Maps from the Committee Bay Multidisciplinary Project (Courtesy of Isabelle McMartin and Tom Skulski) larger image [JPEG, 112.9 kb, 440 X 714, notice]

Area Map showing Committee Bay Multidisciplinary Projects larger image [JPEG, 147.6 kb, 588 X 651, notice]

The Committee Bay Integrated Geoscience and Drift Prospecting projects were a partnership between GSC, Canada-Nunavut Geoscience Office and universities. The aim was to stimulate the level and effectiveness of mineral exploration in a remote part of Nunavut. The project provided bedrock and surficial maps, an aeromagnetic survey and a regional-scale drift prospecting survey across parts of four NTS sheets. In addition to other benefits, the projects trained students and Nunavut residents in prospecting techniques. (TGI project)

Committee Bay Drift Prospecting Survey, Central Nunavut larger image [JPEG, 217.3 kb, 1200 X 920, notice]

Rationale

The principal objective of this project is to produce a regional-scale geochemical database related to the composition of glacially transported sediments within the drift-covered Committee Bay supracrustal belt in central Nunavut. Drift prospecting is essential to complement geophysical, bedrock and surficial mapping for successful mineral exploration in this extensively glaciated region.

Approach

The project incorporates ice-movement indicator mapping, clast provenance, heavy mineral and till geochemical studies, and includes 1) the identification and distribution of chemical and mineralogical components of till associated with known mineralization, 2) the establishment of a geochemical database as a means of determining background and threshold concentrations, and 3) the identification of those regions that show potential for mineralization.

Geology

Reconstructing the ice-movement history is fundamental in order to interpret dispersal patterns observed in the compositional analysis of glacial deposits. Based on the systematic measurement of small-scale ice-movement indicators, three main phases of regional ice movement were identified in the Committee Bay area (see figure above). The oldest phase is characterized by a ubiquitous northward movement tentatively associated with the Last Glacial Maximum (Phase I). During the early deglaciation, Keewatin Sector ice retreated progressively southward and was redirected towards large water bodies on either side of the study area (paleo-Committee Bay and Chantrey Inlet). This resulted in a northeastward flow in the northeastern part of the study area (Phase II - East), and a northwestward flow in the southwest (Phase II -West). As retreat of the ice margin continued inland, the orienting influence of the open waters decreased and the flow shifted to a north-northwesterly direction (Phase III). The Chantrey Moraine System delineates the northern limit of this last regional phase which may be associated with ice flow from the Keewatin Ice Divide.

Surface till over the Committee Bay belt is an appropriate sampling medium for drift prospecting. Till is abundant, locally derived and its provenance reflects a predominant northward direction of glacial transport (see figure on the other side). Till geochemistry (e.g. Cr, Co, Ni) reflects northward glacial transport of geochemically distinct and well-exposed bedrock sources (i.e., ultramafics), forming regional-scale ribbon-shaped trains, parallel to Phase I, or fan-shape trains, reflecting glacial transport in more than one direction, as indicated by the ice-flow chronology. Most of the known gold showings are recognized in the gold grain counts and/or the gold values in the till matrix; gold dispersal trains from significant mineralization are < 1.5 km long and the grains are primarily pristine or modified in shape. A poor association of As with Au prevents the direct use of As in till as a pathfinder element, and reflects the very rare occurrence of arsenopyrite in gold mineralization across the region.

Anorthosite Clasts larger image [JPEG, 208.8 kb, 800 X 676, notice]

Outcomes

The main outcomes of this project were :

1. to increase the level and effectiveness of mineral exploration in the region for Au, Ni-PGE and base metal mineralization
2. to increase geoscience knowledge for northerners and enhance science capacity in Nunavut through co-operation with the Canada-Nunavut Geoscience Office (C-NGO), and
3. to provide excellent training opportunities for geoscience students and northern residents in prospecting techniques.

Regional till provenance studies to trace mineral deposit indicators in under-explored regions addresses the highest priority of the Nunavut Government to stimulate and support new economic growth in Nunavut.

Participants

This endeavor is a contribution to the Geological Survey of Canada Targeted Geoscience Initiative (TGI), and represents a collaboration between the Geological Survey of Canada, the C-NGO and several Canadian universities (i.e, Simon Fraser University, University ofWestern Ontario, University ofVictoria).

More Information

The complete till lithological, mineralogical and geochemical datasets collected as part of this project are presented in GSC Open File 4493 (McMartin et al., 2003). An overview of the Quaternary geology and regional interpretation of the ice-flow history, detailed description of all field and laboratory procedures and a complete list of references for the project are included in the report.

See also: Committee Bay Quaternary Project (C-NGO)

Contact Isabelle McMartin for further information.