydrosphere over time.

      The movement from host rock samples to tailing samples at Parys Mountain, both which consisted of rhyolite and shale classification, showed the concentration of sulphur (S), and showed the highest rates of dissolution for sphalerite and galena, with chalcopyrite proving the most resilient. Evidence for the ability of sulphides to host trace elements such as arsenic (As), nickel (Ni), and molybdenum (Mo) is evident, and the inclusions of lead (Pb), zinc (Zn), and copper (Cu) can occur within pyrite.

      Parys Mountain, with average pH values of 2.44 to 3.60 and highly oxidized waters, is rich in trace metals. The findings of iron (Fe), Cu, Pb, and Zn within samples are derived from the dissolution of pyrrhotite, pyrite, chalcopyrite, galena, and sphalerite respectively. A further input from Fe is derived from sphalerite. The formation of these low pH environments is a direct function of the dissolution of pyrite, whereas other sulphides will predominatly input heavy metals and not hydrogen (H+) ions. The values for water concentrations are all much greater than the drinking water quality set by the World Health Organisation (WHO). Maximum concentrations reach 6072 milligrams/litre (mg/L) Fe, 228.3 mg/L Cu, 125.5 mg Zn, and 33.6 mg/L As. Consequently, the mining impact on this area has lead to environmental contamination. This study has highlighted the need for further research into the dissolution rates of sulphides and to the individual mineralization for each tailing.