Diamonds on the Brodeur Peninsula — A new kimberlite province in Nunavut, Canada

Abstract The Freightrain kimberlite is located on the Brodeur Peninsula, Baffin Island, Nunavut. Twin Mining is exploring the pipe and adjacent land (79 claims/655 km2) using a combination of airborne geophysics, soil sampling, diamond drilling, trenching and bulk sample processing. The pipe originally was discovered by Cominco Limited in 1975, re-evaluated in 1993 by Lumina Investment Corporation, when it was staked as the Zulu pipe, and subsequently covered by three claims in 1998 by Helix Resources who called it Freightrain. The Freightrain pipe coincides with a strong, ovoid-shaped aeromagnetic anomaly. It is the only surface exposure of kimberlite within a 30 km long linear trend of fourteen aeromagnetic anomalies that are up to 600 m in diameter.
The pipe is exposed in the crater facies, near the transition into diatreme facies as indicated by the occurrence of pyroclastic kimberlite characterized by abundant olivine macrocrysts, juvenile lapilli and kimberlite autoliths set in a serpentine-calcite matrix. Olivine, Cr-pyrope garnet and chromite are the most abundant macrocrysts; clinopyroxene, ilmenite and phlogopite mica occur in minor to trace amounts. Garnet and chromite harzburgite, garnet lherzolite, garnet-spinel lherzolite and rare eclogite dominate the xenolith population. Garnet and chromite mineral chemistry indicate encouraging diamond prospectivity and that potentially diamondiferous garnet and chromite harzburgite were the principal sources of diamond in the mantle at the time of kimberlite eruption. Single clinopyroxene grains define an ~42 mW/m2 sub-continental geotherm that is rooted in the diamond stability field. This compares to a slightly hotter geotherm (~48 mW/m2) for adjacent Somerset Island kimberlites with an origin in the graphite stability field. This data accords with the general lack of sub-calcic Cr-pyrope garnet, diamond inclusion chromite and diamond in Somerset Island kimberlites.
Keywords: Industrial minerals, Kimberlite, Brodeur Peninsula, Geology, Geological surveying
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Summary: Exploration properties form a continuum from grass roots to those with favourable geology, geochemical and/or geophysical anomalies, mineralization, showings (prospects), and finally to those with defined mineral deposits. Often, properties exhibit a composite of these categories. The most problematic to value are properties or deposits that are not economically exploitable at the time of the valuation due to a lack of exploration, insufficient grade or tonnage, poor mining conditions, or the...
Publication: CIM Bulletin
Author(s): I.S. Thompson
Keywords: Valuation, Exploration properties, Mineral resources
Issue: 1061
Volume: 95
Year: 2002
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Summary: This paper deals with the results of the variation of thermal conductivity of rocks with pressure on a laboratory scale. For this purpose, the authors have added a pressure-supplying unit to the apparatus developed by Mousset-Jones and McPherson (1986), Önder (1995), Ashworth and Ashworth (1979), and Innaurato and Occella (1989) in order to measure the thermal conductivity under pressure. The values obtained from the tests performed by this new apparatus have been stated using a regression...
Publication: CIM Bulletin
Author(s): Y.S. Durutürk, A. Demirci, A. Keçeciler
Keywords: Mine heat, Geothermal gradients, Heat transfer, Thermal conductivity
Issue: 1061
Volume: 95
Year: 2002
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Summary: The 1990s saw enormous changes in the Canadian coal industry and the future promises to be no less turbulent. While the markets served by Canadian coal producers have changed and buying practices continue to evolve, the coal mining, or supply side, has also changed remarkably in response and now provides the basis for an interesting industry story. The dynamic situation in coal mining has led to some surprising outcomes and seemingly contradictory developments. This paper outlines the changes...
Publication: CIM Bulletin
Author(s): D.O. Downing
Keywords: Coal mining, Supply, Technology, Productivity, Resource development
Issue: 1061
Volume: 95
Year: 2002
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Summary: Recognition of the diamond potential of the Wawa subprovince was initially determined from regional data using a kimberlite model. The world’s largest stable Precambrian craton, the Superior Province, is considered to be favourable for the emplacement of diamondiferous kimberlite. The Wawa area is located near the intersection of intra-craton structures visible in the regional magnetic data. The Enigma project is located north of the town of Wawa in northern Ontario. From field evidence and...
Publication: CIM Bulletin
Author(s): J. Buckle
Keywords: Diamonds, Enigma project, Exploration, Kimberlites
Issue: 1061
Volume: 95
Year: 2002
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Summary: This paper summarizes diamond exploration techniques used in glaciated terrain, focussing on indicator mineral and geochemical methods applied to glacial sediments. Understanding the ice flow history, depositional history, and stratigraphy of glacial sediments is essential to successful sampling, interpretation and follow-up of indicator mineral and geochemical anomalies related to kimberlites. Kimberlite indicator minerals survive glacial transport over long distances and the relative...
Publication: CIM Bulletin
Author(s): M.B. McClenaghan
Keywords: Diamonds, Exploration techniques, Geochemical methods, Kimberlites, Till geochemistry, Glaciated terrain
Issue: 1061
Volume: 95
Year: 2002
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