The Letšeng Diamond Mine comprises two ~91 Ma kimberlite pipes. An update of the geology is presented based on the 2012–2017 detailed investigation of open pit exposures and all available drillcores which included mapping, logging and petrography. Each of the steep-sided volcanic pipes comprises a number of phases of kimberlite with contrasting diamond contents which were formed by the emplacement of at least four batches of mantle-derived magma. The resulting range of textures includes resedimented volcaniclastic kimberlite (RVK), Kimberley-type pyroclastic kimberlite (KPK), coherent kimberlite (CK) and minor amounts of hypabyssal kimberlite (HK). The pipes are compared with KPK occurrences from southern Africa and worldwide. Many features of the Letšeng pipes are similar to KPK infilled pipes particularly those of the widespread Cretaceous kimberlite province of southern Africa. The differences displayed at Letšeng compared to other large KPK pipe infills described from around the world are attributed to the marginal or melnoitic nature of the magma and the upper diatreme to crater setting of the Letšeng pipes, where processes become extrusive. It is concluded that the pipes comprise a variant of Kimberley-type pyroclastic kimberlite emplacement. The classification of many of the Letšeng rocks as KPK is important for developing the internal geology of the pipes as well as for predicting the distribution of diamonds within the bodies.
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Berryman AK, Scott Smith BH, Jellicoe BC (2004) Geology and diamond distribution of the 140/141 kimberlite, Fort à la Corne, Central Saskatchewan, Canada. Proceedings of the 8th International Kimberlite Conference. Lithos 76:99–114
Bezzola M, Hetman C, Garlick G, Creaser R, Hrkac C, Vivian G, Diering M, Nowicki T (2017) Geology and resource development of the Kelvin kimberlite pipe, NWT, Canada. 11th International Kimberlite Conference, Botswana, extended abstract 11IKC-4643
Bloomer AG, Nixon PH (1973) The geology of Letšeng-la-terae kimberlite pipes. In: Nixon PH (ed) Lesotho kimberlites. Lesotho National Development Corporation, pp 20–38
Clement CR (1982) A comparative geological study of some major kimberlite pipes in the Northern Cape and Orange Free State. PhD thesis. University of Cape Town, South Africa
Clement CR, Reid AM (1989) The origin of kimberlite pipes: an interpretation based on a synthesis of geological features displayed by southern African occurrences. In: Ross J, Jaques AL, Ferguson J, Green DH, O'Reilly SY, Danchin RV, Janse AJA (eds) Kimberlites and related rocks. Proceedings of the Fourth International Kimberlite conference, Special Publication - Geological Society of Australia, vol 1, no 14, pp 632–646
Field M, Scott Smith BH (1999) Contrasting geology and near-surface emplacement of kimberlite pipes in Southern Africa and Canada. In: Gurney JJ, Gurney JL, Pascoe MD, Richardson SH (eds) The J.B. Dawson Volume, Proceedings of the VIIth International Kimberlite Conference. Red Roof Design, Capetown, pp 214–237
Field M, Stiefenhofer J, Robey J, Kurszlaukis S (2008) Kimberlite-hosted diamond deposits of southern Africa: a review. Ore Geol Rev 34:33–75
Fitzgerald CE, Hetman CM, Lepine I, Skelton D, McCandless TE (2009) The internal geology and emplacement history of the Renard 2 kimberlite, Superior Province, Quebec, Canada. Proceedings of the 9th International Kimberlite Conference. Lithos 112(S1):513–528
Gem Diamonds Limited (2015) Letter from Venmyn Deloitte to Gem Diamonds Limited on the verification and issue of resource and reserve statements for their Letšeng Diamond asset. 30th June 2015. http://www.gemdiamonds.com/downloads/2016/VMD1865L-Letter-to-Gem-Diamonds-on-Independent-Resource-and-Reserve-2015.pdf
Griffin WL, Batumike JM, Greau Y, Pearson NJ, Shee SR, O’Reilly SY (2014) Emplacement ages and sources of kimberlites and related rocks in southern Africa: U-Pb ages and Sr-Nd isotopes of groundmass perovskite. Contrib Mineral Petr 167:1032
Harder M, Nowicki TE, Hetman CM, Freeman L, Abedu B (2013) Geology and evaluation of the K2 kimberlite, Koidu Mine, Sierra Leone, West Africa. In: DG Pearson et al. (eds), Proceedings of the 10th International Kimberlite Conference. J Geol Soc India Special Issue 2:191–208
Hawthorne JB (1975) Model of a kimberlite pipe. Phys Chem Earth 9:1–15
Hetman CM (2008) Tuffisitic kimberlite (TK): a Canadian perspective on a distinctive textural variety of kimberlite. J Volcan Geotherm Res 174:57–67
Hetman CM, Scott Smith BH, Paul JL, Winter FW (2003) Geology of the Gahcho Kué kimberlite pipes, NWT, Canada: Root to diatreme magmatic transition zones. 8th International Kimberlite Conference, long abstract
Hetman CM, Scott Smith BH, Paul JL, Winter FW (2004) Geology of the Gahcho Kué kimberlite pipes, NWT, Canada: root to diatreme magmatic transition zones. Proceedings of the 8th International Kimberlite Conference. Lithos 76:51–74
