Louise Rush, MSc Candidate
Harquail School of Earth Sciences at Laurentian University
Tracing the origin of metal and fluids in the enigmatic Ag-Ni-Co-As+/-(Bi,U) deposits of Cobalt, Ontario.
Louise's project was developed as a spin-off of Metal Earth and is supported through an Ontario Centre of Excellence Grant and First Cobalt. Louise is conducting her first field season this summer from June-August (2019) in the Cobalt Mining Camp in Northern Ontario. The study area is approximately 25 by 50 km, and is composed of two main study areas: North Cobalt and South Lorrain areas. Her work will be focused on sampling mineralized veins from available sources such as core (provided by First Cobalt), local abandoned mine sites, and museum collections. From this suite, select samples will be used to constrain all relevant aspects of ore formation (i.e., alteration, mineral paragenesis) using detailed petrographic study at different scales combined with state-of-the-art imaging and in situ analysis (SEM-EDS, EMPA). Subsequently, in situ analysis using various micro-beam methods (e.g., LA-ICP-MS, SIMS) will be used to geochemically fingerprint the fluids, hence source reservoirs, using trace elements and both radiogenic (Pb, Sr) and stable (C, S, O, D) isotopes. In addition, fluid inclusions will be used to evaluate the PT evolution of the mineralization and constrain fluid chemistry. The temporal aspect will be constrained through dating of hydrothermal phases (e.g., monazite, carbonate).
"The objective of the 2019 summer fieldwork is to obtain uniformly dispersed samples across the embayment. Samples will come from both First Cobalt Corporations’ 2017 and 2018 drill core and muck piles located at historical pastproducing mines. From this suite, select samples will be analyzed using detailed petrographic work, state-of-the-art imaging, and in situ analyses in order to constrain all relevant aspects of ore formation (ie. alteration, mineral paragenesis). The samples must show textural evidence of syn-precipitation of ore and gangue mineralization. As a potential source for metals in the Cobalt deposits, fine-grained units in the Huronian succession will be sampled to determine metal content. Another main objective is to determine any potential relationship of the high base-metal content of the Archean basement to the Ag-Co-Ni veins." - Louise Rush
Louise will produce a paper based thesis so that she may submit for publication. Major outcomes & questions which she hopes to address in this thesis include:
- Develop effective exploration models for cobalt and silver in the Cobalt Camp and similar environments.
- What are the metal contents of the fluids?
- Is there obvious metal zoning in the Cobalt Camp?
- Where are the fluids sourced from?
- What is the timing of fluid flow and ore generation?
Map of the Cobalt Embayment Study area, divided into a northern and southern zone (Cobalt and South Lorrain, respectively). This map shows the progress of sampling. Download Map here.
Louise Rush next to a beautiful outcrop of pillow basalt.