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Mineralogy and Petrology

, Volume 112, Supplement 2, pp 463–475 | Cite as

Geology and resource development of the Kelvin kimberlite pipe, Northwest Territories, Canada

  • Martina BezzolaEmail author
  • Casey M. Hetman
  • Gareth Garlick
  • Robert Creaser
  • Michael Diering
  • Tom Nowicki
Original Paper
  • 154 Downloads

Abstract

The early Cambrian to late Neoproterozoic Kelvin kimberlite pipe is located in the southeast of the Archean Slave Craton in northern Canada, eight km northeast of the Gahcho Kué diamond mine. Kelvin was first discovered in 2000 by De Beers Canada. Subsequent exploration undertaken by Kennady Diamonds Inc. between 2012 and 2016 resulted in the discovery of significant thicknesses of volcaniclastic kimberlite that had not previously been observed. Through extensive delineation drilling Kelvin has been shown to present an atypical, steep-sided inclined L-shaped pipe-like morphology with an overall dip of 15 to 20°. With a surface expression of only 0.08 ha Kelvin dips towards the northwest before turning north. The body (which remains open at depth) has been constrained to a current overall strike length of 700 m with varying vertical thickness (70 to 200 m) and width (30 to 70 m). Detailed core logging, petrography and microdiamond analysis have shown that the pipe infill comprises several phases of sub-horizontally oriented kimberlite (KIMB1, KIMB2, KIMB3, KIMB4, KIMB7 and KIMB8) resulting from multiple emplacement events. The pipe infill is dominated by Kimberley-type pyroclastic kimberlite or “KPK”, historically referred to as tuffisitic kimberlite breccia or “TKB”, with less common hypabyssal kimberlite (HK) and minor units with textures transitional between these end-members. An extensive HK sheet complex surrounds the pipe. The emplacement of Kelvin is believed to have been initiated by intrusion of this early sheet system. The main pipe-forming event and formation of the dominant KPK pipe infill, KIMB3, was followed by late stage emplacement of additional minor KPK and a hypabyssal to transitional-textured phase along the upper contact of the pipe, cross-cutting the underlying KIMB3. Rb-Sr age dating of phlogopite from a late stage phase has established model ages of 531 ± 8 Ma and 546 ± 8 Ma. Texturally and mineralogically, the Kelvin kimberlite is similar to other KPK systems such as the Gahcho Kué kimberlites and many southern African kimberlites; however, the external morphology, specifically the sub-horizontal inclination of the pipe, is unique. The morphology of Kelvin and the other kimberlites in the Kelvin-Faraday cluster defines a new type of exploration target, one that is likely not unique to the Kennady North Project area. Extensive evaluation work by Kennady Diamonds Inc. has resulted in definition of a maiden Indicated Mineral Resource for Kelvin of 8.5 million tonnes (Mt) of kimberlite at an average grade of 1.6 carats per tonne (cpt) with an average diamond value of US$ 63 per carat (ct).

Keywords

Kimberley-type pyroclastic kimberlite Hypabyssal kimberlite Volcaniclastic Diamonds Emplacement Tuffisitic kimberlite breccia 

Notes

Acknowledgements

Thank you to Kennady Diamonds Inc. and Aurora Geosciences Ltd. for the opportunity to put together this paper and permission to publish the data. Special thank you to Chris Hrkac and Gary Vivian for their tireless project management and support. Thank you to Meilani Smith for her assistance in preparation of the illustrations. And last but by no means least thank you to all staff and field crews at Aurora Geosciences Ltd., SRK Consulting Inc., Mineral Services Canada Inc. and all the other subcontractors that have contributed to the project since 2012. Constructive reviews of Stephen W. Moss and guest editor Bruce Kjarsgaard are greatly appreciated.

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Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Aurora Geosciences Ltd.YellowknifeCanada
  2. 2.SRK Consulting Inc.VancouverCanada
  3. 3.Mineral Services Canada Inc.North VancouverCanada
  4. 4.Earth and Atmospheric SciencesUniversity of AlbertaEdmontonCanada

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