Hetman C, Scott Smith B, Robey J, Nkotsi T, Mohapi M, Mohapi T (2017) Letšeng diamond mine, Lesotho: a variant of Kimberley-type pyroclastic kimberlite emplacement. 11th International Kimberlite Conference, Botswana, extended abstract 11IKC-4688
Lock N (1980) The geology of the Letšeng kimberlites, Lesotho. Unpublished PhD thesis. University of Sheffield
Masun KM, Scott Smith BH (2008) The Pimenta Bueno kimberlite field, Rondonia, Brazil: Tuffisitic kimberlite and transitional textures. Proceedings of the 2006 Kimberlite Emplacement Workshop, Saskatoon, Canada. J Volcan Geotherm Res 174:81–89
Mitchell RH, Skinner EMW, Scott Smith BH (2009) Tuffisitic kimberlites from the Wesselton mine, South Africa: mineralogical characteristics relevant to their formation. Proceedings of the 9th International Kimberlite Conference. Lithos 112(S1):452–464
Mitchell RH, Scott Smith BH, Skinner EMW (2012) Mineralogy of magmaclasts and interclast matrices of Kimberley-type pyroclastic kimberlites from the Kao, Letšeng-la-terae, Lethlakane and premier kimberlite pipes in southern Africa. 10th International Kimberlite Conference, India, poster and extended abstract 10IKC-A-094
Moss S, Webb K, Hetman C, Manyumbu A (2013) Geology of the K1 and K2 kimberlite pipes at Murowa, Zimbabwe. Proceedings of the 10th international kimberlite conference. J Geol Soc India Special Issue 2:35–50
Muntener C, Gaudet M (2018) Geology of the Renard 2 pipe to 1,000 m depth, Renard Mine, Québec, Canada: Insights into Kimberley-type pyroclastic kimberlite emplacement. Miner Petrol, this volume
Muntener C, Scott Smith BH (2013) Economic geology of Renard 3, Quebec, Canada: a diamondiferous, multi-phase pipe infilled with hypabyssal and tuffisitic kimberlite. Proceedings of the 10th International Kimberlite Conference. J Geol Soc India Special Issue 2:241–256
Nixon PH (ed) (1973) Lesotho kimberlites. Lesotho National Development Corporation, Cape and Transvaal Printers, Cape Town, 336 pp
Palmer CE, Ward JD, Stiefenhofer J, Whitelock TK (2008) Volcanological processes and their effect on diamond distribution in the Letšeng satellite pipe, Lesotho. 9th International Kimberlite Conference, Germany, long abstract
Palmer CE, Whitelock TK, Bowen D (2009) A guide to Letšeng diamond mine. Gem Diamonds Limited, 19 pp
Scott Smith BH (1995) Petrology and diamonds. Explor Min Geol 4(2):127–140
Scott Smith BH (2008a) The Fort à la Corne kimberlites, Saskatchewan, Canada: geology, emplacement and economics. J Geol Soc India 91:11–55
Scott Smith BH (2008b) Canadian kimberlites: geological characteristics relevant to emplacement. J Volcan Geotherm Res 174:9–19
Scott Smith BH, Smith SCS (2009) The economic implications of kimberlite emplacement. Proceedings of the 9th International Kimberlite Conference. Lithos 112(S1):10–22
Scott Smith BH, Nowicki TE, Russell JK, Webb KJ, Mitchell RH, Hetman CM, Harder M, Skinner EMW, Robey JV (2013) Kimberlite terminology and classification. Proceedings of the 10th International Kimberlite Conference. J Geol Soc India Special Issue 2:1–17
Scott Smith BH, Nowicki TE, Russell JK, Webb KJ, Mitchell RH, Hetman CM, Robey JV (2018) A glossary of related terms. Scott-Smith Petrology Inc., North Vancouver, Canada, 259 pp
Skinner EMW, Apter DB, Morelli C, Smithson NK (2004) Kimberlites of the Man craton, West Africa. Proceedings of the 8th International Kimberlite Conference. Lithos 76:233–259
Stamm N, Schmidt MW (2017) The petrology and mineralogy of the kimberlite blow in Letšeng-la-Terae: implications for its parental magma composition. 11th International Kimberlite Conference, Botswana, poster and extended abstract 11IKC-4535
Stanley JR, Flowers R, Bell DR (2015) Erosion patterns and mantle sources of topographic change across the southern African plateau derived from shallow and deep records of kimberlites. American Geophysical Union research article. Geochem Geophy Geosy 16:3235–3256
Wood BD, Rameseder B, Scott Smith BH (2013) The Victor Diamond Mine, northern Ontario, Canada: successful mining of a reliable resource. Proceedings of the 10th International Kimberlite Conference. J Geol Soc India Special Issue 2:19–33
The authors would like to thank Letšeng Diamonds (Pty) Ltd. and Gem Diamonds Ltd. for permission to publish the information presented in this paper. Over the past four years multiple site visits were completed and these would not have been possible without the support of the geology department and staff at the Letšeng Mine. We appreciate the comments by Kimberley Webb, reviews by three anonymous experts, and suggestions by guest editor D. Graham Pearson, as they improved this manuscript. Expert drafting by Meilani Smith is much appreciated.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Editorial handling: G. Pearson
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Hetman, C.M., Scott Smith, B., Robey, J. et al. Letšeng diamond mine, Lesotho: a variant of Kimberley-type pyroclastic kimberlite emplacement. Miner Petrol 112, 365–382 (2018). https://doi.org/10.1007/s00710-018-0642-3
- Type IIa diamond
- Tuffisitic kimberlite
- Resedimented volcaniclastic kimberlite
- Kimberley-type pyroclastic kimberlite