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The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcements called the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The SDLRC Blog is a guest commentary by an industry expert about articles, themes and trends in recent issues of the SDLRC.
November 2020
Comments by Brooke Clements
Brooke Clements is President and CEO of Craton Minerals Ltd., a Vancouver-based private diamond exploration company focused on discovering North America's next diamond district. He is also President of JBC Ventures Ltd., a consulting company specializing in mineral exploration and community and government relations. From 2007 to 2015 he was President of Peregrine Diamonds Ltd. where he led the team that discovered the Chidliak diamond district on Baffin Island in the Canadian Arctic. Before that, Brooke was Vice President, Exploration for Ashton Mining of Canada Inc. Under his leadership, Ashton and their partner SOQUEM discovered the Renard diamond district in Quebec where the Renard Diamond Mine commenced production in 2016. From 1982 to 1997, Brooke was an Exploration Geologist and Regional Manager for Exmin Corporation where he conducted diamond exploration programs throughout the United States. He holds a BSc in Geology from Indiana University and an MSc in Economic Geology from the University of Arizona.
Brooke Clements has volunteered to highlight the scientific articles that caught his attention in the monthly reference compilations. The opinions expressed are solely his and he can be reached at .
Canadian Journal of Development Studies: This month Pat dug up three interesting papers in the Canadian Journal of Development Studies related to mining in Africa. Maconachie & Conteh discuss artisanal mining's importance to the Liberian economy and attempt to explain the difficulties in bringing the sector into the formal (taxed) economy. Van Bockstael presents the history of a diamond mining town in Cote d'Ivoire. Hilson summarizes the African Mining Vision, "A Manifesto for More Inclusive Extractive Industry-Led Development".
This is a journal pre-proof of a study of eclogitic diamonds from the Jwaneng mine in Botswana. We have learned a lot of interesting things about diamond ages over the last few years. "Constraining the formation age of individual diamonds from incorporated mineral inclusions and assessing the host diamonds geochemical characteristics allows determination of the complex history of diamond growth in the sub-continental lithospheric mantle (SCLM). It also provides the rare opportunity to study the evolution of the deep cycling of volatiles over time." Sm-Nd isotope systematics were studied for 36 eclogitic garnet and clinopyroxene inclusions from 16
diamonds. They define two diamond ages, Paleoproterozoic (1.8 Ga) and Neoproterozoic (.85 Ga). I find the relatively young diamonds to be fascinating. The authors also state that they have found some evidence for three more poorly constrained diamond ages.
This paper is a comprehensive up to date summary of lamproites and their mineralogy and geochemistry by Roger Mitchell in Geoscience Canada and it is a free download. He states that lamproites are rare and that there are less than 50 true provinces in the world. As only Roger can, he lists criteria for classifying rocks as lamproites with their being two groups, cratonic lamproites and orogenic lamproites. He recommends eliminating the terms Group 2 kimberlites and Orangeite because they are varieties of bona fide lamproites that are restricted to the Kaapvaal craton. He issues the following summary: "As each lamproite province differs with respect to its mineralogy, geochemical evolution, and tectonic setting there is no simple or common petrogenetic model for their genesis. Each province must be considered as the unique expression of the times and vagaries of ancient mantle metasomatism, coupled with diverse and complex partial melting processes, together with mixing of younger asthenospheric and lithospheric material, and, in the case of many orogenic lamproites, with Paleogene to Recent subducted material."
Geologic summaries and maps are presented for six famous lamproite localities: Argyle and Ellendale in Australia, the Prairie Creek group (Arkansas), Finsch Mine (South Africa) and Majhgawan and Saptarshi (India). There are also general descriptions of the Leucite Hills (Wyoming), Kaapvaal lamproites (South Africa) and Tibetan and Indian lamproites. I've always been fascinated with the "youth" of the Leucite Hills cratonic lamproites (3-.89 Ma) and the tectonic and diamond exploration implications.
Dr. Pearson's research team at the University of Alberta found microdiamonds in a 15 kg sample of an Archean conglomerate along the arctic coast in Nunavut. The conglomerate is similar to the Witwatersrand conglomerates in South Africa. The sample was run on a "hunch" at the Saskatchewan Research Council and produced three microdiamonds and it's the only sample processed so far. Dr. Pearson plans to continue his research in the hopes of finding more diamonds and tying down their primary source.
